Abstract:
Embodiments of the invention provide an electric machine module including an electric machine. The electric machine includes a rotor and a stator assembly. The machine includes an output shaft having a longitudinal axis that is circumscribed by a portion of the rotor. The output shaft may comprise an output shaft channel and the rotor may comprise a rotor channel, and the rotor and the output shaft channels may be in fluid communication. The machine further includes a coolant jacket at least partially within a sleeve member that circumscribes at least a portion of the stator assembly, and at least one pump mounted generally concentrically with respect to the output shaft, that is in fluid communication with the coolant jacket. The pump may be internal to the machine, mounted at an interface between the inside and outside of the machine, or alternatively, it may be externally mounted.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 61/525,091 filed on Aug. 18, 2011, the entire contents of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Some electric machines include a stator assembly and a rotor and are housed within a machine cavity. During operation of electric machines, a considerable amount of heat energy can by generated by both the stator and the rotor, as well as other components of the electric machine. As power output from electric machines continues to increase, there is a need to remove heat from the machine to maintain long-life and ensure reliability. Some electric machines are cooled by circulating a coolant through portions of the machine cavity. For example, the coolant can contact the rotor at a generally low tangential speed and then can be accelerated by a combination of friction with the rotor and radial movement further from a center line of rotation of the rotor. Conventional cooling methods can include removing the generated heat energy by circulating a coolant through inner walls of the housing or dispersing a coolant throughout the machine cavity of the housing. 
       SUMMARY 
       [0003]    Some embodiments of the invention provide an electric machine module including an electric machine. The electric machine can include a rotor and an output shaft. The output shaft including a longitudinal axis that can be at least partially circumscribed by the rotor. In some embodiments, the output shaft comprises an output shaft channel that can be coupled to the rotor. In some embodiments, a coolant passage system can be positioned within the rotor and can include an inlet channel in fluid communication with the output shaft channel. In some embodiments, the coolant passage system can include at least one chamber. 
         [0004]    Some embodiments of the invention provide an electric machine module, which can include a housing. In some embodiments, the housing can define at least a portion of a machine cavity. In some embodiments, an electric machine can be positioned within the machine cavity and at least partially enclosed by the housing. In some embodiments, the electric machine can include a rotor that can substantially radially oppose a stator assembly. In some embodiments, the rotor can include a rotor hub, which can include at least an inner diameter. In some embodiments, the rotor hub can also comprise an inlet channel in fluid communication with a coolant inlet, which can be in fluid communication with the machine cavity. The rotor hub can include at least one recess in fluid communication with the inlet channel and an outlet channel. In some embodiments, the outlet channel can be in fluid communication with a coolant outlet, which can be in fluid communication with the machine cavity. In some embodiments, the module can comprise an output shaft that can include a longitudinal axis and to which the rotor hub can be coupled. 
         [0005]    In some embodiments the electric machine can include a coolant jacket substantially circumscribing or at least partially surrounding the stator and containing a coolant. In some embodiments, coolant apertures can fluidly connect the coolant jacket to other components within the housing of the electric machine. Some embodiments comprise a coolant jacket that can be in fluid communication with a coolant source. 
         [0006]    Some embodiments of the invention include at least one pump to aid in coolant influx, efflux, and/or circulation through portions of the electric machine. Some embodiments of the invention utilize multiple pump configurations. The pump can comprise a gerotor-style pump, a gear-type pump, a vane-type pump, or any other conventional pumps. The pump can be generally concentrically positioned with respect to the rotor hub and/or the output shaft, and be positioned substantially within the housing of the electric machine, or immediately outside of the housing, substantially fluidly coupled to at least one component inside the housing. 
         [0007]    In some embodiments, the movement of the electric machine can lead to coolant circulation by the pump. For example, in some embodiments, the pump can be coupled to the rotor hub and/or the output shaft, as the rotor hub, and the movement created by these components can drive operation of the pump. Furthermore, the pump can be fluidly coupled to various elements of the electric machine and can draw some of the coolant from a coolant sump, or external sources, or both. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional view of an electric machine module according to one embodiment of the invention. 
           [0009]      FIG. 2  is a side view of a portion of an electric machine module according to one embodiment of the invention. 
           [0010]      FIG. 3  is a cross-sectional view of the electric machine module of  FIG. 2 . 
           [0011]      FIG. 4  is a side view of a portion of an electric machine module according to one embodiment of the invention. 
           [0012]      FIG. 5  is a cross-sectional view of the electric machine module of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0014]    The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives that fall within the scope of embodiments of the invention. 
