Abstract:
An electrical machine has passages in the rotor. The passages have an inlet port and an exit port disposed at different locations. The passages remove heat from the electrical machine during operation. Another embodiment is an electrical machine rotor. The rotor has passages that remove heat from an electrical machine during operation. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for electrical machines and the cooling of electrical machine rotors and/or stators.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims benefit of U.S. Provisional Patent Application No. 61/801,101 filed Mar. 15, 2013, entitled COOLING OF A ROTOR OF A HIGH SPEED MOTOR; and claims the benefit of U.S. Provisional Patent Application No. 61/802,243 filed Mar. 15, 2013, entitled STATOR CORE AND METHOD OF MANUFACTURING HIGH-SPEED INDUCTION MOTORS, both of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to electrical machines having cooling features, and in particular, motors, generators and motor/generators having cooling features in the rotor and/or stator. 
       BACKGROUND 
       [0003]    Electrical machines that have cooling features, and cooling features for electrical machines that effectively cool the electrical machines remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
       SUMMARY 
       [0004]    One embodiment of the present invention is a unique electrical machine having passages in the rotor, wherein the passages have an inlet port and an exit port disposed at different locations, and remove heat from the electrical machine during operation. Another embodiment is an electrical machine rotor having passages that remove heat from an electrical machine during operation Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for electrical machines and the cooling of electrical machine rotors and/or stators. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0006]      FIG. 1  schematically illustrates some aspects of a non-limiting example of an electrical machine in accordance with an embodiment of the present invention. 
           [0007]      FIG. 2  schematically illustrates some aspects of a non-limiting example of the electrical machine rotor of  FIG. 1  in accordance with an embodiment of the present invention. 
           [0008]      FIG. 3  schematically illustrates some aspects of a non-limiting example of an electrical machine stator in accordance with an embodiment of the present invention. 
           [0009]      FIG. 4  schematically illustrates some examples of the formation of cooling passages of an electrical machine stator in accordance with embodiments of the present invention. 
           [0010]      FIG. 5  schematically illustrates some aspects of a non-limiting example of a cooling passages of an electrical machine stator in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    For 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 nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain embodiments of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
         [0012]    Embodiments of the present invention are directed to cooling features and schemes for cooling electrical machines, such as motors, generators and/or motor generators. In some, but not all embodiments, the electrical machines may be considered high-speed electrical machines. In some, but not all embodiments, the electrical machines may be induction machines or synchronous machines. The rotation of the electrical machine may be exploited for cooling in more than one manner, for example, by mounting a separate fan on the rotor shaft or by mounting or forming a conventional fan onto the rotor. However, such approaches may be cost prohibitive, and in the case of high-speed machines, may not be desirous, e.g., as they might generate more pressure or flow than is desired, or may experience more losses than are preferable, resulting in unnecessarily increased power requirements at the rotor. 
         [0013]    In some embodiments, cooling is provided via the use of cooling passages in the rotor that effectively form a pump or compressor, e.g. an axial and/or centrifugal pump or compressor that induce flow through the rotor and in some embodiments, the stator as well. Some embodiments may generate lower pressures that are more suitable for high speed motors. The pressure may be easily adjusted in the manufacturing process of the rotor, e.g., by altering the positions of one or more openings in laminations in a laminated rotor that form the cooling passages in the rotor, or by altering the size of one or more of the openings to effectively function as an orifice to meter the flow of the cooling fluid (e.g., air). In some embodiments, the cooling scheme is symmetrical, e.g., wherein the cooling fluid flows in both directions, such as from each end to the opposite end of the rotor and/or stator, which in some embodiments may make the temperature distribution across the machine more homogeneous, and in some embodiments less power (pressure) may be needed for a desired volumetric flow of cooling fluid. 
         [0014]    In some embodiments, the stator, e.g., the stator core yoke, may employ axial cooling channels extending therethrough. The cooling passages may be located near the stator slots so that the heat conduction distance is reduced. In some embodiments, the stator is laminated, and the cooling passages may be formed by forming openings in the laminations, and stacking the stator core in such a manner as to achieve the desired alignment between the openings to thereby form the cooling passages. In some embodiments, some of the openings in the laminations may be deflected or shifted relative to others, thereby forming turbulators that increase the heat transfer from the wall of the cooling passage to the cooling fluid. 
