Abstract:
Disclosed herein is a fan motor including: a first bracket having a central portion through which a rotary shaft penetrates, the first bracket having an upper bearing insertion space which is formed in the first bracket and to which an upper bearing for supporting the upper end portion of the rotary shaft is inserted; a second bracket having an upper side to which the first bracket is connected, the second bracket having a lower bearing insertion space which is formed at the central portion of the lower side thereof and to which a lower bearing for supporting the lower end portion of the rotary shaft is inserted; a printed circuit board inserted and fixed into a PCB insertion space formed in the lower side of the second bracket; and a third bracket having an upper side to which the second bracket is connected.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. KR 10-2013-0110192 filed on Sep. 13, 2013, which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fan motor, and more particularly, to a fan motor which can reduce manufacturing costs because a manufacturing process is simple and can effectively prevent penetration of moisture from the outside. 
     2. Background Art 
     In general, a motor used for blowing cold air of a refrigerator or circulating inside air and outside air of a device is called a fan motor. Such a fan motor is mainly installed under humid atmospheres or under environment that dew condensation is formed by changes in temperature. Therefore, because the motor may be out of order due to penetration of moisture into the motor, various studies on a structure for preventing penetration of moisture have been made. 
     Korean Patent Nos. 10-0511324 and 10-1074935 and U.S. Pat. No. 6,577,031 disclose technology to manufacture a motor housing by resin insert molding together with a stator of a motor and a printed circuit board. According to the above-mentioned conventional inventions, because the motor housing is manufactured by resin molding in such a manner that the stator and the printed circuit board are embedded in the motor housing, the motor housing has an effective structure to prevent penetration of moisture into the motor. 
     However, the conventional inventions to manufacture the motor by insert molding have a problem in that they require lots of processes and expenses necessary for insert molding because a mold for insert molding must be manufactured. Moreover, the conventional inventions have difficulty in automation of all processes because it must pass an insert molding process. 
     Therefore, in order to solve the above-mentioned problems, the inventors of the present invention propose a new structure of a fan motor which utilizes a structure that a stator is located inside a bracket and a printed circuit board is mounted outside the bracket to be sealed and which is manufactured at low costs by improving the structure of the housing. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior arts, and it is an object of the present invention to provide a fan motor of a new structure. 
     It is another object of the present invention to provide a fan motor which can lower manufacturing costs because insert molding for manufacturing a motor housing is not applied. 
     It is a further object of the present invention to provide a fan motor which can automate all of manufacturing processes because insert molding for manufacturing the motor housing is not applied. 
     It is a still further object of the present invention to provide a fan motor which can reduce manufacturing costs because just a part of a bracket is made of a flame-resistant material. 
     The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings. 
     To accomplish the above object, according to the present invention, there is provided a fan motor including: a first bracket having a central portion through which a rotary shaft penetrates, the first bracket having an upper bearing insertion space which is formed in the first bracket and to which an upper bearing for supporting the upper end portion of the rotary shaft is inserted; a second bracket having an upper side to which the first bracket is connected, the second bracket having a lower bearing insertion space which is formed at the central portion of the lower side thereof and to which a lower bearing for supporting the lower end portion of the rotary shaft is inserted; a printed circuit board (PCB) inserted and fixed into the upper side of the second bracket; and a third bracket having an upper side to which the second bracket is connected. 
     In another aspect of the present invention, there is provided a fan motor including: a first bracket having a central portion through which a rotary shaft penetrates, the first bracket having an upper bearing insertion space which is formed in the first bracket and to which an upper bearing for supporting the upper end portion of the rotary shaft is inserted; a second bracket having an upper side to which the first bracket is connected, the second bracket having a lower bearing insertion space which is formed at the central portion of the lower side thereof and to which a lower bearing for supporting the lower end portion of the rotary shaft is inserted; a printed circuit board inserted and fixed into a PCB insertion space formed in the lower side of the second bracket; and a third bracket having an upper side to which the second bracket is connected. 
     Here, the second bracket is made of a flame-proof resin material in order to prevent fire and the third bracket is made of a plastic material. 
     Furthermore, the second bracket includes a plurality of flange parts which protrude from the outer rim of the upper side thereof and the third bracket includes a plurality of seating grooves which are formed in the upper side thereof and to which the flange parts are respectively inserted, and each of the flange parts and each of the seating grooves respectively have screw holes for bolt coupling. 
