Patent Publication Number: US-9885361-B2

Title: Centrifugal fan for devices including refrigerators

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority to Korean Patent Application No. 10-2013-0166419, filed on Dec. 30, 2013, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     Embodiments according to the present disclosure relate to a centrifugal fan that can be used in devices such as refrigerators. 
     BACKGROUND 
     In general, a refrigerator provides cool air using a refrigeration cycle, and can cool food and/or prevent it from spoiling. A refrigerator is a device (e.g., an appliance) that can store food and keep it in a fresh state for a relatively long time using cool air. A fan is installed in the refrigerator in communication with a duct that circulates the cool air to and through a cold (refrigeration) compartment and/or a freezer compartment. 
       FIG. 1  is a cross-sectional view of an example of a refrigerator. 
     As illustrated in  FIG. 1 , the refrigerator generally includes an outer case  1  forming an outer frame with an open front surface, and an inner case  2  installed within the outer case  1 . 
     A storage compartment  3  (e.g., the cold compartment or the freezer compartment) is inside the inner case  2 . A door or doors  4  are installed at the open front surface of the outer case  1 , to allow a user to access the cold compartment and/or the freezer compartment. 
     Air from the storage compartment  3  is cooled by exchanging heat with a refrigerant in an evaporator  5 . The cool air circulates between the outer case  1  and the inner case  2  and also circulates within the inner case  2  (e.g., within the storage compartment  3 ). 
     A blower device  10  (e.g., a fan) that circulates the cool air is mounted on the evaporator  5 . 
       FIG. 2  is a cross-sectional view of the blower device  10  installed in the refrigerator of  FIG. 1 . 
     As illustrated in  FIG. 2 , the blower device  10  includes a housing  12  that has an inlet  12   a  and an outlet  12   b , a centrifugal fan at the inlet  12   a  and that receives air through the inlet  12   a  and discharges air to the outlet  12   b , and a motor  16  that drives (rotates) the centrifugal fan. 
     The centrifugal fan includes a plurality of vanes  14  and a shroud  15 . Air flows from the inlet  12   a  of the housing to the outlet  12   b  of the housing. The shroud  15  connects the plurality of vanes  14  and guides the air from the inlet  12   a  to the inside of the centrifugal fan. The bottom  13  connects the plurality of vanes  14  at the side opposite the shroud  15 . 
     The inlet  12   a  of the housing forms a bell mouth  11  that is rounded and forms a surface that curves (widens) toward the centrifugal fan, and that facilitates pulling or suction of air when the centrifugal fan rotates. 
     As such, the centrifugal fan has a structure in which the cool air from the evaporator  5  is introduced in the direction of the shaft of the motor  16  and is discharged in a centrifugal and/or orthogonal direction through the outlet  12   b . The centrifugal fan reduces noise and power consumption in comparison to an axial-flow fan. 
     The shape (e.g., the bell mouth) and the width of the inlet  12   a  are appropriately designed for smooth, laminar air flow. 
     The shroud  15  can be designed to guide air through the inlet  12   a  and through the outlet  12   b . The shape of the shroud  15  can depend on the shapes of the inlet  12   a  and the portion  11   a  of the bell mouth  11 . 
     Air exiting at the outlet  12   b  can swirl, forming a vortex. As a result, collision loss occurs (e.g., reducing air flow) and/or excessive noise is generated. 
     SUMMARY 
     Embodiments according to the present disclosure pertain to a centrifugal fan that can be used in, for example, a refrigerator. A centrifugal fan in embodiments according to the present disclosure can prevent collision loss by preventing occurrence of a vortex by improving the fan&#39;s shroud structure and vanes, and also can reduce noise and power consumption. 
     In one or more embodiments, a centrifugal fan includes: a plurality of vanes arranged radially about a central shaft; a ring-shaped shroud coupled to the vanes and having (i) a curved portion that has a predetermined radius or curvature, and (ii) an angled portion that has a predetermined gradient or angle relative to the curved portion; and a bottom surface coupled to the vanes at the side opposite the shroud; where a ratio (r/R) of an inner diameter r, which is the shortest distance between the vanes and the shaft, and an outer diameter R, which is the longest distance between the vanes and the shaft, is approximately 0.69±0.01. 
     In one or more embodiments, the radius or the curvature of the curved portion of the shroud corresponds to a shape of an inlet of the shroud and an element extending from the shroud. 
     In one or more embodiments, the radius or the curvature of the curved portion of the shroud corresponds to an inlet width of the vanes and an outlet width of the shroud, and the angle of the angled portion relative to the curved portion corresponds to the inlet width and the outlet width of the shroud. 
     In one or more embodiments, a ratio of the outlet width of the shroud to a diameter of the vanes is approximately 0.16±0.01. 
