Abstract:
Embodiments of the invention relate generally to electrical machines and, more particularly, to electrical machines containing a coil block assembly for cooling conductive coils. In one embodiment, the invention provides an electrical machine comprising: at least one tooth coil including: a stator tooth; and at least one conductive coil wound around the stator tooth, forming a plurality of coil turns; a coil block assembly between a first turn and a second turn of the plurality of coil turns, the coil block assembly including: at least two coil blocks, each coil block including a body and a face having at least one recess into the body, wherein the coil blocks are oriented with faces opposed, such that at least one cooling channel is formed by the at least one recess of each coil block.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Many electrical machines, such as wind turbine generators, traction motors, switched-reluctance motors, servo motors, stepper motors, and linear motors include armature or field windings comprising concentrated coils wound around a stator tooth. Such a tooth and its coils are commonly referred to as a tooth coil. Often, the coil arms (coil parts laying in the slot part of a machine) of such tooth coils have a relatively large width and experience an attendant temperature increase during operation. Indirect cooling of such tooth coils using conventional methods is difficult due to the concentration of the coil windings and the extent of temperature increase often experienced. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0002]    Embodiments of the invention relate generally to electrical machines and, more particularly, to electrical machines containing a coil block assembly for cooling conductive coils. 
         [0003]    In one embodiment, the invention provides an electrical machine comprising: at least one tooth coil including: a stator tooth; and at least one conductive coil wound around the stator tooth, forming a plurality of coil turns; a coil block assembly between a first turn and a second turn of the plurality of coil turns, the coil block assembly including: at least two coil blocks, each coil block including a body and a face having at least one recess into the body, wherein the coil blocks are oriented with faces opposed, such that at least one cooling channel is formed by the at least one recess of each coil block. 
         [0004]    In another embodiment, the invention provides an electrical machine comprising: a plurality of tooth coils, each tooth coil including: a stator tooth; and at least one conductive coil wound around the stator tooth, forming a plurality of coil turns; and a coil block assembly between an outer turn of the plurality of coil turns of a first tooth coil and an outer turn of the plurality of coil turns of a second tooth coil, the coil block assembly including a plurality of coil blocks, at least two coil blocks each including: a body; and a first face having at least one recess into the body, wherein the at least two coil blocks are oriented with first faces opposed to form at least one cooling channel including the at least one recess of each of at least two coil blocks. 
         [0005]    In yet another embodiment, the invention provides a coil block comprising: a body including a proximal end having a first thickness and a distal end having a second thickness less than the first thickness; a first face having at least one recess into the body; a first surface substantially perpendicular to the first face; and a second surface angled with respect to the first surface and the first face, whereby a pair of coil blocks oriented with first faces thereof opposed has a substantially trapezoidal shape in cross-section and form at least one cooling channel comprised of the at least one recess of each of the pair of coil blocks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    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: 
           [0007]      FIG. 1  shows a perspective view of a coil block according to an embodiment of the invention. 
           [0008]      FIGS. 2-5  show side views and cross-sectional views of coil block assemblies according to embodiments of the invention. 
           [0009]      FIGS. 6-9  show top and side cross-sectional views of tooth coils according to embodiments of the invention. 
           [0010]      FIG. 10  shows a perspective view of a coil block according to an embodiment of the invention. 
           [0011]      FIG. 11  shows a top cross-sectional view of a coil block assembly according to an embodiment of the invention. 
           [0012]      FIG. 12  shows a top view of a tooth coil and coil block assemblies according to an embodiment of the invention. 
       
    
    
       [0013]    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 among the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Turning now to the drawings,  FIG. 1  shows a perspective view of a coil block  100  according to an embodiment of the invention. Coil block  100  includes a body  10  having a height H, thickness T, and width W, a first face  14 , a second face  12 , a first surface  16 , and a second surface  18 . In the embodiment shown in  FIG. 1 , first face  14  and second face  12  are substantially parallel to each other and substantially perpendicular to each of first surface  16  and second surface  18 , such that body  10  has a substantially rectangular shape in cross section. 
         [0015]    First face  14  includes a plurality of recesses  30 ,  32 ,  34  extending from first surface  16  to second surface  18  and extending into body  10 . Portions of body  10  adjacent recesses  30 ,  32 ,  34  form islands  20 ,  22 ,  24 ,  26  extending substantially to an edge of, and therefore continuing to define, first face  14 . As will be described in greater detail below, in some embodiments of the invention, thickness T is less than width W. In other embodiments of the invention, thickness T varies along height H. 
