Patent Publication Number: US-9416793-B2

Title: Electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of TW application serial no. 101134137, filed on Sep. 18, 2012. The entirety of the above-mentioned patent application is hereby incorporated via reference herein and made a part of specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The disclosure relates to a centrifugal fan. 
     2. Description of the Related Art 
     Nowadays, kinds of thin and portable devices gradually become common application tools in daily life. 
     Electronic devices have a trend to be thinner and have higher performance, the heat dissipation components in the electronic device become smaller due to the reduced inner space. The centrifugal fan is one of the commonly-used active heat dissipation components. 
     In the design of the centrifugal fan, it considers that the shape of the fan blade may cause deformation when the fan operates. The deformation of the fan blade is increased along a direction away from the rotational axis. To avoid that the fan blade hits the upper cover or the lower cover due to the deformation, the fan blade is usually parallel to the upper cover and the lower cover, and a gap is kept as the space for deformation of the fan blade. However, serious backflow is generated in the air outlet of the centrifugal fan, and the volume and the pressure of the air is reduced at the air outlet. 
     BRIEF SUMMARY OF THE INVENTION 
     A centrifugal fan is provided. The centrifugal fan includes a casing and a fan body. The casing includes an upper cover and a lower cover. The fan body is disposed in the casing, and the fan body includes a fan hub and at least a fan blade. The fan hub is connected to the lower cover, and the fan blade includes an air intake portion and an air exhaust portion. The air intake portion is connected to the edge of the fan hub. The air exhaust portion is connected to the air intake portion and disposed between the upper cover and the lower cover. The width of the air exhaust portion is reduced gradually along the direction away from the air intake portion. 
     In one embodiment, the air exhaust portion includes a cross section vertical to the upper cover and the lower cover, and the cross section includes an upper contour line and a lower contour line. The upper contour line includes an upper close point relative to the upper cover. The lower contour line includes a lower close point relative to the lower cover. The vertical distance from the upper contour line to the upper cover is increased from the upper close point along the direction away from the upper close point, and the vertical distance from the lower contour line to the lower cover is increased along the direction away from the lower close point. 
     Since the deformation of the fan blade is getting smaller in the direction close to the fan hub and getting larger in the direction away from the fan hub when the fan blade rotates, the distance from the air exhaust portion of the fan blade to the upper cover or the lower cover is reduced with the decrease of the deformation to increase the volume and the pressure of the air in the air outlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a three-dimensional assembly diagram showing a centrifugal fan in one embodiment. 
         FIG. 1B  is a three-dimensional exploded diagram showing the centrifugal fan in  FIG. 1A . 
         FIG. 2  is a partial sectional schematic diagram showing a cross section of the centrifugal fan in  FIG. 1A  along a line vertical to the upper cover and the lower cover, wherein the fan body is shown by a contour line. 
         FIG. 3  is a partial sectional schematic diagram showing the centrifugal fan in  FIG. 2  in a second embodiment. 
         FIG. 4  is a partial sectional schematic diagram showing the centrifugal fan in  FIG. 2  in a third embodiment. 
         FIG. 5  is a partial sectional schematic diagram showing the centrifugal fan in  FIG. 2  in a fourth embodiment. 
         FIG. 6  is a partial sectional schematic diagram showing a cross section of the centrifugal fan in  FIG. 1A  along a line vertical to the upper cover and the lower cover in another embodiment, wherein the fan body is indicated with a contour line. 
         FIG. 7  is a partial sectional schematic diagram showing a centrifugal fan in  FIG. 6  in a second embodiment. 
         FIG. 8  is a partial sectional schematic diagram showing a centrifugal fan in  FIG. 6  in a third embodiment. 
         FIG. 9  is a partial sectional schematic diagram showing a cross section of the centrifugal fan in  FIG. 6  in a fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1A  is a three-dimensional schematic diagram showing a centrifugal fan  1  in one embodiment.  FIG. 1B  is a three-dimensional exploded diagram showing the centrifugal fan  1  in  FIG. 1A . 
     Referring to  FIG. 1A  and  FIG. 1B , an electronic device with the centrifugal fan  1  may be any electronic device with a heat source inside. The centrifugal fan  1  can be used at any electronic device as long as it has a heat dissipation requirement inside. 