         [0015]    Referring to the drawings, and in particular  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 a motor. In other embodiments, electrical machine  10  may be a generator or may be a motor/generator. In one form, electrical machine  10  is an induction motor. In other embodiments, electrical machine  10  may be a synchronous machine. In still other embodiments, electrical machine  10  may take other forms. In one form, electrical machine  10  is a high-speed electrical machine. In other embodiments, electrical machine  10  may operate at any speed suitable for the particular application. Electrical machine  10  includes a casing  12 , a stator  14 , a shaft  16 , rotor  18  and bearings  20 . Casing  12  is configured to house stator  14 , shaft  16 , rotor  18  and bearings  20 . In one form, bearings  20  are mounted in casing  12 , e.g., an end plate of casing  12 . In other embodiments, bearings  20  may be mounted and coupled to casing  12  via one or more other structures. Bearings  20  are structured to radially support rotor  18 , and to react rotor  18  thrust loads. 
         [0016]    Stator  14  includes a plurality of stator windings  22  and a stator core  24 . Rotor  18  is disposed radially inward of stator core  24 . In one form, stator  14  circumferentially encompasses rotor  18 , although in other embodiments, stator  14  may only partially encompass induction rotor  18 , e.g., in the form of segments disposed circumferentially around stator  14 . Rotor  18  is configured for electromagnetic cooperation with stator  14 , e.g., to convert electrical power into mechanical power for delivery via shaft  16  in some embodiments and/or to convert mechanical power received from shaft  16  into electrical power for delivery via stator  14  in other embodiments. 
         [0017]    Disposed within casing  12  adjacent to rotor  18  are flow guides  26 , which form cooling fluid supply passages  28  and cooling fluid exhaust passages  30 . In the illustrated embodiment, cooling fluid supply passages  28  are formed between rotor  18 , shaft  16 , flow guides  26  and end plates  32 ; and cooling fluid exhaust passages  30  are formed between rotor  18 , stator  14 , flow guides  26  and casing  12 . In other embodiments, cooling fluid supply passages  28  and cooling fluid exhaust passages  30  may be formed by one or more other components and/or disposed in one or more other locations. Cooling fluid supply passages  28  and cooling fluid exhaust passages  30  are operative to respectively supply and discharge the cooling fluid  34 , e.g., air, to and from rotor  18  and electrical machine  10 . 
         [0018]    Referring to  FIG. 2  in conjunction with  FIG. 1 , some aspects of a non-limiting example of electrical machine  10  and rotor  18  in accordance with an embodiment of the present invention are schematically depicted. Rotor  18  extends axially along an axis of rotation  36  about which rotor  18  and shaft  16  rotate, e.g., between an axial position  38  and an axial position  40 . Rotor  18  includes a plurality of cooling passages  42  extending therethrough. In some embodiments, such as the embodiment depicted in  FIGS. 1 and 2 , rotor  18  also includes a plurality of passages  44  extending therethrough. In view of the following description, it will become apparent to those skilled in the art that cooling passages  42  and  44  remove heat from rotor  18  during operation of the electrical machine. Cooling passages  42  include cooling fluid inlet ports  46  and cooling fluid discharge ports  48 ; and cooling passages  44  include cooling fluid inlet ports  50  and cooling fluid discharge ports  52 . Inlet ports  50  and discharge ports  48  are disposed at axial position  38 , and inlet ports  46  and discharge ports  52  are disposed at axial position  40 . It will be understood that embodiments of the present invention are not limited to cooling passages that extend only between the end faces of an electrical machine rotor. For example, in other embodiments, inlet ports  50  and discharge ports  48 , and inlet ports  46  and discharge ports  52  may be disposed at any desired axial position. In addition, in some embodiments, the cooling passages may extend only from one portion to another portion of the electrical machine rotor, not necessarily through the entire axial length of the electrical machine rotor. 
