Induced-draft fan for hot air gun/air dryer

Abstract

An induced-draft fan for hot air gun/air dryer includes a casing, the casing having a motor mount and a plurality of spiral wing guides radially arranged around the fan mount, a fan blade unit, and a fan motor mounted in the motor mount and controlled to rotate the fan blade unit, the fan blade unit having a semispherical body coupled to the fan motor, and a plurality of blades radially spirally arranged around the semispherical peripheral surface of the semispherical body, the blades being curved in direction reversed to the spiral wing guides, each blade having a top wind cut face and a bottom side edge disposed in flush with the bottom edge of the semispherical peripheral surface of the semispherical body.

What the invention claimed is:  
     
         1 . An induced-draft fan for hot air gun/air dryer comprising a casing, a fan motor mounted in said casing, said fan motor comprising a motor shaft, and a fan blade unit coupled to said motor shaft of said fan motor and driven to induce currents of air upon operation of said fan motor, wherein said fan blade unit comprises a semispherical body coupled to said motor shaft of said fan motor, said semispherical body having a semispherical peripheral surface and a bottom edge, and a plurality of blades radially spirally arranged around the semispherical peripheral surface of said semispherical body, said blades each having a top wind cut face and a bottom side edge disposed in flush with the bottom edge of the semispherical peripheral surface of said semispherical body.  
     
     
         2 . The induced-draft fan of  claim 1  wherein said casing comprises a cylindrical peripheral wall, a motor mount suspended inside said cylindrical peripheral wall and adapted to hold said fan motor, and a plurality of wing guides radially connected between said motor mount and said cylindrical peripheral wall, said wing guides being spirally curved in direction reversed to said blades of said fan blade unit.