     Additionally, in case that the printed circuit board is connected to the lower side of the second bracket, the second bracket includes a coil path part through which the coil wound on the stator passes the second bracket and is connected to the printed circuit board. 
     According to the present invention, the fan motor can lower manufacturing costs and automate all of manufacturing processes because insert molding for manufacturing the motor housing is not applied, and reduce manufacturing costs because just a part of a bracket is made of a flame-resistant material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a fan motor according to a preferred embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the fan motor according to the preferred embodiment of the present invention; 
         FIG. 3  is a sectional view of a cut part of the fan motor according to the preferred embodiment of the present invention; 
         FIG. 4  is a perspective view showing a structure of a lower side of the fan motor according to the preferred embodiment of the present invention; 
         FIG. 5  is a sectional view of a cut part of a fan motor according to another preferred embodiment of the present invention; 
         FIG. 6  is a perspective view showing a state before a printed circuit board is not mounted on a lower side of a second bracket; 
         FIG. 7  is a perspective view showing a state where the printed circuit board is mounted on the lower side of the second bracket; and 
         FIG. 8  is a view showing a state where a printed circuit board (PCB) insertion space formed in the lower side of the second bracket is filled with a sealing material. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will be now made in detail to the preferred embodiments of the present invention with reference to the attached drawings. In the drawings, the same components have the same reference numerals even though they are illustrated in different figures, and repeated description of the same components will be omitted. 
       FIG. 1  is a perspective view of a fan motor according to a preferred embodiment of the present invention, and  FIG. 2  is an exploded perspective view of the fan motor according to the preferred embodiment of the present invention. 
     As shown in  FIGS. 1 and 2 , the fan motor according to the preferred embodiment of the present invention includes a first bracket  10 , a second bracket  20 , a third bracket  30 , a printed circuit board (PCB)  40 , and a rotary shaft  50 . 
     The first bracket  10  and the second bracket  20  are made by plastic injection molding and have a structure that they are connected with each other and sealed by ultrasonic fusion, and the second bracket  20  and the third bracket  30  are screw-coupled with each other by bolts B. 
     A rotor  1 , a stator  2 , the printed circuit board  40  and the rotary shaft  50  are located inside the first and second brackets  10  and  20  which are connected with each other by ultrasonic fusion. 
       FIG. 3  is a sectional view of a cut part of the fan motor according to the preferred embodiment of the present invention. 
     In more detail, as shown in  FIG. 3 , the fan motor according to the preferred embodiment of the present invention has a motor housing formed by the first bracket  10 , the second bracket  20  and the third bracket  30  which are connected with each other as described above. 
     The first bracket  10  and the second bracket  20  are connected with each other by ultrasonic fusion. For the ultrasonic fusion, a first fusion groove  21  is formed in the upper face of the second bracket  20 , and a first fusion protrusion  11  is formed on the lower face of the first bracket  10  at a position corresponding to the first fusion groove  21  of the second bracket  20 . 
     Therefore, when ultrasonic waves are applied to the first fusion protrusion  11  to heat the first fusion protrusion  11  after the first fusion protrusion  11  is inserted into the first fusion groove  21 , the first fusion protrusion  11  is melted and adhered to the first fusion groove, and hence, the insides of the first and second brackets  10  and  20  are sealed. Of course, the fusion groove may be formed on the lower face of the first bracket  10  and the fusion protrusion may be formed on the upper face of the second bracket  20 . 
     Furthermore, the second bracket  20  and the third bracket  30  are screw-coupled with each other by the bolts (B) (See  FIG. 1 ), and as shown in  FIG. 2 , a plurality of flange parts  22  protrude from the outer rim of the upper side of the second bracket  20 , and a plurality of seating grooves  32  to which the flange parts  22  are inserted are formed in the upper side of the third bracket  30 . 
     Screw holes  22   a  and  32   a  for bolt coupling are respectively formed in the flange parts  22  and the seating grooves  32 . When bolts B are coupled to the screw holes  22   a  and  32   a  after the flange parts  22  are inserted into the seating grooves  32 , the second bracket  20  is screw-coupled to the upper side of the third bracket  30 . 
     Here, as described above, because the first bracket  10  is joined to the second bracket  20  by ultrasonic fusion, it is preferable that the second bracket  20  be made of a flame-proof resin material in order to prevent fire because many devices, such as the rotor  1 , the stator  2  and the printed circuit board  40 , which generate heat when they are operated are accommodated in the second bracket  20 . Of course, the third bracket  30  also may be made of a flame-proof resin material, but because the flame-proof resin material is very expensive, it is preferable that just the second bracket  20  be made of the flame-proof resin material and the third bracket  30  is made of a general plastic material which is inexpensive. 
