Abstract:
This disclosure proposes designs for a fan shroud that dissipates thermal energy from a motor using a single, externally-powered fan design. Examples of the proposed fan shroud allow the cooling fluid to achieve maximum velocity at a position at which the fan shroud exposes the flow to cooler ambient air that surrounds the fan shroud/motor assembly. In this configuration, the high-velocity cooling fluid draws the cooler ambient air towards the surface of the motor, which, in turn, increases the thermal capacity of the moving cooling fluid to dissipate more thermal energy from the motor.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to structures that dissipate thermal energy and, in particular, to embodiments of a fan shroud that disperse cooling fluid about a motor, e.g., for use to actuate the pitch of a turbine wind blade. 
         [0002]    Motors that operate under prolonged conditions can generate excessive heat. The high temperatures that result from these conditions can reduce performance and shorten the overall lifespan of the motor. To avoid these problems, many motors incorporate one or more fans that move a cooling fluid (e.g., air) over the outer surface of the motor to draw off and disperse thermal energy. These fans may couple with a shroud, which helps direct a majority of the moving fluid towards the outer surface of the motor. 
         [0003]    Designs that improve cooling efficiency and/or cooling rates often increase the amount of cooling fluid that comes in proximity to the outer surface of the motor. For example, some designs utilize additional fans to disperse more fluid into the shroud. Other designs may increase the size (e.g., flow rate) of the fan to meet cooling requirements and demands. When changes to the fan are not practical, however, new designs may introduce changes in the shroud to provide geometry that harnesses the cooling fluid in a manner that facilitates thermal dissipation. Unfortunately, although each of these design choices afford better thermal energy control, the improvements to enhance performance may add costs and complexity to the design that run contrary to product commercialization and budgetary constraints. 
         [0004]    The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    This disclosure proposes designs for a fan shroud that dissipates thermal energy from a motor using a single fan design. Examples of the proposed fan shroud allow the cooling fluid to achieve maximum velocity at a position at which the fan shroud exposes the flow to cooler ambient air that surrounds the fan shroud/motor assembly. In this configuration, the high-velocity cooling fluid draws the cooler ambient air towards the surface of the motor, which, in turn, increases the thermal capacity of the moving cooling fluid to dissipate more thermal energy from the motor. 
         [0006]    This disclosure describes, in one embodiment, a fan shroud for a motor. The fan shroud a top element, a first side element, and a front element. The first side element and the front element couple with the top element at a first end. The first side element terminates at a second end that is spaced apart from the motor a first side distance to form a first side gap. The front element has a front contoured edge proximate to and spaced apart from the motor a first front distance to form a front gap. The first side distance is the same has the first front distance. 
         [0007]    This disclosure also describes, in one embodiment, a fan shroud for a motor. The fan shroud has a top element and a pair of side elements that couple with the top element at a first end and terminate at a second end that is spaced apart from the motor a first side distance and a second side distance to form, respectively, a first side gap and a second side gap. The fan shroud also has a front element that couples with the top element and has a front contoured edge proximate to and spaced apart from the motor a first front distance to form a front gap. The fan shroud further has a back element that couples with the top element and has a back contoured end proximate to and spaced apart from the motor a first back distance to form a back gap. In one example, the first side distance is the same as at least one of the first front distance and the first back distance. 
         [0008]    This disclosure further describes, in one embodiment, a motor assembly with a motor with a central motor axis. The motor assembly includes a motor with a central motor axis. The motor also includes a fan shroud coupled to the motor. The fan shroud comprises a first side element and a front element. The first side element terminates at a second end that is spaced apart from the motor a first side distance to form a first side gap. The front element has a front contoured edge proximate to and spaced apart from the motor a first front distance to form a front gap. The first side distance is the same as the first front distance. 
