Patent Publication Number: US-2018051409-A1

Title: Fan assembly for a dryer appliance

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to fan assemblies for appliances, such as dryer appliances. 
     BACKGROUND OF THE INVENTION 
     Dryer appliances generally include a cabinet with a drum rotatably mounted therein. A motor can selectively rotate the drum during operation of the dryer appliance, e.g., to tumble articles located within a chamber defined by the drum. Dryer appliances also generally include a heater assembly that passes heated air through the chamber of the drum in order to dry moisture laden articles disposed within the chamber. 
     To circulate heated air, certain dryer appliances include a fan assembly positioned within a housing. During operation of the dryer appliance, an impeller of the fan assembly urges a flow of heated air into the chamber of the drum. Such heated air absorbs moisture from articles disposed within the chamber. The impeller also urges moisture laden air out of the chamber through a vent. The vent can be connected to household ductwork that directs the moisture laden air outdoors. 
     Performance of a dryer appliance can be affected by the flow of heated air. For example, dryer appliance performance can be improved by generating a large volume of heated air. Conversely, dryer appliance performance can be negatively affected if the heating assembly generates a low volume of heated air. 
     To improve dryer performance, a size of the impeller can be increased. However, space with a dryer appliance is generally limited or constrained. Thus, increasing a size of the impeller can be difficult. To improve dryer performance, certain dryer appliances include a second motor configured to rotate the impeller. However, motors can be expensive, and adding the second motor to the dryer appliance can increase the cost of the dryer appliance. 
     Accordingly, a dryer appliance with features for improving air flow through the dryer appliance would be useful. In particular, a dryer appliance with features for improving air flow through the dryer appliance without requiring a relatively large impeller or adding a second motor to the dryer appliance would be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present subject matter provides a fan assembly for a dryer appliance. The fan assembly includes an inlet duct that fluidly couples a chamber of the dryer appliance to a fan inlet. The inlet duct includes one or more guide vanes that are configured to direct the air in a manner that improves the pressure rise across the fan, thereby improving appliance performance. For example, the guide vanes may be positioned and oriented to generate a negative pre-swirl of the flow of air, such that the flow of air enters the fan inlet rotating in a direction opposite the direction of rotation of an impeller. Additionally, or alternatively, one or more guide vanes may be positioned and oriented to generate a laminar flow of otherwise turbulent air from the chamber of the dryer appliance. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention. 
     In a first exemplary embodiment, a dryer appliance is provided. The dryer appliance defines a vertical direction. The dryer appliance includes a cabinet defining a vent; a drum rotatably mounted within the cabinet, the drum defining a chamber for receipt of articles for drying; a motor; and a fan assembly defining an axial direction, a radial direction, and a circumferential direction. The fan assembly includes an impeller, the impeller being in mechanical communication with the motor and rotatable about the axial direction to urge a flow of air from the chamber of the drum to the vent of the cabinet. An inlet duct extends between and fluidly couples the chamber and a fan inlet. A guide vane is positioned within the inlet duct and oriented for directing the flow of air within the inlet duct, the guide vane defining an upstream end proximate the chamber and a downstream end proximate the fan inlet, the downstream end of the guide vane defining a tangent line. An exhaust duct extends between and fluidly couples a fan outlet and the vent of the cabinet. 
     In a second exemplary embodiment, a fan assembly for urging a flow of air from a chamber of a dryer appliance is provided. The dryer appliance defines a vertical direction, a lateral direction, and a transverse direction. The fan assembly includes an impeller being rotatable about an axis of rotation in a direction of rotation, the axis of rotation being substantially parallel to the transverse direction. An inlet duct extends between and fluidly couples the chamber and a fan inlet, the inlet duct being defined by a first side wall and a second side wall separated along the transverse direction and a top wall and a bottom wall separated along the vertical direction. A guide vane extends between the first side wall and the second side wall of the inlet duct, the guide vane defining an upstream end proximate the chamber and a downstream end proximate the fan inlet, the downstream end of the guide vane defining a tangent line that substantially aligns with a primary direction of the flow of air. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures. 
