Patent Publication Number: US-8531073-B2

Title: Heat dissipation system and fan thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 200910262180.X, filed in People&#39;s Republic of China on Dec. 25, 2009, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to a heat dissipation system and a fan thereof and, in particular to a heat dissipation system and a fan thereof including an internal-rotor motor. 
     2. Related Art 
     As electronic products progress in their performances, frequencies and calculating speeds and thin sizes, they generate more and more heat in operation resulting in temperature increase. It severely jeopardizes the stability of the electronic products and, meanwhile, reduces their reliability and lifetime. Thus, the heat dissipation has become an important issue for the electronic products. Because fans have advantages of low production cost, technology development and so on, they are frequently used in electronic devices for heat dissipation. 
     Generally speaking, the fan uses a motor as a power source. The motor includes a rotor magnet, a stator coil and other structures, whose arrangement are used to classify the motors into two major categories, the external-rotor motors and the internal-rotor motors. Recently, the external-rotor motors are applied wildly in industry. However, since their rotor magnets are disposed outside the stator coils and distant from the axle center of the shaft (that is, the rotating radiuses of the rotor magnets in the external-rotor motors are larger), the rotational inertias of the rotor magnets are increased and further larger vibrations are frequently generated at high rotating speed. 
     Accordingly, as the motor rotates at higher speed, the requirement of the run-out of the rotor magnet is very critical correspondingly. It increases the cost of mold and the difficulty of production. Moreover, if the side run-out of the rotor magnet is too large, the shaft has to bear an even higher impact force resulting from the vibration. In addition, during the external-rotor motor operates at high speed, the heat generated from the copper wire of the stator coil cannot be dissipated effectively and thereby accumulates inside the motor. It shortens the lifetime of the shaft and causes the abnormality of other elements, and further reduces the integral reliability and efficiency of the fan. 
     In summary, the replacement of the external-rotor motor by the internal-rotor motor to change the position of the rotor magnet can effectively solve most of the aforementioned issues. However, the rotational balance of the internal-rotor motor also has to be adjusted in response to the trend of operation with higher and higher rotating speed. In addition, the heat generated from the copper wire of the stator coil also has to be dissipated effectively to prevent heat accumulation inside the motor resulting in the abnormality of the shaft and other elements. However, no internal-rotor motor able to solve the aforementioned issues appropriately exists nowadays. 
     Therefore, a heat dissipation system and a fan thereof able to effectively increase the reliability of the motor and prolong the lifetime of the shaft at high rotating speed has been desired. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, the present invention is to provide a heat dissipation system and a fan thereof able to effectively increase the reliability of the motor and prolong the lifetime of the shaft at high rotating speed. 
     To achieve the above, the present invention provides a fan including an impeller structure, a rotor structure and a stator structure is disclosed. The impeller structure includes a hub and a plurality of blades. The blades are disposed around the outer periphery of the hub, and one of the blades is higher than the stator structure in vertical direction. The rotor structure includes a shaft and a magnetic element. The shaft is disposed through the magnetic element and connected to the hub. The shaft includes at least one groove disposed at the junction of the shaft and the magnetic element. The magnetic element includes at least one terminal surface in the axial direction, and at least one receptacle is formed on the terminal surface. In one embodiment of the present invention, the terminal surface of the magnetic element includes an outer ring part, and the outer ring part is disposed around the terminal surface along the outer diameter of the magnetic element to form the receptacle. In another embodiment of the present invention, the receptacle of the terminal surface includes a plurality of ribs to divide the receptacle into a plurality of small partitions. 
     In addition, the stator structure is disposed around the outer periphery of the magnetic element. The stator structure includes a top part, and the hub comprises a bottom part. A gap is formed between the top part and the bottom part in horizontal direction. In one embodiment of the present invention, the stator structure includes a plurality of silicon steel plates and a coil assembly winding around the silicon steel plates. The silicon steel plates form an opening, and the stator structure is disposed through the opening. 
     The fan further includes a motor housing, and the rotor structure and the stator structure are disposed in the motor housing. The shaft of the rotor structure passes through the motor housing. The motor housing includes at least one side surface including at least one hole. 
     The fan further includes at least one bearing and one bearing bushing. The bearing is disposed in the bearing bushing, and the bearing bushing is connected to the motor housing. The shaft is disposed through the bearing. 