         [0009]    This brief description of the invention is intended only to provide a brief overview of the subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which: 
           [0011]      FIG. 1  depicts a perspective view of an exemplary embodiment of a fan shroud as part of a motor assembly; 
           [0012]      FIG. 2  depicts a perspective view of an exemplary embodiment of a fan shroud; 
           [0013]      FIG. 3  depicts a front view of the fan shroud of  FIG. 2 ; 
           [0014]      FIG. 4  depicts a perspective view of the fan shroud of  FIG. 2  as part of a motor assembly; 
           [0015]      FIG. 5  depicts a front view of the motor assembly of  FIG. 4 ; 
           [0016]      FIG. 6  depicts a flow pattern of cooling fluid that can occur on the motor assembly of  FIG. 5 ; 
           [0017]      FIG. 7  depicts a side view of the motor assembly of  FIG. 4  to illustrate the flow pattern of cooling fluid of  FIG. 6 ; and 
           [0018]      FIG. 8  depicts an example of a material blank that can be used to form an exemplary embodiment of a fan shroud. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 1  illustrates an exemplary embodiment of a fan shroud  100  that can improve cooling efficiency to maintain the temperature of a motor. The fan shroud  100  is part of a motor assembly  102 . Examples of the motor assembly  102  find use in a variety of applications, namely, to adjust the position of rotor blades found in wind turbine systems. In the example of  FIG. 1 , the motor assembly  102  has a motor  104  with a central motor axis  108 . One or more fasteners  110  couple the fan shroud  100  to the motor  104 . This configuration mounts a fan  112 , which can secure to the fan shroud  100 , in position on the motor  104 . 
         [0020]    Implementation of the motor assembly  102  as part of a wind turbine system often requires the motor  104  to hold the rotor blades in one or more desired positions. To fulfill this requirement, the wind turbine system often maintains power on the motor  104  for extended periods of time. Energizing the motor  104  in this manner generates heat. Operation of the fan  112  dissipates the heat from the motor assembly  102  by flowing cooling fluid (e.g., air) into the fan shroud  100  and proximate the motor  104 . 
         [0021]    As set forth more below, construction of the fan shroud  100  facilitates cooling by improving flow characteristics of the cooling fluid. Embodiments of the fan shroud  100  form gaps with the motor  104  that allow cooling fluid to exit the shroud  100 . In one embodiment, the gaps are sized and configured to prevent formation of vortexes as the cooling fluid disperses from the fan shroud  100 . This feature allows the cooling fluid to flow closely to the motor  104 , thus increasing dissipation of thermal energy from the motor  104  during operation. In other embodiments, the fan shroud  100  has features that allow the cooling fluid to achieve maximum velocity at locations along the motor  104 . These embodiments take advantage of the high velocity of the moving cooling fluid to draw additional, cooler fluid from the environment outside of the fan shroud  100  into the flowstreams that form about the motor  104 . The addition of this cooler fluid expands the thermal capacity of the cooling fluid to increase the amount of heat that can dissipate from the motor  104 , e.g., during extended operation of the motor assembly  102 . 
         [0022]    The fan shroud  100  can embody a unitary or monolithic structure, e.g., that is formed from sheet metal (e.g., steel, stainless steel, aluminum, etc.). The materials of construction may comprise thermally conductive materials that can further enhance thermal dissipation. In other examples, construction of the fan shroud  100  can incorporate a number of individual pieces that secure together using known fasteners (e.g., screws and bolts) and techniques (e.g., welds). 
         [0023]      FIG. 2  illustrates another exemplary embodiment of a fan shroud  200  for use in a motor assembly  202 . The fan shroud  200  has a top element  214  and a plurality of side elements (e.g., a first side element  216  and a second side element  218 ). The fan shroud  200  also has a front element  220  and a back element  222 . As also shown in  FIG. 2 , the top element  214  has an aperture  224 . The front element  220  and the back element  222  have an edge  226  that, in one configuration, has a contour that matches the contour and/or shape of the outer profile of the motor  204 . Examples of outer profile can form a circular shape, e.g., wherein the motor  204  has a generally round and/or cylindrical configuration. 