         FIG. 1  provides a perspective view of a dryer appliance according to an exemplary embodiment of the present subject matter. 
         FIG. 2  provides a perspective view of the exemplary dryer appliance of  FIG. 1  with a portion of a cabinet of the exemplary dryer appliance removed to reveal certain internal components of the exemplary dryer appliance. 
         FIG. 3  provides a perspective view of a fan assembly according to an exemplary embodiment of the present subject matter. 
         FIG. 4  provides a front view of an impeller and an exhaust duct of the exemplary fan assembly of  FIG. 3 . 
         FIG. 5  provides a front cross sectional view of an inlet duct and a guide vane of the exemplary fan assembly of  FIG. 3 . 
         FIG. 6  provides a plot illustrating the pressure rise generated by the exemplary fan assembly of  FIG. 3  with and without the exemplary guide vane of  FIG. 5 . 
         FIG. 7  provides a front cross sectional view of the inlet duct and a plurality of guide vanes according to an alternative exemplary embodiment of the present subject matter. 
         FIG. 8  provides a plot illustrating the pressure rise generated by the exemplary fan assembly of  FIG. 3  with and without the plurality of guide vanes of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     As used herein, the term “article” may refer to but need not be limited to fabrics, textiles, garments (or clothing), and linens. Furthermore, the term “load” or “laundry load” refers to the combination of articles that may be washed together in a washing machine or dried together in a laundry dryer (i.e., a clothes dryer) and may include a mixture of different or similar articles of different or similar types and kinds of fabrics, textiles, garments and linens within a particular laundering process. 
       FIGS. 1 and 2  illustrate a dryer appliance  10  according to an exemplary embodiment of the present subject matter. While described in the context of a specific embodiment of dryer appliance  10 , using the teachings disclosed herein it will be understood that dryer appliance  10  is provided by way of example only. Other dryer appliances having different appearances and different features may also be utilized with the present subject matter as well. For example, dryer appliance  10  illustrated in  FIGS. 1 and 2  is a gas dryer appliance with a combustion chamber  36 . In alternative exemplary embodiments, dryer appliance  10  may be an electric dryer appliance with electric heating elements replacing combustion chamber  36 . 
     Dryer appliance  10  generally defines a vertical direction V, a lateral direction L, and a transverse direction T, which are mutually perpendicular with one another, such that an orthogonal coordinate system is generally defined. Dryer appliance  10  includes a cabinet  12  having a front panel  14  and a rear panel  16  spaced apart from each other along the transverse direction T. In addition, cabinet  12  includes a pair of side panels  18  and  20  spaced apart from each other by front and rear panels  14  and  16  along the lateral direction L. A bottom panel  22  and a top cover  24  are also spaced apart along the vertical direction V. Within cabinet  12  is a drum or container  26  mounted for rotation about an axis that is substantially parallel with the transverse direction T. Drum  26  is generally cylindrical and defines a chamber  27  for receipt of damp articles. 
     Drum  26  also defines an opening  29  for permitting access to the chamber  27  of drum  26 . Opening  29  of drum  26 , e.g., permits loading and unloading of clothing articles and other fabrics from chamber  27  of drum  26 . A door  33  is rotatably mounted at opening  29  and selectively hinders access to chamber  27  of drum  26  through opening  29 . 
     Drum  26  includes a rear wall  25  rotatably supported within cabinet  12  by a suitable fixed bearing. Rear wall  25  can be fixed or can be rotatable. A motor  28  rotates the drum  26  about the transverse direction T through a pulley  30  and a belt  31 . Motor  28  is also in mechanical communication with a fan or air handler  42  such that motor  28  rotates an impeller  43 , e.g., a centrifugal impeller, of air handler  42 . Air handler  42  is configured for drawing air through chamber  27  of drum  26 , e.g., in order to dry articles located therein as discussed in greater detail below. In alternative exemplary embodiments, dryer appliance  10  may include an additional motor (not shown) for rotating impeller  43  of air handler  42  independently of drum  26 . 
