Abstract:
Provided is a fan motor that includes: a rotor that is coupled with a shaft to rotate together; a stator that is installed at a position facing the rotor; a first bracket on a central upper portion of which a first bearing insertion space into which a first bearing coupled to an upper portion of the shaft is inserted is formed; a second bracket which is hermetically coupled to the first bracket and on a central lower portion of which a second bearing insertion space into which a second bearing coupled to a lower portion of the shaft is inserted is formed; a first bearing cover that covers the first bearing insertion space; and a second bearing cover that covers the second bearing insertion space and has an accommodation space formed to extend to the central lower portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims under 35 U.S.C. §119(a) the benefit of Korean Patent Application No. 10-2014-0118331 filed on Sep. 5, 2014, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     (a) Technical Field 
     The present disclosure relates to a fan motor. More specifically, it relates to a fan motor that is capable of lowering the manufacturing costs due to a simple manufacturing process, and is capable of preventing noise and vibration, by minimizing the vertical movement of a shaft. 
     (b) Background Art 
     In general, a motor that is used for blowing the cold air of a refrigerator or circulating the internal and external air of any device is called as a fan motor. In many cases, such a fan motor is installed at a humid place or at an environment where dew condensation occurs depending on the temperature change. Thus, since moisture may penetrate into the motor to cause failures, various structures for preventing the failures have been studied. 
     Korean Patent Nos. 10-0511324 and 10-1074935 and U.S. Pat. No. 6,577,031 disclose a technique for fabricating a motor housing through the resin molding by insert injection, together with a motor stator and a printed circuit board. According to these patents, since the motor housing is manufactured through the resin molding such that the stator and the printed circuit board are buried in the interior of the housing, they have an efficient structure to prevent the moisture from penetrating into the inside of the motor. 
     However, when manufacturing the motor by the above-described insert injection, there is a problem of increases in the process and the cost required for the insert injection, such as fabricating a molding die. Moreover, since the method needs the insert injection process, there are difficulties in automating the entire processes. 
     In addition, in the fan motor according to the prior art, a shaft which rotates together with the rotor may be moved in a vertical direction, i.e., in an axial direction. The rotation of the fan may become slightly unstable due to the axial movement of the shaft, and the noise and vibration may occur accordingly. 
     In order to solve the above-mentioned problems, the present inventors suggest a fan motor of a novel structure that can be manufactured without depending on the insert injection process and prevent the movement of the shaft. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE DISCLOSURE 
     The present invention has been made in an effort to solve the above-described problems associated with prior art. 
     An object of the present invention is to provide a fan motor of a new structure. 
     Another object of the present invention is to provide a fan motor which can reduce manufacturing costs, by not applying the insert injection for fabrication of the motor housing. 
     Still another object of the present invention is to provide a fan motor which can prevent the axial movement of the shaft. 
     All the above objects and other inherent objects of the present invention can be readily accomplished by the invention described below. 
     In one aspect, the present invention provides a fan motor that includes: a rotor that is coupled with a shaft to rotate together; a stator that is installed at a position facing the rotor; a first bracket on a central upper portion of which a first bearing insertion space into which a first bearing coupled to an upper portion of the shaft is inserted is formed; a second bracket which is hermetically coupled to the first bracket and on a central lower portion of which a second bearing insertion space into which a second bearing coupled to a lower portion of the shaft is inserted is formed; a first bearing cover that covers the first bearing insertion space; and a second bearing cover that covers the second bearing insertion space and has an accommodation space formed to extend to the central lower portion. 
     In a preferred embodiment, the fan motor may further include an attracting magnet that is fixed to the lower portion of the accommodation space, and a ring-shaped spacer that is fixed to the upper portion of the attracting magnet. 
     In another preferred embodiment, the spacer may be a magnet. 
     In still another preferred embodiment, the attracting magnet and the spacer may be a magnet formed integrally. 
     In yet another preferred embodiment, the fan motor may further include a spring installed in the lower portion of the accommodation space, and a support plate installed in the upper portion of the spring. 
     In still yet another preferred embodiment, a stopper configured to support the upper portion of the support plate may be formed in the upper portion of the accommodation space. 
     In a further preferred embodiment, the support plate may be a magnet. 