     Referring to  FIG. 1A  and  FIG. 1B , the centrifugal fan  1  includes a casing  10  and a fan body  12 . The casing  10  includes an upper cover  100  and a lower cover  102 , and the upper cover  100  includes an air inlet  100   a . When the upper cover  100  of the casing  10  is combined with the lower cover  102 , an air outlet  104  is formed at the edge of the same side of the upper cover  100  and the lower cover  102 . The fan body  12  includes a fan hub  120  and a plurality of fan blades  122 . The fan body  12  is disposed in the casing  10  and between the upper cover  100  and the lower cover  102 . The fan hub  120  of the fan body  12  is pivotally connected to a motor (not shown) at the lower cover  102  and faces to an air inlet  100   a  of the upper cover  100 . 
     When the fan body  12  is driven by the motor, the fan blade  122  brings the air outside the casing  10  into the casing  10  via the air inlet  100   a  and exhausts the air out of the casing  10  via the air outlet  104 . Moreover, an air intake opening  102   a  can be formed at the portion of the lower cover  102  facing to the air inlet  100   a  of the upper cover  100 . 
       FIG. 2  is a partial sectional schematic diagram showing a cross section of the centrifugal fan  1  in  FIG. 1A  along a line vertical to the upper cover  100  and the lower cover  102 , and the fan body  12  is shown by a contour line. 
     The fan blade  122  includes an air intake portion  122   a  and an air exhaust portion  122   b . The air intake portion  122   a  is connected to the edge of the fan hub  120 , and the air exhaust portion  122   b  is connected to the air intake portion  122   a . When the fan body  12  rotates, the air intake portion  122   a  brings the air outside the casing  10  into the casing  10  via the air inlet  100   a  of the upper cover  100 , and the air exhaust portion  122   b  exhausts the air out the casing  10  via the air outlet  104  when it rotates to the air outlet  104 . 
     The air exhaust portion  122   b  is between the upper cover  100  and the lower cover  102 , and the air exhaust portion  122   b  includes an upper contour line L 1  and a lower contour line L 2 . The upper contour line L 1  includes an upper close point P 1  (that is the point of the upper contour line L 1  closest to the upper cover  100 ) relative to the upper cover  100 . The lower contour line L 2  includes a lower close point P 2  (that is the point of the lower contour line L 2  closest to the lower cover  102 ) relative to the lower cover  102 . The vertical distance between the upper contour line L 1  and the upper cover  100  is increased from the upper close point P 1  along the direction A away from the upper close point P 1  (that is, away from the fan hub  120 ). 
     The vertical distance between the lower contour line L 2  and the lower cover  102  is increased from lower close point P 2  along the direction A away from the lower close point P 2  (that is, away from the fan hub  120 ). A connection between the upper close point P 1  of the upper contour line L 1  and the lower close point P 2  of the lower contour line L 2  can be regarded as a turning region T 1  between the air intake portion  122   a  and the air exhaust portion  122   b . The width of the air exhaust portion  122   b  of the fan blade  122  is reduced gradually from the turning region T 1  along the direction A far away the fan hub  120 . 
     In this embodiment, the turning region T 1  of the fan blade  122  is disposed at the edge of the air inlet  100   a  of the upper cover  100  (that is the upper close point P 1  of the upper contour line L 1  and the lower close point P 2  of the lower contour line L 2  is aligned with the edge of the air inlet  100   a ), which is not limited herein. The turning region T 1  of the fan blade  122  also can be formed at the portion even further away from the fan hub  120  along the direction A away from the fan hub  120  (for example the upper close point P 1  of the upper contour line L 1  and the lower close point P 2  of the lower contour line L 2  are between the upper cover  100  and the lower cover  102  but not at the edge of the air inlet  100   a ). 
     In this embodiment, the angle α 1  between the upper contour line L 1  of the air exhaust portion  122   b  and the upper cover  100  is same to the angle α 2  between the lower contour line L 2  and the lower cover  102 , which is not limited herein. In another embodiment, the distance between the upper close point P 1  and the fan hub  120  is different from that between the lower close point P 2  and the fan hub  120 , and the angle α 1  between the upper contour line L 1  and the upper cover  100  is different from the angle α 2  between the lower contour line L 2  and the lower cover  102 . 
