Electric machine cooling system and method

Embodiments of the invention provide an electric machine module including a module housing, which can at least partially define a machine cavity. In some embodiments, an electric machine can include a stator assembly and a rotor assembly and can be positioned in the machine cavity. In some embodiments, the module housing can include a coolant transport network, which can include at least one passage in fluid communication with at least one first annulus and at least one second annulus. In some embodiments, the first annulus can be substantially axially adjacent to an axial end of the stator assembly and the second annulus can be substantially axially adjacent to an axial end of the rotor assembly. In some embodiments, the annuli can include a plurality of annulus apertures.

BACKGROUND

Some methods for cooling an electric machine can include passing a coolant around an outer perimeter of the electric machine inside of a cooling jacket. The coolant extracts at least a portion of the heat produced by a stator, which can lead to cooling of the electric machine. For some machines, cooling can be further improved by spraying coolant from the cooling jacket directly onto end turns of the stator, which can cool the end turns. However, the coolant temperature increases as the coolant flows in a circumferential direction around the cooling jacket. As a result, the coolant is at an elevated temperature when it is sprayed onto the end turns of the stator, which can reduce the level of heat extracted from the end turns.

SUMMARY

Some embodiments of the invention provide an electric machine module including a module housing, which can at least partially define a machine cavity. In some embodiments, an electric machine can include a stator assembly and a rotor assembly and can be positioned in the machine cavity. In some embodiments, the module housing can include a coolant transport network, which can include at least one passage in fluid communication with at least one first annulus and at least one second annulus. In some embodiments, the first annulus can be located substantially axially adjacent to an axial end of the stator assembly and the second annulus can be substantially axially adjacent to an axial end of the rotor assembly. In some embodiments, one or more of the annuli can include a plurality of apertures.

Some embodiments of the invention can include an electric machine module including a module housing. In some embodiments, the module housing can include a first housing member coupled to a second housing. Also, in some embodiments, the first housing member and the second housing member can each include an annular region and an end region. In some embodiments, the module housing can include at least one coolant inlet positioned through a portion of the module housing. In some embodiments, a coolant transport network can be positioned within portions of the module housing and can be in fluid communication with the at least one coolant inlet. In some embodiments, the coolant transport network can include at least one passage positioned through a portion of each of the housing members and in fluid communication with the coolant inlet. Also, in some embodiments, the end regions of the housing members can include at least one first annulus and at least one second annulus extending axially inward from the end regions and in fluid communication with the passages.

DETAILED DESCRIPTION

FIG. 1illustrates an electric machine module10according to one embodiment of the invention. The module10can include a module housing12comprising a sleeve member14, a first end cap16, and a second end cap18. An electric machine20can be housed within a machine cavity22at least partially defined by the sleeve member14and the end caps16,18. For example, the sleeve member14and the end caps16,18can be coupled via conventional fasteners (not shown), or another suitable coupling method, to enclose at least a portion of the electric machine20within the machine cavity22. In some embodiments, the sleeve member14can be formed so that at least one of the end caps14,16is substantially integral with the sleeve member14. In some embodiments the housing12can comprise a substantially cylindrical canister and a single end cap (not shown). Further, in some embodiments, the module housing12, including the sleeve member14and the end caps16,18, can be fabricated from 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. In some embodiments, the housing12can be fabricated using different methods including casting, molding, extruding, and other similar manufacturing methods.

The electric machine20can be, without limitation, an electric motor, such as a hybrid electric motor, an electric generator, or a vehicle alternator. In one embodiment, the electric machine20can be a High Voltage Hairpin (HVH) electric motor or an interior permanent magnet electric motor for hybrid vehicle applications.

The electric machine20can include a rotor assembly24, a stator assembly26, including stator end turns28, and bearings30, and can be disposed about an output shaft34. As shown inFIG. 1, the stator26can substantially circumscribe a portion of the rotor24. In some embodiments, the rotor assembly24can also include a rotor hub33, or can have a “hub-less” design (as shown inFIGS. 6-9).

