Abstract:
Systems are disclosed that assist in cooling generator rotor coils. In one embodiment, the system includes a stator; a rotor positioned within the stator, the rotor having: a spindle; groups of coils disposed about the spindle, each of the groups of coils including a plurality of ducts; a plurality of subslots disposed about the spindle, each of the plurality of subslots extending between the spindle and one of the groups of coils, wherein each of the plurality of subslots is in fluid communication with the one of the groups of coils; and a first baffle disposed in one of the plurality of subslots for directing a coolant into at least one of the plurality of ducts.

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to generator coil cooling baffles. More specifically, the subject matter disclosed herein relates to generator coil cooling baffles within a generator rotor. 
     Dynamoelectric machines such as electrical generators conventionally include a rotor and a stator. The rotor is conventionally provided with field windings (rotor coils) that excite the generator while receiving current from an excitation source. The stator is provided with windings from which electrical power is output. During operation, electrical current traveling through rotor coils generates heat. If this heat is not conducted away from the rotor coils, it may cause diminished performance of the generator. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Systems are disclosed that assist in cooling generator rotor coils. In one embodiment, the system includes a stator; a rotor positioned within the stator, the rotor having: a spindle; groups of coils disposed about the spindle, each of the groups of coils including a plurality of ducts; a plurality of subslots disposed about the spindle, each of the plurality of subslots extending between the spindle and one of the groups of coils, wherein each of the plurality of subslots is in fluid communication with the one of the groups of coils; and a first baffle disposed in one of the plurality of subslots for directing a coolant into at least one of the plurality of ducts. 
     A first aspect of the invention provides a dynamoelectric machine comprising: a stator; a rotor positioned within the stator, the rotor having: a spindle; groups of coils disposed about the spindle, each of the groups of coils including a plurality of ducts; a plurality of subslots disposed about the spindle, each of the plurality of subslots extending between the spindle and one of the groups of coils, wherein each of the plurality of subslots is in fluid communication with the one of the groups of coils; and a first baffle disposed in one of the plurality of subslots for directing a coolant into at least one of the plurality of ducts. 
     A second aspect of the invention provides a rotor comprising: a spindle; groups of coils disposed about the spindle, each of the groups of coils including a plurality of ducts; a plurality of subslots disposed about the spindle, each of the plurality of subslots extending between the spindle and one of the groups of coils, wherein each of the plurality of subslots is in fluid communication with the one of the groups of coils; and a first baffle disposed in one of the plurality of subslots for directing a coolant into at least one of the plurality of ducts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which: 
         FIG. 1  shows a three-dimensional perspective view of a portion of a generator rotor according to embodiments of the invention. 
         FIG. 2  shows a cross-sectional schematic view of a portion of a generator according to embodiments of the invention. 
         FIG. 3  shows a cross-sectional schematic view illustrating embodiments of the coil cooling baffles of  FIG. 2 . 
         FIGS. 4A-4D  show cross-sectional views of coil cooling baffles according to embodiments of the invention. 
         FIGS. 5-8  show cross-sectional schematic views illustrating embodiments of obstructing fluid flow according to embodiments of the invention. 
     
    
    
     It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As indicated above, aspects of the invention provide generator coil cooling baffles.  FIGS. 1-8  show different aspects of a generator, and specifically, configurations providing for cooling of generator coils  120 .  FIG. 1  shows a three-dimensional perspective view of a portion of a rotor  10 . Rotor  10  may include a spindle  100  and groups of coils  120  disposed about spindle  100 . Each group of coils  120  may include a plurality of ducts  110 . Further, rotor  10  may include a plurality of subslots  140  disposed about spindle  100 . Each subslot  140  may extend between spindle  100  and group of coils  120  and may be in fluid communication with group of coils  120 . Further aspects of the generator and rotor  10  will be described with reference to  FIGS. 2-8 . 
       FIG. 2  shows a cross-sectional schematic view of portions of a generator  5 , including a stator  20  and rotor  10  positioned within stator  20 . The cross-sectional view of portions of rotor  10  includes a cross-sectional view of two groups of coils  120 , one located above spindle  100 , and one located below spindle  100 . It is understood that the terms “above” and “below” are merely illustrative, and that groups of coils  120  may be located anywhere about spindle  100 . As shown, rotor  10  may have spindle  100  and groups of coils  120  disposed about spindle  100 . Spindle  100  may be formed of, for example, iron. Further, spindle  100  may include a plurality of teeth (not shown) extending radially outward toward stator  20 . Each group of coils  120  may include plurality of ducts  110 . Rotor  10  may also include subslot  140  extending between spindle  100  and group of coils  120 . Subslot  140  may be in fluid communication with plurality of ducts  110 . Subslot  140  may have at least one opening  102  which may allow for input of coolant  125 . Further, rotor  10  may include a first baffle  150  disposed in subslot  140 . First baffle  150  may direct a coolant  125  into at least one of plurality of ducts  110 . When rotor  10  is rotated with respect to stator  20 , an electrical current is created in groups of coils  120 , generating electricity. This electricity may be used in a variety of applications including, for example, powering homes and/or buildings. 