     Furthermore, in the condition that the width of the fan blade  122  is gradually reduced from the turning region T 1  along the direction A away from the fan hub  120 , the upper contour line L 1  and the lower contour line L 2  of the air exhaust portion  122   b  can be various according to deformation direction of the fan blade  122  when the fan body  12  rotates in the casing  10 . 
       FIG. 3 ,  FIG. 4  and  FIG. 5  are partial sectional schematic diagrams showing the centrifugal fan  1  in  FIG. 2  in different embodiments. The same symbols denote the same components in  FIG. 2 , and the connection of the components is not illustrated any more. 
     Referring to  FIG. 3 , if the fan blade  122  deforms toward the upper cover  100  of the casing  10  when the fan body  12  rotates in the casing  10 , the vertical distance from the upper contour line L 1  of the air exhaust portion  122   b  to the upper cover  100  is increased gradually from the upper close point P 1  along the direction A away from the upper close point P 1  (that is away from the fan hub  120 ), and the lower contour line L 21  of the air exhaust portion  122   b  is parallel to the lower cover  102  (that is, every point in the lower contour line L 21  can be regarded as the lower close point P 2 ). 
     Referring to  FIG. 4 , if the fan blade  122  deforms toward the casing  10  of the lower cover  102  when the fan body  12  rotates in the casing  10 , the vertical distance from the lower contour line L 2  of the air exhaust portion  122   b  to the lower cover  102  is increased gradually from the lower close point P 2  along the direction A away from the lower close point P 2  (that is, the direction away from the fan hub  120 ), and the upper contour line L 11  of the air exhaust portion  122   b  is parallel to the upper cover  100  (that is, every point of the upper contour line L 11  can be regard as the upper point P 1 ). 
     The upper contour line L 1  and the lower contour line L 2  of the air exhaust portion  122   b  are straight lines in the embodiment, which is not limited herein. 
     Referring to  FIG. 5 , the difference between the embodiment in  FIG. 5  and the embodiment in  FIG. 2  is that the upper contour line L 12  and the lower contour line  122  of the air exhaust portion  122   b  are curve lines. 
     However, one of the upper contour line L 1  and the lower contour line L 2  in  FIG. 2  also may be a straight line, and the other is a curve line. 
       FIG. 6  is a partial sectional schematic diagram showing the cross section of the centrifugal fan  1  in  FIG. 1A  along a line vertical to the upper cover  100  and the lower cover  102 , and the fan body  32  is shown by a contour line. The casing  10  in this embodiment is same to that in  FIG. 2 , the structure of the casing  10  is omitted herein. 
     The air exhaust portion  322   b  of the fan blade  322  is disposed between the upper cover  100  and the lower cover  102 , and the air exhaust portion  322   b  includes an upper contour line L 3  and a lower contour line L 4 . The upper contour line L 3  includes an upper parallel part L 3   a  and an upper oblique part L 3   b . The upper parallel part L 3   a  is between the air intake portion  322   a  and the upper oblique part L 3   b , and it is parallel to the upper cover  100 . 
     The vertical distance from the upper oblique part L 3   b  to the upper cover  100  is increased gradually along the direction A away from the upper parallel part L 3   a  (that is, away from the fan hub  320 ). The lower contour line L 4  includes a lower part L 4   a  and a lower oblique part L 4   b . The lower parallel part of the lower contour line L 4  is between the air intake portion  322   a  and the lower oblique part L 4   b , and it is parallel to the lower cover  102 . The vertical distance from the lower parallel oblique part L 4   b  to the lower cover  102  is increased gradually along the direction A away from the lower parallel part L 4   a  (that is away from the fan hub  320 ). 
     The zone between the upper parallel part L 3   a  of the upper contour line L 3  and the lower parallel part L 4   a  of the lower contour line L 4  can be regarded as the turning region T 2  of the fan blade  322 , and it is formed between the air intake portion  322   a  and the air exhaust portion  322   b . The width of the fan blade  322  is reduced gradually from the fan hub  320  along the direction A away from the back over region T 2 . 
