Patent Publication Number: US-6910862-B2

Title: Airflow guiding structure for a heat-dissipating fan

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an airflow guiding structure for a heat-dissipating fan. 
     2. Description of Related Art 
       FIG. 1  of the drawings illustrates a typical heat-dissipating fan including a casing  10 , an air inlet  11  defined in a side of the casing  10 , an air outlet  12  defined in the other side of the casing  10 , a base  13 , and a plurality of ribs  14 . The base  13  is secured by the ribs  14  in the air outlet  12 . A stator (not shown) and an impeller (not shown) are mounted to the base  13 . When the impeller turns, air is sucked into the casing  10  via the air inlet  11  and exits the casing  10  via the air outlet  12  to dissipate heat from an object such as a fin or a central processing unit. 
     Although the above-mentioned heat-dissipating fan provides a certain heat-dissipating effect, the heat-dissipating operation can only be performed on an object directly below the air outlet  12 , as the airflow can only flow along an axial direction of the casing  10 . In a case that the object is not located directly below the air outlet  12 , the airflow cannot flow through the object in a uniform manner, resulting in non-uniform heat dissipation and poor heat-dissipating effect. On the other hand, since the object is generally mounted in a limited space such as in a notebook type computer (or a laptop computer) in a position not directly below the base  13  or outside the area of air outlet, the heat-dissipating effect is adversely affected. The heat-dissipating effect is also adversely affected if the object is too large to be completely within an area directly below the heat-dissipating fan. Further, turbulence tends to occur when the airflow is passing through the ribs  14 . Noise is thus generated while having a lower heat-dissipating effect. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is to provide an air-guiding structure for a heat-dissipating fan that includes at least one guiding ring in an air outlet of the heat-dissipating fan for concentrating and guiding airflow, increasing wind pressure, reducing wind noise, and improving the overall heat-dissipating efficiency. 
     Another object of the present invention is to provide an air-guiding structure for a heat-dissipating fan that includes at least one guiding ring in an air outlet of the heat-dissipating fan. The guiding ring extends radially inward or outward relative to a longitudinal direction of the casing, thereby concentrating and guiding airflow, increasing wind pressure, reducing wind noise, and improving the overall heat-dissipating efficiency. 
     A further object of the present invention is to provide an air-guiding structure for a heat-dissipating fan that includes at least one guiding ring in an air outlet of the heat-dissipating fan. An inclination angle of the guiding ring is selected to guide airflow to a desired area for concentrated heat dissipation or for enlarging the heat-dissipating area, thereby improving the overall heat-dissipating efficiency and making the assembly and design of the heat-dissipating fan more flexible. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the invention, a heat-dissipating fan includes a casing having an air outlet, a base mounted in the air outlet, an impeller being mounted on the base and having a plurality of blades, a plurality of ribs each extending between the base and the casing along a radial direction of the base, and at least one guiding ring fixedly mounted to the ribs. The guiding ring has an axial length that is longer than a width of the guiding ring in the radial direction. The guiding ring guides and divides airflow passing through the air outlet when the impeller is turning. 
     In an embodiment of the invention, the guiding ring extends in a direction parallel to a longitudinal direction of the casing. In another embodiment of the invention, the guiding ring extends downward and radially outward. In a further embodiment of the invention, the guiding ring extends downward and radially inward. 
     In still another embodiment of the invention, the guiding ring includes an annular inner face extending downward and radially inward and an annular outer face extending downward and radially outward. The guiding ring has a triangular section, with the annular inner face and the annular outer face meeting at a common annular ridge. 
     The ribs may incline along an air-driving direction of the blades of the impeller. Each rib has two rib sections respectively on two sides of the guiding ring, the rib sections having different inclining angles. The guiding ring may include a rounded guiding portion in a top thereof adjacent to an air inlet side of the casing. 
     In accordance with a second aspect of the invention, a heat-dissipating fan includes a casing having an air outlet, a base mounted in the air outlet, an impeller being mounted on the base and having a plurality of blades, a plurality of ribs each extending between the base and the casing along a radial direction of the base, a first guiding ring fixedly mounted to the ribs and located between the base and the casing, and a second guiding ring fixedly mounted to the ribs and located between the first guiding ring and the casing. The first guiding ring and the second guiding ring guide and divide airflow passing through the air outlet when the impeller is turning. 
