Abstract:
A system for cooling an electrical machine is disclosed. The electrical machine includes a rotor, a stator, and at least one cooling pathway extending through the stator. During operation of the electrical machine, fluid flows through the pathway and carries away heat generated by the electrical machine.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosure relates to a system for cooling an electrical machine. More particularly, the present disclosure relates to a system for cooling stator laminations and coils of the electrical machine. 
         [0003]    2. Description of the Related Art 
         [0004]    Electrical machines, including motors and generators, operate by rotating a rotor relative to a stator that surrounds the rotor. Electrical machines generate heat during operation that flows radially outward from the rotor to the stator to an exterior housing. To cool the electrical machine, air or a liquid coolant may be directed through channels located in the exterior housing, through apertures located in sealed laminations of the stator, or through channels located between coils of the stator, for example. 
       SUMMARY 
       [0005]    The present disclosure provides a system for cooling an electrical machine. The electrical machine includes a rotor, a stator, and at least one cooling tube extending through the stator. During operation of the electrical machine, fluid flows through the tube and carries away heat generated by the machine. 
         [0006]    According to an embodiment of the present disclosure, an electrical machine is provided including: a rotor; and a stator. The stator including a lamination stack that includes a plurality of laminations aligned coaxially, the lamination stack defining a central bore sized to receive the rotor and defining at least one cooling bore, the lamination stack defining a first end and a second end, a fluid input plate disposed within the lamination stack and spaced apart from the first end and second end; and a cooling fluid positioned in the at least one cooling bore. 
         [0007]    According to another embodiment of the present disclosure, an electrical machine fluid transport device is provided. The device including a body having a first side and a second side; a fluid input defined in the body; an internal passageway defined in the body and fluidly linked to the input; a first output defined in the first side and fluidly linked to the internal passageway; and a second output defined in the second side and fluidly linked to the internal passageway. 
         [0008]    According to yet another embodiment of the present disclosure, a plate for use with a motor stator is provided. The plate includes a body sized and shaped to abut a lamination of a stack of laminations of the motor stator. The body including: a first output orifice positioned to align with a fluid conduit of the lamination, and a first facet positioned adjacent the first output orifice to receive fluid from the first output orifice, the first facet including a first facet output, the first facet sized and shaped and located such that fluid exiting the first facet via the first facet output is directed onto a winding of the motor stator. 
         [0009]    According to yet another embodiment of the present disclosure, an electrical machine is provided. The machine includes a rotor and a stator. The stator including at least one coil; a lamination stack that includes a plurality of laminations aligned coaxially, the lamination stack defining a central bore sized to receive the rotor and defining at least one cooling bore, the lamination stack defining a first end and a second end; and an end piece having at least one fluid outlet defined therein, the at least one fluid outlet including spray nozzles that receive fluid from within the lamination stack and direct the fluid onto the at least one coil. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The above-mentioned and other features of the present disclosure will become more apparent and the present disclosure itself will be better understood by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a perspective view of an embodiment of a motor including a rotor and a stator with cooling pathways extending therethrough; 
           [0012]      FIG. 2  is a top plan view of the stator of  FIG. 1  shown with a stator end cap in place; 
           [0013]      FIG. 3  is a top plan view of the stator of  FIG. 1  shown with a stator end cap removed; 
           [0014]      FIG. 4  is a schematic illustration of cross-section of the stator of  FIG. 1 ; 
           [0015]      FIG. 5  is a schematic illustration of cross-section of the stator of  FIG. 1  showing fluid travel therein; and 
           [0016]      FIG. 6  is a top plan view of the input plate of the stator of  FIG. 1 . 
       
    
    
       [0017]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION 
       [0018]      FIG. 1  provides an illustrative electrical machine in the form of motor  10 . Although the electrical machine is illustrated and described herein as motor  10 , machines of the present disclosure may also include generators, for example. Motor  10  includes rotor  12 , stator  14 , and, optionally, housing (not shown) surrounding stator  14 . In operation, power is supplied to motor  10  to rotate rotor  12  relative to the surrounding stator  14 . 
         [0019]    Stator  14  includes lamination stack  20  and coils  22 . Lamination stack  20  includes a plurality of individual laminations  24  layered and secured together axially. Lamination stack  20  further includes input plates  44  and end caps  16  therein. Adjacent laminations  24 , input plates  44 , and end caps  16  may be secured together by welding, with a bonding agent, with a fastening device, or by another suitable technique. 
         [0020]    As shown in  FIG. 3 , each lamination  24  is a disk-shaped body constructed of electrical steel or another suitable ferromagnetic material. Lamination  24  includes an outer periphery  26  and an inner periphery  28  that defines a central aperture  30 . When laminations  24  are layered together, adjacent central apertures  30  align to form a central bore  32  that extends axially through lamination stack  20 . Central bore  32  is sized to receive rotor  12  ( FIG. 1 ). Inner periphery  28  of lamination  24  also includes a plurality of radially-spaced winding teeth  40 . Adjacent winding teeth  40  define winding slots  42  therebetween. 