     The rotary shaft  50  is located by passing through the central portions of the first bracket  10  and the second bracket  20 . The lower end portion of the rotary shaft  50  is supported in rotation by a lower bearing  51 , and the upper end portion is supported in rotation by an upper bearing  52  which is located inside the central portion of the first bracket  10 . 
     The lower bearing  51  is located in a lower bearing insertion space  23  formed at the central portion of the lower side of the second bracket  20 , and the upper portion of the lower bearing  51  is forcedly pressed and fixed to a lower bearing pressing part  24  which is formed on the upper portion of the central portion of the lower bearing insertion space  23 . The lower portion of the lower bearing  51  is supported by a lower board push  25 . 
     A lower felt  26  for supplying oil which is lubricating oil to support rotation of the bearing is mounted on the outer circumferential surface of the lower bearing  51 . Furthermore, a lower oil return washer insertion part  27  is formed on the upper portion of the lower bearing pressing part  24 , and a lower oil return washer  28  is inserted into the lower oil return washer insertion part  27  in order to prevent oil from flowing out of the upper portion of the lower bearing  51 . 
     The lower bearing insertion space  23  of the second bracket  20  in which the lower bearing  51  is located is covered sealed and joined by a lower bearing cover  60 . For this, a second fusion groove  29  is formed in the lower side of the second bracket  20 , and a second fusion protrusion  61  is formed on the upper side of the lower bearing cover  60  at a position corresponding to the second fusion groove  29 . 
     After the second fusion protrusion  61  is inserted into the second fusion groove  29 , when ultrasonic waves are applied to the second fusion protrusion  61  to heat the second fusion protrusion  61 , the second fusion protrusion  61  is melted and adhered to the second fusion groove  29 . Therefore, the lower bearing cover  60  is joined to the lower side of the second bracket  20  so as to isolate the lower bearing insertion space  23  from the outside, and hence, the present invention can prevent penetration of outside moisture. Of course, the fusion groove may be formed on the lower side of the second bracket  20  and fusion protrusion may be formed on the upper side of the lower bearing cover  60 . 
     As described above, when the lower bearing cover  60  is joined to the lower side of the second bracket  20 , an end of the rotary shaft  50  penetrating the central portion of the second bracket  20  is located in a space part  62  formed inside the central portion of the bearing cover  60 . 
     The upper bearing  52  is inserted into an upper bearing insertion space  12  of the first bracket  10 , and is forcedly pressed and fixed to an upper bearing pressing part  13  formed inside the central portion of the first bracket  10 . The lower portion of the upper bearing  51  is supported by an upper board push  14 . 
     An upper felt  15  is located on the outer circumferential surface of the upper bearing  52 , and the upper felt  15  contains oil for promoting rotation of the bearing. The upper bearing insertion space  12  which is a space to which the upper bearing  52  is inserted is sealed and covered by an upper bearing cover  70 . 
     For this, a third fusion groove  16  is formed at the central portion of the inner face of the first bracket  10 , and an upper fusion protrusion  71  is formed on the upper bearing cover  70  at a position corresponding to the third fusion groove  16 . The upper fusion protrusion  71  is melted, sealed and adhered to the third fusion groove  16  by ultrasonic fusion. Of course, the upper fusion protrusion  71  may be formed in a shape of the fusion groove and the third fusion groove  16  may be formed in a shape of the fusion protrusion. 
     An upper oil return washer insertion part  72  is formed inside the central portion of the upper bearing cover  70 . An upper oil return washer  73  is inserted into the upper oil return washer insertion part  72  in order to prevent an oil leakage to the upper portion of the upper bearing  52 . 
     In the fan motor according to the preferred embodiment of the present invention, the motor housing is completely assembled when the second bracket  20  is screw-coupled to the third bracket  30 , the printed circuit board  40 , the stator  2  and the rotor  1  are located on the second bracket  20 , and the first bracket  10  is fused to the second bracket  20  with ultrasonic waves. 
     Therefore, the fan motor according to the preferred embodiment of the present invention is more convenient in manufacturing process than the conventional inventions to form the motor housing by insert injection molding and can reduce manufacturing costs. Additionally, in consideration of the risk of fire, the second bracket  20  which includes many devices, such as the rotor  1 , the stator  2  and the printed circuit board  40 , generating heat when they are operated is made of a flame-proof resin material which is relatively expensive, and the third bracket  30  is made of a general plastic material which is relatively inexpensive. 