     Preferably, each of the first guiding ring and the second guiding ring has an axial length and a width in the radial direction, with the axial length being longer than the width. 
     In an embodiment of the invention, the first guiding ring extends downward and radially outward and the second guiding ring extends downward and radially inward. In another embodiment of the invention, the first guiding ring extends downward and radially inward and the second guiding ring extends downward and radially outward. 
     In a further embodiment of the invention, the first guiding ring includes an annular inner face extending downward and radially inward and an annular outer face extending downward and radially outward, and the second guiding ring includes an annular inner face extending downward and radially inward and an annular outer face extending downward and radially outward. Each of the first guiding ring and the second guiding ring has a triangular section, with the annular inner face and the annular outer face of the first guiding ring meeting at a common annular ridge, and with the annular inner face and the annular outer face of the second guiding ring meeting at another common annular ridge. 
     Other objects, advantages and novel features of this invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view, partly cutaway, of a conventional heat-dissipating fan; 
         FIG. 2  is a perspective view, partly cutaway, of a heat-dissipating fan with a first embodiment of an air guiding structure in accordance with the present invention; 
         FIG. 3  is a top view of the heat-dissipating fan in  FIG. 2 ; 
         FIG. 4  is a sectional view taken along line  4 — 4  in  FIG. 3 ; 
         FIG. 4A  is an enlarged view of a circled portion of  FIG. 4 ; 
         FIG. 5  is a perspective view, partly cutaway, of a heat-dissipating fan with a second embodiment of the air guiding structure in accordance with the present invention; 
         FIG. 6  is a top view of the heat-dissipating fan in  FIG. 5 ; 
         FIG. 7  is a sectional view taken along line  7 — 7  in  FIG. 6 ; 
         FIG. 8  is a sectional view similar to  FIG. 7 , illustrating a heat-dissipating fan with a third embodiment of the air guiding structure in accordance with the present invention; 
         FIG. 9  is a sectional view similar to  FIG. 7 , illustrating a heat-dissipating fan with a fourth embodiment of the air guiding structure in accordance with the present invention; 
         FIG. 10  is a perspective view, partly cutaway, of a heat-dissipating fan with a fifth embodiment of the air guiding structure in accordance with the present invention; 
         FIG. 11  is a top view of the heat-dissipating fan in  FIG. 10 ; 
         FIG. 12  is a sectional view taken along line  12 — 12  in  FIG. 11 ; 
         FIG. 13  is a sectional view similar to  FIG. 12 , illustrating a heat-dissipating fan with a sixth embodiment of the air guiding structure in accordance with the present invention; and 
         FIG. 14  is a sectional view similar to  FIG. 12 , illustrating a heat-dissipating fan with a seventh embodiment of the air guiding structure in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention are now to be described hereinafter in detail, in which the same reference numerals are used in the preferred embodiments for the same parts as those in the prior art to avoid redundant description. 
     Referring to  FIGS. 2 ,  3 ,  4 , and  4 A, a heat-dissipating fan with a first embodiment of an air guiding structure in accordance with the present invention includes a casing  10 , an air inlet  11 , an air outlet  12 , a base  13 , a plurality of ribs  14 , and a guiding ring  15 . The casing  10  may be made of plastics or metal, with the air inlet  11  and the air outlet  12  being respectively defined in two opposite sides of the casing  10 . The base  13  is located in the air outlet  12 , and an impeller  20  ( FIG. 4 ) is mounted on the base  13 . The ribs  14  extend between the base  13  and the casing  10  along a radial direction of the base  13 . The guiding ring  15  is located between the base  13  and the casing  10  ( FIG. 4 ) and extends along a longitudinal direction of the casing  10 . Further, the guiding ring  15  extends across the ribs  14  and is fixedly mounted to the ribs  14 . As illustrated in  FIG. 4A , the guiding ring  15  has an axial length L that is preferably longer than a width W of the guiding ring  15  in the radial direction. Further, the guiding ring  15  has a rounded guiding portion  150  in a top end thereof adjacent to the air inlet side of the casing  10 , thereby reducing turbulence. Further, the ribs  14  may incline along an air-driving direction of a plurality of blades  21  of the impeller  20 . 