         [0021]    As shown in  FIG. 2 , each end of lamination stack  20  includes an end cap  16 . End cap  16  is a non-ferromagnetic disk-shaped piece that is substantially similarly dimensioned to laminations  24 . End caps  16  thus have winding slots  42  that align with winding slots  42  of lamination stack  20 . Additional features of end caps  16  are discussed below. 
         [0022]    When laminations  24  are layered together with end caps  16 , wires, such as insulated copper wires, extend through winding slots  42  and wrap around winding teeth  40  to form coils  22 . Outer periphery  26  of lamination  24  may include any number of alignment features (not shown), such as indentations, protrusions, and/or markings, to indicate when adjacent laminations  24  are properly aligned. 
         [0023]    Referring still to  FIG. 3 , each lamination  24  also includes a plurality of flow apertures  50 . Flow apertures  50  are positioned to be between adjacent coils  22  of stator  14 , as shown in  FIG. 3 . In  FIG. 3 , endcap  16  is removed to show flow apertures  50 . Placing flow apertures  50  between adjacent coils  22  cools the coils  22  directly, rather than indirectly through lamination stack  20 . In addition to apertures  50 , cooling tubes  60  may be inserted therein between adjacent coils  22  and hydroformed against coils  22  as described with respect to cooling bores  52  of lamination stack  20  in U.S. patent application Ser. No. 12/262,721 (METHOD OF MANUFACTURING COOLING CHANNELS IN STATOR LAMINATIONS, filed Oct. 31, 2008) which is expressly incorporated herein by reference. 
         [0024]    Flow apertures  50  may be formed in laminations  24  by any suitable method. For example, after (or while) lamination  24  is stamped from a metal sheet, flow apertures  50  may be formed by cutting or punching holes into the metal sheet. As another example, flow apertures  50  may be formed during a molding process. Flow apertures  50  may be circular, oval, triangular, or another suitable shape. The illustrated embodiment includes triangular apertures  50 . When laminations  24  are layered together, adjacent apertures  50  cooperate to form a plurality of cooling bores  52  that extend through lamination stack  20 . In an embodiment, cooling bores  52  extend through lamination stack  20  in a direction essentially parallel to central bore  32 . This parallel arrangement may be achieved by aligning adjacent flow apertures  50  directly on top of one another. 
         [0025]    While the specification has described flow apertures  50  as being defined by laminations  24 , cooling tubes (not shown) may also be placed within flow apertures  50  to define cooling bores  52 . Cooling tubes may be constructed of a thermally conductive material, such as copper, a copper alloy, aluminum, or an aluminum alloy, or another suitable material, such as steel or a steel alloy. Embodiments are also envisioned where cooling tubes are non-ferrous but still thermally conductive. 
         [0026]    In addition to laminations  24 , stator  14  also includes one or more input plates  44 ,  FIG. 6 . In the illustrated embodiment of  FIGS. 4 &amp; 6 , input plate  44  is similarly sized to lamination  24  with respect to outer and inner periphery  26 ,  28 . However, input plate  44  is thick enough such that input aperture  46  is defined therein and is non-ferrromagnetic. Additionally, input plates  44  are envisioned having a greater diameter than laminations  24 . Input aperture  46  is a multi-diametered aperture that extends from outer periphery  26  to portion  48  of cooling bore  52 . Portion  48  forms a “T” with input aperture  46 . In one embodiment, an input aperture  46  is provided for each cooling bore  52 . In another embodiment, shown in  FIG. 6 , a single input aperture  46  is provided and input plate  44  includes a circumferential passageway  54  therein that link input aperture  46  to all cooling bores  52 . Furthermore, it should be appreciated that embodiments are envisioned where multiple input apertures  46  are provided and each is coupled to more than one but less than all cooling bore  52 . In the embodiments where a single input aperture  46  serves more than one cooling bore  52 , circumferential pathways  54  are provided within input plates  44 . Outer portion  47  of input aperture  46  is sized to receive a hose or other conduit that seals to outer portion  47  to supply cooling oil thereto. While  FIGS. 4 and 5  show stator  14  having a single input plate  46 , embodiments are envisioned where more than one input plate is disposed within lamination stack  20 . Additionally, while  FIG. 6  shows one side of input plate  44  with portions of cooling bores  52  defined therein, it should be appreciated that the opposing side also contains portions of cooling bores  52  defined therein. 
