Heat dissipation device having centrifugal fan

Abstract

A heat dissipation device includes a centrifugal fan, a fan duct and a fin assembly. The centrifugal fan has an air outlet. The fan duct is fixed to the air outlet. The fan duct includes a plurality of guiding plates spaced from each other. A channel is defined between every two neighboring guiding plates. Each of the guiding plates includes a near end near the air outlet and a far end opposite to the near end away from the air outlet. The widths of the channels at the near ends are larger comparing to the portions of the air outlet when having smaller quantity of airflow, and are smaller comparing to the portions of the air outlet when having large quantity of airflow. Widths of the channels at the far ends are equal to each other. The fin assembly is positioned at the far ends of the guiding plates.

1 . A heat dissipation device comprising:
 a centrifugal fan having an air outlet, a plurality of quantities of airflow generated from the centrifugal fan being different at a plurality of different portions of the air outlet;   a fan duct fixed to the air outlet of the centrifugal fan, the fan duct comprising a plurality of guiding plates spaced from each other, a channel being defined between every two neighboring guiding plates, each of the guiding plates comprising a near end near the air outlet and a far end opposite to the near end and away from the air outlet, the widths of the channels at the near ends being larger in comparison to the portions of the air outlet when having smaller quantity of airflow, and being smaller in comparison to the portions of the air outlet when having larger quantity of airflow, and the widths of the channels at the far ends being equal to each other; and   a fin assembly positioned at the far ends of the guiding plates.   
     
     
         2 . The electronic device of  claim 1 , wherein the quantity of airflow decreases from one side of the air outlet to an another side of the air outlet, and the widths of the channels at the near ends increase from the one side of the air outlet to the another side of the air outlet. 
     
     
         3 . The heat dissipation device of  claim 2 , wherein the quantity of the guiding plates is five, and the ratio of the widths of the channels at the near ends along a direction from the one side to the another side of the air outlet is 1:1.5:2:4. 
     
     
         4 . The heat dissipation device of  claim 1 , wherein the fin assembly comprises a plurality of fins, the fins having a plurality of passages defined therebetween, and the passages being communicated with the channels. 
     
     
         5 . The heat dissipation device of  claim 1 , wherein the fan duct further comprises a connecting plate on which the guiding plates are extended, the connecting plate comprising a first end near the air outlet and a second end opposite to the first end, the length of the first end being substantially equal to the width of the air outlet, the second end being longer than the first end, and the each of the guiding plates being bent along a direction from the first end to the second end. 
     
     
         6 . The heat dissipation device of  claim 1 , wherein the fan duct further comprises two positioning plates respectively extending rearwards from two outermost guiding plates, and two supporting plates respectively extending inwardly from the two positioning plates, and a receiving space being defined by the positioning plates and the supporting plates for receiving the fin assembly. 
     
     
         7 . The heat dissipation device of  claim 1 , wherein heights of the guiding plates are equal to that of the air outlet. 
     
     
         8 . A centrifugal fan comprising:
 a housing defining a receiving room, an air inlet and an air outlet therein;   an impeller rotatably received in the receiving room, an airflow entering through the air inlet and driven by the impeller to expel air outside of the receiving room through the air outlet, the strength of the airflow being different at a plurality of different portions of the air outlet; and   a plurality of guiding plates fixed at the air outlet and spaced from each other, a channel being defined between every two neighboring guiding plates, each of the guiding plates comprising a near end near the air outlet and a far end away from the air outlet, the widths of the channels at the near ends being larger in comparison to the portions of the air outlet when having smaller quantity of airflow, and being smaller in comparison to the portions of the air outlet when having larger quantity of airflow, and the widths of the channels at the far ends being equal to each other.   
     
     
         9 . The centrifugal fan of  claim 8 , wherein the housing comprises a top cover, a bottom cover, a first auxiliary wall and a second auxiliary wall positioned between the top and bottom covers, the air outlet being enclosed by the top and bottom covers, the first and second auxiliary walls, the strength of the airflow increasing from the first auxiliary wall to the second auxiliary wall, and the widths of the channels at the near ends increase from the second auxiliary wall to the first auxiliary wall. 
     
     
         10 . The centrifugal fan of  claim 9 , wherein the quantity of the guiding plates is five, and the ratio of the widths of the channels at the near ends along a direction from the second auxiliary wall to the first auxiliary wall is 1:1.5:2:4. 
     
     
         11 . The centrifugal fan of  claim 9  further comprising a connecting plate positioned at a same horizontal plane with the bottom cover, and the guiding plates extending upwardly from the connecting plate. 
     
     
         12 . The centrifugal fan of  claim 11 , wherein the connecting plate comprises a first end in contact with the bottom cover and a second end opposite to the first end, the width of the connecting plate increasing from the first end to the second end, and the guiding plates bending along a direction along the first end to the second end. 
     
     
         13 . The centrifugal fan of  claim 11 , wherein the guiding plates are of the same height as the air outlet, and two outermost guiding plates are abutting against the first and second auxiliary walls, respectively. 
     
     
         14 . The centrifugal fan of  claim 13 , wherein the two outermost guiding plates extend rearwards to form two positioning plates, a supporting plate extending horizontally from the positioning plates, the positioning and supporting plates enclosing to define a receiving space adapted for receiving a fin assembly. 
     
     
         15 . The centrifugal fan of  claim 13 , wherein a securing plate extends outwardly from a top of one of the two outermost guiding plates, a locking plate extending downwardly from the securing plate, and an auxiliary plate extending outwardly and horizontally from the locking plate, the auxiliary plate and the connecting plate being at a same horizontal plane and defining a plurality of securing holes therein for securing the centrifugal fan.