     Generator  5  may have a middle portion  121  and two end portions  111 . The terms “end portion” and “middle portion” may be used herein to refer to the end portions and middle portion of generator  5 , rotor  10 , stator  20 , groups of coils  120  or subslot  140 . Further, the term “end portions” generally refers to those portions of generator  10  closest to openings  102 , while the term “middle portion” generally refers to the portion of generator  5  which is farther from openings  102  than end portions  111 . End portions  111  do not encompass areas generally referred to as end-windings by those skilled in the art, but rather, are areas abutting the end-windings. End portions  111  and middle portion  121  may encompass larger or smaller portions of generator  5  than shown in the figures. The functions of generator  5 , and specifically, subslot  140  and first baffle  150  of rotor  10 , will be further explained with reference to  FIG. 3 . 
       FIG. 3  shows a close-up cross-sectional view of part of end portion  111  ( FIG. 2 ). Specifically,  FIG. 3  shows a close-up cross-sectional view of part of one group of coils  120  at end portion  111 . End portion  111  may include a portion of spindle  100  and one group of coils  120  disposed about spindle  100 , as well as subslot  140  and first baffle  150 . As will be described herein, subslot  140  may be in fluid communication with plurality of ducts  110 . First baffle  150  may be disposed in subslot  140 . In one embodiment, first baffle  150  may include one or more substantially planar members. However, as will be described with reference to  FIGS. 4A-D , first baffle  150  may include a plurality of members in a variety of arrangements. First baffle  150  may be formed of, for example, metals, plastics and/or composite materials. Also shown in  FIG. 3  is an alternative embodiment in which a second baffle  152  (shown in phantom) is included in subslot  140 . Second baffle  152  may be substantially identical in size, shape and/or material type to first baffle  150 , or may be of a different size, shape and/or material type. Additionally, more than two baffles may be included in subslot  140 . 
     Further, as shown by fluid flow arrows, plurality of ducts  110  may also be in fluid communication with an air gap  104 . Air gap  104  may be any region outside of group of coils  120  that allows coolant to exit plurality of ducts  110 . Air gap  104  may, for example, provide an inlet to a chimney (not shown). This chimney may allow for heated coolant to exit generator  5  ( FIG. 2 ) and prevent decreased performance of generator  5 . 
       FIG. 3  further shows flow arrows indicating flow of coolant  125  through end portion  111  and toward air gap  104 . In practice, coolant  125  flows to air gap  104  via subslot  140  and plurality of ducts  110 , thus transferring heat from group of coils  120  via plurality of ducts  110 . Plurality of ducts  110  may be formed as apertures drilled into group of coils  120  which allows for transfer of heat from group of coils  120  to coolant  125 . Where group of coils  120  include copper, plurality of ducts  110  may be formed by any conventional method for drilling through copper. 
     Coolant  125  may comprise, for example, ambient air or hydrogen. However, coolant  125  may take any gas form capable of carrying heat from group of coils  120  via plurality of ducts  110 . Coolant  125  may be supplied from a reservoir or tower (not shown), and may flow through cavities (not shown) surrounding and/or running alongside group of coils  120 . First baffle  150  allows more coolant  125  to flow through plurality of ducts  110  located at end portion  111  than to those located at middle portion  121 . Where more coolant is supplied to plurality of ducts  110  located at end portion  111 , more heat is transferred from group of coils  120  at end portion  111 . This keeps group of coils  120  at end portion  111  cooler, and helps to avoid the effects of over-heating at end portion  111 . 
     Turning to  FIGS. 4A-4D , a plurality of baffle configurations are shown.  FIGS. 4A-4C  show different baffles  250 ,  350 ,  450  which may extend over a length of at least two of the plurality of ducts  110 , similarly to first baffle  150  ( FIG. 3 ). Baffles  250 ,  350  may include one or more substantially planar members, and/or may include additional members oriented at obtuse angles with the one or more substantially planar members. Further, baffle  450  may include a plurality of substantially planar members, each member oriented at substantially right angles to an adjacent member.  FIG. 4D  shows two smaller baffles  550 ,  650 , which may be located adjacent one of plurality of openings  160  ( FIG. 3 ). Baffles  550 ,  560  may be part of a group of baffles, any number of which may be located adjacent one of plurality of openings  160 . Baffles  250 ,  350 ,  450 ,  550 ,  650  may be disposed within subslot  140 . Baffles  250 ,  350 ,  450 ,  550 ,  650  may be operably connected to group of coils  120  or attached to spindle  100 . 
       FIG. 5  shows a close-up cross-sectional view of an alternative embodiment. In this case, baffle  150  has been removed, and some of plurality of ducts  110  have been replaced with larger ducts  210 . Larger ducts  210  may function substantially similarly to plurality of ducts  110 , but may have larger openings  260  and greater volume capacity. Larger ducts  210  consume more of coolant  125  than plurality of ducts  110  due to these larger openings  260  and greater volume capacity. Where more coolant is supplied to larger ducts  210  located at end portion  111 , more heat is transferred from group of coils  120  at end portion  111 . This keeps group of coils  120  at end portion  111  cooler, and helps to avoid the effects of over-heating at end portion  111 . 