       FIG. 4  is a perspective view showing a structure of a lower side of the fan motor according to the preferred embodiment of the present invention. 
     In the meantime, a wire  41  for connecting the printed circuit board  40  with an external power supply is mounted on the printed circuit board  40 . As shown in  FIG. 4 , the wire  41  passes through the upper side of the second bracket  20  and the lower side of the third bracket  30  and extends to the outside. 
     In this instance, in order to extend the wire  41  to the outside stably and to prevent twisting of the wire  41 , the second bracket  20  has a wire groove  29  (See  FIG. 2 ) formed in the outer rim portion of the upper side thereof, and the third bracket  30  has a wire passing hole  33  formed at one side of the lower side thereof for allowing the wire  41  to pass. 
     Additionally, the third bracket  30  further has a wire holder  34  mounted on the lower side thereof for holding the wire  41  to prevent the wire  41  from deviating from the position by an external shock. In this instance, the wire  41  passing the lower side of the third bracket  30  is extended to the outside through the wire passing hole  33  in a state where it is fixed on the lower side of the third bracket  30  by the wire holder  34 , and hence, it can prevent that the wire  41  deviates from the designated position or is twisted even though an external shock or vibration is applied. 
     The printed circuit board  40  is electrically connected to a coil (not shown) wound on the stator  2  located at the upper side inside the second bracket  20  in order to apply electricity to the stator  2  to thereby operate the motor. 
       FIG. 5  is a sectional view of a cut part of a fan motor according to another preferred embodiment of the present invention,  FIG. 6  is a perspective view showing a state before a printed circuit board is not mounted on a lower side of a second bracket,  FIG. 7  is a perspective view showing a state where the printed circuit board is mounted on the lower side of the second bracket, and  FIG. 8  is a view showing a state where a printed circuit board (PCB) insertion space formed in the lower side of the second bracket is filled with a sealing material. 
     Meanwhile, as shown in  FIGS. 5 to 7 , the fan motor according to another preferred embodiment of the present invention includes the printed circuit board  40  which is mounted on the lower side of the second bracket  20 . For this, a printed circuit board (PCB) insertion space  81  is formed in the lower side of the second bracket  20 . 
     In this instance, because the printed circuit board  40  is exposed to the outside in a state where it is inserted into the PCB insertion space  81 , when the printed circuit board  40  is inserted into the PCT insertion space  81  in order to fix the printed circuit board  40  stably and to prevent penetration of moisture from the outside, as shown in  FIG. 8 , the remaining space except a space where the printed circuit board  40  occupies in the PCB insertion space  81  is filled with a sealing material S. 
     As described above, in case that the printed circuit board  40  is mounted on the lower side of the second bracket  20 , the motor housing is manufactured through the steps of locating the rotary shaft  50 , the rotor  1  and the stator  2  are located on the second bracket  20 , fusing and joining the first bracket  10  to the second bracket  20  by ultrasonic fusion, and joining the second bracket  20  to the third bracket  30  via bolts B. Therefore, the fan motor according to the preferred embodiment of the present invention is more convenient in manufacturing than the conventional inventions which form the motor housing by insert injection molding, and can reduce manufacturing costs. 
     In the meantime, when the printed circuit board  40  is mounted on the lower side of the second bracket  20 , the coil (not shown) wound on the stator  2  passes the second bracket  20  and is electrically connected to the printed circuit board  40 . For this, as shown in  FIG. 6 , a coil path part  82  through which the coil passes is formed in the second bracket  20 . Therefore, the coil wound on the stator  2  gets out of the lower side of the second bracket  20  and is connected to the printed circuit board  40 . 
     Moreover, when the printed circuit board  40  is mounted on the lower side of the second bracket  20 , because the wire  41  connected to the printed circuit board  40  naturally passes the lower side of the second bracket  20 , a guide groove  83  for promoting a stable mounting of the wire  41  and preventing twisting of the wire  41  is formed in the lower side of the second bracket  20 . Of course, as described above, the third bracket  30  has the wire passing hole  33  formed in one side of the lower side thereof, and not shown in the drawing, but the wire holder  34  which is described above may be formed additionally. 
     While the present invention has been described with reference to the particular illustrative embodiment, it is not to be restricted by the embodiment but only by the appended claims. It will be understood by those skilled in the art that simple modifications and changes of the embodiments within the scope of the present invention belong to the scope of the present invention.