Patent Publication Number: US-11025135-B2

Title: Electrical machine with liquid cooling

Description:
TECHNICAL FIELD 
     The present application relates generally to electrical machines and more particularly, but not exclusively, to electrical machines with liquid cooling. 
     BACKGROUND 
     Electrical machines remain an area of interest. Some existing systems have various shortcomings, drawbacks and disadvantages relative to certain applications. For example, in some electrical machine configurations, power density may be increased by providing cooling. Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY 
     One embodiment of the present invention is a unique electrical machine. Another embodiment is another unique electrical machine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for electrical machines. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  schematically illustrates some aspects of a non-limiting example of an electrical machine in accordance with an embodiment of the present invention. 
         FIG. 2  schematically illustrates a cross-sectional view of some aspects of a non-limiting example of a rotor and a stator of an electrical machine in accordance with an embodiment of the present invention. 
         FIG. 3  schematically illustrates a cross-sectional view of some aspects of a non-limiting example of a rotor and a stator of an electrical machine in accordance with an embodiment of the present invention. 
         FIG. 4  schematically illustrates some aspects of a non-limiting example of an electrical machine in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     Referring to  FIG. 1 , some aspects of a non-limiting example of an electrical machine  10  in accordance with an embodiment of the present invention are schematically depicted. In one form, electrical machine  10  is an internal permanent magnet (IPM) motor employing rare earth magnets. In other embodiments, electrical machine  10  may be an external permanent magnet motor. In still other embodiments, electrical machine  10  may be an induction motor, a switched reluctance, synchronous reluctance, or permanent magnet assisted reluctance motor, a permanent magnet motor, or any other type of motor, generator or motor/generator. In various embodiments, electrical machine  10  may be a radial flux machine, an axial flux machine or a machine having a three-dimensional (3D) flux path. In one form, electrical machine  10  is an industrial electrical machine, e.g., an industrial motor. In other embodiments, electrical machine  10  may not be an industrial electrical machine. 
     Electrical machine  10  includes a shaft  12 , a rotor  14  having permanent magnets (poles)  16 , a stator  18  having a plurality of stator windings  20 , a housing  22  and bearings  24 . Shaft  12  and rotor  14  rotate about an axis of rotation  26 , which defines an axial direction  28 . In one form, shaft  12  is coupled or affixed to rotor  14 . In other embodiments, shaft  12  may be integral with rotor  14 . Shaft  12  rotates with rotor  14 , and may be considered a part of rotor  14 . 
     Shaft  12  is constructed to support rotor  14  and react radial and axial or thrust loads from rotor  14 . In one form, shaft  12  is operative to transmit mechanical power from electrical machine  10  as an output of electrical machine  10 . In other embodiments, shaft  12  may be operative to transmit mechanical power to and/or from electrical machine  10 . Shaft  12  is axially and radially positioned by bearings  24 . Shaft  12  and bearings  24  define axis of rotation  26  and corresponding axial direction  28 . 
     Rotor  14  and stator  18  are in magnetic communication with each other. Rotor  14  is in magnetic cooperation with stator  18  to develop torque. Each of rotor  14 /poles  16  and stator  18  have a construction that is operative to direct magnetic flux toward and away from each other. In some embodiments, rotor  14  may include other operative sources of magnetic flux, e.g., bus bars, windings or both, in conjunction with or in place of permanent magnets  16 . 
     Stator  18  includes a laminated stator core  30 . Stator windings  20  are disposed within passages  32  in laminated stator core  30 . In one form, stator windings  20  are copper conductors. In other embodiments, aluminum and/or other conductor materials may be employed in addition to or in place of copper. Stator windings  20  are constructed for magnetic communication and cooperation with poles  16 . Stator windings  20  have overhangs  34  that extend beyond the ends of stator core  30 , e.g., extend to the left and to the right of stator core  30  (in the perspective of the view of  FIG. 4 ). 
     Housing  22  includes an endplate  36  disposed at one end of housing  22  and a second endplate  38  disposed at the other end of housing  22 . In one form, endplate  36  is a non-drive end endplate, and endplate  38  is a drive-end endplate, or pulley endplate. In other embodiments, endplate  36  may be the drive-end endplate, and endplate  38  may be the non-drive end endplate. One or both of endplates  36  and  38  may be integral with housing  22 . In some embodiments, housing  22  also includes a conduit box  40 , which may or may not be integral, depending upon the embodiment. Other embodiments may not include a conduit box. 
