Centrifugal Impeller and Centrifugal Blower

Abstract

A centrifugal impeller includes a cover, a base opposite the cover and a plurality of blades. The cover has an inlet. The plurality of blades surround the inlet and are arranged between and connect the cover and the base. Inlet edges of one end of the blades adjacent the center of the impeller define a cavity in communicate with the inlet. The dimension of the cavity gradually decreases along the direction from the cover towards the base.

1 . A centrifugal blower comprising an electric motor and a centrifugal impeller driven by the motor, the centrifugal impeller comprising: a cover, a base opposite the cover and a plurality of blades, the cover having an inlet, the plurality of blades surrounding the inlet and arranged between and connecting the cover and the base, inlet edges of ends of the blades adjacent the center of the impeller defining a cavity in communication with the inlet, wherein the dimension of the cavity gradually decreases in the direction from the cover towards the base. 
     
     
         2 . The blower of  claim 1 , wherein each inlet edge forms an angle γ with the base in the range of 55° to 75°. 
     
     
         3 . The blower of  claim 1 , wherein each inlet edge forms an angle γ with the base in the range of 62° to 70°. 
     
     
         4 . The blower of  claim 1 , wherein each inlet edge forms an angle γ with the base in the range of 65° to 68°. 
     
     
         5 . The blower of  claim 1 , wherein each blade 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. 
     
     
         6 . The impeller of  claim 5 , wherein the radius of the second arc segment is greater than the radius of the first arc segment. 
     
     
         7 . The blower of  claim 1 , further comprises a diffuser and a casing mounted to the diffuser, the diffuser being mounted to the motor and disposed between the motor and the impeller, the impeller being received in a chamber defined by the diffuser and the casing, the casing having an opening facing the inlet of the impeller. 
     
     
         8 . The blower of  claim 7 , wherein the diffuser has a plurality of guide holes and a plurality of smoothly curved diffusing passages each extending from an outer end to an inner end, the air flow generated by the impeller flowing from one side of the diffuser adjacent the 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. 
     
     
         9 . The blower of  claim 8 , wherein the diffuser has a plurality of passage walls forming the diffusing passages, one end of at least one of the passage walls adjacent the center of the diffuser has a guide portion for guiding the air flow in adjacent diffusing passages to two sides of a mounting portion connecting the diffuser to the motor. 
     
     
         10 . The blower of  claim 9 , wherein the image of the guide portion in the radial section of the motor is raindrop-shaped. 
     
     
         11 . The blower of  claim 9 , wherein ends of two of the passage walls of the diffuser adjacent the center of the diffuser has two streamlined guide portions which are diametrically opposite to each other. 
     
     
         12 . The blower of  claim 11 , wherein the motor includes a stator comprising a stator core and stator windings wound about teeth of the stator core, and the two guide 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 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 the hollow space and located at two sides of the guide portions. 
     
     
         14 . The blower of  claim 13 , wherein the side wall has a plurality of inclined guide slopes, the guide holes being located at the ends of the guide slopes. 
     
     
         15 . The blower of  claim 11 , wherein each of the guide portions has a mounting hole for receiving a fastener for fixing the diffuser to the motor.