         [0019]    For each respective passage  42  and  44 , discharge ports  48  and discharge ports  52  are disposed radially outward of inlet ports  46  and inlet ports  50 . As a result of this outer radial displacement of discharge ports  48 ,  52  relative to inlet ports  46 ,  50 , the rotation of rotor  18  generates centrifugal or centripetal forces on the cooling fluid  34  disposed within passages  42  and  44 , These forces impart a radially outward velocity to the cooling fluid disposed within cooling passages  42  and  44 , thus forming a centrifugal pump or compressor that generates a pressure rise between inlet ports  46 ,  50  and discharge ports  48 ,  52 , thereby pumping cooling fluid through passages  42  and  44  from inlet ports  46 ,  50  to discharge ports  48 ,  52 , and thus pumping the cooling fluid through cooling passages  42  and  44 , and hence providing cooling to rotor  18 . 
         [0020]    Electrical machine  10  includes seals  54 , which are configured to prevent or reduce the recirculation of fresh and exhausted cooling fluid between the inlet ports  46 ,  50  and discharge ports  48 ,  52  on rotor  18 . In one form, seals  54  are labyrinth seals. In other embodiments, seals  54  may be any contacting or noncontacting seal or flow discourager. In one form, seals  54  include tips extending from flow guides  26  into a groove in rotor  18 . In other embodiments, seals  54  may be formed with other geometries, and may not be incorporated as part of flow guides  26 . 
         [0021]    In some embodiments, for each respective passage  42  and  44 , inlet ports  46 ,  50  may be disposed at different circumferential positions than discharge ports  48 ,  52 , i.e., wherein during the rotation of rotor  18 , discharge ports may lead or may lag the inlet ports, by which rotor  18  effectively functions as an axial pumps or compressor, e.g., in such a manner that a shrouded fan does so. This relative positioning of inlet ports  46 ,  50  and discharge ports  48 ,  52  may be employed to augment the pressure rise generated across rotor  18  during operation, or to reduce the pressure rise. 
         [0022]    In some embodiments, inlet ports  46 ,  50  and discharge ports  48 ,  52  may be at the same radial position, but may be located at different circumferential positions such that rotor  18  functions purely as an axial flow machine. Thus in various embodiments, the inlet ports and discharge ports of the cooling passages may be located so that rotor  18  effectively functions as a centrifugal pump/compressor, an axial pumps/compressor, both an axial and centrifugal pump/compressor, or may position the inlet ports and discharge ports such that the pressure rise generated by centrifugal/centripetal effects are reduced by those generated by axial flow effects, or may position the inlet ports and discharge ports such that the pressure rise generated by centrifugal/centripetal effects are reduced by those generated by axial flow effects. 
         [0023]    In one form, cooling passages  42  and  44  extend linearly between their respective inlet and discharge ports. In other embodiments, cooling passages  42  and  44  may be geometrically configured, arranged or disposed in any suitable fashion. For example, in some embodiments, substantially all of one or more of the cooling passages may be horizontal, e.g., maintaining the same radial position along the bulk of the length of rotor  18 , but having the inlet ports and discharge ports located at the different radial and/or axial positions in order to achieve the desired pressure rise across the cooling passages to achieve the desired level of pumping of the cooling fluid. One form, cooling passages  42  and  44  have a relatively constant cross-section area or flow area between their respective inlet ports and discharge ports. In other embodiments, the cross-sectional area or flow area may vary between their respective inlet ports and discharge ports in accordance with the needs of the particular application. In one form, cooling passages  42  and  44  each have a single inlet port and a single discharge port. In other embodiments, cooling passages  42  and  44  may each have more than one inlet port and/or discharge port. 
         [0024]    In some embodiments, rotating and/or stationary guide vanes may be employed, e.g., to augment, control, or fine-tune the flow through cooling passages  42  and  44 . For example, in the embodiment of  FIG. 1 , electrical machine  10  includes rotating inlet guide vanes  56  and  58 , e.g., extending from rotor  18 ; rotating discharge guide vanes  60  and  62 , e.g. extending from rotor  18 ; stationery inlet guide vanes  64  and  66 , extending from flow guides  26 ; and stationery discharge guide vanes  68  and  70 , e.g. extending from flow guides  26 . In various embodiments, electrical machine  10  may include one or more of rotating inlet guide vanes, stationery inlet guide vanes, rotating discharge guide vanes, and stationary discharge guide vanes. Although guide vanes  56 ,  58 ,  60 ,  62 ,  64 ,  66 ,  68  and  70  extend from respective rotor  18  and flow guides  26  in the illustrated embodiment, in other embodiments, the guide vanes may extend from, or be a part of, or be affixed to any suitable component. 