     Drum  26  is configured to receive heated air that has been heated by a heater assembly  34 , e.g., in order to dry damp articles disposed within chamber  27  of drum  26 . Heater assembly  34  includes a combustion chamber  36 . As discussed above, during operation of dryer appliance  10 , motor  28  rotates drum  26  and impeller  43  of air handler  42  such that air handler  42  draws air through chamber  27  of drum  26  when motor  28  rotates impeller  43 . In particular, ambient air, shown with arrow A a , enters combustion chamber  36  via an inlet  38  due to air handler  42  urging such ambient air A a  into inlet  38 . Such ambient air A a  is heated within combustion chamber  36  and exits combustion chamber  36  as heated air, shown with arrow A h . Air handler  42  draws such heated air A h  through a back duct  40  to drum  26 . The heated air A h  enters drum  26  through a plurality of holes  32  defined in rear wall  25  of drum  26 . 
     Within chamber  27 , the heated air A h  can accumulate moisture, e.g., from damp articles disposed within chamber  27 . In turn, air handler  42  draws moisture laden air, shown as arrow A m , through a screen filter  44  which traps lint particles. Such moisture laden air A m  then enters a front duct  46  and is passed through air handler  42  to an exhaust duct  48 . From exhaust duct  48 , such moisture laden air A m  passes out of clothes dryer  10  through a vent  49  defined by cabinet  12 . 
     Front duct  46  and exhaust duct  48  form a conduit  47  that extends between and connects chamber  27  of drum  26  and vent  49 . Conduit  47  places chamber  27  of drum  26  and vent  49  in fluid communication in order to permit moisture laden air A m  to exit dryer appliance  10 . Air handler  42  is in fluid communication with conduit  47 , and impeller  43  of air handler  42  is positioned within conduit  47 . 
     A cycle selector knob  50  is mounted on a cabinet backsplash  52  and is in communication with a controller  54 . Signals generated in controller  54  operate motor  28  and heater assembly  34  in response to a position of selector knob  50 . Alternatively, a touch screen type interface may be provided. As used herein, “processing device” or “controller” may refer to one or more microprocessors or semiconductor devices and is not restricted necessarily to a single element. The processing device can be programmed to operate dryer appliance  10 . The processing device may include, or be associated with, one or memory elements such as e.g., electrically erasable, programmable read only memory (EEPROM). 
       FIG. 3  provides a perspective view of a fan assembly  100  according to an exemplary embodiment of the present subject matter. Fan assembly  100  may be used in any suitable dryer appliance. For example, fan assembly  100  may be used in dryer appliance  10 , e.g., as air handler  42  ( FIG. 2 ). Thus, fan assembly  100  may be positioned within cabinet  12 , e.g., at front duct  46 , such that fan assembly  100  draws in and receives moisture laden air A m  from chamber  27  of drum  26 . As discussed in greater detail below, fan assembly  100  includes features for increasing a pressure rise and flow rate of a flow of air F ( FIG. 5 ) passing through fan assembly  100 . Performance of dryer appliance  10  may be improved by increasing the pressure rise and flow rate of the flow of air F through fan assembly  100 , as will be understood by those skilled in the art. 
     Referring now generally to  FIGS. 3 and 4 , fan assembly  100  includes an inlet duct  102 , a fan housing  104 , and an exhaust duct  106 . Fan housing  104  may define a fan inlet  110  and a fan outlet  112 , and may generally couple inlet duct  102  and exhaust duct  106 , e.g., to form a single conduit such as conduit  47  ( FIG. 2 ). More specifically, inlet duct  102  extends between and fluidly couples chamber  27  and fan inlet  110 , and exhaust duct  106  extends between and fluidly couples fan outlet  112  and vent  49  of cabinet  12 . In this manner, fan assembly  100  provides a continuous flow path for directing the flow of air F, e.g., including moisture laden air A m , from chamber  27  and out of vent  49 . 