     Bearings  24  are constructed to react shaft  12  and rotor  14  axial or thrust loads in axial direction  28 , and to react shaft  12  and rotor  14  radial loads perpendicular to axis of rotation  26 . Housing  22  is constructed to enclose stator  18  and react loads associated with stator  18 , e.g., torque loads and any other loads generated due to magnetic interaction between stator  18  and rotor  14  during the operation of electrical machine  10 . Housing  22  is also constructed to react thrust loads delivered through bearings  24 . 
     In order to increase the power density of electrical machine  10 , it is desirable to provide cooling, e.g., liquid cooling. Accordingly, embodiments of electrical machine  10  include provisions for providing liquid cooling of rotor  14  and/or of stator  18 , e.g., of the stator windings  20 , in particular, the winding overhangs  34 . For example, rotor  14  includes a plurality of cooling passages  42  extending therethrough from one end  44  of rotor  14  to the other end  46  of rotor  14 . In one form, the cooling passages  42  are oil-cooling passages for passing oil to remove heat from rotor  14 . In other embodiments, other liquids or fluids may be used as heat transfer fluids. Each cooling passage  42  includes an inlet  48  for receiving cooling oil and an outlet  50  for discharging the oil. 
     Referring also to  FIG. 2 , non-limiting examples of cooling passages  42  for an IPM rotor  14  are illustrated. In the example of  FIG. 2 , air pockets between permanent magnets  16  are used as cooling passages  42 . The shape of cooling passages  42  may vary with the needs of the application. In other embodiments, cooling passages  42  may also or alternatively be formed at other locations. For instance, in another non-limiting example, cooling passages may be formed in air pockets adjacent to permanent magnets  16  in the same cavities in which the permanent magnets  16  are located, such as cooling passages  42 A. The shape of cooling passages  42 A may vary with the needs of the application. For surface-mounted permanent magnet rotors, cooling passages  42  may be disposed between and/or radially inward of the permanent magnets. 
     Referring also to  FIG. 3 , non-limiting examples of cooling passages  42  for an induction rotor  14  are illustrated. In the example of  FIG. 3 , cooling passages  42  are formed radially inward of induction rotor windings or bars  52 . In other embodiments, cooling passages  42  may also or alternatively be formed at other locations. For instance, in another non-limiting example, cooling passages may be formed in air pockets adjacent to rotor windings or bars  52  in the same cavities in which the rotor windings or bars  52  are disposed, such as cooling passages  42 B. The shape of cooling passages  42 B may vary with the needs of the application. 
     Referring also to  FIG. 4 , some aspects of a non-limiting example of electrical machine  10  in accordance with an embodiment of the present invention are illustrated. In the embodiment of  FIG. 4 , electrical machine  10  includes an end plate in the form of an oil distribution member  60 , and at least one oil delivery nozzle  62 . In one form, oil delivery nozzle  62  is stationary, and directs oil across an air gap to a rotating oil distribution member  60 . Oil distribution member  60  has a radially inward portion  64  and a radially outward portion  66 . Radially outward portion  66  is disposed adjacent to the inlets  48  of the cooling passages  42 , e.g., adjacent to and radially outward from inlets  48 . Oil delivery nozzle  62  is constructed to discharge and direct oil toward radially inward portion  64  of oil distribution member  60 . The oil discharged by oil delivery nozzle  62  may be in the form of one or more oil sprays, one or more oil streams and/or one or more oil drips. Oil distribution member  60  is constructed to receive the oil discharged by oil delivery nozzle  62 , and to direct the oil to inlets  48  of cooling passages  42  to cool rotor  14 . 
     Oil distribution member  60  is coupled to rotor  14 , and is constructed to rotate with rotor  14 . In some embodiments, all or part of oil distribution member  60  may be integral with or part of rotor  14 . In one form, oil distribution member  60  is conical, e.g., cone shaped or the frustum of a hollow cone. The cone angle may vary with the needs of the application. In other embodiments, oil distribution member  60  may have any suitable geometric shape, another non-limiting example of which may be a bucket shape. Oil distribution member  60  includes an inner surface  68  and an outer surface  70 . Oil delivery nozzle  62  is constructed to direct oil to the inner surface  68  of oil distribution member  60 . For example, in some embodiments, oil delivery nozzle  62  is spaced apart axially from oil distribution member  60 , e.g., across an air gap, and for example, is located to the right of oil distribution member  60  in the depiction of  FIG. 4 . In such embodiments, oil delivery nozzle  62  may be constructed to direct the oil to a rotating surface  72 , e.g., of rotor  14  or shaft  12 . Rotating surface  72  is constructed to sling the oil radially outward and into contact with inner surface  68  of oil distribution member  60 . In other embodiments, oil delivery nozzle  62  may be located radially inward of all or a portion of oil distribution member  60 , and may direct oil directly at inner surface  68  of oil distribution member  60 . Rotating oil distribution member  60  is constructed to trap the oil received from oil delivery nozzle  62  using inner surface  68  and to increase the pressure of the oil, e.g., in the manner of a centrifugal pump, and to supply the pressurized oil to inlets  48  of cooling passages  42  with enough pressure to force the oil through cooling passages  42 . Rotating oil distribution member  60  traps the oil radially, and traps the oil axially in such a manner as to prevent oil flow in a direction away from the rotor, and permit pressure buildup due to centrifugal force. Cooling passages  42  permit the trapped oil to escape through the body of the rotor, providing cooling to the rotor. 
