Patent Publication Number: US-2022235795-A1

Title: Fan and electric machine assembly and methods therefor

Description:
BACKGROUND 
     The field of the invention relates generally to fans and, more particularly, to cooling fans for motor assemblies. 
     Many known electric machines such as electric motors generate heat during operation. At least some known motors are provided with a cooling fan rotatably coupled thereto, and the fan rotates during operation of the motor to produce air flow over the motor housing to facilitate cooling the motor. However, at least some known fans direct an insufficient volume of airflow that produces a less than optimal motor cooling effect, especially at the opposite end of the motor from the fan. 
     BRIEF DESCRIPTION 
     In one embodiment, a motor assembly having a rotational axis is provided. The motor assembly includes a motor housing comprising a plurality of cooling openings extending therethrough and defining a chamber. The motor assembly also includes a stator fixedly coupled to the motor housing and positioned within the chamber. A rotor is coupled to at least one of the motor housing and the stator, wherein the rotor is configured to rotate about the axis and is positioned within the chamber. The motor assembly also includes a fan rotatably coupled to the motor. The fan includes a first inlet side on a first axial side of the fan and a second inlet side on a second, opposing, axial side of the fan. The fan is configured to draw cooling air in a first direction through the at least one cooling opening into the first inlet side, and the fan is also configured to draw cooling air in a second, opposite direction into the second inlet side. 
     In another embodiment, a fan for a motor assembly having a rotational axis and a housing having a plurality of cooling openings is provided. The fan includes a central hub, a plurality of circumferentially-spaced spokes extending from the central hub, and a plurality of circumferentially-spaced blades coupled to the plurality of spokes in a one-to-one relationship such that a radially inner edge of each blade is positioned radially outward from the central hub. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary electric motor assembly; 
         FIG. 2  is a top view of the motor assembly shown in  FIG. 1 ; 
         FIG. 3  is a bottom view of the motor assembly shown in  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the electric motor assembly shown in  FIG. 1  taken along line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of the electric motor assembly shown in  FIG. 1  taken along line  5 - 5  in  FIG. 2 ; 
         FIG. 6  is a perspective view of the electric motor assembly shown in  FIG. 1  illustrating an exemplary fan with an exterior shroud removed; and 
         FIG. 7  is an enlarged top view of the fan and motor assembly. 
     
    
    
