Fan structure

Abstract

A fan includes a blade assembly rotatably supported in a frame. The blade assembly includes a cylinder having an outer surface to which blades are mounted and an inner surface to which magnets are mounted. The blade assembly has an axle concentric with the cylinder. The frame includes a casing made of silicone steel that is fixed inside the frame and supports a bearing device. The bearing device defines a central bore rotatably receiving the axle of the blade assembly therein with the cylinder of the blade assembly fit over and spaced from the casing. Windings of conductive wires are encased and fixed in the casing and surround the bearing device for being electrically powered to generate a magnetic field that interacts with the magnetic means of the blade assembly to rotate the blade assembly. The casing includes opposite upper and lower disks with tabs extending between the upper and lower disks. The tabs extends from a circumference of the upper disk and have free ends fit into corresponding notches defined in the lower disk with a major surface of the tabs extending along a circumferential direction of the disks. Portions of the lower disk project beyond the tabs and are positioned in correspondence to the magnets of the blade assembly for magnetically attracting and thus maintaining the blade assembly in a close position with respect to the lower disk to eliminate “pump” action of the blade assembly.

What is claimed is:  
     
         1 . A fan comprising: 
 a blade assembly comprising a cylinder having an outer surface to which blades are mounted and an inner surface to which magnet means is attached, the blade assembly comprising an axle concentric with the cylinder; and    a frame rotatably supporting the blade assembly, a casing made of silicone steel being fixed in the frame and supporting a bearing device that defines a central bore rotatably receiving the axle of the blade assembly therein with the cylinder of the blade assembly fit over and spaced from the casing, windings of conductive wires being encased and fixed in the casing and surrounding the bearing device for being electrically powered to generate a magnetic field that interacts with the magnetic means of the blade assembly to rotate the blade assembly, the casing comprising opposite upper and lower disks with tabs extending between the upper and lower disks, the tabs having a major surface extending along a circumferential direction of the disks.    
     
     
         2 . The fan as claimed in  claim 1 , wherein the lower disk forms a number of notches in and spaced along a circumference thereof, the tabs being integrally formed with the upper disk and extending from a circumference of the upper disk, the tabs having free ends respectively fit into the notches of the lower disk.  
     
     
         3 . The fan as claimed in  claim 1 , wherein the upper disk defines a central hole and the lower disk forms a hub substantially aligned with the central hole of the upper disk, the bearing device being received in and retained by the central hole of the upper disk and the hub of the lower disk.  
     
     
         4 . The fan as claimed in  claim 1 , wherein the lower disk forms a plurality of portions spaced along a circumference thereof and projecting beyond the tabs, the portions being positioned in correspondence to the magnet means of the blade assembly for attracting and thus retaining the blade assembly in a close position.