         [0024]    The fan shroud  200  also comprises one or more mounting features (e.g., a first mounting feature  228  and a second mounting feature  230 ) that secure to one or more of the front element  220  and the back element  222 . In one embodiment, the mounting features  228 ,  230  are found on both the front element  220  and the back element  222 . The mounting features  228 ,  230  can form an L-bracket with a first portion  232  that extends radially and a second portion  234  that extends axially, e.g., relative to the axis of the motor (e.g., central motor axis  108  of  FIG. 1 ). The first portion  232  can secure with the fan shroud  200 , e.g., to one of the front element  220  and the back element  222 . The second portion  234  can have an opening  236  that can receive a fastener (e.g., fasteners  110  of  FIG. 1 ) to secure the fan shroud  200  in position on the motor (e.g., motor  104  of  FIG. 1 ), as shown in the example of  FIG. 1  above. 
         [0025]      FIG. 3  illustrates a front view of the fan shroud  200  of  FIG. 2 . The fan shroud  200  has a shroud axis  238  and a centerline  240  that extends through the shroud axis  238 . In one example, the shroud axis  238  forms a center point for the shape that defines the contour of the edge  226 . The side elements  216 ,  218  secure to the top element  214  at a first end  242  and terminate at a second end  244 . As shown in  FIG. 3 , the ends  244  of the first side element  216  and the second side element  218  subtend an angle  246  about the shroud axis  238 . 
         [0026]    In one embodiment, the fan shroud  200  is symmetric about the centerline  240 , e.g., where the first side element  216  and the second side element  218  are positioned an equal distance with respect to the centerline  240 . This configuration locates the second end  244  of the first side element  216  diametrically opposite of the second end  244  of the second side element  218 . However, in other configurations, the fan shroud  200  can forgo such symmetry and still promote optimal flow dynamics of the cooling fluid to improve cooling efficiency, as discussed above. To this end, values for the angle  246  can vary, e.g., greater than and/or less than 90° and/or in a range of 100° to 180°. This disclosure contemplates that the angle  246  includes reasonable manufacturing tolerances understood by artisans familiar with relevant techniques to manufacture embodiments of the fan shrouds described herein. 
         [0027]    The side elements  216 ,  218  can take a variety of shapes. For example, the side elements  216 ,  218  can form a plane and/or a planar surface that extends from the first end  242  to the second end  244  and axially from the front element  114  to the back element  116 . In other embodiments, the side elements  216 ,  218  can form a curvilinear surface, e.g., that curves inward and/or outward relative to the centerline  240  from the first end  242  to the second end  244 . This curvature can form concave and/or convex feature in the side elements  216 ,  218 . Selection of the appropriate shape of the side elements  216 ,  218  can vary as necessary to tune the flow characteristics (e.g., velocity) of the air transiting out of the fan shroud  200 , as disclosed herein. 
         [0028]      FIGS. 4 ,  5 ,  6 , and  7  illustrate the fan shroud  200  in position on the motor  204  of the motor assembly  202 . In the perspective view of  FIG. 4 , the shroud axis  238  aligns with the central motor axis  208  of the motor  204 . The first side element  216  and the second side element  218  form side gaps (e.g., a first side gap  248  and a second side gap  250 ) where the side element  216 ,  218  is spaced apart from the motor  204  at the second end  244 . The edge  226  of the front element  220  and the back element  222  also forms a front gap  252  and a back gap, identified generally by the numeral  254 . The configuration of the gaps  248 ,  250 ,  252 ,  254  allow cooling fluid to exit the fan shroud  200 , e.g., during operation of the fan  212 . 