Components of the electric machine20such as, but not limited to, the rotor assembly24, the stator assembly26, and the stator end turns28can generate heat during operation of the electric machine20. These components can be cooled to increase the performance and the lifespan of the electric machine20.

Referring toFIGS. 2-9, in some embodiments, the module housing12can comprise different configurations. In some embodiments, the module housing12can comprise at least two housing members coupled together. More specifically, in some embodiments, the module housing12can include a first housing member34coupled to a second housing member36. In some embodiments, each of the housing members34,36can comprise a substantially cylindrical canister shape, including an end region38and an annular region40. In some embodiments, the annular region40aof the first housing member34can include a smaller outer diameter relative to an inner diameter of the annular region40bof the second housing member36. As a result, in some embodiments, at least a portion of the module housing12can be fabricated by positioning at least a portion of the annular region40aof the first housing member34within the annular region40bof the second housing member36. For example, as shown inFIGS. 2-3, in some embodiments, the outer diameter of the annular region40aof the first housing member34can be positioned so that it is immediately adjacent to the inner diameter of the annular region40bof the second housing member36. Moreover, in some embodiments, after positioning the housing member34,36with respect to each other, the module housing12can be further coupled using conventional fasteners, adhesives, welding, braising, or other methods of coupling.

In some embodiments, the module housing12can comprise at least one coolant jacket42. As shown inFIG. 1, in some embodiments, the sleeve member14can comprise the coolant jacket42. As shown inFIGS. 6-9, in some embodiments, at least a portion of the coolant jacket42can be substantially formed between portions of the annular regions40a,40b(i.e., between portions of the outer diameter of annular region40aand the inner diameter of annular region40b). In some embodiments, the coolant jacket42can substantially circumscribe at least a portion of the electric machine20. More specifically, in some embodiments, the coolant jacket42can substantially circumscribe at least a portion of an outer diameter of the stator assembly26, including the stator end turns28. Further, in some embodiments, the coolant jacket42can contain a coolant that can comprise transmission fluid, ethylene glycol, an ethylene glycol/water mixture, water, oil, motor oil, a gas, a mist, any combination thereof, or a similar substance.

In some embodiments, the module housing12can comprise at least one coolant inlet44, although in other embodiments, the module housing12can comprise a plurality of coolant inlets44. For example, in some embodiments, the coolant jacket42can be in fluid communication with a coolant source (not shown) via the coolant inlets44, which can pressurize the coolant prior to or as it is being dispersed into the coolant jacket42, so that the pressurized coolant can circulate through the coolant jacket42. In some embodiments, the coolant inlets44can be positioned through a portion of the module housing12(i.e., the sleeve member14and/or the end caps16,18or the first and/or second housing members34,36) in a generally lower region (i.e., relative to the output shaft32) of the module housing12, and can be in fluid communication with at least both of the coolant jacket42and the coolant source. For example, in some embodiments, the coolant inlets44can be positioned at a generally lowermost position (i.e., a 6 o'clock position) with respect to the output shaft32. In other embodiments, the coolant inlets44can be positioned in other locations through portions of the module housing12. Moreover, in some embodiments, the module housing12can comprise a plurality of coolant inlets44positioned at regular or irregular intervals around portions of a perimeter of the module housing12.

Also, in some embodiments, the module housing12can include a plurality of coolant jacket apertures46so that the coolant jacket42can be in fluid communication with the machine cavity22. In some embodiments, the coolant apertures46can be positioned substantially adjacent to the stator end turns28. More specifically, in some embodiments, the coolant jacket apertures46can be positioned through portions of an inner wall48of the sleeve member14. In other embodiments, the coolant jacket apertures46can be positioned through portions of the annular region40aof the first housing member34. Further, in some embodiments, the coolant jacket apertures46can be positioned through a generally upper portion of the module housing12(i.e., relative to the output shaft32), although in other embodiments, the coolant jacket apertures46can be positioned at regular or irregular intervals through portions of the module housing12(i.e., the inner wall48or the annular regions40aand/or40b) or can be positioned in a generally lower portion of the module housing12.

