Patent Publication Number: US-8113801-B2

Title: Fan and motor thereof

Description:
BACKGROUND OF THE INVENTION 
     This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 097115306, filed in Taiwan, Republic of China on Apr. 25, 2008, the entire contents of which are hereby incorporated by reference. 
     FIELD OF INVENTION 
     The present invention relates to a fan and a motor thereof. More particularly, the present invention relates to the coil configuration of a fan and an inner rotor motor thereof. 
     DESCRIPTION OF THE RELATED ART 
     Since the fan applied to the current electronic apparatus or system has become smaller, it is necessary to enhance the heat dissipation efficiency of the fan within the limited space of the product. To achieve this goal, it is an applicable way to adjust the blade area of the fan. 
     In general, the motor of the fan divided into an outer-rotor motor and an inner-rotor motor according to the dispositions of the rotor and stator. For example, the conventional inner-rotor fan uses an inner-rotor motor for driving the blades to rotate. However, since the silicon steel sheet and windings of the stator occupy a certain part of the space between the frame and blades. Thus, the areas of the outlet and inlet of the fan are restricted accordingly, thereby decreasing the air flux of the fan. In addition, the windings must be wound on the silicon steel sheets so that the producing and manufacturing costs of the fan are increased. 
     Moreover, the conventional minimized DC motor includes the windings and magnetic rings without the magnetic conductive yoke. Therefore, the motor may have the drawbacks of worse efficiency and magnetic leakage. In addition, since the conventional DC motor has the design without offset, the motor may be uneasily enabled when the rotor is located at the enabling dead point. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, the present invention is to provide a fan and a motor thereof that have simplified winding configuration of the stator so as to decrease the producing and manufacturing costs and improve the efficiency of the fan. 
     To achieve the above, the present invention discloses a fan including a motor which includes a housing, a rotor assembly and a stator assembly. The rotor assembly includes a rotor, which includes blades and is accommodated in the housing. The stator assembly is disposed in the housing corresponding to the rotor assembly. The stator assembly includes a coil disposed around the rotor. The coil is a flat helix structure formed by a continuous wire, and the flat helix structure forms a cylindrical plane perpendicular to a radius plane of the motor. 
     As mentioned above, the fan and the motor of the present invention have the coil, which is disposed around the rotor and is a flat helix structure formed by a continuous wire. Thus, the magnetic pole disposition and the winding configuration of the stator in the motor of the present invention are changed. By this configuration, the inner space of the fan is efficiently used so as to increase the area for accommodating additional blades. The present invention not only change the conventional configuration of the stator, which occupies more inner space of the frame, but also simplify the winding process and reduce the manufacturing time for the winding process, thereby speeding up the assembling process and decreasing the manufacturing cost. The present invention also has two magnetic conductive structures, thus the magnetic path can be smoother and the magnetic flux of the magnetic ring and winding can be increased. Accordingly, the efficiency of the motor can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the subsequent detailed description and accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is an exploded illustration showing a fan and an inner-rotor motor according to an embodiment of the present invention; and 
         FIG. 2  is a sectional illustration showing the assembled fan of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
     With reference to  FIG. 1 , a fan according to an embodiment of the present invention includes an inner-rotor motor, which has a housing  11 , a rotor assembly  12  and a stator assembly  13 . The rotor assembly  12  includes a rotor  121 , which has several blades  122  and is accommodated in the housing  11 . In addition, the rotor  121  can be telescoped within a magnetic element, or the rotor  121  can be directly made of a magnetic material without the disposition of the magnetic element. A first magnetic conductive element  123  is disposed on an inner surface of the rotor  121  for providing a closed magnetic loop. The stator assembly  13  is disposed in the housing  11  corresponding to the rotor assembly  12 . The stator assembly  13  includes a coil  131  disposed around the rotor  121 . The coil  131  is a flat helix structure formed by a continuous wire, and the flat helix structure forms a cylindrical plane perpendicular to a radius plane of the motor. In details, the flat helix structure includes a plurality of spiral segments, and the center axis of each spiral segment is located on the radius plane. In this embodiment, the center axis of the spiral segment is perpendicular to the shaft of the rotor  121  and passes through the shaft. 
     The above-mentioned inner-rotor motor further includes a shaft  14  and a bearing  15 , which are disposed in the housing  11 . The shaft  14  is telescoped within the bearing  15 . The coil  131 , which is a flat helix structure disposed around the rotor  121 , forms a plurality of induced magnetic zones. The winding numbers of adjacent two parts of the coil  131  corresponding to adjacent two induced magnetic zones are different, so that the magnetic forces of adjacent two induced magnetic zones are different. Thus, the rotor  121  can be biased due to the different magnetic forces, thereby enabling the fan  1 . In addition, the winding directions of adjacent two parts of the coil corresponding to adjacent two induced magnetic zones are different, so that the adjacent two induced magnetic zones generate reverse magnetic lines. The reverse magnetic lines can be acted with the rotor  121  with magnetic force so as to generate the rotational torque. The rotor  121  with magnetic force itself or the magnetic element of the rotor  121  has a plurality of magnetic poles, which are disposed corresponding to the above-mentioned induced magnetic zones. 
     In addition, the stator assembly  13  further includes a second magnetic conductive element  132 , which is made of magnetic conductive yoke. The second magnetic conductive element  132  has an opening O, which is disposed between any two adjacent induced magnetic zones so as to allow a part of the magnetic lines to be leaked out. Thus, the rotor assembly  12  and the stator assembly  13  can be biased to start the rotor  121  to rotate. 
     The housing  11  includes a main body  111  and a cover body  112  connected with each other. The material of the main body  111  and the cover body  112  includes metal or a plastic material. The cover body  112  can be a circuit board, which has a driving device D. The driving device D can be, for example, a surface mount technology (SMT) electronic element disposed between the stator assembly  13  and the cover body  112 . The main body  111  includes at least one first fixing structure  111   a , and the cover body  112  includes at least one second fixing structure  112   a  disposed corresponding to the first fixing structure  111   a . The first fixing structure  111   a  is disposed on a periphery of the main body  111 , and the second fixing structure  112   a  is disposed on a periphery of the cover body  112 . The first fixing structure  111   a  and the second fixing structure  112   a  are a set of a recess and a protrusion. That is, when one of the first fixing structure  111   a  and the second fixing structure  112   a  is a protrusion, the other one thereof is a recess. 
     In summary, the fan and motor of the present invention have the coil, which is disposed around the rotor and is a flat helix structure formed by a continuous wire. Thus, the disposition of the induced magnetic zones and the winding configuration of the stator in the motor of the present invention modified compared to conventional stator changed. By this configuration, the inner space of the fan can be efficiently used so as to increase the area for accommodating additional blades. The present invention not only change the conventional configuration of the stator, which occupies more inner space of the frame, but also simplify the winding process and reduce the manufacturing time for the winding process, thereby speeding up the assembling process and decreasing the manufacturing cost. The present invention also has two magnetic conductive structures, thus the magnetic path can be smoother and the magnetic flux of the magnetic ring and winding can be increased. Accordingly, the efficiency of the motor can be improved. 
     Although the present invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the present invention.