Heat dissipation device with convection driven impeller

Abstract

An exemplary heat dissipation device includes a base, spaced fins, a bracket, a shaft and a first impeller. The base directly contacts a heat-generating source. The fins are mounted on the base to dissipate heat transferred from the base by nature convection and thermal radiation. The bracket is mounted on the fins and includes a rotor. The shaft is engaged with the rotor and is located above of the fins. The first impeller is located at above of the bracket and engaged with a top end of the shaft. Heat generated by the heat-generating source is absorbed by the base and then is transferred to the fins for dissipation. Air around the fins and the base is heated and moves upwards to drive the first impeller to rotate.

What is claimed is: 
     
         1 . A heat dissipation device for dissipating heat generating from a heat-generating electronic component, the heat dissipation device comprising:
 a base for directly contacting the heat-generating electronic component;   a plurality of spaced fins radially mounted on the base to dissipate heat transferred from the base by convection and thermal radiation, the fins cooperatively defining a receiving chamber between inner edges thereof;   a bracket mounted on the fins and comprising a rotor;   a shaft extending through and engaged with the rotor, top and bottom ends of the shaft located at opposite top and bottom sides of the bracket;   a first impeller located above the bracket and engaged with the top end of shaft; and   a second impeller received in the receiving chamber of the fins and engaged with the bottom end of the shaft;   wherein heat generated by the heat-generating electronic component is absorbed by the base and then is transferred to the fins for dissipation, air around the fins and the base is heated and moves upwards to drive the first impeller to rotate, and the second impeller rotates in unison with the first impeller to agitate air in the receiving chamber.   
     
     
         2 . The heat dissipation device as in  claim 1 , wherein each fin is an elongated plate, and a width of each fin is generally increased from a top end thereof away from the base to a bottom end thereof mounted on the base. 
     
     
         3 . The heat dissipation device as in  claim 2 , wherein the fins are evenly angularly spaced from each other, and each two adjacent fins cooperatively define an air passage therebetween. 
     
     
         4 . The heat dissipation device as in  claim 2 , wherein the base is a disk-like sheet, and the fins are mounted on a top surface of the base. 
     
     
         5 . The heat dissipation device as in  claim 4 , wherein outer edges of the fins are located inwardly from a periphery of the base. 
     
     
         6 . The heat dissipation device as in  claim 1 , wherein the bracket further comprises a connecting portion abutting against top ends of the fins, an engaging portion enclosed by the connecting portion, and a plurality of ribs located between the connecting portion and the engaging portion and interconnecting the connecting portion and the engaging portion, and the rotor is received in the engaging portion and rotatable relative to the engaging portion. 
     
     
         7 . The heat dissipation device as in  claim 1 , wherein each of the first impeller and the second impeller is a centrifugal impeller made of lightweight material. 
     
     
         8 . The heat dissipation device as in  claim 7 , wherein the first impeller comprises a hub and a plurality of blades radially extending from an outer periphery of the hub, and the blades extend outwardly and slantwise from the hub and are equally angularly spaced from each other. 
     
     
         9 . The heat dissipation device as in  claim 8 , wherein each blade is an elongated sheet with an arc-shaped transverse cross-section, and a width of each blade is increased from an inner end connecting the hub to an outer end away from the hub. 
     
     
         10 . The heat dissipation device as in  claim 7 , wherein the second impeller comprises a hub and a plurality of blades radially extending from an outer periphery of the hub, and each blade is a vertical, rectangular sheet. 
     
     
         11 . The heat dissipation device as in  claim 10 , wherein a diameter of the first impeller as defined by the blades thereof is larger than a diameter of the second impeller as defined by the blades thereof. 
     
     
         12 . A heat dissipation device for dissipating heat generating from a heat-generating source, the heat dissipation device comprising:
 a base for directly contacting the heat-generating source;   a plurality of spaced fins mounted on the base to dissipate heat transferred from the base by convection and thermal radiation;   a bracket mounted on the fins and comprising a rotor;   a shaft engaged with the rotor and located above the fins; and   a first impeller located above the bracket and engaged with a top end of the shaft;   wherein heat generated by the heat-generating source is absorbed by the base and then is transferred to the fins for dissipation, and air around the fins and the base is heated and moves upwards to drive the first impeller to rotate.   
     
     
         13 . The heat dissipation device as in  claim 12 , wherein the first impeller comprises a hub and a plurality of blades radially extending from an outer periphery of the hub, and the blades extend outwardly and slantwise from the hub and are equally angularly spaced from each other. 
     
     
         14 . The heat dissipation device as in  claim 13 , wherein each blade is an elongated sheet with an arc-shaped cross-section and a width of each blade is increased from an inner end connecting the hub to an outer end away from the hub. 
     
     
         15 . The heat dissipation device as in  claim 12 , further comprising a second impeller enclosed by the fins, the shaft extending through the rotor and engaging with the second impeller, and the second impeller rotates in unison with the first impeller. 
     
     
         16 . The heat dissipation device as in  claim 15 , wherein the second impeller comprises a hub and a plurality of blades radially extending from an outer periphery of the hub, and each blade is a vertical, rectangular sheet. 
     
     
         17 . The heat dissipation device as in  claim 12 , wherein each fin is an elongated plate, and a width of each fin is generally increased from a top end thereof away from the base to a bottom end thereof mounted on the base. 
     
     
         18 . The heat dissipation device as in  claim 17 , wherein the base is a disk-like sheet and the fins are radially mounted on a top surface of the base, and evenly spaced from each other along a circumferential direction of the base. 
     
     
         19 . The heat dissipation device as in  claim 17 , wherein inner edges of the fins cooperatively define a receiving chamber therebetween, and an inner diameter of the receiving chamber is decreased from top to bottom. 
     
     
         20 . The heat dissipation device as in  claim 12 , wherein the bracket comprises a connecting portion abutting against top ends of the fins, an engaging portion enclosed by the connecting portion, a plurality of ribs located between the connecting portion and the engaging portion and interconnecting the connecting portion and the engaging portion, and the rotor received in the engaging portion and rotatable relative to the engaging portion.