     Oil distribution member  60  is constructed to drive the cooling oil received from oil delivery nozzle  62  into the inlets  48  of cooling passages  42 , and along and through cooling passages  42  to cool rotor  14 , and to discharge the oil from outlets  50  of cooling passages  42 , e.g., based on the oil pressure generated by oil distribution member  60 . For example, due to the location of the cone-shaped radially outward portion  66  of oil distribution member  60  being proximate to inlets  48  of cooling passages  42  and inner surface  68  being radially outward of inlets  48 , the oil pressurized by oil distribution member  60  is driven by the pressure into inlets  48  of cooling passages  42 , is driven along the length of cooling passage  42  and is then discharged out of cooling passages  42  at outlets  50  of cooling passages  42 . A subset of stator winding overhangs  34 , i.e., stator winding overhangs  34 A, are disposed at least partially directly radially outward of outlets  50  of cooling passages  42 . Outlets  50  are constructed to discharge the oil received from oil distribution member  60  via cooling passages  42 , and to sling the oil outward, e.g., radially outward, and into contact with winding overhangs  34 A on the left side of  FIG. 4  to cool overhangs  34 A with the oil. 
     In some embodiments, one or more oil delivery nozzles  62  are also or alternatively constructed to direct oil to the outer surface  70  of oil distribution member  60 . In some embodiments (not shown), one or more oil delivery nozzles  62  are also or alternatively constructed and positioned to direct oil to outer surface  78  of end plate  76  to sling the oil radially outward for additional cooling of overhangs  34 A. In various embodiments, the oil may be directed in the form of one or more oil streams, oil sprays and/or oil drips. In some embodiments, separate oil delivery nozzle(s)  62  may be employed to direct oil to the outer surface  70  of oil distribution member  60  and to inner surface  68  of oil distribution member  60 . 
     Oil distribution member  60  is disposed at least partially directly radially inward of a subset of stator winding overhangs  34 , i.e., stator winding overhangs  34 B. Oil distribution member  60  is constructed to sling the oil outward, e.g., radially outward, and into contact with winding overhang  34 B to cool winding overhang  34 B with oil. Thus, in some embodiments, one or more oil delivery nozzles  62  may be employed to direct oil to both the inner surface  68  and outer surface  70  of oil distribution member  60 . In some such embodiments, oil distribution member  60  may be constructed to provide oil cooling to rotor  14  and to stator windings  20 , e.g., winding overhangs  34 , simultaneously, by directing oil from the stationary oil delivery nozzles  62  across an air gap  74  to the rotating oil distribution member  60 . In some embodiments, an end plate  76 , e.g., a cone shaped end plate similar in shape to oil distribution member  60  may be employed on the opposite side of rotor  14  for balancing purposes. In other embodiments, end plate  76  may have any suitable geometric shape, or may have a different profile, e.g., a cone facing in a direction opposite to that illustrated in  FIG. 4 . Some embodiments may not include end plate  76 . The outer region of cone shaped end plate  76  is radially inward of outlets  50  of cooling passages  42 , e.g., and thus does not present an obstacle to oil flow through outlets  50  and the slinging of cooling oil onto overhangs  34 A. 
     In some embodiments, oil delivery nozzle(s)  62  may be controlled to selectively vary the amount of oil directed to stator overhangs  34 A and/or  34 B, and/or vary the amount of oil directed to rotor  14 , i.e., to cooling passages  42 . For example, at some operating conditions, it may be desirable to direct more oil to cool stator overhangs  34 A and  34 B, whereas in other embodiments, it may be more desirable to direct more oil to cool rotor  14  via cooling passages  42 . In some embodiments, a rotation of one or more oil delivery nozzle(s)  62  may be controlled to selectively vary the amount of oil directed to inner surface  68  and outer surface  70  of oil distribution member  60 . In some embodiments, valves may be employed to control oil flow through one or more discharge openings in oil delivery nozzle(s) to vary the amount of oil directed to inner surface  68  and outer surface  70  of oil distribution member  60  and/or to vary the amount of oil directed to stator overhangs  34 A and/or  34 B, and/or to vary the amount of oil directed to rotor  14 , i.e., to cooling passages  42 . 