     Other aspects and preferred embodiments of the invention are discussed infra. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a perspective view illustrating a fan motor according to the present invention; 
         FIG. 2  is an exploded perspective view illustrating a fan motor according to the present invention; 
         FIG. 3  is a cross-sectional view illustrating a cross-section of a fan motor according to an embodiment of the present invention; 
         FIG. 4  is a perspective view illustrating a state in which a second bearing cover of the fan motor according to one embodiment of the present invention is disassembled; 
         FIG. 5  is a cross-sectional view illustrating a cross-section of a fan motor according to another embodiment of the present invention; and 
         FIG. 6  is a perspective view illustrating a state in which a second bearing cover of the fan motor according to another embodiment of the present invention is disassembled. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
       FIG. 1  is a perspective view of a fan motor according to the present invention, and  FIG. 2  is an exploded perspective view. 
     As illustrated in  FIGS. 1 and 2 , a fan motor according to an embodiment of the present invention is configured to mainly include a rotor  1 , a stator  2 , a shaft  3 , a printed circuit board (PCB)  4 , a first bracket  10  and a second bracket  20 . 
     The first bracket  10  and the second bracket  20  have a structure which is made up of a plastic injection material and sealed by being mutually coupled. Meanwhile, although it is preferred that the first bracket  10  and the second bracket  20  be sealed by ultrasonic fusion and coupled to each other so as to prevent the moisture from penetrating into the interior of the first bracket  10  and the second bracket  20 , it is not necessarily limited to the ultrasonic fusion, and it is also possible to apply various coupling types that are performed by applying a curable adhesive material, a sealing material, a thread-bolt coupling, forced fitting or the like either alone or jointly. In this specification, the coupling using the ultrasonic fusion will be described as an example. 
     Inside the first bracket  10  and the second bracket  20  coupled to each other by the ultrasonic fusion, a rotor  1 , a stator  2 , a shaft  3  and a printed circuit board  4  are located. Coils (not shown) wound around the stator  2  is electrically connected to the printed circuit board  4 , and a wire  4   a  is drawn from the printed circuit board  4  so as to be electrically connected to an external power supply or the like from the printed circuit board  4 . 
     A first bearing insertion space (see reference numeral  12  in  FIG. 3 ) is formed inside an upper portion of the center of the first bracket  10 , and the first bearing  31  is inserted into the first bearing insertion space. Further, the first bearing insertion space  12  is covered by a first bearing cover  40  coupled to the lower portion thereof. A hole through which the shaft passes is formed in the center of the first bearing cover  40 . 
     In the outer lower portion of the center of the second bracket  20 , a second bearing insertion space (see reference numeral  22  in  FIG. 3 ) is formed, and a second bearing (see reference numeral  32  in  FIG. 3 ) is inserted into the second bearing insertion space. In addition, the second bearing insertion space  22  is covered by a second bearing cover (see reference numeral  50  in  FIG. 3 ) coupled to the lower portion thereof. 
       FIG. 3  is a cross-sectional view illustrating the fan motor according to an embodiment of the present invention. 
     Referring to  FIG. 3 , in the fan motor according to an embodiment of the present invention, as described above, the first bracket  10  and second bracket  20  are coupled to each other to form one motor housing. The first bracket  10  and the second bracket  20  are preferably sealing-coupled by ultrasonic fusion. For the ultrasonic fusion, a bracket fusion groove  21  is formed on the upper surface of the second bracket  20 , and a bracket fusion protrusion  11  is formed at a position corresponding to the bracket fusion groove  21  of the second bracket  20  on the lower surface of the first bracket  10 . 
     Thus, after inserting the bracket fusion protrusion  11  into the bracket fusion groove  21 , when heat is applied to the bracket fusion protrusion  11  by applying ultrasonic wave thereto, since the bracket fusion protrusion  11  is melted and stuck to the bracket fusion groove, a coupling part between the first and second brackets  10 ,  20  is sealed. Of course, it is also possible to form a fusion groove on a lower surface of the first bracket  10  and to form a fusion protrusion on an upper surface of the second bracket  20 . 
     Here, as described above, as the first bracket  10  is coupled to the second bracket  20  by ultrasonic fusion, devices that generate a lot of heat during operations, such as the rotor  1 , the stator  2  and the printed circuit board  4 , are housed inside the first and second brackets  10 ,  20 . Accordingly, it is preferred that the first and second brackets  10 ,  20  be manufactured with a flame-retardant resin material for fire prevention. 