     To achieve the above, the present invention also provides a heat dissipation system including at least one fan, a plurality of static blades and a frame body. The fan includes an impeller structure, a rotor structure and a stator structure. The impeller structure includes a hub and a plurality of blades. The blades are disposed around the outer periphery of the hub, and one of the blades is higher than the stator structure in vertical direction. The rotor structure includes a shaft and a magnetic element. The shaft is disposed through the magnetic element and connected to the hub. The shaft includes at least one groove disposed at the junction of the shaft and the magnetic element. The magnetic element includes at least one terminal surface in the axial direction, and at least one receptacle is formed on the terminal surface. In one embodiment of the present invention, the terminal surface of the magnetic element includes an outer ring part, and the outer ring part is disposed around the terminal surface along the outer diameter of the magnetic element to form the receptacle. The receptacle of the terminal surface includes a plurality of ribs to divide the receptacle into a plurality of small partitions. 
     In addition, the stator structure is disposed around the outer periphery of the magnetic element. The stator structure includes a top part, and the hub includes a bottom part. A gap is formed between the top part and the bottom part in horizontal direction. In one embodiment of the present invention, the stator structure includes a plurality of silicon steel plates and a coil assembly winding around the silicon steel plates. The silicon steel plates form an opening, and the stator structure is disposed through the opening. Moreover, the static blades are disposed around the outer periphery of the fan. The fan and the static blades are disposed in the frame body, and connected to the fan and the static blades respectively. 
     The fan further includes a motor housing, and the rotor structure and the stator structure are disposed in the motor housing. The shaft of the rotor structure passes through the motor housing. The motor housing includes at least one side surface including at least one hole. 
     The fan further includes at least one bearing and one bearing bushing. The bearing is disposed in the bearing bushing, and the bearing bushing is connected to the motor housing. The shaft is disposed through the bearing. 
     In summary, since the heat dissipation system and the fan thereof in accordance with the present invention include the receptacle on the terminal surface of the magnetic element of the rotor structure in the axial direction for containing a balance material, the rotor structure can be tested for its dynamic balance before the assembly of the motor and, furthermore, the balance material can be filled into the receptacle to maintain the rotor structure in good dynamic balance at high rotating speed. It effectively prevents the lifetime of the shaft from being shortened by vibration. Moreover, the heat generated from the coil of the stator structure of the fan and the heat dissipation system thereof in accordance with the present invention can be dissipated positively with the air flow generated during the fan is in operation. It protects the lifetime of the shaft and the normal functions of other elements against the damage resulting from the accumulation of heat inside the motor. Accordingly, the heat dissipation system and the fan thereof in accordance with the present invention are able to effectively increase the reliability of the motor and prolong the lifetime of the shaft at high rotating speed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a cross-sectional figure of a fan in accordance with a preferable embodiment of the present invention; 
         FIG. 2A  is an enlarged figure of the rotor structure shown in  FIG. 1 ; 
         FIG. 2B  is an enlarged figure of another aspect of the rotor structure in accordance with the preferably embodiment of the present invention; 
         FIG. 2C  is an enlarged figure of other aspect of the rotor structure in accordance with the preferably embodiment of the present invention; 
         FIG. 3  is a schematic figure of the air flow during the fan shown in  FIG. 1  is in operation; 
         FIGS. 4A and 4B  are a cross-sectional figure of another fan  5  in accordance with the preferable embodiment of the present invention and a schematic figure of the air flow during the fan  5  is in operation; 
         FIG. 5  is a cross-sectional figure of a heat dissipation system in accordance with a preferably embodiment of the present invention; and 
         FIG. 6  is a cross-sectional figure of another heat dissipation system in accordance with the preferable embodiment. 
     
    
    
     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. 
       FIG. 1  is a cross-sectional figure of a fan  2  in accordance with one preferable embodiment of the present invention. The fan  2  includes an impeller structure  21  and an internal-rotor motor. The internal-rotor motor includes a rotor structure  22  and a stator structure  23 . 
     The impeller structure  21  includes a hub  211  and a plurality of blades  212  disposed around the outer periphery of the hub  211 . The material of the hub  211  and the blades  212  includes, for example, aluminum, aluminum magnesium alloy or plastic. The hub  211  and the blades  212  can be integrally formed as one piece, or can be two separated elements initially and then be combined with each together. The hub  211  can be connected to the blades  212  by, for example but not limited to, locking or injection molding. 
     The rotor structure  22  includes a shaft  221  and a magnetic element  222 . The shaft  221  is disposed through the magnetic element  222  and connected to the hub  211 . The hub  211  can be connected to the shaft  221  by, for example, mounting, locking or adhesion. 
     The shaft  221  includes at least one groove  221 s disposed at the junction of the shaft  221  and the magnetic element  222 . In the present embodiment, three grooves  221 s are taken for example and disposed at the junction. However, the amount of the grooves  221 s is not only limited to three. The disposition of the grooves  221 s expands the combination area between the shaft  221  and the magnetic element  222  and thereby improves the combination force between the shaft  221  and the magnetic element  222  as the shaft  221  is connected to the magnetic element  222  by adhesion. 