     In one or more embodiments, a ratio of the inlet width of the vanes to the diameter of the vanes is approximately 0.24±0.01. 
     In one or more embodiments, the vanes have an inlet angle (e.g., that may be formed by tangents of the vanes [for example, at or from a center of the vanes] and a virtual inner circle C 1  of the vanes) may be approximately 25°±1. 
     In one or more embodiments, the vanes have an outlet angle (e.g., that may be formed by tangents of the vanes [for example, from the center of the vanes] and a virtual outer circle C 2  having of the vanes) may be approximately 37°±1. 
     In one or more embodiments, the vanes have a solidity ratio of approximately 1.0±0.1. Solidity may be defined as a ratio (L/P) of a pitch P, or the length of an arc that connects the outlet angles of adjacent vanes, to a chord L or the shortest distance between a front edge or periphery of a vane (e.g., the location of the vertex of the inlet angle) is and a rear edge or periphery of the vane (e.g., the location of the vertex of the outlet angle). 
     According to one or more embodiments of the present disclosure, the speed or rotation rate of the fan motor can be reduced (e.g., by approximately 100 to 150 rpm for a given air volume and/or flow rate, such as a flow rate of 35 CMH [cubic meters per hour]) relative to a conventional centrifugal fan. 
     According to one or more embodiments of the present disclosure, noise can be reduced (e.g., by approximately 3 to 4 dB) and/or power consumption can be reduced by approximately 22 to 30% for a given air volume and/or flow rate (e.g., a volume of 35 CMH), as compared with the conventional centrifugal fan. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an example of a refrigerator. 
         FIG. 2  is a cross-sectional view of the blower device installed in the refrigerator of  FIG. 1 . 
         FIG. 3  is a diagram of a blower device in one or more exemplary embodiments according to the present disclosure. 
         FIG. 4  is a cross-sectional view of the vanes of the exemplary centrifugal fan in one or more embodiments according to the present disclosure, along line A-A′ of  FIG. 3 . 
         FIGS. 5( a ), 5( b ), and 5( c )  illustrate vortex characteristics for various shroud shapes. 
         FIG. 5( d )  illustrates air flow for a shroud in one or more exemplary embodiments according to the present disclosure. 
         FIG. 6  is a diagram illustrating comparative experimental results for noise level versus air volume flow rate. 
         FIG. 7  is a diagram illustrating comparative experimental results for power consumption versus air volume flow rate. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. 
     In describing the exemplary embodiments, technical content that is well known in the technical field to which the present disclosure belongs and is not directly associated with the present disclosure may not be described. This is to more clearly describe and/or transfer the technical content by omitting unnecessary description(s). 
     Some components may be exaggerated in size or omitted or schematically illustrated in the accompanying drawings. The drawings are not necessarily drawn to scale. The same reference numerals refer to the same or corresponding components in each drawing. 
       FIG. 3  is a diagram of a blower device  50  that includes a centrifugal fan  60  that can be used in, for example, a refrigerator or air conditioner in one or more exemplary embodiments according to the present disclosure.  FIG. 4  is a cross-sectional view of the fan wheel and/or vanes of the centrifugal fan along line A-A′ of  FIG. 3 . 
     Referring to  FIG. 3 , the blower device  50  includes a housing  52  that has an inlet  52   a  and an outlet  52   b , a centrifugal fan  60  in the housing  52 , and a motor  70  that drives (e.g., rotates) the centrifugal fan  60  via a shaft  72 . 
     The housing  52  forms part of a flow path that circulates air into and through, for example, a refrigerator. 
     Cool air enters the centrifugal fan  60  through the inlet  52   a  of the housing  52 . The inlet  52  forms a bell mouth  51 . The bell mouth  51  is used to more efficiently introduce air into and through the housing  52 . The bell mouth  51  is convex (the bell mouth widens from the surface facing the motor  70  towards the inlet  52   a  of the housing  52 ). 
     As illustrated in  FIG. 3 , the centrifugal fan  60  includes a plurality of vanes  62 . Air is introduced through the inlet  52   a  of the housing  52  and flows to the outlet  52   b  of the housing  52 . A ring-shaped shroud  64  connects the edges (e.g., upper exterior edges) of the plurality of vanes  62 , and guides air from the inlet  52   a  to the inside of the centrifugal fan  60 . A bottom surface  66  connects edges of the plurality of vanes  62  at the side opposite the shroud  64 . 
     In other words, with reference to  FIG. 4 , the circle C 1  corresponds to the inner edges of the vanes  62 , which are on the bottom surface  66  and inside the shroud  64 , and the circle C 2  corresponds to the outer diameter of the ring-shaped shroud  64 . Part of the bottom edge of each of the vanes  62  is connected to the bottom portion  66 , and part of the top edge of each of the vanes is connected to the shroud  64 . The vanes  62  may curve. In one embodiment, they may have a convex outer surface (e.g., facing away from the shaft  72  and/or towards the outlet  52   b ) and a substantially convex inner surface (e.g., facing towards the shaft  72 ); otherwise, the vanes  62  may be planar or substantially planar, and have a rectangular or substantially rectangular cross-section. 