     As shown in  FIG. 3 , according to the exemplary embodiment, fan assembly  100  generally defines an axial direction A, e.g., that is substantially parallel to the transverse direction T of dryer appliance  10 . Fan assembly further defines a radial direction R that extends perpendicular to the axial direction A and a circumferential direction C that extends around the axial direction A in a plane defined by the radial direction R. Fan assembly  100  may further include an impeller  118  that is rotatably mounted within fan housing  104  and has an axis of rotation extending substantially parallel to the axial direction A. As used herein, when used to specify a directional orientation, “substantially” is intended to refer to within ten degrees of the stated direction. 
     As illustrated, fan housing  104  defines a volute  120  of fan housing  104  that is sized and configured for receiving impeller  118 . Impeller  118  includes a base plate  122  and a plurality of blades  124  extending therefrom. More specifically, the plurality of blades  124  extend from base plate  122  toward the fan inlet  110  substantially along the axial direction A. Base plate  122  and blades  124  thereby define a plurality of passages  126  for directing the flow of air F during rotation of impeller  118  about the axial direction A. Blades  124  are spaced apart from each other, e.g., along the circumferential direction C. In particular, blades  124  may be spaced apart from each other such that blades  124  are uniformly dispersed or distributed along the circumferential direction C. Blades  124  may be any size, shape, and orientation suitable for drawing the flow of air F in through fan inlet  110  during rotation of impeller  118  about the axial direction A. For example, as illustrated, each of the plurality of blades  124  define a concave surface  134  oriented toward a direction of rotation (indicated by arrow  132  in  FIG. 4 ) of the impeller  118 . 
     Impeller  118  may be placed in mechanical communication with a motor, such as motor  28 , that selectively rotates impeller  118  about an axial direction A within fan housing  104 . For example, according to the illustrated embodiment, base plate  122  has a substantially circular shape, e.g., in a plane that is perpendicular to the axial direction A, such that base plate  122  is substantially disk-shaped. Base plate  122  includes a mounting feature  128  for mounting base plate  122  to a motor, such as motor  28 . Mounting feature  128  is positioned at a center  130  of base plate  122  and can be any suitable mechanism for mounting impeller  118  to motor  28 . For example, mounting feature  128  may include threads for securing impeller  118  to motor  28 . In this manner, impeller  118  is rotated about axis of rotation in the direction of rotation  132 . In this manner, impeller  118  may draw the flow of air F into impeller  118  along the axial direction A. 
     During operation of fan assembly  100 , impeller  118  may rotate about the axial direction A within volute  120  of fan housing  104  such that impeller  118  draws the flow of air F into fan housing  104  via fan inlet  110 . In addition, impeller  118  may urge the flow of air F through fan housing  104  to fan outlet  112  and exhaust duct  106  during operation of fan assembly  100 . More specifically, the flow of air F may flow into fan housing  104  flowing along a direction that is substantially parallel to the axial direction A. Within volute  120 , the flow of air F may be urged outward along the radial direction R, along directions that are perpendicular to the axial direction A. 
     Inlet duct  102 , fan housing  104 , and exhaust duct  106  may be constructed of or with any suitable material. For example, these components may be constructed of or with a single continuous or integral piece of plastic. Alternatively, inlet duct  102 , fan housing  104 , and exhaust duct  106  may be separate parts that are mechanically joined, e.g., by using mechanical fasteners or by welding. According to alternative exemplary embodiments, these components may also be constructed of a metal, such as steel. 