     The turning region T 2  of the fan blade  322  is formed at the edge of the air inlet  100   a  at the upper cover  100  (that is, the upper parallel part L 3   a  of the upper contour line L 3  and the lower parallel part L 4   a  of the lower contour line L 4  are aligned with the edge of the air inlet  100   a ), which is not limited herein. In one embodiment, the back over region T 2  of the fan blade  322  can be even further away from the fan hub  320  along the direction away from the fan hub  320 . Moreover, in another embodiment, the turning region T 2  of the fan blade  322  can be increased along the direction A away from the fan hub  320  (that is, the length of the upper parallel part L 3   a  and the lower parallel part L 4   a  is increased along the direction A away from the fan hub  320 ). 
     An angle α 3  between the upper oblique part L 3   b  of the upper contour line L 3  and the upper cover  100  is same to an angle α 4  between the lower oblique part L 4   b  of the lower contour line L 4  and the lower cover  102 , which is not limited herein. In another embodiment, the distance from the fan hub  320  to the intersection of the upper parallel part L 3   a  and the upper oblique part L 3   b  is different from that from the fan hub  320  to the Intersection of the lower parallel part L 4   a  and the lower oblique part L 4   b . Consequently the angle α 3  between the upper oblique part L 3   b  and the upper cover  100  is different from the angle α 4  between the lower oblique part L 4   b  and the lower cover  102 . 
     Moreover, in the condition that the width of the fan blade  322  is reduced gradually from the back over region T 2  along the direction A away from the fan hub  320 , the upper contour line L 3  and the lower contour line L 4  of the air exhaust portion  322   b  can be various according to deformation direction of the fan blade  322  when the fan body  32  rotates in the casing  10 . 
       FIG. 7 ,  FIG. 8  and  FIG. 9  are partial sectional schematic diagrams showing the centrifugal fan  3  in  FIG. 6  in different embodiments, in these embodiments, the same symbols denote the same components in  FIG. 6 , and the connection of the components is not illustrated any more. 
     Referring to  FIG. 7 , if the fan blade  322  deforms toward the upper cover  100  of the casing  10  when the fan body  32  rotates in the casing  10 , the vertical distance from the upper oblique part L 3   b  of the upper contour line L 3  to the upper cover  100  is increased gradually along the direction A away from the upper parallel part L 3   a  (that is away from the fan hub  320 ), and the lower contour line L 41  of the air exhaust portion  322   b  is parallel to the lower cover  102 . 
     Referring to  FIG. 8 , if the fan blade  322  deforms toward the lower cover  102  of the casing  10  when the fan body  32  rotates in the casing  10 , the vertical distance from the lower oblique part L 4   b  of the lower contour line L 4  to the lower cover  102  is increased gradually along the direction A away from the lower parallel L 4   a  (that is away from the fan hub  320 ), and the upper contour line L 31  is parallel to the upper cover  100 . 
     The upper oblique part L 3   b  of the upper contour line L 3  and the lower oblique part L 4   b  of the lower contour line L 4  are straight lines, which is not limited herein. 
     Referring to  FIG. 9 , the difference between the embodiment in  FIG. 9  and that in  FIG. 6  is the upper oblique part L 32   b  of the upper contour line L 32  and the lower oblique part L 42   b  of the lower contour line L 42  in the air exhaust portion  322   b  are curve lines. 
     However, one of the upper oblique part L 3   b  of the upper contour line L 3  and the lower oblique part L 4   b  of the lower contour line L 4  also may be a straight line and the other is a curve line. 
     In sum up, the gap between the fan blade and the tipper cover or the lower cover is reduced according to the embodiments. Consequently, the loss of the air backflow from the air outlet to the air inlet of the fan blade is reduced, and the volume and pressure of the exhausted air are increased. 
     Although the present disclosure has been described in considerable detail with reference to certain preferred embodiments thereof, the disclosure is not for limiting the scope. Persons having ordinary skill in the art may make various modifications and changes without departing from the scope. Therefore, the scope of the appended claims should not be limited to the description of the preferred embodiments described above.