         [0025]    In one form, the rotating and stationery inlet guide vanes are configured to direct cooling fluid into inlet ports  46  and  50  and to increase pressure in the cooling fluid in locations adjacent to inlet ports  46  and  50 , in order to increase the flow of cooling fluid through passages  42  and  44 , e.g., in a manner similar to compressor blades and vanes. The rotating and stationery discharge guide vanes are configured to decrease pressure in locations adjacent to discharge ports  48  and  52 , in order to increase the amount of flow of cooling fluid through passages  42  and  44 . For example, the discharge guide vanes may reduce discharge turbulence by shielding the discharge port from recirculation vortices and the like, and entrain the cooling fluid into the slipstream adjacent to the rotor, e.g., functioning in a manner similar to that of an ejector, for example, by generating a local rotating low pressure field at the locations of the discharge ports  48  and  52 . 
         [0026]    Referring now to  FIGS. 3-5 , in some embodiments, stator  14 , or more particularly, the stator core  24  or the stator core yoke of electrical machine  10 , includes axial turbulated cooling passages  72  extending therethrough, for removing heat from stator core  24  during the operation of electrical machine  10  via the use of a cooling fluid, e.g., cooling fluid  34 . For example, in some embodiments, discharge ports  48  and  52  are in fluid communication with cooling fluid inlet ports  74  of turbulated cooling passages  72 , and provide a flow of cooling fluid  34  into and through turbulated cooling passages  72 . In such embodiments, rotor  18  may be configured to provide cooling fluid  34  at a sufficient flow rate such that its temperature does not become undesirably high as it passes through rotor  18 , hence allowing a desired amount of cooling of stator  14 . In other embodiments, cooling fluid  34  may be cooled by a heat exchanger and/or one or more other heat absorbers prior to entry into turbulated cooling passages  72 . In other embodiments, cooling fluid inlet ports  74  of turbulated cooling passages  72  may be in fluid communication with another source of pressurized cooling fluid in addition to or in place of cooling fluid pressurized by rotor  18 . 
         [0027]    In one form, turbulated cooling passages  72  are located near the stator slots, e.g., close to windings  22 , so that the heat conduction distance is minimized. In one form, stator core  24  is formed of a plurality of laminations  76  that are stacked together, e.g., some of which are illustrated as laminations  76 A- 76 H in  FIG. 5 . Openings in the laminations are aligned in a desired fashion to form the cooling passages through the cooling passages through the stator  24 . In contrast to a smooth cooling passage, e.g., wherein the openings are substantially aligned, and wherein the alignment makes the cooling passage smooth, turbulated cooling passages  72  generate turbulence and increased convective heat transfer by misaligning at least some of the openings in the laminations so that turbulated cooling passages  72  are not smooth. For example, in various embodiments of the present invention, at least one or more openings  78  in laminations  76  are offset relative to other openings  78  in laminations  76  so as to form turbulated flowpaths for the cooling fluid (i.e., turbulated cooling passages  72 ), which increases the convective heat transfer from the walls of the turbulated cooling passages  72  to cooling fluid  34 . 
         [0028]    Although it may be possible to form turbulators by inserting wire spirals or inserting or forming other features into smooth cooling passages in order to provide turbulation, such additional features may increase cost, for example by requiring additional components or requiring additional manufacturing steps and/or assembly steps. Thus, it is desirable to have a turbulated passage that does not require additional components, and to have methods of forming the cooling passages that have little or no effect on the time and cost of manufacturing the stator core  24 . 
         [0029]    High-speed electrical machines are smaller in size compared to standard 50/60 Hz machines with the same power level. As a consequence, powerful cooling is desirable in high-speed electrical machines, since the loss density is often much higher than in conventional electrical machines. Some high-speed electrical machines, e.g., 100-600 kW electrical motors, may be cooled from the outer surface of the housing enclosing the stator core, which requires that the heat be conducted, e.g., from the windings, through the core yoke, the core-housing shrink fit, and the housing. However, this may not be feasible in some high-speed machines, because the heat to be removed is too high relative to the heat path cross-sectional area, which in some cases can lead to overheating. Overheating is of particular concern regarding the stator windings, where increased temperatures have a detrimental effect on the effective life of the electrical machine. 