     The magnetic element  222  of the present invention can be, for example, an annular magnetic body with hollow cylindrical structure, and disposed around the shaft  221  corresponding to the stator structure  23 . The material of the magnetic body  222  includes, for example, ferrite, soft ferrite magnet, highly magnetic alloy, magnetic material or a combination thereof. 
       FIG. 2A  is an enlarged figure of the rotor structure  22  shown in  FIG. 1 . The magnetic element  222  includes at least one terminal surface  223  in the axial direction, and at least one receptacle S 1  is formed on the terminal surface  223 . One terminal surface  223  is respectively formed on the top side and the bottom side of the magnetic element  222 , and at least one receptacle S 1  is formed on the terminal surface  223 . The terminal surface  223  of the magnetic element  222  can include an outer ring part  223   a , and the outer ring part  223   a  is disposed around the terminal surface  2223  along the outer diameter of the magnetic element  222  to form the aforementioned receptacle S 1 . 
     However, the rotor structure in accordance with the present invention can have different aspects. As shown in  FIG. 2B , the receptacle S 2  of the terminal surface  323  includes a plurality of ribs  323   b  to divide the receptacle S 2  into a plurality of small partitions. Alternatively, as shown in  FIG. 2C , the receptacle S 3  of the terminal surface  423  includes a plurality of ribs  423   b  to divide the receptacle S 3  into a plurality of small partitions. 
     Therefore, the receptacle (such as the aforementioned receptacles S 1 , S 2 , S 3 , or the small partitions formed by the ribs  323   b  or  423   b ) formed on the terminal surface in the axial direction of the magnetic element in accordance with the present invention can be used to contain the balance material. Thus, the rotor structure can be tested for its dynamic balance before the assembly of the motor, and the balance material can be filled into the receptacle to maintain the rotor structure in good dynamic balance at high rotating speed and thereby prevent the lifetime of the shaft from being shortened by vibration. 
     As shown in  FIG. 1 , the stator structure  23  includes a plurality of silicon steel plates and a coil assembly winding around the silicon steel plates. The silicon steel plates form an opening  231 , and the shaft  221  of the stator structure  22  is disposed through the opening  231 . The stator structure  23  is disposed around the outer periphery of the magnetic element  222 , and, consequently, the silicon steel plates and the coil assembly of the stator structure  23  are disposed around the outer periphery of the magnetic element  222 . The stator structure  23  includes a top part  232 , and the hub  211  includes a bottom part  211   a . A gap d 1  is formed between the top part  232  of the stator structure  23  and the bottom part  211   a  of the hub  211  in horizontal direction. In addition, one of the blades  212  is higher than the stator structure  21  and the top part  232  thereof in vertical direction. 
     The fan  2  of the present embodiment can further include a motor housing  24 , and the rotor structure  22  and the stator structure  23  are disposed in the motor housing  24 . The shaft  221  of the rotor structure  22  passes through the motor housing  24 . The motor housing  24  includes at least one side surface  241  including at least one hole  241   a . In the present embodiment, the motor housing  24  includes one side surface  241  on the top side and the bottom side respectively and is taken for example. Furthermore, one hole  241   a  is formed on the top side surface and the down side surface  241  respectively. 
     The fan  2  can further include at least one bearing  251  and one bearing bushing  252 . The bearing  251  is disposed in the bearing bushing  252 , and the bearing bushing  252  is connected to the motor housing  24 . The shaft  221  is disposed through the bearing  251 . The fan  2  of the present embodiment includes two bearings  251 . One of them is disposed in the bearing bushing  252 , and the other is disposed close to the impeller structure  21 . 
       FIG. 3  is a schematic figure of the air flow during the fan  2  shown in  FIG. 1  is in operation. Since the gap d 1  is formed between the top part  232  of the stator structure  23  and the bottom part  211   a  of the hub  211  in horizontal direction and the one of the blades  212  of the impeller structure  21  is higher than the stator structure  23  and the top part thereof in vertical direction, the downward air flow can be emitted by passing through the gap d 1 , the hole  241   a  of the top side surface  241  of the motor housing  24 , the coil assembly of the stator structure  23 , and then the hole  241   a  of the bottom side surface  241  of the motor housing  24  during the fan  2  is in operation. In addition, the heat of the coil assembly can be dissipated from the surface of the motor housing  24  as well. 
     Accordingly, the heat generated by the coil assembly of the stator structure  23  of the fan  2  in accordance with the present invention can be dissipated with the air flow generated during the fan  2  is in operation. In other words, the configuration of the fan  2  in accordance with the present invention can dissipate the heat generated inside the motor positively and perform better than a conventional fan dissipating heat only by nature cooling. It prevents the accumulation of the heat inside the motor from shortening the lifetime of the shaft and causing the abnormality of other elements. 