In some embodiments, as the pressurized coolant circulates through the coolant jacket42, at least a portion of the coolant can exit the coolant jacket42through the coolant jacket apertures46and enter the machine cavity22. Also, in some embodiments, the coolant can contact the stator end turns28, which can lead to at least partial cooling of the stator assembly26. After exiting the coolant jacket apertures46, at least a portion of the coolant can flow through portions of the machine cavity22and can contact some module10elements, which, in some embodiments, can lead to at least partial cooling of the module10. Further, in some embodiments, some portions of the coolant can circulate through the coolant jacket42and can receive a portion of the heat energy produced during electric machine20operations.

In some embodiments, the module housing12can comprise a coolant transport network50. In some embodiments, the coolant transport network50can comprise a single passage52. In some embodiments, the coolant transport network50can include a plurality of passages52positioned within the module housing12. For example, in some embodiments, as shown inFIGS. 2-9, the end regions38aand38bof each of the housing members34,36can each include passages52. Although, in other embodiments, the sleeve member14and/or the end caps16,18can comprise passages (not shown). Further, in some embodiments, at least one passage52can be positioned through a portion of the annular region40bof the second housing member36and/or the annular region40aof the first housing member34. Moreover, in some embodiments, at least a portion of the passages52can be in fluid communication with at least one coolant inlet44so that the coolant can be introduced from the coolant source and pass into the coolant transport network50and the passages52. For example, in some embodiments, as shown inFIG. 6-9, passages52in the first housing member34and the second housing member36can be in fluid communication with multiple coolant inlets44.

In some embodiments, the coolant transport network50can comprise at least one plug53. More specifically, in some embodiments, at least one plug53can be positioned within at least one passage52to prevent material amounts of coolant from flowing through the passage52. For example, as shown inFIGS. 8-9, the plug53can be positioned in a passage52so that the passages52positioned in the first housing member34can be substantially sealed from the passages52positioned in the second housing member36. As a result, at least a portion of the coolant circulating through the passages52of the first housing member36originates from a coolant inlet44coupled to the first housing member34. In some embodiments, one or more plugs53can be positioned in the passages52to create a desired coolant flow route to meet user requirements.

In some embodiments, the coolant transport network50can further comprise a first annulus54and a second annulus56. In some embodiments, each of the end regions38a,38bof each of the housing members34,36can comprise both a first annulus54and a second annulus56. In other embodiments, either end region38a,38bcan include one of, both of, or neither of a first annulus54and/or a second annulus56. More specifically, in some embodiments, the annuli54,56can axially extend inward from the end regions38a,38b. For example, in some embodiments, the housing members34,46can be formed so that the annuli54,56are integral with the end regions38a,38b. In other embodiments, the annuli54,56can be coupled to the end regions38a,38busing conventional coupling techniques (i.e., welding, braising, fasteners, adhesives, etc.). Further, in some embodiments, the end caps16,18and/or the sleeve member14can comprise one of, both of, or neither of a first annulus54and/or a second annulus56. In some embodiments, the first annulus54and the second annulus56can be generally concentric, as shown inFIGS. 2-9. In some embodiments, the first annulus54can comprise a generally larger diameter, and in other embodiments, the second annulus56can comprise a generally larger diameter (i.e., either the first annulus54or the second annulus56can be positioned at a more radially outward position). Although in some embodiments the annuli54,56can comprise a generally circular and/or hemispherical shape, the annuli54,56can comprise other shapes including, but not limited to, elliptical, square, rectangular, regular or irregular polygonal, or any combination thereof.