         [0030]      FIG. 4  depicts 3 different examples of stator cores  24 A,  24 B and  24 C for purposes of describing two methods of forming turbulated passages  72 . The stator cores are formed as laminations stacked together in such a way as to form a cooling passage. Stator core  24 A with openings  78 A represents a case wherein all openings  78  are in substantial alignment with each other and with stator teeth  80 , thus forming a non-turbulated (smooth) cooling passage. The openings  78 A in each lamination maintain the same alignment relative to stator teeth  80  as the openings  78 A in the other laminations and/or the laminations all face in the same direction. 
         [0031]    Stator core  24 B with openings  78 B represent a methodology of forming turbulated cooling passages  72 , wherein the openings  78 B in the laminations  76  are all offset from alignment relative to the stator teeth  80 , and all openings  78 B have the same angular or positional offset from stator teeth  80 , in which case turbulated cooling passages  72  are formed by facing at least one of the laminations in a direction opposite to at least another of the laminations. In the view depicted in  FIG. 5 , under the methodology employed with regard to openings  78 B, every lamination faces in the opposite direction of an adjacent lamination. In other embodiments, only one or some laminations may face oppositely than others. The combination of the offset of the openings, and the fact that the laminations face in opposite directions, generates the turbulating features that render passages  72  to be turbulated cooling passages. 
         [0032]    Stator core  24 C with openings  78 C represent a methodology of forming turbulated cooling passages  72 , wherein two different lamination geometries are used, e.g., wherein one lamination geometric configuration employs openings having a first angular or positional relationship relative to stator teeth  80 , and another lamination geometric configuration employs openings having a second angular or positional relationship relative to stator teeth  80  that is different from the first angular or positional relationship. In the depiction of  FIG. 4 , each pair openings  78 C in the first lamination geometric configuration are offset from alignment with stator teeth  80  in a direction towards each other, whereas each pair of openings  78 C in the second lamination geometric configuration are offset from alignment with stator teeth  80  in a direction away from each other. Stated differently, every first opening  78 C, circumferentially, is rotated about axis of rotation  36  in one direction, e.g., clockwise, and every second opening, circumferentially, is rotated in the opposite direction, e.g., anti-clockwise or counter-clockwise. It will be understood that any suitable variation in angular or positional relationship of the openings relative to stator teeth  80  as between the two lamination geometries may be employed. In some embodiments, more than two different lamination geometric configurations may be employed. In the example depicted in  FIG. 5 , under the methodology employed with regard to openings  78 C, every adjacent lamination faces in the same direction. The combination of two or more lamination geometric configurations having different offsets of the openings relative to stator teeth  80  generates the turbulated cooling passages  72 . 
         [0033]    Embodiments of the present invention include an electrical machine rotor, comprising: a rotor configured for electromagnetic cooperation with a stator of an electrical machine and structured to rotate about an axis of rotation, wherein the rotor extends along the axis of rotation and includes a first cooling passage extending therethrough and having a first cooling fluid inlet port disposed at a first axial location along the axis of rotation, the first cooling passage also having a first cooling fluid discharge port in fluid communication with the first cooling fluid inlet port and disposed radially outward of the first cooling fluid inlet port at a second axial location spaced apart from the first axial location in a first axial direction along the axis of rotation, wherein the first cooling passage removes heat from the rotor during rotation of the rotor. 
         [0034]    In a refinement, the first cooling passage extends linearly between the first cooling fluid inlet port and the first cooling fluid discharge port. 
         [0035]    In another refinement, the electrical machine rotor further comprises a rotating and/or stationary guide vane disposed adjacent to the first cooling fluid inlet port, wherein the guide vane is configured to increase fluid pressure at the first cooling fluid inlet port. 
         [0036]    In another refinement, the electrical machine rotor further comprises a rotating and/or stationary guide vane disposed adjacent to the first cooling fluid discharge port wherein the guide vane is configured to decrease fluid pressure at the first cooling fluid discharge port. 