     The shaft  3  is located through the centers of the first bracket  10  and the second bracket  20 . Rotation of an upper portion of the shaft  3  is supported by a first bearing  31  located inside the center of the first bracket  10 , and rotation of a lower portion of the shaft  3  is supported by a second bearing  32 . 
     The first bearing  31  is inserted into the first bearing insertion space  12  of the first bracket  10 , and is fixed by being press-fitted to a first bearing press-fit portion  13  which is formed inside the center of the first bracket  10 . The lower portion of the first bearing  31  is supported by a first board push  14 . Also, a first felt  15  is positioned on an outer peripheral surface of the first bearing  31 , and the first felt  15  keeps oil for smooth rotation of the bearing. The first bearing insertion space  12  as a space, into which the first bearing  31  is inserted, is sealed and covered by a first bearing cover  40 . In the interior of the center of the first bearing cover  40 , i.e., on the inside of a first fusion protrusion  42 , a projecting part capable of supporting the first board push  14  is formed. Further, in the upper portion of the first bearing press-fit portion  13 , a first oil return washer insertion portion  16  is formed, and a first oil return washer  17  is inserted into the first oil return washer insertion portion  16 , thereby preventing oil from flowing out to the upper side of the first bearing  31 . 
     For primary coupling of the first bearing cover  40 , the first bearing cover  40  is formed with a first press-fit protrusion  41  to protrude at a position corresponding to the inner circumferential periphery portion of the first bearing insertion space  12 . The first press-fit protrusion  41  may be a number of individual protrusions and may have a shape projecting in one circumferential shape. The first press-fit protrusion  41  is primarily coupled by being press-fitted around the inner circumference of the first bearing insertion space  12 . 
     Furthermore, for secondary coupling, a first fusion groove  18  is formed in the inner surface center of the first bracket  10 , and the first bearing cover  40  is formed with a first fusion protrusion  42  at a position corresponding to the position of the first fusion groove  18 . The first fusion protrusion  42  is coupled by being fused and sealed to the first fusion groove  18  by ultrasonic fusion. Of course, the first fusion protrusion  42  may be formed as a form of a fusion groove, and the first fusion groove  18  may be formed as a form of a fused protrusion. Meanwhile, although it is preferred that the first bearing cover  40  and the first bracket  10  be coupled to each other by being sealed through the ultrasonic fusion as described above, it is not necessarily limited to the ultrasonic fusion, and it is also possible to apply various coupling types that are performed by applying a curable adhesive material, a sealing material, a thread-bolt coupling, forced fitting or the like either alone or jointly. 
     The second bearing  32  is located in the second bearing insertion space  22  formed in the center of the lower surface of the second bracket  20 , and the upper portion of the second bearing  32  is fixed by being press-fitted into the second bearing press-fit portion  23  formed in the center of the upper portion of the second bearing insertion space  22 . The lower portion of the second bearing  32  is supported by a second board push  24 . A second felt  25  configured to supply oil as lubricating oil for the rotational support of the bearing is installed on the outer circumferential surface of the second bearing  32 . Further, a second oil return washer insertion portion  26  is formed above the second bearing press-fit portion  23 , and the second oil return washer  27  is inserted into the second oil return washer insertion portion  26 , thereby preventing the oil from flowing out to the upper side of the second bearing  32 . 
     The second bearing insertion space  22  of the second bracket  20 , in which the second bearing  32  is located, is covered by the second bearing cover  50  and sealed at the same time and coupled. The second bearing cover  50  is formed with the second press-fit protrusion  51  at a position corresponding to the periphery of the second bearing insertion space  22 . The second press-fitting protrusion  51  may be a number of individual protrusions and may have a shape projecting in one circumferential shape. The second press-fitting protrusion  51  is coupled by being press-fitted around the inner periphery of the second bearing insertion space  22 . Meanwhile, the second bearing cover  50  needs to isolate the second bearing insertion space  22  by being sealed from the outside in order to prevent the penetration of moisture or the like thereinto. 
     For that, a second fusion groove  28  is formed on the lower surface of the second bracket  20 , and a second fusion protrusion  52  is formed on the upper surface of the second bearing cover  50  at a position corresponding to the second fusion groove  28 . After inserting the second fusion protrusion  52  into the second fusion groove  28 , when heat is applied to the second fusion protrusions  52  by applying the ultrasonic wave thereto, the second fusion protrusions  52  is melt and stuck to the second fusion groove  28 . Accordingly, the second bearing cover  50  is coupled to a lower surface of the second bracket  20  to isolate the second bearing insertion space  22  from the outside, thereby making it possible to prevent penetration of external moisture thereinto. Of course, it is also possible to form the fusion protrusion on the lower surface of the second bracket  20  and to form the fusion groove on the upper surface of the second bearing cover  50 . Meanwhile, although it is preferred that the second bearing cover  50  and the second bracket  20  be coupled to each other by being sealed through the ultrasonic fusion as described above, it is not necessarily limited to the ultrasonic fusion, and it is also possible to apply various coupling types that are performed by applying a curable adhesive material, a sealing material, a thread-bolt coupling, forced fitting or the like either alone or jointly 
     In this way, when the second bearing cover  50  is coupled to the lower surface of the second bracket  20 , a distal end of the shaft  3  penetrating the center of the second bracket  20  is located in the accommodation space  53  that extends downward and is formed on the inside of the center of the second bearing cover  50 . 
     Meanwhile, the shaft  3  rotates at a high speed together with the rotation of the rotor  1  in accordance with the operation of the fan motor, and the shaft  3  can vertically moves in accordance with the rotation operation. Such a movement becomes a cause of noise and vibration generated during operation of the motor. A structure for preventing this will be described with reference to  FIG. 4 . 
       FIG. 4  is a perspective view illustrating a state in which a second bearing cover  50  of the fan motor according to one embodiment of the present invention is disassembled. 
     Referring to  FIGS. 3 and 4  together, in the center of the second bearing cover  50 , an accommodation space  53  formed inside by extending downward is formed. An attracting magnet  60  is inserted and fixed into the accommodation space  53 . A spacer  61  is located around the upper portion of the attracting magnet  60  and around the lower end of the shaft  3 . The attracting magnet  60  exerts a constant force of drawing the shaft  3  to prevent the shaft  3  from moving upward. The spacer  61  serves to fix the attracting magnet  60  in position, and it can also be applied by selecting a suitable material such as resin or a rubber material. Meanwhile, a separate magnet of the same material as the attracting magnet  60  may be applied to the spacer  61 . Meanwhile, the spacer  61  can also be one magnet integrally with the attracting magnet  60 . 
       FIG. 5  is a cross-sectional view illustrating a cross-section of a fan motor according to another embodiment of the present invention, and  FIG. 6  is a perspective view illustrating a state in which a second bearing cover  50  of the fan motor according to another embodiment of the present invention is disassembled. 
     As illustrated in  FIGS. 5 and 6 , the fan motor according to another embodiment of the present invention is identical to the motor according to one embodiment, except that some configurations installed in the accommodation space  53  of the second bearing cover  50  differ. Specifically, a support plate  71  is installed above the accommodation space  53  formed in the second bearing cover  50 , a spring  72  is installed below the support plate  71 , and the spring  72  pushes the support plate  71  upward. The upper portion of the support plate  71  is supported by a stopper  54  formed around the upper portion of the accommodation space  53 . The stopper  54  may be formed in a number of individual shapes and may be formed in one circumferential shape. The stopper  54  is preferably formed integrally with the second bearing cover  50 . When the shaft  3  moves downward, the support plate  71  pushes the lower end of the shaft  3  upward by elasticity of the spring  72  that pushes the support plate  71  from the lower portion, thereby preventing the movement of the shaft  3 . Although a material of the support plate  71  is not particularly limited, it is possible to apply a plastic resin, a rubber material or the like that has high wear resistance. Meanwhile, the support plate  71  may be formed as a magnet. When applying the support plate  71  as a magnet, since the shaft  3  is pulled by an attractive power, it is possible to effectively prevent the vertical movement of the shaft  3  and to prevent noise and vibration through the stable rotation. 
     The present invention has an effect of providing a fan motor which is capable of reducing the manufacturing costs and preventing the axial movement of the shaft, by not applying the insert injection for fabrication of the motor housing. 
     The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.