     DETAILED DESCRIPTION 
     The methods and systems described herein facilitate providing a motor assembly for cooling a rotating device such as a motor. The motor assembly includes a rotational axis and a motor housing comprising a plurality of cooling openings extending therethrough and defining a chamber. The motor assembly also includes a stator fixedly coupled to the motor housing and positioned within the chamber. A rotor is coupled to at least one of the motor housing and the stator, wherein the rotor is configured to rotate about the axis and is positioned within the chamber. The motor assembly also includes a fan rotatably coupled to the motor. The fan includes a first inlet side on a first axial side of the fan and a second inlet side on a second, opposing, axial side of the fan. The fan is configured to draw cooling air in a first direction through the at least one cooling opening into the first inlet side, and the fan is also configured to draw cooling air in a second, opposite direction into the second inlet side. 
     During operation, the fan rotates to draw cooling air through the housing openings and the chamber to pass around or through the stator and the rotor for cooling. More specifically, a first end frame of the housing includes a first plurality of cooling openings and a second end frame of the housing includes a second plurality of cooling openings. These openings are in flow communication through the chamber to channel cooling air through the chamber to facilitate cooling the motor. Additionally, the fan draws cooling air from the side of the fan opposite the motor such that to fan draws cooling from two opposite directions simultaneously. 
       FIG. 1  is a perspective view of an electric motor assembly  100 ,  FIG. 2  is a top view of motor assembly  100 , and  FIG. 3  is a bottom view of motor assembly  100 . Furthermore,  FIG. 4  is a cross-sectional view of electric motor assembly  100  taken along line  4 - 4  in  FIG. 3 , and  FIG. 5  is a cross-sectional view of electric motor assembly  100  taken along line  5 - 5  in  FIG. 2 . 
     In the exemplary embodiment, motor assembly  100  includes a motor housing  102  that includes a first end frame  104  and an opposing second end frame  106 . End frames  104  and  106  define a chamber  108  of housing  102  that contains motor  110  therein. More specifically, motor  110  includes a stator  112  fixedly coupled to housing  102  and a rotor  114  rotatably coupled to at least one of housing  102  and stator  112 . Stator  112  and rotor  114  are housed within chamber  108 . Motor  110  also includes a shaft  116  extending through chamber  108  and around which rotor  114  is positioned. Shaft  116  extends along a rotational axis  118  of motor assembly  110  about which rotor  114  rotates during operation of motor  110 . 
     In the exemplary embodiment, motor assembly  110  also includes a shroud  120  coupled to motor housing  102  and a fan  122  positioned between shroud  120  and second end frame  106 . Shroud  120  includes a primary inlet  124  defined in shroud  120  opposite housing  102 . Shroud  120  may also include a screen  126  extending across primary inlet  124  to restrict access to fan  122 . In the exemplary embodiment, shroud  120  further includes at least one outlet  128  through which fan  122  channels cooling air. More specifically, housing  102  may include one or more modules  130  extending radially from end frames  104  and  106 . Outlets  128  of shroud  120  are configured to channel cooling flow from within shroud  120  through or across a plurality of cooling fins  132  on modules  130  to facilitate cooling various electrical components housed within modules  130 . Additionally, second end frame  106  also includes a plurality of cooling fins  134  extending away from chamber  108  that facilitate cooling motor  110 . 
     As best shown in  FIGS. 4 and 5 , housing  102  includes a plurality of cooling openings  136  extending through housing  102  and configured to facilitate cooling motor  110 . Specifically, during operation, fan  122  rotates to draw cooling air through openings  136  and chamber  108  to pass around or through stator  112  and rotor  114  for cooling. More specifically, first end frame  104  includes a first plurality of cooling openings  138  and second end frame  106  includes a second plurality of cooling openings  140 . Openings  138  and  140  are in flow communication through chamber  108  to channel cooling air through chamber  108  to facilitate cooling motor  110 . Alternatively, end frames  104  and  106  each include a single circumferential cooling opening defined at least partially around shaft  116 . 
     In the exemplary embodiment, openings  138  and  140  are circumferentially-spaced about axis  118 . Additionally, first plurality of openings  138  in first end frame  104  are positioned radially inward of second plurality of openings  140  in second end frame  106 . 
     In the exemplary embodiment, fan  122  is operatively coupled to rotor  114  such that rotation of rotor  114  causes rotation of fan  122 . In one embodiment, fan  122  is coupled to an exterior surface of second end frame  106  and positioned outside chamber  108 . In another embodiment, fan  122  is positioned within chamber  108  and is on an inner surface side of second end frame  106 . Furthermore, in the exemplary embodiment, fan  122  includes a first inlet side  142  adjacent second end frame  106  and a second inlet side  144  adjacent shroud  120 . As such, inlets  142  and  144  are on opposing axial sides of fan  122 . 
     In operation, rotation of fan  122  causes air to enter shroud  120  through shroud inlet  124  in a first direction, and then enter an interior  146  of fan  122  through fan second inlet side  144 , which is axially aligned with shroud inlet  124 . Furthermore, the low pressure within fan interior  146  causes cooling air to flow in a second direction opposite the first direction through openings  138  in end frame  104 , into chamber  108 , through openings  140  in end frame  106 , passed cooling fins  134 , and then through first inlet side  142  into interior  146 . Fan  122  then discharges the cooling air through outlets  128  in shroud  120 . As such, fan  122  draws cooling air from two opposite directions simultaneously to provide additional cooling to motor  110 . 
     In one embodiment, rotor  114  includes a plurality of rotor openings  115  defined therethrough to enable cooling air to flow through rotor  114  in addition to around rotor  114  within chamber  108 . Similarly, in one embodiment, stator  112  may also include a plurality of stator openings  113  enable cooling air to flow through stator  112  in addition to around stator  112  within chamber  108 . In the exemplary embodiment, openings  113  and  115  are in flow communication with cooling openings  138  and  140  of first end frame 1-4 and second end frame  106 , respectively, to allow air flow through stator  112  and/or rotor  114  and through inlet  142  of fan  122 . 
     Although openings  113  and  115  are shown in  FIGS. 4 and 5  are being formed on an interior of stator  112  and rotor  114 , openings  113  and  115  may be formed at any radial location within stator  112  and rotor  114  that facilitates cooling and enables operation of motor assembly  100  as described herein. Furthermore, although motor  110  is illustrated as a radial flux motor, in some embodiments, motor  110  is an axial flux motor. 
     In the exemplary embodiment, fan  122  includes a central hub  148 , a plurality of spokes  150  extending radially from hub  148 , and a plurality of blades  152  coupled to the plurality of spokes  150  in a one-to-one relationship. Central hub  148  includes a plurality of openings  154  and terminates at the meeting of hub  148  and spokes  150 . In the exemplary embodiment, fan  122  does not include a back plate such that fan  122  is free of material between adjacent spokes  150 . More specifically, first inlet side  142  of fan  122  is defined between adjacent spokes  150 . As such, cooling air is able to flow through openings  140  in second end frame  106  and between spokes  150  into interior  146  of fan  122 . 
     As best shown in  FIG. 7 , second plurality of openings  140  in second end frame  106  are positioned radially inward of radially inner edge  158  of blades  152 . Furthermore, second plurality of openings  140  in second end frame  106  are positioned radially outward of radially outer edge  156  of central hub  148 . As such, second openings  140  are substantially radially aligned with spokes  150 . Such a configuration allows for cooling air to flow through chamber  108  and into inlet  142  of fan  122 . Additionally, openings  154  allow any cooling air that gets channeled below hub  148  to flow upward through hub  148  and into fan interior  146 . 
     Fan  122  further includes a stiffening ring  160  coupled proximate a radially outer edge  162  of blades  152 . Because fan  122  does not include a back plate that extends to blades  152 , stiffening ring  160  secures blades  152  in place and prevents twisting. 
     The methods and systems described herein facilitate providing a motor assembly for cooling a rotating device such as a motor. The motor assembly includes a rotational axis and a motor housing comprising a plurality of cooling openings extending therethrough and defining a chamber. The motor assembly also includes a stator fixedly coupled to the motor housing and positioned within the chamber. A rotor is coupled to at least one of the motor housing and the stator, wherein the rotor is configured to rotate about the axis and is positioned within the chamber. The motor assembly also includes a fan rotatably coupled to the motor. The fan includes a first inlet side on a first axial side of the fan and a second inlet side on a second, opposing, axial side of the fan. The fan is configured to draw cooling air in a first direction through the at least one cooling opening into the first inlet side, and the fan is also configured to draw cooling air in a second, opposite direction into the second inlet side. 
     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.