Patent ID: 7503746

Claim:
A fan of a heat sink, said heat sink comprising a housing enclosing a space, said housing having an air inlet communicating with said space formed on a top surface thereof and an air outlet communicating with said space formed on a side thereof, said fan being installed in said housing, the fan comprising: a hub, comprising a circular sidewall facing said air inlet; a plurality of ribs, alternately disposed around said hub, wherein a distal end of said ribs are connected to said circular sidewall; and a set of blades, connected to a proximal end of said ribs, comprising an outer ring surrounding said circular sidewall of said hub, a plurality of alternately arranged first blades extending upwards from a top surface of said outer ring, a guiding ring connected to an inner side of said first blades and a plurality of second blades positioned at said inner side of said first blades and extending upwards from said top side of said guiding ring, wherein said proximal end of said ribs are connected to said guiding ring having an inclined slope extending from the hub towards the outer ring, wherein when said fan rotates, an air flow is guided from said air inlet to a space between said first and second blades, an air flow area is increased to increase a pressure and volume of air exiting to outside, and wherein said slope of said guiding ring is adopted for smoothly flowing air between said first and second blades and finally exiting said air to outside via said air outlet.