By way of example only, in some embodiments, the first annulus54can be positioned substantially axially adjacent to at least one axial side of the stator assembly26. In some embodiments, each housing member34,36can each comprise at least one first annulus54, and, as a result, the first annuli54can be positioned substantially axially adjacent to both axial sides of the stator assembly26. Further, in some embodiments, the second annulus56can be positioned substantially axially adjacent to at least one axial side of the rotor assembly24. In some embodiments, each housing member34,36can each comprise at least one second annulus56, and, as a result, the second annuli56can be positioned substantially axially adjacent to both axial sides of the rotor assembly24and radially inward from the stator assembly26. In other embodiments, the relative positions of the annuli54,56can be substantially reversed (i.e., the first annulus54can be positioned substantially axially adjacent to the rotor assembly24and the second annulus56can be positioned substantially axially adjacent to the stator end turns28).

As shown inFIGS. 6-9, in some embodiments, the first annulus54and/or the second annulus56can be in fluid communication with the passages52. In some embodiments, the first annulus54and/or the second annulus56can extend axially inward from the end regions38a,38b, as shown inFIGS. 6-9. In some embodiments, the annuli54,56can extend different distances from the end regions38a,38b(i.e., the first annulus54can extend a lesser axial distance from the passages52relative to the second annulus56or vice versa).

Further, in some embodiments, the first annulus54and/or the second annulus56can comprise a plurality of annulus apertures58. More specifically, in some embodiments, the annulus apertures58can be positioned through a portion of the first annulus54and/or the second annulus56so that the annuli54,56can be in fluid communication with the machine cavity22. In some embodiments, the annulus apertures58can comprise a nozzle, an orifice, or other structure capable of guiding, directing, and/or urging coolant toward some elements of the module10.

In some embodiments, the coolant can circulate from the coolant inlets44through the passages52and portions of the coolant can pass through the annuli54,56and can efflux from at least some of the annulus apertures58toward some of the module10elements. In some embodiments, at least a portion of the annulus apertures58can be configured to direct the coolant in a generally radial direction, a generally axial direction, or a combination thereof. By way of example only, in some embodiments, the annulus apertures58of the first and the second annuli54,56can be configured to direct coolant in a generally axially inward direction. As a result, in some embodiments, coolant can be directed toward both the rotor assembly24and the stator assembly26.

Further, in some embodiments, the annulus apertures58can be differently configured. For example, in some embodiments, the annulus apertures58of the second annulus56can be configured to direct coolant in a generally radially outward direction and the annulus apertures58of the first annulus54can be configured to direct coolant in a generally axially direction. As a result, in some embodiments, at least a portion of the coolant exiting at least some of the annulus apertures58of both annuli54,56can be directed toward the stator assembly26. The annulus apertures58can comprise other configurations capable of directing portions of the coolant in other directions to meet user requirements.

In some embodiments, allowing the coolant spray to impact the stator assembly26both axially and radially can effectively “flood” portions of the stator assembly26, including portions of the stator end turns28, thereby increasing the amount of coolant in contact with the stator end turns28, which can increase cooling of the stator assembly26and the electric machine20. Further, in some embodiments, by allowing portions of the coolant to impact the rotor assembly24, the coolant can receive at least a portion of the heat energy produced by the rotor assembly24and its components (i.e., magnets), which can further enhance electric machine20cooling.

In some embodiments, the coolant transport network50can enhance cooling relative to some electric machine modules comprising a coolant jacket alone. As shown inFIGS. 6-9, the coolant transport network50and the cooling jacket42can be in fluid communication with each other and can each receive coolant from the fluid source via at least some of the coolant inlets44(i.e., the coolant transport network50is not receiving the coolant directly from the cooling jacket42, where such coolant can be at a higher temperature due to already receiving heat energy from the stator assembly26). As a result, the temperature of the coolant passing through portions of the passages52and the annuli54,56can be at a lower temperature prior to being placed into contact with the elements of the module10, and, as a result can at least partially increase the amount of heat energy removed from the module10. In some embodiments, the coolant transport network50can receive at least a portion of the coolant directly from the cooling jacket42.

In some embodiments, at least a portion of the coolant sprayed into the machine cavity22can eventually flow towards a drain (not shown) in the electric machine module10due to gravity. The coolant at the drain can be circulated back to the fluid source (e.g., by a pump), re-cooled (either at the fluid source or at another location), and re-circulated back to the module10.