Miniature heat-dissipating fan device

Abstract

A miniature heat-dissipating fan device is disclosed, which comprises: a frame; a shaft, pivotally connected to the frame; at least a planar coil, each being received in the frame and formed in a wave winding manner; at least a permanent magnet, each being connected to the shaft while being positioned about parallel to the at least one planar coil for enabling the generation of an alternating multipolar magnetic field; a plurality of blades, being disposed at positions corresponding to the at least one permanent magnet while centering around the axis of the shaft in a centrifugal manner; and at least a magnetically permeable back iron, disposed at a side of the at least one planar coil and being structured with a geometrical shape matching to the wave winding planar coil; wherein the plural blades are integrated with the at least one permanent magnet for enabling the same to rotate with the at least one permanent magnet synchronously. In an exemplary embodiment of the invention, the planar coil is structured with at least a hollowed area, each having a Hall-effect sensor embedded therein. With the aforesaid device, not only it can be structured as a thin-type device with improved convection efficiency, but also the magnetic flux density is increased.

1 . A miniature heat-dissipating fan device, comprising:
 a frame;   a shaft, pivotally connected to the frame;   at least a planar coil, each being received in the frame and formed in a wave winding manner;   at least a permanent magnet, each being connected to the shaft while being positioned about parallel to the at least one planar coil for enabling the generation of an alternating multipolar magnetic field;   a plurality of blades, being disposed in a manner that each is coupled to the at least one permanent magnet so as to rotate with the at least one permanent magnet synchronously; and   at least a magnetically permeable back iron, each being disposed at a side of the at least one planar coil and being structured with a geometrical shape matching to the wave winding planar coil;   wherein the planar coil comprises at least one layer of coil being wound on a same level, and on such level, said layer is formed by a plurality of turns of coil which is formed by continuous wire wound symmetrically around the radial center of the planar coil, each turn of coil has a plurality of convex pole portion and corresponding concave pole portion, the convex pole portion and the corresponding concave pole portion consists of a arc section and two line sections, the center of the arc section is the radial center which is also the center the two line sections radially pointing to virtually, and each line section is common-owned by the adjacent convex pole portion and concave pole portion.   
     
     
         2 . The miniature heat-dissipating fan device of  claim 1 , wherein Rmax is the maximum radius of the outer rim of the permanent magnet and Rmin is the minimum radius of the permanent magnet; Ri 1  is the smaller radius of the most inner turn of the planar coil of a wave winding and Ri 2  is the smaller radius of the most outer turn of the planar coil of the wave winding; Ro 1  is the larger radius of the most outer turn of the planar coil of the wave winding and Ro 2  is the larger radius of the most inner turn of the planar coil of the wave winding, wherein Ro 1 <=Rmax and Ri 1 >=Rmin, Ro 1 −Ri 1 =Rs=the area for the wave winding and Ri 2 −Ri 1 =Ro 2 −Ro 1 <=0.3*(Rmax−Rmin). 
     
     
         3 . The miniature heat-dissipating fan device of  claim 1 , wherein the plural blades are disposed centering around the axis of the shaft in a centrifugal manner while coupling to the at least one permanent magnet. 
     
     
         4 . The miniature heat-dissipating fan device of  claim 2 , wherein each of the permanent magnet is shaped like a flat disc. 
     
     
         5 . The miniature heat-dissipating fan device of  claim 1 , wherein each of the permanent magnet is made of a material containing ferrite or boron ferric aluminum, while it is integrally formed with the plural blades. 
     
     
         6 . The miniature heat-dissipating fan device of  claim 1 , wherein the wave winding of each planar coil is in a wave shape selected from the group consisting of a square wave, a triangle wave and a sine wave. 
     
     
         7 . The miniature heat-dissipating fan device of  claim 1 , wherein the winding of each planar coil can be in series or parallel manner. 
     
     
         8 . The miniature heat-dissipating fan device of  claim 1 , wherein the miniature heat-dissipating fan device has two permanent magnets arranged therein while the plural blades are sandwiched between the two permanent magnets. 
     
     
         9 . The miniature heat-dissipating fan device of  claim 8 , wherein there are two planar coils to be received inside the frame at positions respectively corresponding to the outer sides of the two permanent magnets opposite to those facing the blades. 
     
     
         10 . The miniature heat-dissipating fan device of  claim 1 , wherein each planar coil is formed on an object selected from a flexible multilayer printed circuit board and a rigid printed circuit board. 
     
     
         11 . The miniature heat-dissipating fan device of  claim 10 , wherein each planar coil is integrated with a Hall-effect sensor. 
     
     
         12 . The miniature heat-dissipating fan device of  claim 1 , wherein each planar coil is structured with at least a hollowed area, each having a Hall-effect sensor embedded therein. 
     
     
         13 . The miniature heat-dissipating fan device of  claim 12 , wherein each hollow area is arranged at a position between two neighboring wave crests of each wave-winding planar coil. 
     
     
         14 . The miniature heat-dissipating fan device of  claim 12 , wherein each hollow area is structured to channel through the planar coil from edge to edge. 
     
     
         15 . The miniature heat-dissipating fan device of  claim 12 , wherein the thickness of the Hall-effect sensor is no larger than that of the planar coil. 
     
     
         16 . The miniature heat-dissipating fan device of  claim 1 , wherein the frame is comprised of a sleeve and a base in a manner that an accommodating space is formed by the enclosure of the sleeve and the base so as to be used for receiving the shaft, the at least one planar coil, the at least one permanent magnet, the plural blades and the magnetically permeable back iron. 
     
     
         17 . The miniature heat-dissipating fan device of  claim 16 , wherein the sleeve is a cylinder having a plurality of radial-type outlets formed thereon. 
     
     
         18 . The miniature heat-dissipating fan device of  claim 16 , wherein the sleeve is a cylinder having at least an axial-type outlet formed thereon.