     Embodiments of the present invention include an electrical machine, comprising: a stator including a plurality of stator windings; a rotor in magnetic cooperation with the stator, the rotor including a plurality of cooling passages extending therethrough, each cooling passage including an inlet for receiving oil and an outlet for discharging the oil; a rotating oil distribution member coupled to the rotor, the oil distribution member including a radially inward portion and a radially outward portion, the radially outward portion being disposed adjacent to the inlets of the plurality of cooling passages; and a stationary oil delivery nozzle constructed to discharge oil toward the radially inward portion of the oil distribution member, wherein the oil distribution member is constructed to receive the oil discharged by the oil delivery nozzle, and to direct the oil to the inlets of the cooling passages to cool the rotor. 
     In a refinement, the oil distribution member is coupled to the rotor and is constructed to rotate with the rotor. 
     In another refinement, the oil distribution member is conical. 
     In yet another refinement, the stator windings include a winding overhang disposed at least partially directly radially outward of the outlets of the plurality of cooling passages; and wherein the outlets are constructed to discharge the oil and sling the oil outward and into contact with the winding overhang to cool the winding overhang with the oil. 
     In still another refinement, the oil distribution member includes an inner surface and an outer surface; and wherein the oil delivery nozzle is constructed to direct the oil to the inner surface. 
     In yet still another refinement, the oil delivery nozzle is constructed to direct the oil to a rotating surface; and wherein the rotating surface is constructed to sling the oil radially outward and into contact with the inner surface of the oil distribution member. 
     In a further refinement, the oil distribution member is constructed to increase a pressure of the oil received from the oil delivery nozzle. 
     In a yet further refinement, the oil distribution member is constructed to drive the oil into the inlets of the cooling passages, along and through the cooling passages and to discharge the oil from outlets of the cooling passages. 
     In a still further refinement, the oil delivery nozzle is constructed to direct the oil to the outer surface of the oil distribution member. 
     In a yet still further refinement, the stator windings include a winding overhang; and wherein the oil distribution member is disposed at least partially directly radially inward of the winding overhang and constructed to sling the oil outward and into contact with the winding overhang to cool the winding overhang with the oil. 
     In another further refinement, the oil delivery nozzle is spaced apart axially from the oil distribution member. 
     Embodiments of the present invention include an electrical machine, comprising: a stator having a plurality of stator windings, the stator windings including a first overhang; a rotor in magnetic cooperation with the stator; an oil distribution member coupled to the rotor, the oil distribution member being disposed at least partially directly radially inward of the first overhang; and at least one oil delivery nozzle constructed to discharge oil toward the oil distribution member, wherein the oil distribution member is constructed to sling the oil outward and into contact with the first winding overhang to cool the winding overhang with the oil. 
     In a refinement, the rotor includes a plurality of cooling passages extending therethrough, each cooling passage having an inlet for receiving the oil; wherein the oil distribution member is constructed to direct oil to the inlets of the cooling passages and through the cooling passages to cool the rotor. 
     In another refinement, the stator windings have a second winding overhang; wherein each cooling passage includes an outlet for discharging the oil, and wherein the outlets are constructed to sling the oil into contact with the second winding overhang to cool the second winding overhang with the oil. 
     In yet another refinement, at least one oil delivery nozzle is constructed to direct the oil to a rotating surface; and wherein the rotating surface is constructed to sling the oil radially outward and into contact with the oil distribution member. 
     In still another refinement, the oil distribution member is constructed to increase a pressure of the oil received from the oil delivery nozzle and supply pressurized oil to the inlets of the cooling passages. 
     In yet still another refinement, the oil distribution member is conical. 
     In a further refinement, the at least one oil delivery nozzle is spaced apart axially from the oil distribution member. 
     In a yet further refinement, the oil distribution member includes an inner surface and an outer surface; and wherein the at least one oil delivery nozzle is constructed to direct the oil to both the inner surface and the outer surface. 
     In a still further refinement, the at least one oil delivery nozzle is constructed to vary the amount of oil directed to the inner surface and to vary the amount of oil directed to the outer surface 
     In a yet still further refinement, the oil distribution member is constructed to provide oil cooling to the rotor and to the stator windings simultaneously. 
     In another further refinement, the at least one oil delivery nozzle is constructed to vary the amount of oil provided to the rotor and to vary the amount of oil provided to the stator windings. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. 
     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.