Heat dissipating fan

Abstract

A heat-dissipating fan has a housing and an impeller. The housing has a receiving space and one or more guide rings. The receiving space forms an airflow inlet and an airflow outlet. The guide ring is mounted near the airflow outlet and has one or two guide surfaces formed thereon and facing the airflow inlet. The impeller is mounted rotatably in the receiving space and has a hub and multiple blades. Airflow channels formed between adjacent blades each have a cross-section narrowed from a top end of the guide ring to the airflow outlet. Each blade has a receiving notch formed in a bottom edge thereof, corresponding to a cross-section of the guide ring and defines a gap between the blade and the guide ring. Airflow is speeded up in the airflow channels based on Venturi effect, such that a heat-dissipating efficiency of the fan is improved.

1 . A heat-dissipating fan comprising
 a housing ( 2 ) having a receiving space ( 21 );   the receiving space ( 21 ) is formed in a center of the housing ( 2 ) and forms an airflow inlet and an airflow outlet; the airflow inlet and the airflow outlet being formed respectively at a top end and a bottom end of the housing ( 2 ); the hub bracket ( 23 ) being mounted in the receiving space ( 21 ); the support ribs ( 22 ) being formed in a lower end of the receiving space ( 21 ); the support ribs ( 22 ) locate between and connect to the hub bracket ( 23 ) and an inner wall of the receiving space ( 21 );   a guide ring mounted coaxially around an outer wall of the hub bracket ( 23 ) near the airflow outlet;   a drive device being a motor having a stator ( 24 ) and a rotor; the stator ( 24 ) is mounted on the hub bracket ( 23 ) and has an axial hole ( 25 ) formed in a center thereof;   an impeller ( 1 ) mounted in the receiving space ( 21 ) of the housing ( 2 ) and having a hub ( 11 ), a shaft ( 12 ) and multiple blades ( 13 ); the hub ( 11 ) receiving the rotor; the shaft ( 12 ) being mounted at a center of the hub ( 11 ), protruding downward and being inserted into to the axial hole ( 25 ) in the stator ( 24 ) to mount the impeller ( 1 ) in the receiving space ( 21 ); therefore, the rotor in the hub ( 11 ) in cooperation with the stator ( 24 ) in hub bracket ( 23 ) drives the impeller ( 1 ) to rotate; the blades ( 13 ) being mounted around an outer wall of the hub ( 11 ) and form multiple airflow channels ( 14 ) each locating between adjacent blades ( 13 ) and having a cross-section smoothly narrowing from a top end of the guide ring to the airflow outlet; each of the blades ( 13 ) has a receiving notch.   
   
   
       2 . The heat-dissipating fan as claimed in  claim 1 , wherein the guide ring ( 26 ) has a guide surface ( 27 ) formed thereon; the guide surface ( 27 ) is formed on an outside of the guide ring ( 26 ), wherein the outside is away from the hub bracket ( 23 );
 the receiving notch ( 131 ) is formed in one corner side at a bottom edge of the blade ( 13 ), corresponds to a cross-section of the guide ring ( 26 ) and defines a gap between the bottom edge of the blade ( 13 ) and the guide surface ( 27 ) of the guide ring ( 26 ).   
   
   
       3 . The heat-dissipating fan as claimed in  claim 1 , wherein the guide ring ( 28 ) is mounted on the supporting ribs ( 22 ) near the airflow outlet and has two guide surfaces ( 281 ) formed thereon; the guide surfaces ( 281 ) are respectively formed on an outside and an inside of the guide ring ( 28 ); and
 the receiving notch ( 131 A) of each blade of the impeller is a concave notch at a middle side and is corresponds to a cross-section of the guide ring ( 28 ) with two guide surfaces ( 281 ).   
   
   
       4 . The heat-dissipating fan as claimed in  claim 1 , wherein the guide ring ( 41 ) has a guide surface formed thereon; the guide surface is formed on an outside of the guide ring, wherein the outside is away from the hub bracket ( 23 );
 the receiving notch is formed in one corner side at a bottom edge of the blade ( 13 ), corresponds to a cross-section of the guide ring ( 41 ) and defines a gap between the bottom edge of the blade ( 13 ) and the guide surface of the guide ring ( 26 ); and   the heat dissipating fan further comprising:   a second guide ring ( 42 ) mounted coaxially around an outer wall of the hub bracket ( 23 ) near the airflow outlet;   the second guide ring ( 42 ) mounted on the supporting ribs ( 22 ) near the airflow outlet and has two guide surfaces formed thereon; the guide surfaces being respectively formed on an outside and an inside of the guide ring ( 42 ); and   a receiving notch ( 131 C) of each blade of the impeller being a concave notch at a middle side and being corresponds to a cross-section of the guide ring ( 28 ) with two guide surfaces ( 281 ).