Abstract:
One aspect of the invention provides a motor comprising a housing; a rotating shaft disposed in the housing and supported by the housing; a stator disposed in the housing; a rotor configured to rotate with respect to the stator and integrally fastened with a rotating shaft; and an impeller mounted over an outer wall of the rotating shaft and comprising at least one wing, wherein the rotating shaft is formed of a hollow shaft so as to contain oil therein, the rotating shaft comprising at least a through hole radially extending toward the impeller such that the oil contained in the rotating shaft can be discharged through the through hole and scattered by the at least one wing.

Description:
CROSS-REFERENCE(S) TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Korean Patent Application No. 10-2014-0010128, filed on Jan. 28, 2014, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present invention relate to a motor, and more particularly, to a motor having a cooling function capable of cooling a heated portion of the motor by making oil charged in the motor circulate the motor at the time of driving the motor. 
         [0004]    2. Description of Related Art 
         [0005]    A motor which generates a torque when being supplied with electric power has various structures. When operating the motor, heats are generated in various parts of the motor. Such heats would limit the power of the motor and/or deteriorate the parts of the motor. Thus, various configurations for cooling the various portions of the motor are proposed. 
       SUMMARY 
       [0006]    One aspect of the invention provides a motor comprising a housing; a rotating shaft disposed in the housing and supported by the housing; a stator disposed in the housing; a rotor configured to rotate with respect to the stator and integrally fastened with a rotating shaft; and an impeller mounted over an outer wall of the rotating shaft and comprising at least one wing, wherein the rotating shaft is formed of a hollow shaft so as to contain oil therein, the rotating shaft comprising at least a through hole radially extending toward the impeller such that the oil contained in the rotating shaft can be discharged through the through hole and scattered by the at least one wing. 
         [0007]    An embodiment of the present invention is directed to a motor having a cooling function capable of radiating heat generated at the time of driving the motor, by automatically circulating oil charged therein by rotating a rotating shaft without a separate component for circulating the oil. 
         [0008]    Other features and advantages of the present invention can be understood by the following description, and become apparent with reference to the embodiments of the present invention. Also, it is obvious to those skilled in the art to which the present invention pertains that the features and advantages of the present invention can be realized by the means as claimed and combinations thereof. 
         [0009]    In accordance with an embodiment of the present invention, there is provided a motor having a cooling function in which a rotor integrally fastened with a rotating shaft inside a stator is installed inside a housing, wherein the rotating shaft is formed of a hollow shaft to charge oil therein and is provided with a through hole which radially penetrates through the rotating shaft and an outer side of a portion at which the rotating shaft is provided with the through hole is coupled with an impeller which discharges the oil discharged from the through hole in a radius direction of the rotating shaft. 
         [0010]    The rotating shaft may have a portion adjacent to an end thereof provided with the through hole. 
         [0011]    The through hole may be formed along a circumference of the rotating shaft at a predetermined interval. 
         [0012]    The impeller may be coupled with the rotating shaft so as to position the through hole between two adjacent wings of the impeller. 
         [0013]    The number of through holes which is formed at the rotating shaft may be equal to the number of wings of the impeller. 
         [0014]    A gap may be formed between an outer side of the impeller and an inner side of the housing to circulate the oil. 
         [0015]    The housing may be provided with an oil passage through which the oil discharged from the impeller is again introduced into the rotating shaft. 
         [0016]    In the housing, a portion at which the impeller is installed may be provided with a bearing supporting the rotating shaft. 
         [0017]    The bearing may have one side exposed to the oil passage. 
         [0018]    A middle of the oil passage may be provided with an oil tank in which the oil is stored. 
         [0019]    The housing may be provided with a cooling water channel through which cooling water is circulated and the oil passage may be provided at an outer side of the cooling water channel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a cross-sectional view illustrating a motor. 
           [0021]      FIG. 2  is a perspective view illustrating a rotor, a rotating shaft, and a bearing in the motor shown in  FIG. 1 . 
           [0022]      FIG. 3  is a cross-sectional view illustrating a motor having a cooling function in accordance with an embodiment of the present invention. 
           [0023]      FIG. 4  is a cross-sectional view taken along the line A-A of  FIG. 3 . 
           [0024]      FIG. 5  is a perspective view illustrating a rotating shaft and an impeller in the motor having a cooling function in accordance with an embodiment of the present invention. 
           [0025]      FIG. 6  is a perspective view illustrating the rotating shaft and the impeller in the motor having a cooling function in accordance with an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    Hereinafter, a motor having a cooling function in accordance with embodiments of the present invention will be described with reference to the accompanying drawings. 
         [0027]    In an example illustrated in  FIGS. 1 and 2 , an induction motor  100  includes a rotor  125  which is integrally fastened with a rotating shaft  131  inside a stator  121 . In this configuration, when a current is applied to a stator coil installed in the stator  121 , an induction current is generated in the rotor  125  to rotate the rotor  125 , thereby generating a torque. 
         [0028]    In the induction motor  100 , the rotor  125  may generate higher heat than other parts, due to the induction current generated in the rotor  125 . In addition, the rotor  125  generates high heat, and therefore as a bearing  135  supporting the rotating shaft  131 , a bearing of a general specification is not applied, but a bearing of a special specification which may withstand against high heat is applied, such that motor cost may be increased. 
         [0029]    Meanwhile, to radiate heat generated from the motor  100 , a technology that the motor has a pump and an oil tank provided therein and when the motor  100  rotates, the pump connected to the rotating shaft  131  of the motor  100  is driven to circulate oil stored in an oil tank has been proposed. 
         [0030]    However, as described above, when the oil for cooling is forcibly circulated by the pump, a size of the motor  100  may be increased and manufacturing cost may be increased. 
         [0031]    Further, since the bearing  135  supporting the rotating shaft  131  of the motor  100  may not be lubricated, the bearing of a special specification which may be used at high heat needs to be applied. 
         [0032]    Referring to  FIGS. 3-6 , in a motor having a cooling function in accordance with an embodiment of the present invention in which a rotor  25  which is integrally fastened with a rotating shaft  31  inside a stator  21  is installed inside a housing  10 , the rotating shaft  31  is formed of a hollow shaft to charge oil therein and is provided with a through hole  31   a  which radially penetrates through the rotating shaft  31  and an outer side of a portion at which the rotating shaft  31  is provided with the through hole  31   a  is coupled with the impeller  33  which radially discharges the oil discharged from the through hole  31   a.    
         [0033]    The housing  10  forms an appearance of the motor  1  and has a stator  21 , a rotor  25 , a rotating shaft  31 , and the like, provided therein. 
         [0034]    The housing  10  may be provided with a cooling water channel  11  through which cooling water supplied from the outside is circulated to cool heat generated from the motor  1 . 
         [0035]    The stator  21  is fixedly installed inside the housing  10 . The stator  210  is present in a state in which a coil is wound around the stator  10 , and therefore, when the stator  21  is applied with electric power, the coil is magnetized and thus the motor  1  outputs a torque. 
         [0036]    The rotor  25  is rotatably installed inside the stator  21 . The rotor is formed in an aluminum ingot form and when the coil of the stator  21  is magnetized, an induction current is generated in the rotor  25  and thus the rotor  25  rotates about the stator  21 . 
         [0037]    The rotating shaft  31  is integrally formed with the rotor  25  at a rotating center of the rotor  25 . The rotating shaft  31  has a hollow shaft form in which an inside is hollow and the inside of the rotating shaft  31  is charged with oil. 
         [0038]    Further, one side of the rotating shaft  31  is provided with the through hole  31   a  which penetrates through the inside and an outside of the rotating shaft  31 . The through holes  31   a  are formed along a circumference of the rotating shaft  31  at a predetermined interval and the oil charged in the rotating shaft  31  through the through hole  31   a  is discharged to the outside of the rotating shaft  31 . 
         [0039]    In particular, the through hole  31   a  of the rotating shaft  31  is distant from the middle of the rotating shaft  31  so as to be formed at a portion adjacent to one end thereof, such that in the inside of the rotating shaft  31 , oil flows in a direction from a portion where the through hole  31   a  is not formed to a portion where the through hole  31   a  is formed (direction from right to left in  FIG. 3 ). 
         [0040]    The impeller  33  is coupled with an outer side of the portion where the through hole  31   a  is formed at the rotating shaft  31 . The impeller  33  is provided with wings along the circumference of the rotating shaft  31  at the same interval. As the impeller  33  rotates, the wings serve to discharge a fluid positioned at a center of the impeller  33  to the outside. 
         [0041]    When the impeller  33  is coupled with the rotating shaft  31 , the impeller  33  is coupled with the rotating shaft  31  so that the through holes  31   a  are positioned between adjacent wings. 
         [0042]    Further, the number of through holes  31   a  which are formed at the rotating shaft  31  may be equal to the number of wings of the impeller  33 . 
         [0043]    As illustrated in  FIG. 4 , when the rotating shaft  31  is provided with four through holes  31   a  at an interval of 90°, the impeller  33  is also provided with four wings and the through hole  31   a  is positioned between adjacent wings. 
         [0044]    Further, a gap is formed between an outer circumference of the impeller  33  and an inner side of the housing  10  and thus the oil discharged from the impeller  33  may flow along the gap. 
         [0045]    Therefore, the oil discharged from the rotating shaft  31  through the through hole  31   a  is discharged to the outside by the impeller  33 . 
         [0046]    An oil passage  12  is formed in the housing  10  and thus forms a passage through which the oil discharged from one end of the rotating shaft  31  is introduced into the other end of the rotating shaft  31 . The oil passage  12  radiates heat absorbed from the rotor  25  and the rotating shaft  31  to the outside while the oil discharged from the rotating shaft  31  flows along the housing  10 . 
         [0047]    Meanwhile, a bearing  35  is installed in the housing  10  to support the rotating shaft  31  and one side of the bearing  35  is installed in the housing  10  to be exposed to the oil passage  12 . 
         [0048]    A middle of the oil passage  12  is provided with the oil tank  13  in which the oil is stored. 
         [0049]    Further, the oil passage  12  is positioned outside the cooling water channel  11  in the housing  10 . 
         [0050]    An action of the motor having a cooling function in accordance with the embodiment of the present invention having the above configuration will be described below. 
         [0051]    When electric power is applied to the motor  1 , a torque is output from the motor  1  while the rotor  25  and rotating shaft  31  rotate about the stator  21 . 
         [0052]    When the rotating shaft  31  rotates, the oil positioned inside the rotating shaft  31  is discharged to the outer side of the impeller  33  while the impeller  33  fastened with the rotating shaft  31  rotates together. When the impeller  33  rotates, a pressure of a rotating center of the impeller  33  and the rotating shaft  31  is lowered and thus a negative pressure is generated, and a positive pressure is generated at the impeller  33  and therefore as illustrated in  FIG. 4 , the oil is discharged to the outer side of the impeller  33  along the wings of the impeller  33  from the center of the rotating shaft  31  through the through hole  31   a.    
         [0053]    Meanwhile, since the impeller  33  is fastened with a portion adjacent to one end of the rotating shaft  31 , the oil flows in a direction from the other end to one end in the rotation shaft  31  and the oil is circulated inside the motor while the oil discharged from the impeller  33  is again introduced into the other end of the rotating shaft  31  through the oil passage  12 . 
         [0054]    As described above, the rotor  25  and the rotator  31  are cooled while the oil circulates the inside of the motor  1 . When heat is generated by the driving of the motor  1 , the oil is automatically circulated only by the driving of the motor without forcibly circulating the oil, thereby cooling the rotor  25  and the rotating shaft  31 . The oil is circulated by a process of making the oil flow inside the rotating shaft  31 , discharging the oil through the through hole  31   a  which is formed at one end of the rotating shaft  31 , and introducing the oil into the other end of the rotating shaft  31  through the oil passage  12 . In the process of making the oil flowing inside the rotating shaft  31 , the oil absorbs the heat generated from the rotor  25  and the rotating shaft  31 . Meanwhile, the oil is cooled by radiating heat through the housing  10  while the oil flows through the oil passage  12  formed in the housing  10 . The oil cooled as described above is again introduced into the rotating shaft  31  and thus absorbs the heat generated from the rotor  25  and the rotating shaft  31 . As the foregoing process is repeated, the center portion of the motor  1 , that is, the rotor  25  and the rotating shaft  31  may be cooled. 
         [0055]    Further, the bearing  35  supporting the rotating shaft  31  has one side exposed on the oil passage  12  and therefore the oil circulating the oil passage  12  is supplied to the bearing  35 , thereby cooling the bearing  35  and lubricating the bearing  35 . 
         [0056]    The heat generated from the stator  21  is cooled by cooling water which flows in the cooling water channel  11  which is formed in a circumferential direction of the housing  10 . 
         [0057]    As described above, the oil is automatically circulated by the driving of the motor  1  without forcibly circulating the oil charged in the rotating shaft  31  to cool the rotor  25  and the rotating shaft  31 , thereby improving the efficiency of the motor. 
         [0058]    Further, the component for forcibly circulating the oil is not required and as the bearing  35  supporting the rotating shaft  31 , the bearing of a general specification, not the high-temperature bearing may be applied, thereby reducing the manufacturing cost of the motor. 
         [0059]    Since a motor having a cooling function in accordance with the embodiments of the present invention has the above configuration, it is possible to emit the heat generated from the rotor and the rotating shaft of the motor to the outside, by making the oil charged in the rotating shaft be automatically circulated inside the motor when the motor starts to drive. 
         [0060]    Further, the separate component for forcibly circulating the oil within the motor is not required, thereby reducing the number of parts configuring the motor and the size of the motor. 
         [0061]    Further, the oil is supplied to the bearing supporting the rotating shaft while the oil is circulated, thereby lubricating the bearing. 
         [0062]    Further, since the temperature of the rotating shaft is reduced due to the circulation of oil, as the bearing for supporting the rotating shaft, the bearing of a general specification, not the high-temperature bearing, may be used, thereby reducing the manufacturing cost of the motor. 
         [0063]    The foregoing embodiments are only examples to allow a person having ordinary skill in the art to which the present invention pertains to easily practice the present invention. Accordingly, the present invention is not limited to the foregoing embodiments and the accompanying drawings, and therefore, a scope of the present invention is not limited to the foregoing embodiments. Accordingly, it will be apparent to those skilled in the art that substitutions, modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims and can also belong to the scope of the present invention.