       FIG. 6  shows a close-up cross-sectional view of another alternative embodiment. In this case, baffle  150  has been removed, and tapered subslot  340  is substantially tapered from end portion  111  to middle portion  121 . Tapered subslot  340  may be constructed such that spindle  100  tapers from end portion  111  toward middle portion  121 . In this case, spindle  100  may be manufactured or modified to create tapered subslot  340 , such that spindle  100  has a larger diameter at middle portion  121  than at end portions  111 . Further, spindle  100  may be manufactured or modified in a variety of forms capable of obstructing flow of coolant  125 . Alternatively, tapered subslot  340  may be constructed of multiple members, which when combined, may provide for substantial tapering from end portion  111  to middle portion  121 . For example, wedge baffle  390  (shown in phantom) may be disposed in subslot  340  to provide for tapering and obstruction of the flow of coolant  125  toward middle portion  121 . Wedge baffle  390  is shown as a wedge-shaped attachment, however, wedge baffle  390  may take a variety of forms capable of obstructing flow of coolant  125 . Wedge baffle  390  may be attached to spindle  100  (as shown in phantom), or alternatively, may be attached to group of coils  120 . In any case, tapered subslot  340  will cause a greater quantity of coolant  125  to flow through plurality of ducts  110 . Where more coolant is supplied to plurality of ducts  110  located at end portion  111 , more heat is transferred from group of coils  120  at end portion  111 . This keeps portions of group of coils  120  at end portion  111  cooler, and helps to avoid the effects of over-heating at end portion  111 . 
       FIG. 7  shows a close-up cross-sectional view of another alternative embodiment. In this case, subslot cover  490  may act similarly to wedge baffle  390  of  FIG. 6 . However, subslot cover  490  of  FIG. 7  may be located closer to group of coils  120 . Subslot cover  490  is shown as a stepped cover, however, it may take a variety of forms. Further, subslot cover  490  may be formed of one or a plurality of members. For example, subslot cover  490  may contain one or more substantially angled members or one or more substantially rounded members. Subslot cover  490  may be disposed in subslot  140  during a portion of rotor assembly. For example, subslot cover  490  may be inserted into subslot  140  after spindle  100 , and group of coils  120  have been separated from one another. Subslot cover  490  may be independently movable and may obstruct a portion of subslot  140 . Subslot cover  490  may be placed in different portions of end portion  111  of subslot  140 . In any case, subslot cover  490  causes a greater quantity of coolant  125  to flow through plurality of ducts  110  located at end portion  111 . Where more coolant is supplied to plurality of ducts  110  located at end portion  111 , more heat is transferred from group of coils  120  at end portion  111 . This keeps portions of group of coils  120  at end portion  111  cooler, and helps to avoid the effects of over-heating at end portion  111 . 
       FIG. 8  shows a close-up cross-sectional view of another alternative embodiment. In this case, the pitch ( 1 ) between plurality of ducts  110  may vary such that a portion of plurality of ducts  110  located near end portion  111  may have a smaller pitch than those located near middle portion  121 . As is known in the art, the term “pitch” may refer to a linear distance between two similar openings. In this case, pitch  1  and pitch  1 ′ illustrate different linear distances between two sets of openings  160 . Similarly to embodiments discussed with respect to  FIG. 3 , a smaller pitch between plurality of ducts  110  located near end portion  111  provides greater cooling to end portion  111 . This is possible because a greater total cross-sectional area is available for flow of coolant  125  near end portion  111 . Where pitch  1  is smaller than pitch  1 ′, a greater number of plurality of ducts  110  are located near end portion  111 . While this may not provide greater flow of coolant  125  through each of plurality of ducts  110 , it provides for a greater total quantity of coolant  125  flowing through end portion  111 . Where the total quantity of coolant  125  supplied to plurality of ducts  110  located at end portion  111  increases, more heat is transferred from group of coils  120  at end portion  111 . This keeps portions of group of coils  120  at end portion  111  cooler, and helps to avoid the effects of over-heating at end portion  111 . 
     While several aspects of the invention are shown and described herein with reference to one group of coils  120  and one subslot  140 , it is understood that these aspects may apply to more than one subslot  140  and more than one group of coils  120  disposed about spindle  100 . Further, combinations and variations of aspects of the invention may be used in different groups of coils  120  and subslots  140  disposed about the same spindle  100 . For example, one group of coils  120  disposed about spindle  100  may increase coolant flow through plurality of ducts  110  using a first baffle  150  in subslot  140 , while another group of coils  120  disposed about spindle  100  may increase coolant flow through plurality of ducts  110  using varied pitches between plurality of ducts  110 . This example is merely illustrative, and it is understood that aspects of the invention may be combined and interchanged in a variety of manners. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.