         [0027]    As previously noted, endplates  16  are similarly dimensioned to laminations  24 . Endplates have distribution facets  72  and output metering apertures  74 . Output metering apertures  74  are aligned with cooling bores  52 . The sizing of output metering apertures  74  is customized to provide desired flow characteristics for the particular location on stator  14  where the aperture is located. Distribution facets  72  are areas of increased thickness sized to fit between adjacent coils end windings of coils  22 . Distribution facets  72  are sized and shaped to receive cooling oil from output metering apertures  74  and direct it to adjacent end windings of coils  22 . Motor  10 , in operation, has a defined orientation relative to gravity. Accordingly, distribution facets  72  are each customized in recognition that each output metering aperture  74  can assume a unique relation to adjacent end windings for coils  22  and gravity. 
         [0028]    The cooling fluid may include, for example, oil, water, a mixture of water and ethylene glycol, a mixture of water and propylene glycol, or another suitable heat transfer fluid. Exemplary cooling fluids are capable of removing more heat from motor  10  than air, for example. As illustrated schematically in  FIG. 5 , the cooling fluid travels from source tank S, into input aperture  46  of input plate  44  (via pump  71  and a filter), inward to portion  48 , laterally through cooling tube  60  (where present) through lamination stack  20 , out of output metering apertures  74 , into distribution facets  72 , along end windings of coil  22  (adjacent to facets  72  and not shown in  FIG. 5 ), and ultimately to destination tank D. The direction of fluid flow is indicated by arrow F. Heat generated by motor  10  is transferred from lamination stack  20 , through the walls of cooling tubes  60  (where present), and into the cooling fluid flowing therein. The direction of heat flow is indicated by arrow H. The heated fluid that is delivered to destination tank D may be cooled and recycled back to source tank S. 
         [0029]    Referring still to  FIG. 5 , input aperture  46  of input plate  44  is coupled to fluid lines  70 . Fluid lines  70  may be constructed of flexible rubber tubing, for example. As illustrated schematically in  FIG. 5 , fluid lines  70  direct the cooling fluid from source tank S to input aperture  46  of input plate  44  via pump  71 . According to an exemplary embodiment of the present disclosure, fluid lines  70  are also coupled to a housing in which motor  10  is located. The housing contains the fluid that is output from apertures  74  and flowed across the end windings of coils  22  ( FIG. 2 ). 
         [0030]    To promote even cooling of lamination stack  20 , substantially equal flow is desired in all cooling bores  52 . However, it will be appreciated that gravity operates on motor  10  and the fluid. For embodiments where a single inlet aperture  46  is coupled to more than one cooling bore  52 , the cooling bores  52  are potentially located at different heights (due to the differing radial locations). For this reason, or any other reason tending to cause uneven distribution, the sizing of output metering apertures  74  is customized. For any cooling bore  52  that would naturally tend to collect an increased amount of fluid therein, such cooling bore  52  is provided with a smaller output metering aperture  74  to equalize the flow experienced by that cooling bore  52  with other cooling bores  52 . Furthermore, output metering apertures  74  are sized such that the collective output of all output metering apertures  74  for a given input aperture  46  is equal to the supply of fluid being input to the input aperture  46  that serves the one or more output metering apertures  74 . Accordingly, the situation does not arise where certain cooling bores  52  are receiving adequate cooling fluid while other cooling bores  52  receive less than necessary amounts. 
         [0031]    While the above customization has been described as seeking uniform flow and uniform cooling. It should be appreciated that the flow characteristics can be adjusted to non-uniform flow if operational designs and parameters result in non-uniform heat production in motor  10 . 
         [0032]    Once the cooling fluid is expelled from output metering apertures, the fluid encounters distribution facets  72 . Distribution facets  72  define pooling vessels  73  each having a lip  75 . Pooling vessels  73  each fill up and ultimately overflow with fluid, similarly to that often seen in water fountains. Distribution facets  72  are sized and shaped to direct fluid onto adjacent end windings of coils  22 . In that the orientation of the various facets  72  relative to gravity is known, facets  72  are sized and shaped differently to direct fluid to adjacent end windings of coils  22 . As shown most clearly in  FIG. 2 , facets  72  on either side of vertical centerline  76  are mirror images of each other. Facets  72   a,  on either side of the top center coil  22  are shaped such that fluid overflows onto both adjacent coils  22 . The balance of the facets  72  are shaped such that fluid overflows proximate the higher end of the lower adjacent coil  22 . This results in gravity causing increased flow over a greater portion of the end windings of coils  22 . 
         [0033]    While facets  72  are shown and described as defining a pooling vessels  73 , embodiments are envisioned where facets  72  provide sprays that, via pressurization of the fluid, can eject the fluid to be sprayed onto adjacent coils  22 . In such embodiments, spray can be applied to both adjacent coils rather than just those for which gravity would allow the fluid to fall downwardly onto. 
         [0034]    While this invention has been described as having preferred designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.