         [0015]      FIG. 1  illustrates an electric machine module  10  according to one embodiment of the invention. The electric machine module  10  can include an electric machine  12  and a housing  14 . The electric machine  12  can be disposed within a machine cavity  16  defined at least partially by an inner wall  18  of the housing  14 . The electric machine  12  can include a rotor  20 , a stator  22 , and stator end turns  24 . The electric machine  12  can be disposed about an output shaft  26 . In some embodiments, the electric machine  12  also can include a rotor hub  28  (as shown in  FIG. 1 ), or can have a “hub-less” design (not shown). In some embodiments, the rotor hub  28  can be coupled to the output shaft  26  so that at least a portion of torque generated by the operation of the electric machine  12  can transfer from the rotor hub  28  to the output shaft  26 . In some embodiments, the torque can be transferred to remote locations via the output shaft  26 . 
         [0016]    In some embodiments, the housing  14  can comprise a sleeve member  13 , a first end cap  15 , and a second end cap  17 . For example, the sleeve member  13  and the end caps  15 ,  17  can be coupled via conventional fasteners (not shown), or another suitable coupling method, to enclose at least a portion of the electric machine  12  within the machine cavity  16 . In some embodiments, the housing can comprise a substantially cylindrical canister and a single end cap (not shown). In some embodiments, the housing  14 , including the sleeve member  13  and the end caps  15 ,  17 , can comprise materials that can generally include thermally conductive properties, such as, but not limited to aluminum or other metals and materials capable of generally withstanding operating temperatures of the electric machine while serving as good conductors of thermal energy. In some embodiments, the housing  14  can be fabricated using different methods including casting, molding, extruding, and other similar manufacturing methods. 
         [0017]    The electric machine  12  can be, without limitation, an electric motor, such as a hybrid electric motor, an electric generator, or a vehicle alternator. In one embodiment, the electric machine can be a High Voltage Hairpin (HVH) electric motor for use in a hybrid vehicle. 
         [0018]    The electric machine  12  can include a rotor  20  including a rotor hub  28  a stator assembly  23  including stator end turns  24 , and bearings  27 , that can be disposed about an output shaft  26 . As shown in  FIG. 1 , the stator  22  can substantially circumscribe a portion of the rotor  20 . In some embodiments, the electric machine  12  can also include a rotor hub  28  or can have a “hub-less” design (not shown). During normal operation of the electric machine  12 , the significant heat is generated by one or more components as described, including, but not limited to, the rotor  20 , the stator assembly  23 , and the stator end turns  24 . One or more of these components can be cooled to increase the performance and the lifespan of the electric machine  12 . 
         [0019]    In some embodiments, as shown in  FIG. 1 , the housing  14  can include a coolant jacket  30 . The coolant jacket  30  can substantially circumscribe or at least partially surround the stator  22  and can be configured and arranged to contain a coolant. The coolant can be ethylene glycol, propylene glycol, water, a mixture of water and either ethylene glycol or propylene glycol, different oils, including motor oil, transmission oil, or any other similar substance. In some embodiments, coolant apertures (not shown) can fluidly connect the coolant jacket  30  with the machine cavity  16  so that a portion of the coolant circulating through the coolant jacket  30  can disperse into the machine cavity  16 . Also, in some embodiments, the coolant jacket  30  can be in fluid communication with a coolant source (not shown) which can pressurize the coolant prior to or as it is being dispersed into the coolant jacket  30 , so that the pressurized first coolant can circulate through the coolant jacket  30  and some of the coolant can exit the coolant jacket  30  through the coolant apertures. In some embodiments, the coolant apertures can be positioned substantially radially outward from the stator end turns  24  so that some of the coolant exiting the coolant apertures can be directed toward the stator end turns  24 . 