         [0029]      FIG. 5  shows a front view of the fan shroud  200  of  FIG. 4 . As can be seen in  FIG. 5 , the configuration of the side gaps  248 ,  250  provide space between the side elements  216 ,  218  and the motor  204 . The amount of space can be defined at the second end  244  by a first side distance between the first side element  216  and the motor  204  and a second side distance between the second side element  216  and the motor  204 . In one example, the first side distance and/or the second side distance are axially constant from the front (e.g., the front element  220 ) to the back (e.g., the back element  222 ) of the fan shroud  200 . This feature maintains the space axially along the central axis  208  of the motor  204 . The configuration of the front gap  252  and the back gap  254  provide space between the edge  226  of the front element  220  (and the back element  222  ( FIG. 4 )) and the motor  204 . The amount of space can be defined by a first front distance between the edge  226  of the front element  220  and the motor  204  and a first back distance between the edge  226  of the back element  222  and the motor  204 . The shape and contour of the edge  226  can determine the values of first front distance and the first back distance. 
         [0030]    Selection of the distances (e.g., the first side distance, the second side distance, the first front distance, and the first back distance) can determine how the fluid disperses about the motor  204 . In one implementation, the space formed by the first gap  248 , the second gap  250 , the front gap  252 , and the back gap  254  are the same, i.e., the first side distance, the second side distance, the first front distance, and the first back distance are the same. 
         [0031]      FIGS. 6 and 7  illustrate one exemplary flow pattern that develops using embodiments of the fan shroud disclosed herein. In  FIG. 6 , the flow pattern includes a plurality of primary side airstreams (e.g., a first primary side airstream  256  and a second primary side airstream  258 ). A plurality of peripheral side airstreams (e.g. a first peripheral side airstream  260  and a second peripheral side airstream  262 ) can enter the primary side airstreams  256 ,  258  near the second end  244  of the side elements  216 ,  218 .  FIG. 7  depicts a side view of the fan shroud  200  of  FIG. 4  to illustrate additional features of the exemplary flow pattern. In  FIG. 7 , the flow pattern further includes a plurality of primary front airstreams  264  and a plurality of primary back airstreams  266 . 
         [0032]    As shown in  FIGS. 6 and 7 , the configuration of the fan shroud  200  allows cooling fluid to exit the fan shroud  200  via the side, front, and back as the cooling fluid traverses the motor  204 . When the distances are the same (and/or have similar values, the cooling fluid flows evenly out of the fan shroud  200  via the gaps  248 ,  250 ,  252 ,  254 . As discussed above, this feature allows the cooling fluid to flow close to the motor  204  for distances farther away from the fan shroud to improve heat dissipation that cools the motor  204 . In one example, the primary side airstreams  256 ,  258  exit the fan shroud  200  at a maximum velocity and at a low pressure. These characteristics of the primary side airstreams  256 ,  258  permits cooler fluid (e.g., peripheral side airstreams  260 ,  262 ) from outside of the fan shroud  200  to mix with the cooling fluid to improve thermal dissipation during operation of the fan  212 . This feature introduces additional cooling fluid in proximity of the surface of the motor  204  to achieve optimal heat transfer for a given flow rate and pressure drop without requiring additional fans or other air moving devices. 
         [0033]      FIG. 8  illustrates an example of a material blank  300  that can be used to form the fan shrouds  100 ,  200  of  FIGS. 1 ,  2 ,  3 ,  4 ,  5 ,  6 , and  7 . Examples of the material blank  300  can embody a square and/or generally rectangular piece of sheet metal having a material thickness of from about 0.5 mm to about 10 mm. As shown in  FIG. 8 , this material can be cut, e.g., laser cut, to form one or more of the features of the fan shrouds contemplated herein. For example, the laser cutting can create an opening  302 , one or more radial surfaces (e.g., a first radial surface  304  and a second radial surface  306 ), and tabs  308  with penetrating apertures  310 . In one embodiment, the material blank  300  can have a number of bend lines  312 , about which the material of the material blank  300  is shaped and formed to form the general shape and characteristics of the fan shrouds discussed above. 
         [0034]    As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
         [0035]    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 language of the claims.