     Referring now generally to  FIGS. 3 through 8 , fan assembly  100  may include features for increasing the pressure rise and flow rate across fan assembly  100 . In addition, or alternatively, fan assembly  100  may include features for reducing the likelihood of a stall condition or improving flow stability of fan assembly  100 . As used herein, “stall” is intended to refer to a dip on the fan curve that corresponds to instability in operation due to separation of airflow along the blades of a fan. These features will be described in detail below. 
     As illustrated in  FIG. 5 , fan assembly  100  includes a guide vane  150  positioned within inlet duct  102  and oriented for directing the flow of air F within inlet duct  102 . Guide vane  150  defines an upstream end  152  proximate chamber  27  and a downstream end  154  proximate fan inlet  110 . The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the flow of air F flows, and “downstream” refers to the direction to which the flow of air F flows. 
     As illustrated in  FIG. 5 , downstream end  154  of guide vane  150  defines a tangent line  156 . Notably, because guide vane  150  directs the flow of air F, tangent line  156  substantially corresponds to the primary direction of the flow of air F off guide vane  150 . In order to capture the flow of air F and direct it toward fan inlet  110 , inlet duct  102  defines an inlet chamber  160 . Inlet chamber  160  is generally bounded by a curved end wall  162  that is configured to capture the flow of air F. More specifically, the curved end wall  162  may include a top portion  164  that is disposed above a bottom portion  166  along the vertical direction V. Inlet chamber  160  is adjacent fan inlet  110  along the axial direction A and corresponds substantially in shape with impeller  118 . According to the illustrated embodiment, guide vane  150  is positioned entirely within inlet duct  102  outside of inlet chamber  160 . In this manner, guide vane  150  redirects the flow of air F into inlet chamber  160  along a specific trajectory as described below. However, according to alternative embodiments, guide vane  150  may extend into inlet chamber  160 . 
     According to an exemplary embodiment, guide vane  150  is positioned and oriented for directing the flow of air F onto or towards top portion  164  of curved end wall  162 . In this manner, as shown in  FIG. 5 , the flow of air F swirls within inlet chamber  160  in a direction opposite a direction of rotation  132  of impeller  118 . According to an exemplary embodiment, guide vane  150  may be positioned such that tangent line  156  intersects at least one of the plurality of blades  124  substantially perpendicular to concave surface  134 , e.g., when viewed in a plane that is perpendicular to the axial direction A. More specifically, the flow of air F may flow into inlet chamber  160  such that its trajectory would perpendicularly strike concave surface  134  if traveling along the same plane along the axial direction A. According to another embodiment, tangent line  156  may generally intersect impeller  118  proximate top portion  164  of curved end wall  162 . 
     According to various embodiments of the present subject matter, guide vane  150  may be any suitable size and shape. In addition, one or multiple guide vanes may be positioned and oriented in any suitable manner to achieve the results described. For example, guide vane  150  may define a length along the lateral direction L that is approximately the same as the diameter of impeller  118 . Alternatively, the length of guide vane  150  along the lateral direction L may be shorter or longer than the diameter of impeller  118 . For example, according to the illustrated embodiment, the length of guide vane  150  along the lateral direction L is approximately two times the diameter of impeller  118 . 
     Guide vane  150  may extend across a depth of inlet duct  110 . More specifically, inlet duct  110  may include a first side wall  170  ( FIG. 3 ) and a second side wall  172  ( FIG. 5 ) separated along the axial direction A. In addition, inlet duct  110  may include a bottom wall  174  and a top wall  176  separated along the vertical direction V. The depth of inlet duct  110  may be defined along the axial direction A between first side wall  170  and second side wall  172 . Guide vane  150  may generally define a concave surface  180  that is oriented substantially in the vertical direction V (e.g., and/or faces screen filter  44  or chamber  27 ) such that it captures a large portion of the flow of air F that is flowing through inlet duct  102 . According to the illustrated embodiment, bottom wall  174  is curved and is designed to redirect the flow of air F, which enters inlet duct  102  with a substantially vertical trajectory, toward fan inlet  110 . Guide vane  150  may be positioned and oriented such that upstream end  152  is positioned closer to bottom wall  174  than downstream end  154 . In this manner, guide vane  150  is configured to turn the flow of air F more than bottom wall  174 , lifting the flow of air F up to direct at least a portion of the flow of air F along the trajectory described above for generating a negative pre-swirl. 
