Smoke exhauster having an improved fan device

Abstract

A smoke exhauster includes a motor and a fan device attached to a housing. The fan device includes an upper and a lower plates each having an outer peripheral portion, and a number of fan blades secured between the outer peripheral portions of the upper and the lower plates for forming a chamber in the fan device. The lower plate has a bore for air to flow or to be drawn into the chamber of the fan device. The fan blades each has an inner section partially extended inward of the bore of the lower plate and has a curvature smaller than the other portion of the blade.

I claim:  
     
         1 . A smoke exhauster comprising: 
 a) a housing,    b) a motor attached to said housing, and    c) a fan device attached to said motor and driven by said motor, said fan device including: 
 i) an upper plate including an outer peripheral portion,  
 ii) a lower plate including an outer peripheral portion and including a bore formed therein, and  
 iii) a plurality of fan blades secured between said outer peripheral portions of said upper and said lower plates for defining a chamber between said upper and said lower plates and said fan blades, said chamber of said fan device being communicating with said bore of said lower plate for allowing air to flow and to be drawn into said chamber of said fan device.  
   
     
     
         2 . The smoke exhauster according to  claim 1 , wherein said upper and said lower plates each includes a plurality of slits formed in said outer peripheral portion thereof, said fan blades each includes an upper and a lower portions each having at least one ear extended therefrom and engaged through said slits of said upper and said lower plates, for securing said fan blades between said outer peripheral portions of said upper and said lower plates.  
     
     
         3 . The smoke exhauster according to  claim 1 , wherein said motor includes a lower portion, said upper plate includes a recess formed therein for receiving said lower portion of said motor.  
     
     
         4 . The smoke exhauster according to  claim 1 , wherein said motor includes a spindle, said upper plate includes a hub secured thereto and attached to said spindle of said motor, for securing said fan device to said spindle of said motor.  
     
     
         5 . The smoke exhauster according to  claim 1 , wherein said fan blades each includes a first section partially extended inward of said bore of said lower plate.  
     
     
         6 . The smoke exhauster according to  claim 5 , wherein said fan blades each includes a second section extended from said first section and disposed between said outer peripheral portions of said upper and said lower plates, said second section includes a curvature greater than that of said first section of said fan blade.  
     
     
         7 . The smoke exhauster according to  claim 6 , wherein said fan blades each includes a third section extended from said second section and disposed between said outer peripheral portions of said upper and said lower plates, said second section includes a curvature less than that of said third section of said fan blade.