Diagonal fan

Abstract

A diagonal fan is disclosed and includes a frame and an impeller. The frame includes an inlet, an outlet, an accommodation space and a guiding wall. The inlet and the outlet are communicated through the accommodation space. The guiding wall is extended along an axial direction to the accommodation space. The impeller is accommodated within the accommodation space and includes a conical section shell. When the impeller is rotated, an airflow flowing is generated. The outer diameter of the hub of the impeller is expended gradually in a direction from the inlet toward the outlet, so that the flowing direction of the airflow is expended gradually around the peripheral of the impeller. A gap having a spacing distance is substantially maintained to form a backflow channel. A backflow is transported through an intake section, a horizontal section and an exhaust section of the backflow channel, and converged with the airflow.

What is claimed is: 
     
         1 . A diagonal fan, comprising:
 a frame comprising an inlet, an outlet, an accommodation space and a guiding wall, wherein the inlet and the outlet are disposed at two opposite sides of the frame, respectively, and in fluid communication with each other through the accommodation space, wherein the guiding wall is connected to an inner wall surface of the frame, and the guiding wall is extended from a periphery of the inlet along an axial direction into the accommodation space; and   an impeller accommodated within the accommodation space of the frame, wherein when the impeller is rotated, an airflow flowing from the inlet to the outlet is generated, wherein the impeller comprises a conical section shell, and a gap having a spacing distance is substantially maintained between the inner wall surface of the frame, and an outer wall and an upper end of the conical section shell to form a backflow channel, wherein the impeller comprises a hub, and the outer diameter of the hub of the impeller is expended gradually in a direction from the inlet toward the outlet so that the flowing direction of the airflow is expended gradually around a periphery of the impeller,   wherein the backflow channel comprises an intake section, a horizontal section and an exhaust section, the intake section is located adjacent to a lower end of the conical section shell and in fluid communication with the exhaust section through the horizontal section, and the upper end of the conical section shell is at least partially shielded by the guiding wall to form the exhaust section, wherein when the airflow flows from the inlet to the outlet, a backflow is transported from the intake section, flows through the horizontal section, is exhausted out through the exhaust section, and is converged with the airflow, wherein the conical section shell comprises a plurality of balance holes disposed around the lower end of the conical section shell, the horizontal section is spatially corresponding to the plurality of balance holes, and the backflow channel further comprises a second horizontal section spatially corresponding to the upper end of the conical section shell,   wherein the conical section shell comprises a plurality of balance holes disposed around the lower end of the conical section shell, the horizontal section is spatially corresponding to the plurality of balance holes, and the backflow channel further comprises a second horizontal section spatially corresponding to the upper end of the conical section shell.   
     
     
         2 . The diagonal fan according to  claim 1 , wherein the backflow flows in the intake section along a direction reversed to that of the backflow flowing in the exhaust section. 
     
     
         3 . The diagonal fan according to  claim 1 , wherein the backflow flows in the horizontal section along a direction perpendicular to the axial direction. 
     
     
         4 . The diagonal fan according to  claim 1 , wherein the backflow flows in the exhaust section along a direction identical to that of the airflow flowing. 
     
     
         5 . The diagonal fan according to  claim 1 , wherein the impeller comprises the hub, a cylindrical part and a plurality of blades, wherein the cylindrical part is configured to accommodate a rotor and a stator, the hub is disposed on the cylindrical part, the plurality of blade are spaced apart and disposed on the hub, and the plurality of blades are connected between the hub and the conical section shell, wherein when the impeller is rotated, the airflow is formed to flow through the plurality of blades and between the hub and the conical section shell. 
     
     
         6 . The diagonal fan according to  claim 5 , wherein the frame comprises an upper frame and a lower frame assembled with each other to form the inlet, the outlet and the accommodation space, wherein the inlet and the guiding wall are disposed on the upper frame. 
     
     
         7 . The diagonal fan according to  claim 6 , wherein the upper frame comprises an upper frame plate disposed on an upper end of the upper frame, the inlet is located at the upper frame, and the guiding wall is connected to the upper frame plate and extended downwardly from the periphery of the inlet into the accommodation space. 
     
     
         8 . The diagonal fan according to  claim 7 , wherein the lower frame comprises a lower frame plate, a base and a plurality of static blades, the lower frame plate is spatially corresponding to the upper frame plate, and the plurality of static blades are disposed between the base and the lower frame plate to form the outlet between the lower frame plate and base. 
     
     
         9 . The diagonal fan according to  claim 8 , wherein the base further comprises a tube, the stator comprises a winding and a printed circuit board disposed on a periphery of the tube, and the rotor comprises a magnetic shell, a magnet and a shaft, wherein the magnetic shell is disposed within the cylindrical part of the impeller and configured to accommodate the magnet, the shaft, the winding and a part of the tube, the magnet is disposed on an inner wall of the magnetic shell and spatially corresponding to the winding, the shaft is disposed at a center of the magnetic shell, and the shaft is disposed in the tube through a bearing. 
     
     
         10 . The diagonal fan according to  claim 9 , wherein a chamber is formed between the base and the tube, and configured to accommodate an electronic component on the printed circuit board. 
     
     
         11 . The diagonal fan according to  claim 1 , wherein the inlet has an inlet diameter, the outlet has an outlet diameter, and the inlet diameter is less than the outlet diameter. 
     
     
         12 . The diagonal fan according to  claim 1 , wherein the frame has a frame diameter, the inlet has an inlet diameter, the outlet has an outlet diameter, a ratio of the inlet diameter to the frame diameter is ranged from 0.5 to 0.7, and a ratio of the outlet diameter to the frame diameter is ranged from 0.8 to 0.98. 
     
     
         13 . The diagonal fan according to  claim 1 , wherein the frame has a frame diameter, the inlet has an inlet diameter, the outlet has an outlet diameter, a ratio of the inlet diameter to the frame diameter is ranged from 0.6 to 0.8, and a ratio of the outlet diameter to the frame diameter is ranged from 0.8 to 0.98. 
     
     
         14 . The diagonal fan according to  claim 1 , wherein the frame has a frame diameter, and a ratio of the spacing distance to the frame diameter is ranged from 0.01 to 0.02. 
     
     
         15 . The diagonal fan according to  claim 1 , wherein the frame, the upper end of the conical section shell and the guiding wall are at least partially overlapped in view of a radial direction.