         [0020]    In some embodiments, a second portion of the coolant can originate from a substantially radially inward position of the module  10 . In some embodiments, the output shaft  26  can include an output shaft coolant channel (not shown) and the rotor hub  28  can include a rotor hub coolant channel (not shown) in fluid communication with the machine cavity  16 . In some embodiments, the rotor hub coolant channel can be in fluid communication with the output shaft coolant channel. For example, in some embodiments, the second portion of the coolant can circulate through the output shaft coolant channel, flow through the rotor hub coolant channel, and then can disperse into the machine cavity  16  where it can contact some of the elements of the module  10  to aid in cooling. Furthermore, any coolant exiting any one or more rotor hub coolant channels or any one or more output shaft coolant channels may, following travel within the machine cavity  16 , enter the coolant jacket  30  through any one or more coolant apertures. Conversely in some embodiments, any coolant exiting the coolant jacket  30  through any one or more coolant apertures can travel within the machine cavity  16  and subsequently enter one or more rotor hub coolant channels or any one or more output shaft coolant channels. Moreover, in some embodiments, as the coolant circulates, it can receive at least a portion of the heat energy produced by any other portions of the rotor  20 . For example, in some embodiments, the output shaft  26  can include at least one output shaft channel and at least one output shaft coolant outlet so that the coolant can flow through the channel and at least a portion of the coolant can exit the output shaft channel. In some embodiments, the output shaft coolant outlet can comprise a plurality of output shaft coolant outlets (not shown). Furthermore, in some embodiments, more than one output shaft coolant outlet can be included. Also, in some embodiments, output shaft coolant outlets can be positioned along the axial length of the output shaft  26  so that the coolant can be dispersed to different areas of the module  10  and machine cavity  16 , including the bearings  27 . In some embodiments, the output shaft coolant channels can comprise both axially oriented and radially oriented sections, (not shown), so that the module  10  can function without the output shaft coolant outlet. Moreover, in some embodiments, some modules  10  can be configured and arranged with outlets in different locations so that coolant flow rates can be varied. 
         [0021]    According to some embodiments of the invention, the module  10  can comprise at least one pump  34  to aid in coolant influx, efflux, and/or circulation through portions of the module  10 . In some embodiments, the pump  34  can comprise a gerotor-style pump, a gear-type pump, a vane-type pump, or other any other conventional pumps. According to some embodiments of the invention, the pump  34  can employ the motive energy transferred by the rotor hub  28  and/or the output shaft  26  to aid in circulating the coolant. For example, in some embodiments, the pump  34  can comprise a positive displacement type pump, such as a gerotor-style pump, as shown in  FIG. 2 , although as previously mentioned, in other embodiments, the pump  34  can comprise other types of pumps. In some embodiments the pump  34  can be generally concentrically positioned with respect to the rotor hub  28  and/or the output shaft  26 . For example, in some embodiments, the pump  34  and the rotor hub  28  and/or the output shaft  26  can be coupled together so that movement of the rotor hub  28  and/or output shaft  26  can at least partially supply any movement necessary to operate the pump  34 . 
         [0022]    In some embodiments that comprise a gerotor-style pump, the pump can comprise an inner rotor  38  that may generally comprise a trochoidal inner rotor with external teeth, and an outer rotor  40  formed with intersecting circular arcs with teeth meshing with the external teeth of the inner rotor  38 . As shown in  FIG. 2 , the inner rotor  38  has 5 ‘teeth’ and the outer rotor  40  has 6 ‘teeth’. In alternative embodiments of the invention, the number of inner rotor  38  teeth, and outer rotor  40  teeth, may be smaller or larger. In some embodiments, the relationship between the inner rotor teeth and outer rotor follows a rule in which the inner rotor has N teeth, the outer rotor has N+1 teeth. 
         [0023]    In some embodiments, the inner rotor  38  can be coupled to the rotor hub  28  and/or the output shaft  26 , and the outer rotor  40  can be coupled to at least one the end caps  15 ,  17  (i.e., either the inner wall  18  or the outer wall  32 ) or other locations proximal to the module  10 , as previously mentioned. For example, in some embodiments, the inner rotor  38  can be coupled to elements of the module  10  so that the inner rotor  38  is generally concentric with the rotor hub  28  and/or the output shaft  26 , and the outer rotor  40  is generally concentric with the inner rotor  38  (e.g., the outer rotor  40  is generally radially outward relative to at least a portion of the inner rotor  38 ). In some embodiments, the rotor hub  28  and/or output shaft  26  can move during operation of the electric machine  12 , which can lead to movement of the inner rotor  38 , and the interaction of the inner rotor  38  and the outer rotor  40  can create both a suction force and a pressure force in the pump  34 , which can be transferred to at least a portion of the coolant in contact or adjacent to the pump  34 . As a result, in some embodiments, the pump  34  can aid in circulation of the coolant through the module  10 . 