         [0037]    In still another refinement, the rotor includes a second cooling passage extending through the rotor; the second cooling passage has a second cooling fluid inlet port disposed at a third axial location along the axis of rotation; the second cooling passage has a second cooling fluid discharge port disposed at a fourth axial location along the axis of rotation; the second cooling fluid discharge port is spaced apart from the second cooling fluid inlet port in a second axial direction opposite the first axial direction; and the second cooling fluid discharge port is disposed radially outward of the second cooling fluid inlet port. 
         [0038]    In yet still another refinement, the first and fourth axial positions are substantially the same axial position, and wherein the second and third axial positions are substantially the same axial position. 
         [0039]    In a further refinement, the rotor has a first end and a second end, and wherein the first cooling fluid inlet port and the second cooling fluid discharge port are disposed at the first end; and wherein the second cooling fluid inlet port and the first cooling fluid discharge port are disposed at the second end. 
         [0040]    In a yet further refinement, the first cooling fluid inlet port and the first cooling fluid discharge port are disposed at different circumferential positions; and the second cooling fluid inlet port and the second cooling fluid discharge port are disposed at different circumferential positions. 
         [0041]    In a still further refinement, the rotor is an induction machine rotor or a synchronous machine rotor. 
         [0042]    Embodiments of the present invention include an electrical machine, comprising: a stator; a rotor in electromagnetic cooperation with the stator; a shaft extending from the rotor; and a bearing structured to radially support the shaft and the rotor, wherein the shaft is structured to support the rotor and to rotate about an axis of rotation; wherein the rotor extends along the axis of rotation and includes a first cooling passage extending therethrough and having a first cooling fluid inlet port disposed at a first axial location along the axis of rotation, the first cooling passage also having a first cooling fluid discharge port in fluid communication with the first cooling fluid inlet port and disposed radially outward of the first cooling fluid inlet port at a second axial location spaced apart from the first axial location in a first axial direction along the axis of rotation, wherein the first cooling passage removes heat from the rotor during rotation of the rotor. 
         [0043]    In a refinement, the rotor includes a second cooling passage extending therethrough and having a second cooling fluid inlet port disposed at a third axial location along the axis of rotation, the second cooling passage also having a second cooling fluid discharge port in fluid communication with the second cooling fluid inlet port and disposed radially outward of the second cooling fluid inlet port at a fourth axial location spaced apart from the third axial location in a second axial direction along the axis of rotation opposite the first axial direction, wherein the second cooling passage removes heat from the rotor during rotation of the rotor. 
         [0044]    In another refinement, the first cooling fluid inlet port is disposed at a different circumferential position on the rotor than the first cooling fluid discharge port. 
         [0045]    In yet another refinement, the stator includes a stator cooling passage extending through the stator. 
         [0046]    In still another refinement, the stator is formed of a plurality of laminations stacked together, wherein each lamination includes an opening; wherein the openings in the laminations form the stator cooling passage; and wherein the stator cooling passage is a turbulated cooling passage. 
         [0047]    In yet still another refinement, the laminations include a plurality of stator teeth; wherein the openings have a same geometry; and the openings in all of the laminations have the same alignment relative to the stator teeth. 
         [0048]    In a further refinement, the laminations include a plurality of stator teeth; and wherein at least some of the openings in the laminations have a different alignment relative to the stator teeth than others of the openings in the laminations. 
         [0049]    In a yet further refinement, at least one of the laminations faces in a direction opposite to at least one of the other laminations. 
         [0050]    In a still further refinement, the rotor includes a plurality of first cooling passages, and the first cooling passages are disposed at an angle relative to an outer surface of the rotor. 
         [0051]    Embodiments of the present invention include an electrical machine, comprising: a stator, a rotor configured for electromagnetic cooperation with the stator; a shaft extending from the rotor; a bearing structured to radially support the shaft and the rotor; and means for cooling at least one of the rotor and the stator during rotation of the rotor. 
         [0052]    In a refinement, the electrical machine includes means for cooling the rotor and means for cooling the stator; wherein the means for cooling the rotor includes means for pressurizing a fluid; and wherein the means for cooling the stator includes means for cooling the stator using the pressurized fluid. 
         [0053]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore, it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that 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” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.