         [0016]      FIG. 2  shows a side view of a coil block assembly  900  comprising a pair of coil blocks  100 ,  200 . Coil block  100  is stacked beside and oriented opposite to coil block  200 , i.e., with recesses open to opposite directions. In such an arrangement, portions of recesses  30 ,  32 ,  34  in coil block  100  extending furthest into body  10  expose similar portions of the recesses of coil block  200 , thereby forming cooling channels  140 ,  142 ,  144 , through which airflow  150 ,  152 ,  154  may pass. 
         [0017]    In the embodiments shown in  FIGS. 1 and 2 , recesses  30 ,  32 ,  34  and islands  22 ,  24  have a substantially sinusoidal shape. Other shapes may be used, of course, including a rectangular, ovoid, semicircular, etc. The shape or shapes employed will depend, for example, on the size of coil blocks  100 ,  200  and the desired size and/or shape of cooling channels  140 ,  142 ,  144 . Similarly, while each of coil blocks  100 ,  200  are shown in  FIG. 2  as having three recesses ( 30 ,  32 ,  34  in coil block  100 ), this is not essential. The number of recesses employed will depend, for example, on the size of the coil block and the desired amount of airflow through the coil block assembly. In addition, while each of the recesses  30 ,  32 ,  34  is shown as extending into body  10  in a direction substantially parallel to width W (i.e., substantially normal to thickness T and height H), this also is not essential. In some embodiments of the invention, recesses may extend into body  10  at an angle relative to width W, thickness T, and/or height H. 
         [0018]    Similarly, while the coil block assemblies according to various embodiments of the invention are shown and described as including two coil blocks, this is not essential. For example, more than two coil blocks could be stacked as shown herein to form thicker coil block assemblies with deeper cooling channels. Merely for the sake of simplicity and ease of explanation, coil block assemblies according to embodiments of the invention are shown and described as including two coil blocks. Similarly, coil block assemblies according to embodiments of the invention may be milled or otherwise formed from a single block of material. In such embodiments, “coil blocks” refer to the portions of the block resembling distinct units or pieces, as would be understood by one skilled in the art. 
         [0019]      FIGS. 3 and 4  show side views of coil block assembly  900  along first face  14  of coil block  100  and second face  112  of coil block  200 , respectively. In  FIG. 3 , it can be seen that cooling channels  140 ,  142 ,  144  are formed by the central portions of recesses  30 ,  32 ,  34  of coil block  100  and recesses  130 ,  132 ,  134  (shown in phantom) of coil block  200 .  FIG. 4  shows coil block assembly  900  along first face  114  of coil block  200 , such that recesses  30 ,  32 ,  34  of coil block  100  are shown in phantom, as they would be obscured by second face  12  thereof. 
         [0020]    Materials suitable for use in coil blocks  100 ,  200  include non-magnetic, non-metallic materials capable of withstanding the temperatures encountered within coil windings of an electrical machine. Such materials include, but are not limited to: textolite, fluoroplastics, nylons, glass-epoxy plastics, glass-fiber plastics, laminated bakelite insulation (paper-based laminate). In some embodiments of the invention, coil blocks  100 ,  200  are bonded together to form coil block assembly  900 . Such bonding may include melting and joining coil blocks  100 ,  200 , applying an adhesive therebetween, or any other known or later-developed bonding method or technique. The method or technique employed will depend, at least in part, on the materials from which coil blocks  100 ,  200  are composed. 
         [0021]      FIG. 5  shows a side view of coil block assembly  900  to illustrate how a size and/or shape of cooling channels  141 ,  143 ,  145  may be varied by offsetting coil block  100  with respect to coil block  200 . Here, coil blocks  100 ,  200  are offset such that a portion of second faces  12 ,  112  are positioned beyond first face  14 ,  114  of the opposing coil block, thereby increasing the sizes of cooling channels  141 ,  143 ,  145 , as compared to  FIG. 2 . Offsetting coil blocks  100 ,  200  in the opposite direction, such that second faces  12 ,  112  are positioned laterally within a space between first faces  14 ,  114  will decrease the sizes of cooling channels  141 ,  143 ,  145 , as compared to  FIG. 2 . 
         [0022]      FIG. 6  shows a schematic top cross-sectional view of a tooth coil  1000  comprising a stator tooth  300  surrounded by coil turns  400 . As shown in  FIG. 6 , stator tooth  300  is rectangular in cross-section, although this is not essential. Coil turns  400  include an inner turn  410  and an outer turn  420  stacked substantially parallel to a radial axis R of stator tooth  300 . As will be understood by one skilled in the art, inner turn  410  and outer turn  420  will be connected in series or in parallel. For the sake of simplicity, this is not shown in  FIG. 6 . 