         [0024]    In some embodiments of the invention, the module  10  can employ multiple pump configurations. In some embodiments, pumps  34  of more than one style can be employed to enhance coolant circulation (e.g. two different styles of pump in one end cap or two different styles of pump in each of the end caps  15 ,  17 ). For example, in some embodiments, a first pump  34  can be coupled to either or both of the end caps  15 ,  17  and can be configured to circulate oil from a remote location to the coolant jacket  30  and/or the output shaft and rotor hub coolant channels (not shown). Further, in some embodiments, a second pump  34  can be coupled to either the same end cap  15 ,  17  as the first pump, or can be coupled to the other end cap  15 ,  17 . In some embodiments, the second pump can be configured to transport a portion of the coolant to a remote location, after the coolant flows through portions of the module  10 . For example, in some embodiments, the first pump can draw the coolant from a remote location, which can lead to a portion of the coolant dispersing into the machine cavity  16  to aid in cooling the machine  12 . Then, in some embodiments, after the coolant flows toward the bottom of the housing  14 , the second pump can direct the coolant either back to the same remote location or a different location. Moreover, either the first pump and/or the second pump can circulate a portion of the coolant through the module  10  more than one time before circulating it out of the module  10 . 
         [0025]    Moreover, in some embodiments, the pump  34  can at least partially drive coolant flow when the electric machine  12  is substantially not in operation. In some embodiments, for a period of time after the electric machine  12  substantially ceases operating, cooling can continue to be beneficial for the module  10 . In some embodiments, an accumulator (not shown) can be coupled to the module  10 , the fluid circulatory system, and/or the pump  34 . In some embodiments, the accumulator can comprise a reservoir including a spring diaphragm, an air diaphragm, or another similar diaphragm-like or reservoir structure. In some embodiments, the accumulator can fluidly connect to the pump  34  via the fluid circulatory system (for example as shown in  FIG. 4  and  FIG. 5  as  400 ,  415 ,  420 , and  425 ), so that at least a portion of the coolant that the pump  34  circulates flows into the accumulator. For example, in some embodiments, the pump can circulate the coolant so that the coolant entering the accumulator can compress the diaphragm-like structure. As a result, when the diaphragm-like structure is not under pressure created by the pump  34  (e.g., when the module  10  is not in operation), the accumulator can direct at least a portion of the coolant to circulate through the coolant jacket  30 , the output shaft coolant channel, and/or the rotor hub coolant channel, which can lead to further cooling although the pump  34  is substantially not in operation. 
         [0026]    In some embodiments, the pump  34  can be coupled to and/or positioned within either one of or both of the end caps  15 ,  17 . In some embodiments, the pump  34  can be generally positioned along the inner wall  18  of the end caps  15 ,  17 , and in some other embodiments, the pump  34  can be positioned elsewhere in the machine cavity  16 . In some embodiments, the pump  34  can be positioned substantially outside of the machine cavity  16 , as shown in  FIGS. 2 and 3 . For example, in some embodiments, the pump  34  can be coupled to an outside wall  32  of the end caps  15 ,  17 , or other portions of the housing  14 . For example, in some embodiments, the pump  34  can be coupled to the outside wall  32  substantially within a sealed structure  36 . As shown in  FIG. 3 , in some embodiments, at least one of the end caps  15 ,  17  can comprise the sealed structure  36  as a substantially integral element (e.g., at least one of the end caps  15 ,  17  is formed with the sealed structure  36 ) or an element coupled to at least one of the end caps  15 ,  17  (e.g., the sealed structure  36  is coupled to at least one of the end caps  15 ,  17  via any conventional coupling methods so that the sealed structure  36  is substantially impermeable to any coolant flowing out of the machine cavity  16 ). 
         [0027]    As shown in  FIG. 4  and  FIG. 5 , in some embodiments of the invention, the coolant can flow through a substantially sealed system. In some further embodiments, the sealed structure  36  can be in fluid communication with the machine cavity  16  and a fluid circulatory system (shown in  FIG. 4  and  FIG. 5  as  400 ,  415 ,  420  and  425 ), so that the pump  34  can aid in circulating the coolant. For example, in some embodiments, the fluid circulatory system can include a sump  400 , a coolant scavenge line  420  via a first end of the scavenge line  415 , at least partially submerged in a coolant  410 , and coolant delivery lines  425  designed to deliver high pressure coolant to at least one component in the machine cavity  16 . 
         [0028]    Further, in some embodiments, the coolant passage system  425  and  420  can comprise other configurations. As shown in  FIG. 4  and  FIG. 5 , in some embodiments, the coolant passage system can function without at least some of the output shaft coolant channels and rotor coolant outlets. For example, in some embodiments, the coolant passage system can comprise an inlet coolant scavenge line  420  with a first end of the scavenge line  415  fluidly coupled with a coolant sump. In some embodiments, the inlet coolant scavenge line  420  can fluidly connect the machine cavity  16  via the pump  34  and with at least some of the pressurized coolant lines  425 . Moreover, in some embodiments, multiple inlet coolant scavenge lines  420  can fluidly connect multiple inlet channels  425  to the machine cavity  16  via the pump  34 . In some embodiments, the multiple inlet channels  425  can be configured to receive coolant from the machine cavity  16  so that the coolant can enter an output line (not shown), and then flow through coolant sump  400 , and the inlet coolant scavenge line  420 , and then re-enter the machine cavity  16  via the pump  34 , and pressurized coolant lines  425 . 