     According to the illustrated embodiment, guide vane  150  always extends in a plane that is substantially perpendicular to an inner surface of first sidewall  170 . In this manner, guide vane  150  generally directs the flow of air F in a plane perpendicular to the axial direction A, but has little effect on the direction of flow along the axial direction A. However, according to alternative embodiments, guide vane  150  may twist or extend along a plane that is not perpendicular to the inner surface of first side wall  170 . For example, according to an exemplary embodiment, guide vane  150  may twist about an axis parallel to the radial direction R or may extend from first side wall  150  at an angle of approximately sixty degrees. 
     Operation of dryer appliance  10  having a fan assembly  100  and guide vane  150  according to exemplary embodiment illustrated in  FIG. 5  results in improved appliance performance. For example,  FIG. 6  illustrates fan curves of fan assembly  100  both with guide vane  150  configured to generate a negative pre-swirl in inlet chamber  160  and without guide vane  150  (identified as “baseline” curve). The fan curves illustrate the pressure rise across fan assembly  100  versus flow rate through the fan assembly  100 . 
     As illustrated in  FIG. 6 , the presence of guide vane  150  within inlet duct  102  results in a larger flow rate or pressure rise across fan assembly  100 . Notably, this increased pressure rise results in improved performance of dryer appliance  10 . In addition, the stall point of the baseline curve is smoothed out, resulting in more stable and improved operation of fan assembly  100  in the stall region of the fan curve. These improvements may be due, at least in part, to the fact that guide vane  150  guides the flow of air F to generate a negative pre-swirl within the inlet chamber  160 . The flow of air F is then drawn along the axial direction A through fan inlet  110  while still rotating opposite the direction of rotation  132  of impeller  118  ( FIG. 5 ). As a result, the flow turning angle is increased as the flow of air F impacts concave surface  134  of blades  124  in a direction close to perpendicular. Blades  124  must then turn the flow of air F through a large turning angle to discharge it through passages  126  and out volute  120 . This large turning angle results in increased pressure rise and improved dryer performance. 
     Although  FIG. 5  illustrates the use of a single guide vane  150  for generating a negative pre-swirl flow of air F within inlet chamber  160 , it should be appreciated that this is only an exemplary configuration used for the purpose of explaining aspects of the present subject matter. Guide vane  150  may be a different size, shape, position, orientation, material, etc. Moreover, more than one guide vane may be used to direct the flow of air F. Other configurations are also possible. 
     Referring now to  FIG. 7 , an alternative embodiment of fan assembly  100  will be described which may be used to improve performance of fan assembly  100  in the stall region of the fan curve. For this exemplary embodiment, fan assembly  100  is similar to that described above except that guide vane  150  is removed and replaced by guide vanes  190 . Guide vanes  190  may be similar to guide vane  150  in size, shape, material, etc., but are generally positioned and oriented to straighten the flow of air F directly into or towards a center  192  of fan inlet  110 . 
     According to the illustrated embodiment, guide vanes  190  comprise two vanes that are spaced equidistant between bottom wall  174  and top wall  176 . In this manner, guide vanes  190  define passageways  194  that are configured to “straighten” the flow of air F prior to entering inlet chamber  160 . More specifically, the flow of air F entering inlet duct  102  from chamber  27  is typically turbulent. This turbulence can result in instable performance of fan assembly  100 , particularly in the stall region of the fan curve (see  FIG. 8 ). However, by straightening the flow of air F using guide vanes  190 , thereby directing a more laminar flow of air F into inlet chamber  160 , performance of fan assembly  100  at low flow rate may be more stable. 
     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 include 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.