     With reference to  FIG. 3 , the shroud  64  is separated from a neighboring element  51   a  that is connected to (extends from) the bell mouth  51  by a predetermined interval or distance. 
     The shroud  64  includes a curved portion  64   a  that has a predetermined radius or curvature, and an angled portion  64   b  that is angled by a predetermined amount (e.g., in degrees) relative to the curved portion  64   a . Alternatively, the angled portion  64   b  may be angled by a predetermined amount (e.g., in degrees) relative to the planar portion of the bottom portion  66 . 
     More specifically, the radius or curvature of the curved portion  64   a  is set according to the shapes of the inlet  52   a  and the element  51   a . The radius or curvature of the curved portion  64   a  is set according to an inlet width or depth  621  and an outlet width or depth  622  of the shroud  64 . The angle or gradient of the angled portion  64   b  may also be set according to the inlet width or depth  621  and the outlet width or depth  622  of the shroud  64 . 
     In one or more embodiments, the inlet width or depth  621  is the actual width of the vanes  62  at the edge closest to the center of the centrifugal fan, without considering the thickness of the bottom surface  66  of the centrifugal fan  60  (e.g., the inlet width  621  is the distance between the top/outer edge of the shroud  64  and the top/inner side of the bottom portion  66 ). The ratio of the inlet width  621  to the diameter of the centrifugal fan  60  (e.g., the diameter of the fan wheel) is 0.24±0.01, or in the range of approximately 0.24±0.01. The outlet width  622  is the actual width of the vanes  62  at the edges farthest from the center of the centrifugal fan, without considering the thickness of the shroud  64  (e.g., the outlet width  622  is the distance from the bottom/inner edge of the shroud  64  and the bottom/outer side of the bottom portion  66 ). The ratio of the outlet width  622  to the diameter of the centrifugal fan  60  may be 0.16±0.01, or in the range of approximately 0.16±0.01. 
     As illustrated in  FIG. 4 , the vanes  62  have cross-sections that are shaped like an airplane wing or airfoil; in embodiments according to the present disclosure, the thickest cross-sectional portion of each vane is at or near the middle of the vane. Each of the vanes  62  includes a positive pressure surface  62   a  and a negative pressure surface  62   b . The positive pressure surface may also be known as the pressure surface, and the negative pressure surface may be known as the suction surface. When the centrifugal fan  60  is turning, the vane  62  pushes air; thus, the pressure on the positive pressure surface  62   a  is higher than atmospheric pressure, and pressure is lower than atmospheric pressure on the negative pressure surface  62   b . Each vane  62  includes: a front peripheral portion  62   c  on the pressure surface  62   a  and the negative pressure surface  62   b  that contacts cool air introduced through the inlet  52   a ; and a rear peripheral portion  62   d  on an outer circumference of the centrifugal fan  60  on the pressure surface  62   a  and the negative pressure surface  62   b , and which discharges cool air to the outlet  52   b.    
     The vanes  62  form a virtual inner circle C 1  with a radius r from the motor shaft  72  to the front peripheral portion  62   c , and also form a virtual outer circle C 2  with a radius R from the motor shaft  72  to the rear peripheral portion  62   d . The inner radius r is the shortest distance between an inner edge of a vane of the plurality of vanes and the shaft, and an outer radius R is the longest distance between an outer edge of the vane and the shaft. The diameter of the circle C 1  may be referred to herein as the minimum fan wheel diameter and thus the radius r may be referred to as the minimum fan wheel radius. The diameter of the circle C 2  may be referred to herein as the maximum fan wheel diameter and thus the radius R may be referred to as the maximum fan wheel radius. 
     In one or more embodiments according to the present disclosure, the ratio r/R (the radius r of the inner circle C 1  to the radius R of the outer circle C 2 ) is 0.69±0.01, or in a range of approximately 0.69±0.01. 
     An inlet angle α is defined herein as the angle between a tangent of the inner circle C 1  and the front peripheral portion  62   c  of a vane  62 . The angle α may also be known as the angle of attack. In one or more embodiments according to the present disclosure, the inlet angle α may be 25°±1, or in a range of approximately 25°±1. An outlet angle β is defined herein as the angle between a tangent of the outer circle C 2  and the rear peripheral portion  62   d  of a vane  62 . The angle β may also be known as the blade angle. In one or more embodiments according to the present disclosure, the outlet angle β may be 37°±1, or in a range of approximately 37°±1. 
