Fan

Abstract

A fan includes a casing and a fan blade. The casing has at least one air inlet and an air outlet. The fan blade is disposed in the casing. An air flow compression area is defined in the casing. An auxiliary air inlet is disposed on the casing at the air flow compression area. Furthermore, another fan includes a casing and a fan blade. The casing has an upper casing, a lower casing and a side casing located between the upper casing and the lower casing. The upper casing or the lower casing has at least one air inlet, and the side casing has an air outlet. The fan blade is disposed in the casing. An internal space of the casing is defined as an air flow compression area. An auxiliary air inlet is disposed on the casing at the air flow compression area.

What is claimed is: 
     
         1 . A fan, comprising:
 a casing having at least one air inlet and an air outlet; and   a fan blade disposed in the casing, wherein an air flow compression area is defined in the casing, an air flow pressure in the air flow compression area is lower than the atmospheric pressure outside the casing, and the casing has an auxiliary air inlet disposed at the air flow compression area.   
     
     
         2 . The fan according to  claim 1 , wherein the casing comprises an upper casing, a lower casing, and a side casing located between the upper casing and the lower casing, the upper casing and the lower casing respectively have the air inlet, and the air outlet is located at the side casing. 
     
     
         3 . The fan according to  claim 1 , wherein the casing comprises an upper casing, a lower casing, and a side casing located between the upper casing and the lower casing; a first point is defined at a position of the side casing which is closest to an axle center of the fan blade, a second point is defined at a position of the side casing which is farthest from the air outlet; a connecting line from the first point to the axle center of the fan blade and a connecting line from the second point to the axle center of the fan blade form an included angle, and an internal space of the casing covered by the included angle is defined as the air flow compression area. 
     
     
         4 . The fan according to  claim 3 , wherein the auxiliary air inlet is located on at least one of the upper casing, the lower casing, and the side casing. 
     
     
         5 . The fan according to  claim 3 , wherein the side casing comprises a curved line segment and two straight line segments connected to two opposite ends of the curved line segment, the curved line segment surrounds the fan blade, and the air outlet is located between the two straight line segments. 
     
     
         6 . A fan, comprising:
 a casing comprising an upper casing, a lower casing, and a side casing located between the upper casing and the lower casing, the upper casing or the lower casing having at least one air inlet, and the side casing having an air outlet; and   a fan blade disposed in the casing, wherein a first point is defined at a position of the side casing which is closest to an axle center of the fan blade, a second point is defined at a position of the side casing which is farthest from the air outlet, a connecting line from the first point to the axle center of the fan blade and a connecting line from the second point to the axle center of the fan blade form an included angle; an internal space of the casing covered by the included angle is defined as an air flow compression area; and an auxiliary air inlet is disposed on the casing at the air flow compression area.   
     
     
         7 . The fan according to  claim 6 , wherein the upper casing and the lower casing have the air inlet respectively. 
     
     
         8 . The fan according to  claim 6 , wherein an air flow pressure in the air flow compression area is lower than the atmospheric pressure outside the casing. 
     
     
         9 . The fan according to  claim 6 , wherein the auxiliary air inlet is located on at least one of the upper casing, the lower casing, and the side casing. 
     
     
         10 . The fan according to  claim 6 , wherein the side casing comprises a curved line segment and two straight line segments connected to two opposite ends of the curved line segment, the curved line segment surrounds the fan blade, and the air outlet is located between the two straight line segments.