     In addition, the fan  2  in accordance with the present invention is not limited to any specific application, and can be applied in electronic equipment such as heat dissipation systems, computers, optical disk drivers, hard disk drivers, optical devices or color wheels. The appearance and the shape of the fan  2  in accordance with the present invention are not limited as well, and the configuration of the fan  2  can be adjusted in accordance with its practical function and field. 
       FIGS. 4A and 4B  are a cross-sectional figure of another fan  5  in accordance with the preferable embodiment of the present invention and a schematic figure of the air flow during the fan  5  is in operation. 
     The situation of the fan  5  is similar to that of the aforementioned fan  2 . Since the gap d 2  is formed between the top part  532  of the stator structure  53  and the bottom part  511   a  of the hub  511  in horizontal direction and one of the blades  512  of the impeller structure  51  is higher than the stator structure  53  and the top part  532  thereof in vertical direction, the downward air flow can be emitted by passing through the gap d 2 , the hole  541   a  of the top side surface  541  of the motor housing  54 , the coil assembly of the stator structure  53 , and then the hole  541   a  of the bottom side surface  541  of the motor housing  54  during the fan  5  is in operation. 
     In addition, the heat of the coil assembly can be dissipated from the surface of the motor housing  54  as well. Accordingly, the heat generated by the coil assembly of the stator structure  53  of the fan  5  in accordance with the present invention can be dissipated with the air flow generated during the fan  5  is in operation. In other words, the configuration of the fan  5  in accordance with the present invention can dissipate the heat generated inside the motor positively and perform better than a conventional fan dissipating heat only by nature cooling. It prevents the accumulation of the heat inside the motor from shortening the lifetime of the shaft and causing the abnormality of other elements. 
       FIG. 5  is a cross-sectional figure of a heat dissipation system in accordance with the preferably embodiment of the present invention. The heat dissipation system  6  includes at least one fan  7 , a plurality of static blades  61  and a frame body  62 . In the present embodiment, the heat dissipation system  6  including one fan  7  is taken for exemplary description. In addition, the fan  7  of the present embodiment is provided with all of the technical characteristics of the fan  2  or the fan  5  of the aforementioned embodiment, and the detailed description thereof will be omitted. 
     The static blades  61  are disposed at the out periphery of the fan  7 . Herein, the static blades  61  are disposed around the out periphery of the fan  7 . The fan  7  and the static blades  61  are disposed in the frame body  62 , and the frame body  62  is connected to the fan  7  and the static blades  61  respectively. The material of the static blades  61  and the frame body  62  can include, for example but not limited to, metal or plastic. In the present embodiment, the static blades and the frame body  62  are integrally formed as one piece. The fan  7  is connected to the frame body  62  by, for example not limited to, locking or injection mounting. 
     In addition, the heat dissipation system  6  in accordance with the present invention is not limited to any specific application, and can be applied in electronic equipment such as computers, optical disk drivers, hard disk drivers, optical devices or color wheels. 
       FIG. 6  is a cross-sectional figure of another heat dissipation system in accordance with the preferable embodiment. The major difference between the heat dissipation system  8  and the aforementioned heat dissipation system  6  is that the heat dissipation system  8  includes two side-by-side fans  9  disposed in the frame body  82 . In addition, the static blades  81  between two fans  9  are connected to each other, and respectively connected to the frame body  82 . The fan  9  of the heat dissipation system  8  is provided with all of the technical characteristics of the fan in accordance with the aforementioned embodiment, and the detail description thereof will be omitted. 
     The heat dissipation system in accordance with the present invention also can include two or more than two fans disposed side-by-side or overlapping to each other in the frame body. Thus, the amount and the arrangement of the fans disposed in the frame body can be adjusted based on the needs of users, and are not limited to the aforementioned. 
     In summary, since the heat dissipation and the fan thereof in accordance with the present invention include the receptacle on the terminal surface of the magnetic element of the rotor structure in the axial direction for containing a balance material, the rotor structure can be tested for its dynamic balance before the assembly of the motor and the balance material can be filled into the receptacle to maintain the rotor structure in good dynamic balance at high rotating speed. It effectively prevents the lifetime of the shaft from being shortened by vibration. Moreover, the heat generated from the coil of the stator structure of the fan and the heat dissipation system thereof in accordance with the present invention can be dissipated positively with the air flow generated during the fan is in operation. It protects the lifetime of the shaft and the normal functions of other elements against the damage resulting from the accumulation of the heat inside the motor. Accordingly, the heat dissipation system and the fan thereof in accordance with the present invention are able to increase the reliability of the motor and prolong the lifetime of the shaft at high rotating speed effectively. 
     Although the 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 invention.