     The outer tips and/or edges of the vanes  62  are separated from each other by a pitch P, which may be the length of an arc that connects the outer tips/edges of adjacent vanes (e.g., the length of an arc that connects an outlet angle β in the outer circle C 2  between the rear periphery portions  62   d  of any one vane and the nearest vane adjacent thereto and an outlet angle β of the nearest/adjacent vane  62 ). If the vanes  62  are uniformly spaced, then the pitch is the circumference of the outer circle C 2  divided by the number of vanes  62 . At least one of the vanes  62  has a chord (e.g., a one-dimensional line from the innermost edge to the outermost edge, or between the vertices of the inner and outer angles) having a length L. A chord may also be a straight line that connects the front peripheral portion  62   c  and the rear peripheral portion  62   d . In other words, a chord is generally a straight line connecting the leading and trailing edges of a vane  62 . Typically, all of the vanes  62  have the same chord. In one or more embodiments according to the present disclosure, the ratio L/P, or blade solidity ratio, of the chord L and the pitch P is in the range of 1.0±0.1. 
       FIGS. 5( a ), 5( b ), and 5( c )  illustrate a vortex caused by different shroud shapes that may be used in conventional centrifugal fans. 
     As illustrated in  FIG. 5( a ) , when a shape  81  of the shroud has a round or curved portion  81   a  and a horizontal portion  81   b , a vortex occurs at an interface between the round portion  81   a  and the horizontal portion  81   b , generally toward the outlet. 
     As illustrated in  FIG. 5( b ) , when a shape  82  of the shroud has a tapered portion  82   a  and a horizontal portion  82   b , a vortex larger than that of  FIG. 5A  occurs in the horizontal portion  81   b , past the interface between the round portion  81   a  and the horizontal portion  81   b , toward the outlet. 
     As illustrated in  FIG. 5( c ) , when a shape  83  of the shroud from a horizontal inlet  83   a  is only tilted (e.g., tapered surface  83   b ), collision loss resistance with a duct at or near the outlet is generated by a shaft-direction velocity component (e.g., of the air flow from the fan). 
       FIG. 5( d )  illustrates an exemplary air flow using embodiments of a shroud according to the present disclosure (e.g., the shroud  64  of  FIG. 3 ). As illustrated in  FIG. 5( d ) , in one or more embodiments according to the present disclosure, the shape  84  of the shroud  64  includes a curved portion  84   a  ( 64   a ) and an angled portion  84   b  ( 64   b ). Consequently, a vortex does not occur within or below the shroud or at the outlet, and collision losses are reduced. 
       FIG. 6  is a diagram illustrating comparative results of experiments measuring noise level versus air volume flow rate in a centrifugal fan according to exemplary embodiment(s) of the present disclosure (e.g., having a shroud with a shape similar to or the same as  FIG. 5( d ) ) and in a conventional centrifugal fan (e.g., having a shroud with a shape similar to or the same as  FIG. 5( a ) ).  FIG. 7  is a diagram illustrating results of experiments measuring power consumption versus air volume/flow rate in a centrifugal fan according to exemplary embodiment(s) of the present disclosure and in a conventional centrifugal fan. 
     A noise level result  91   b  for the centrifugal fan  60  according to exemplary embodiment(s) of the present disclosure and a noise level result  91   a  for the conventional centrifugal fan are illustrated in  FIG. 6 . The centrifugal fan  60  generates less noise than the conventional centrifugal fan. For example, at an air volume flow rate of 35 CMH, the noise level of the centrifugal fan  60  is in the range of 21 to 22 dB (A), and the noise level of the conventional centrifugal fan is in the range of 24 to 25 dB (A). Thus, the noise level of the centrifugal fan  60  is 3 to 4 dB (A) lower than that of the conventional centrifugal fan. Alternatively, at the same noise level, the fan according to embodiment(s) of the present disclosure can move or circulate a volume of air over time that is about 15-20% or greater than the conventional centrifugal fan. 
     Meanwhile, a power consumption result  92   b  for the centrifugal fan  60  according to exemplary embodiment(s) of the present disclosure and a power consumption result  92   a  for the conventional centrifugal fan are illustrated in  FIG. 7 . The power consumption of the present exemplary centrifugal fan  60  is lower than that of the conventional centrifugal fan. For example, the power consumption of the present exemplary centrifugal fan  60  is approximately 1.75 W for an air volume/flow rate of 35 CMH, and the power consumption of the conventional centrifugal fan is approximately 2.5 W at that air volume/flow rate. Thus, the power consumption of the centrifugal fan  60  is approximately 22 to 30% lower than that of the conventional centrifugal fan, and the improvement may increase at higher air flow rates. 
     From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. The exemplary embodiments disclosed in the specification of the present disclosure will not limit the present disclosure. The scope of the present disclosure will be interpreted by the claims below, and it will be construed that all techniques within the scope equivalent thereto belong to the scope of the present disclosure.