     Still referring to  FIG. 4 , when the impeller turns 20, the blades  21  of the impeller  20  introduce airflow into the casing  10  via the air inlet  11  and expel the airflow via the air outlet  12 , thereby dissipating heat from an object such as a fin or central processing unit (not shown). When the airflow passes through the guiding ring  15  and the ribs  14 , the guiding ring  15  divides the airflow into an inner portion  17  that is guided toward a center of the air outlet  12  and an outer portion  16  that is guided flows through an outer section of the air outlet  12  between the ribs  14  and the casing  10 . Thus, the heat-dissipating fan provides a reliable concentrated heat-dissipating effect within a specific area. Also, the heat-dissipating fan is suitable for use in a limited space (e.g., in a notebook type computer or laptop computer), as the airflow can be guided to an object in a position not directly below the air outlet  12 . Thus, the guiding ring  15  provides an air-guiding effect. 
     Further, as illustrated in  FIGS. 2 and 3 , the ribs  14  also provide an air-guiding effect when the ribs  14  incline along an air-driving direction of a plurality of blades  21  of the impeller  20 . Meanwhile, the rib sections  14   a  and  14   b  of the ribs  14  respectively on two sides of the guiding ring  15  may have different inclination angles according to need. 
       FIGS. 5 through 7  illustrate a heat-dissipating fan with a second embodiment of the air guiding structure in accordance with the present invention. In this embodiment, the guiding ring  15  extends downwardly (downstream) and radially outward away from the base  13 , best shown in  FIG. 7 . 
     Still referring to  FIG. 7 , when the impeller turns 20, the blades  21  of the impeller  20  introduce airflow into the casing  10  via the air inlet  11  and expel the airflow via the air outlet  12 , thereby dissipating heat from an object such as a fin or central processing unit (not shown). When the airflow passes through the guiding ring  15  and the ribs  14 , the guiding ring  15  that extends downwardly and radially outward divides the airflow into an inner portion  17  that is guided downward and an outer portion  16  that is guided downward and outward to an area outside the air outlet  12 . Thus, more area can be cooled by the heat-dissipating fan. Also, the heat-dissipating fan is suitable for use in a limited space (e.g., in a notebook type computer or laptop computer), as the airflow can be guided to an object in a position not directly below the air outlet  12  or to an object having a relatively large size for more uniform heat dissipation. Thus, the guiding ring  15  provides an air-guiding effect. 
     Further, as illustrated in  FIG. 7 , following the inclining direction of the guiding ring  15 , the wind pressure is increased by the guiding ring  15 . Further, since the wind pressure of the outer portion  16  of the airflow exiting the air outlet  12  is increased due to downward and radially outward inclination of the guiding ring  15 , the inner portion  17  of the airflow tends to flow radially inward, providing a concentration effect for the airflow for dissipating heat. The air flowing efficiency is thus improved. 
     Further, as illustrated in  FIG. 5 , the ribs  14  also provide an air-guiding effect when the ribs  14  incline along an air-driving direction of a plurality of blades  21  of the impeller  20 . Meanwhile, the rib sections  14   a  and  14   b  of the ribs  14  respectively on two sides of the guiding ring  15  may have different inclination angles according to need. 
       FIG. 8  illustrates a heat-dissipating fan with a third embodiment of the air guiding structure in accordance with the present invention. In this embodiment, the guiding ring  15  extends downward (downstream) and radially inward. Thus, an inner portion  17  of airflow is guided toward an object directly below the base  12 , providing improved heat-dissipating efficiency. Following the inclining direction of the guiding ring  15 , the wind pressure is increased by the guiding ring  15 . Further, since the wind pressure of the inner portion  17  of the airflow exiting the air outlet  12  is increased due to downward and radially inward inclination of the guiding ring  15 , the outer portion  16  of the airflow tends to flow radially inward, providing a concentration effect for the airflow for dissipating heat. 
       FIG. 9  illustrates a heat-dissipating fan with a fourth embodiment of the air guiding structure in accordance with the present invention, wherein the guiding ring (now designated by  15 ′) includes an annular inner face  151  extending downwardly (downstream) and radially inward and an annular outer face  152  extending downwardly and radially outward. Preferably, the guiding ring  15 ′ has a triangular section, with the annular inner face  151  and the annular outer face  152  meeting at a common annular ridge  153 . By this arrangement, the airflow is divided by the guiding ring  15 ′ into an inner portion  17  that is directed toward an area directly below the base  13  and an outer portion  16  that is directed toward an area outside the air outlet  12 . The heat-dissipating area is thus increased, and the heat-dissipating efficiency of an object directly below the base  13  is improved. Further, following the inclining direction for the guiding ring  15 ′, the wind pressure is increased by the guiding ring  15 ′, as the sectional area in the air outlet side is decreased. 