         [0023]    A plurality of coil block assemblies  900 ,  902 ,  904  are positioned between inner turn  410  and outer turn  420 , forming a space  500  therebetween.  FIG. 7  shows a side cross-sectional view of tooth coil  1000 , along line A of  FIG. 6 , with a portion of outer turn  420  partially cut away for purposes of description. Airflow  150 ,  152 ,  154  circulates through space  500  ( FIG. 6 ) and through cooling channels  140 ,  142 ,  144  ( FIG. 2 ) of coil block assemblies  900 ,  902 . 
         [0024]      FIG. 8  shows a partial top cross-sectional view of airflow  150 ,  152 ,  154  though coil block assemblies  900 ,  902 . As can be seen, airflow  150 ,  152 ,  154  circulating through space  500  encounters coil block assembly  900  and passes into recesses ( 30 ,  32 ,  34  in  FIG. 2 ), through cooling channels  140 ,  142 ,  144 , and exits through recesses of coil block  200 . Airflow  150 / 152 / 154  then continues through space  500  until encountering coil block  902 , through which it passes analogously to coil block  900 . 
         [0025]    Coil block assemblies according to embodiments of the invention may be used in other configurations. For example,  FIG. 9  shows a partial top cross-sectional view of a portion of a tooth coil  2000  according to another embodiment of the invention. Here, coil turns  412 ,  422  are stacked axially, i.e., substantially perpendicular to a radial axis R of stator tooth  300 . That is, as shown in  FIG. 9 , coil turns  412 ,  422  are stacked into and out of the page. For purposes of illustration, upper coil turn  422  is shown partially cut away. 
         [0026]    Similar to the embodiment shown in  FIGS. 6 and 7 , the positioning of coil block assemblies  900 ,  902  between lower coil turn  412  and upper coil turn  422  in  FIG. 9  forms a void (not shown in  FIG. 9 ) therebetween. Airflow  150 ,  152 ,  154  circulates through the void and coil block assemblies  900 ,  902 , similar to the pattern shown in  FIG. 8 . 
         [0027]    While the coil block assemblies  900 ,  902 ,  904  in the preceding figures have been shown as comprising a pair of coil blocks  100 ,  200 , each having substantially the same shape and structure, this is not essential. It may be desirable, for example, to employ a coil block assembly having a non-rectangular cross-sectional shape and/or a coil block assembly comprising coil blocks having different shapes and/or structures. 
         [0028]    For example,  FIG. 10  shows a perspective view of a coil block  101  according to another embodiment of the invention. Here, the thickness of coil block  101  varies along its width W from a first thickness T 1  at first face  15  to a second thickness T 2  at second face  13  (shown in phantom), first thickness T 1  being greater than second thickness T 2 . 
         [0029]      FIG. 11  shows a cross-sectional top view of a coil block assembly  910  comprising a pair of opposed coil blocks  101 ,  201 . Coil block  101  is shown as in  FIG. 10 . Coil block  201  has a thickness greater at second face  113  than at first face  115 . When placed together as shown in  FIG. 11 , coil blocks  101 ,  201  give coil block assembly  910  a trapezoidal shape in cross-section. As in other embodiments of the invention described above, recesses  31 ,  131  in coil blocks  101 ,  201  form a cooling channel  147 . Airflow  151  enters cooling block assembly  910  through recess  31  of coil block  101 , passes into cooling channel  147 , and exist coil block assembly  910  through recess  131  of coil block  201 . 
         [0030]      FIG. 12  shows a partial cross-sectional top view of adjacent tooth coils  1000 ,  1001  in an electrical machine in which a coil block assembly  910  such as that in  FIG. 11  may be employed. Outer turns  420 ,  421  define a slot  600  between adjacent tooth coils  1000 ,  1001 . While substantially rectangular coil block assemblies such as those shown in  FIGS. 2-5  may be used within portions of slot  600  in which outer turns  420 ,  421  are substantially parallel, their utility in other locations is reduced. In  FIG. 12 , a coil block assembly  910  having a substantially trapezoidal shape in cross-section is located between portions of outer turns  420 ,  421  that are not parallel. As such, airflow (not shown) through slot  600  passes through coil block assembly  910  before exiting slot  600 . 
         [0031]    Situations and locations in which coil block assemblies having other shapes may be useful will be apparent to those skilled in the art and are within the scope of the invention. Similarly, the coil blocks and coil block assemblies shown above, and the contexts in which they are employed, are merely illustrative and provided for purposes of illustration and should not be considered as limiting the scope of the invention. 
         [0032]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0033]    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 related or 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 language of the claims.