         [0029]    In some embodiments, the pump  34  can fluidly couple, via the fluid circulatory system, to the coolant jacket  30 , the output shaft coolant channel, the rotor hub coolant channel, and a coolant sump  400  positioned substantially at or near a bottom of the housing  14 , and/or locations remote to the module  10 . For example, in some embodiments, because the pump  34  can be coupled to the rotor hub  28  and/or the output shaft  26 , as the rotor hub  28  and the output shaft  26  move during operation, the movement created by the electric machine  12  can drive operation of the pump  34 . As a result, the pump  34 , fluidly coupled to various elements of the module  10  via the fluid circulatory system, can aid in circulating at least a portion of the coolant through the coolant jacket  30  and/or through the output shaft and rotor hub coolant channels. Moreover, in some embodiments, the pump  34  can draw some of the coolant from the coolant sump  400  and circulate it through the coolant jacket  30 , and the other coolant channels. Also, in some embodiments, the pump  34  can draw coolant from sources external to the module  10 , in addition to, or in place of drawing coolant from the coolant sump  400 . 
         [0030]    Additionally, in some embodiments, the pump  34  also can scavenge a portion of the coolant after it enters the machine cavity  16 . For example, in some embodiments, after the coolant enters the machine cavity  16  and flows over a portion of the module  10  elements, a portion of the coolant can either enter the fluid circulatory system through at least one drain (not shown) positioned near the bottom of the housing  14 , or can enter the coolant sump at or near the bottom of the housing  14 . In some embodiments, the pump  34  (e.g. via pump  34  operations driven by machine  12  operations) can circulate a portion of the coolant from the drain and/or the coolant sump  400 , to either the coolant jacket  30 , and/or the output shaft and rotor hub coolant channels (not shown). In some embodiments, the pump  34  can also circulate a portion of the coolant from the drain and/or the coolant sump, to a heat-exchange element (not shown), and some of the heat energy transferred to the coolant from the module  10  can be removed, and the coolant can be recirculated. 
         [0031]    In some embodiments, the pump  34  can fluidly connect, via the fluid circulatory system to the coolant jacket  30 , and function without the presence of an output shaft coolant channel, a rotor hub coolant channel, or both. For example, in some embodiments, because the pump  34  can be coupled to the rotor hub  28  and/or the output shaft  26 , as the rotor hub  28  and the output shaft  26  move during operation, the movement created by the electric machine  12  can drive operation of the pump  34 . As a result, the pump  34 , fluidly coupled to various elements of the module  10  via the fluid circulatory system, can aid in circulating at least a portion of the coolant through the coolant jacket  30 . For example, in some embodiments, coolant fluid from the coolant sump  400 , the pump  34  (e.g. via pump  34  operations driven by machine  12  operations), can circulate a portion of the coolant to the coolant jacket  30 . During this operation, coolant fluid moves into the machine cavity and can absorb thermal energy from at least one component in the machine cavity, including, but not limited to the rotor hub  28 , the stator and the stator end turns. As a result, in general, coolant fluid initially entering the machine cavity via the pump  34  will be at a lower temperature upon first entering the machine cavity  16 , than when it enters the coolant jacket  30 . In some embodiments, the pump  34  also can circulate a portion of the coolant from the drain and/or the coolant sump to a remote location, where some of the coolant can enter a heat-exchange element (not shown), and some of the heat energy transferred to the coolant from the module  10  can be removed, and the coolant can be recirculated. Moreover, in some embodiments, the pump  34  can draw some of the coolant from the coolant sump  400  and circulate it through the coolant jacket  30 . Also, in some embodiments, the pump  34  can draw coolant from sources external to the module  10 , in addition to, or in place of drawing coolant from the coolant sump  400 . 
         [0032]    In some embodiments, some of the previously mentioned pump configurations can be beneficial relative to configurations using a generally external pump configuration. In some embodiments, because external pumps may not be required and coolant can be pumped and/or scavenged by the pumps  34 , the general size of the module  10  can be reduced as can the cost of production. In some embodiments, the space into which the module  10  can be installed in downstream applications can be reduced because no external pumps are needed to accompany the module  10 . 
         [0033]    It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein