Centrifugal Impeller and Centrifugal Blower

Abstract

A centrifugal blower includes an electric motor, a centrifugal impeller driven by the motor, a diffuser mounted to the motor and disposed between the motor and the centrifugal impeller, and a casing mounted to the diffuser. The centrifugal impeller is received in a chamber defined by the diffuser and the casing. the casing defines an opening facing the inlet of the centrifugal impeller. The diffuser has a plurality of passage walls, and a plurality of diffusing passages, each bounded by neighboring passage walls. The diffuser further has at least one mounting portion connected to one of the passage walls. A cross section of each of the diffusing passages is increased form an outer end to an inner end thereof and no throat is formed in each of the diffusing passages.

1 . A centrifugal blower comprising:
 an electric motor;   a centrifugal impeller driven by the motor;   a diffuser mounted to the motor and disposed between the motor and the centrifugal impeller; and   a casing mounted to the diffuser, the centrifugal impeller being received in a chamber defined by the diffuser and the casing, the casing having an opening facing the inlet of the centrifugal impeller;   wherein the diffuser has a plurality of passage walls, and a plurality of diffusing passages, each bounded by neighboring passage walls, the diffuser further has at least one mounting portion connected to one of the passage walls, a cross section of each of the diffusing passages is increased form an outer end to an inner end thereof and no throat is formed in each of the diffusing passages.   
     
     
         2 . The centrifugal blower of  claim 1 , wherein said at least one mounting portion is connected to an inner ends of the corresponding one of the passage walls, each of said at least one mounting portion comprises a cylindrical surface protrudes towards the center of the diffuser. 
     
     
         3 . The centrifugal blower of  claim 2 , wherein the cylindrical surface is connected to the corresponding one of the passage walls with a smooth transition; the passage wall connected to said at least one mounting portion has a variable thickness, which gradually increases from the outer end to the inner end thereof; said at least one mounting portion together with the corresponding passage wall connected thereto has a raindrop-shaped contour. 
     
     
         4 . The centrifugal blower of  claim 1 , wherein said at least one mounting portion comprises two mounting portions respectively connected to the inner ends of two of passage walls and diametrically opposite to each other. 
     
     
         5 . The centrifugal blower of  claim 1 , wherein the centrifugal impeller comprises
 a cover defining an inlet;   a base opposite the cover; and   a plurality of blades sandwiching between the cover and the base, the plurality of blades surrounding the inlet, inlet edges of ends of the blades adjacent the center of the centrifugal impeller defining a cavity in communication with the inlet, the dimension of the cavity gradually decreasing in the direction from the cover towards the base.   
     
     
         6 . The centrifugal blower of  claim 5 , wherein each inlet edge forms an angle γ with the base in the range of 55° to 75°. 
     
     
         7 . The centrifugal blower of  claim 6 , wherein each inlet edge forms an angle γ with the base in the range of 62° to 70°. 
     
     
         8 . The centrifugal blower of  claim 7 , wherein each inlet edge forms an angle γ with the base in the range of 65° to 68°. 
     
     
         9 . The centrifugal blower of  claim 5 , wherein each blade has a thickness, which is invariable along longitudinal direction thereof, and comprises first and second arc segments which have different radii, the first arc segment being located at a radially inner portion of the blade, and the second arc segment being located at a radially outer portion of the blade. 
     
     
         10 . The centrifugal blower of  claim 9 , wherein the radius of the second arc segment is greater than the radius of the first arc segment. 
     
     
         11 . The centrifugal blower of  claim 1 , wherein the diffuser defines a plurality of guide holes, the air flow generated by the centrifugal impeller flowing from one side of the diffuser adjacent the centrifugal impeller to the side of the diffuser adjacent the motor via the guide holes, outer ends of the diffusing passages being in communication with corresponding guide holes and inner ends of the diffusing passages being in communication with one another. 
     
     
         12 . The centrifugal blower of  claim 4 , wherein the motor comprises a stator comprising a stator core and stator windings wound about teeth of the stator core, and the two mounting portions are respectively located at gaps between the stator windings so as to guide the air flow in the diffusing passages to the stator windings. 
     
     
         13 . The centrifugal blower of  claim 12 , wherein the diffuser has an end wall and a side wall extending from the end wall towards the motor, the passage walls and the diffusing passages being formed inside a space defined by the end wall and the side wall, axial ends of the stator windings extending into a space defined by the inner ends of the passage walls and located at two sides of the mounting portions. 
     
     
         14 . The centrifugal blower of  claim 13 , wherein the side wall has a plurality of guide slopes which extends from the end wall towards the motor in a direction inclined as regard to an axial direction of the diffuser, the guide holes being located at the ends of the guide slopes away from the end wall. 
     
     
         15 . The centrifugal blower of  claim 1 , wherein each of said at least one mounting portion defines a mounting hole for receiving a fastener for fixing the diffuser to the motor.