       FIGS. 10 through 12  illustrate a heat-dissipating fan with a fifth embodiment of the air guiding structure in accordance with the present invention, wherein an additional guiding ring is provided. In particular, a first guiding ring  15   a  and a second guiding ring  15   b  are mounted between the base  13  and the casing  10  and extend across the ribs  14 . Further, the first guiding ring  15   a  is located between the base  13  and the second guiding ring  15   b.    
     The first guiding ring  15   a  extends downward (downstream) and radially outward, and the second guiding ring  15   b  extends downward and radially inward, with a gap  19  being defined between a lower end  15   c  of the first guiding ring  15   a  and a lower end  15   d  of the second guiding ring  15   b , best shown in  FIG. 12 . 
     By this arrangement, an intermediate portion  18  of the airflow is guided to an area directly below the gap  19  between first and second guiding rings  15   a  and  15   b  to concentrate the airflow and to improve the heat-dissipating effect of an object located in this area. Further, following the inclining directions of the first and second guiding rings  15   a  and  15   b , the wind pressure is increased by the first and second guiding rings  15   a  and  15   b . Further, since the wind pressure of the intermediate portion  18  of airflow is increased, an inner portion  17  of the airflow and an outer portion  16  of the airflow tend to flow toward the area directly below the gap  19  between the first and second guiding rings  15   a  and  15   b , thereby dissipating heat with concentrated airflow. 
       FIG. 13  illustrates a heat-dissipating fan with a sixth embodiment of the air guiding structure in accordance with the present invention modified from the fifth embodiment. In this embodiment, the first guiding ring  15   a  extends downward (downstream) and radially inward, and the second guiding ring  15   b  extends downward and radially outward. 
     By this arrangement, an inner portion  17  of the airflow is directed toward an area directly below the base  13 , and an outer portion  16  of the airflow is directed toward an area outside the air outlet  12 . The area subjected to heat-dissipating operation is increased. This arrangement is also applicable to a limited space for reliably guiding airflow to an object not directly located below the air outlet  12  and to an object having a relatively large size for more uniform heat dissipation. Further, following the inclining directions of the first and second guiding rings  15   a  and  15   b , the wind pressure is increased by the first and second guiding rings  15   a  and  15   b . Further, since the wind pressures of the inner portion  17  of the airflow and the outer portion  16  of the airflow are increased, the middle portion  18  of the airflow between the first and second guiding rings  15   a  and  15   b  tend to flow toward an area directly below the base  13  and an area outside the air outlet  12 , providing concentrated airflow for heat dissipation. 
       FIG. 14  illustrates a heat-dissipating fan with a seventh embodiment of the air guiding structure in accordance with the present invention. In this embodiment, the first guiding ring (now designated by  15   a ′) includes an annular inner face  154  extending downward and radially inward and an annular outer face  155  extending downward and radially outward, and the second guiding ring (now designated by  15   b ′) includes an annular inner face  156  extending downward and radially inward and an annular outer face  157  extending downward and radially outward. Preferably, the first guiding ring  15   a ′ has a triangular section, with the annular inner face  154  and the annular outer face  155  meeting at a common annular ridge  158 . Similarly, the second guiding ring  15   b ′ has a triangular section, with the annular inner face  156  and the annular outer face  157  meeting at a common annular ridge  159 . 
     By this arrangement, the airflow is divided by the guiding rings  15   a ′ and  15   b ′ into an inner portion  17  that is directed toward an area directly below the base  13 , an intermediate portion  18  below an area between the first and second guiding rings  15   a ′ and  15   b ′, and an outer portion  16  that is directed toward an area outside the air outlet  12 . The heat-dissipating area is thus increased. Further, following the inclining direction of the guiding rings  15   a ′ and  15   b ′, the wind pressure is increased by the guiding rings  15   a ′ and  15   b ′, as the sectional area in the air outlet side is decreased. 
     Further, as illustrated in  FIGS. 2 through 14 , the direction of the airflow guided by means of at least one guiding ring follows from the number, the inclining direction, and the inclining angle of the guiding ring(s) in response to the size, location, and shape of the blades  21  of the impeller  20  and of the object (such as fins) to be dissipated as well as the amount of heat to be dissipated. 
     While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.