Abstract:
There is provided an open-type induction motor, and more particularly, to an open type induction motor in which a rotor has a structure allowing air to flow therein, thus enhancing cooling efficiency of the rotor and a stator. The open-type induction motor includes: a stator including an iron stator core having a radial duct hole and a stator coil wound around the iron stator core; and a rotor disposed in a hollow of the stator so as to be rotatable by magnetism generated by the stator coil, and including a rotational shaft, a plurality of iron rotor cores stacked in an axial direction of the rotational shaft and coupled to the rotational shaft, a rotor coil coupled to the plurality of iron rotor cores, and duct plates stacked between the plurality of iron rotor cores and outwardly discharging air present at the inner side of the iron rotor cores.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority of Korean Patent Application No. 10-2013-0128335 filed on Oct. 28, 2013, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to an open-type induction motor, and more particularly, to an open type induction motor in which a rotor has a structure allowing air to flow therein, thus enhancing cooling efficiency of the rotor and a stator. 
     An induction motor includes a shaft supporting a rotor, the rotor rotatably supported by the shaft, a stator positioned to face the rotor and generating magnetism to enable the rotor to rotate, a frame press-fitting the stator to protect and support the stator, brackets fastened to front and rear sides of the frame, an inlet formed in the front bracket to allow ambient air to be drawn therethrough, an outlet formed in the rear bracket to outwardly discharge air drawn through the inlet, and a ventilation fan installed within the rear bracket rotating to intake and discharge air to decrease an internal temperature of the frame 
     When power is applied, the rotor supported by the shaft rotates at high speed, due to magnetism generated by the stator, driving the induction motor. 
     Here, since the rotor rotates, an internal temperature of the induction motor increases. 
     Thus, in order to cool the interior of the induction motor, a ventilation fan provided within the rear bracket of the frame is driven to allow ambient air to be drawn in through the inlet formed in the front bracket and pass between the rotor and the stator. 
     After ambient air is drawn in according to the rotation of the ventilation fan and passes between the rotor and the stator to decrease an increased internal temperature of the inductor motor, the air is outwardly discharged through the outlet formed in the rear bracket of the frame according to the continuous rotation of the ventilation fan, thus allowing for a continuous high output of the induction motor. 
     The open-type inductor motor is disclosed in Korean Patent Laid Open Publication No. 2001-0036665. 
     However, in the related art open-type induction motor, since air only flows in an axial direction through a ventilation hole penetrating through the rotor in the axial direction and the space between the rotor and the stator, cooling efficiency of the rotor and the stator is low. 
     In addition, since the related art open-type induction motor requires the ventilation fan to enable ambient air to be introduced to the rotor and the stator, high manufacturing costs are incurred, and mechanical loss is generated due to driving of the ventilation fan, reducing efficiency of the motor. 
     SUMMARY 
     An aspect of the present disclosure may provide an open type induction motor including a rotor and a stator with enhanced cooling efficiency. 
     According to an aspect of the present disclosure, an open-type induction motor may include: a stator including an iron stator core having a radial duct hole and a stator coil wound around the iron stator core; and a rotor disposed in a hollow of the stator so as to be rotatable by magnetism generated by the stator coil, and including a rotational shaft, a plurality of iron rotor cores stacked in an axial direction of the rotational shaft and coupled to the rotational shaft, a rotor coil coupled to the plurality of iron rotor cores, and duct plates stacked between the plurality of iron rotor cores and outwardly discharging air present at the inner side of the iron rotor cores. 
     Each of the iron rotor cores may include air holes allowing air to flow therethrough in an axial direction of the rotational shaft, and the duct plate may include a plurality of radially formed blade portions and duct slit portions formed between the plurality of blade portions, communicating with the air holes of the iron rotor cores, and extending and cut outwardly of the iron rotor cores. 
     The duct slit portions may correspond to the plurality of air holes provided in the iron rotor cores, respectively, and may be radially formed outwardly from an inner side of the duct plates. 
     The duct plates may include a slit extending portion in which widths of outer ends of the duct slit portion are increased as the ends of the blade portions are tapered. 
     The iron rotor cores and the duct plate may have a coil coupling hole in which the rotor coil is coupled. 
     The duct plate may be disposed in a position not aligned with a duct hole of the iron stator core with respect to an axial direction of the rotational shaft. 
     The induction motor may further include a frame allowing the stator and the rotor to be installed therein and having an air inlet allowing ambient air to be introduced to an interior of the frame therethrough. 
     The induction motor may further include an air guide provided on both sides within the frame and guiding air introduced through the air inlet of the frame toward the rotor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a partial cross-sectional view of an open-type induction motor according to an exemplary embodiment of the present disclosure; 
         FIG. 2  is a partial cross-sectional perspective view of the open-type induction motor illustrated in  FIG. 1 ; 
         FIGS. 3A and 3B  are a plan view of an iron rotor core of a rotor and a plan view of a duct plate included in the open-type induction motor illustrated in  FIG. 1 ; 
         FIG. 4  is a plan view illustrating an overlapping state of the iron rotor core and the duct plate illustrated in  FIG. 3 ; and 
         FIG. 5  is a partial cross-sectional view illustrating air flow within the open-type induction motor illustrated in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
     The disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 
     In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
     An open-type induction motor according to an exemplary embodiment of the present disclosure will be described with reference to  FIGS. 1 through 5 . 
       FIG. 1  is a partial cross-sectional view of an open-type induction motor according to an exemplary embodiment of the present disclosure,  FIG. 2  is a partial cross-sectional perspective view of the open-type induction motor,  FIGS. 3A and 3B  are a plan view of an iron rotor core and a plan view of a duct plate,  FIG. 4  is a plan view illustrating an overlapping state of the iron rotor core and the duct plate, and  FIG. 5  is a partial cross-sectional view illustrating air flow within the open-type induction motor. 
     As illustrated in  FIGS. 1 through 5 , an open-type induction motor  100  according to an exemplary embodiment of the present disclosure may include a frame  110 , a stator S, a rotor R, and an air guide  170 . 
     The frame  110  forms an appearance of the open-type induction motor  100  according to an exemplary embodiment and may have an internal space in which the stator S, the rotor R, and the air guide  170  as described hereinafter are installed. 
     The frame  110  may have air inlets  112  allowing ambient air to be introduced to an interior of the frame  110 . In an exemplary embodiment, the air inlets  112  may be provided in brackets (not shown) coupled to both sides of the frame  110 , but the present disclosure is not limited thereto. 
     In an exemplary embodiment, the air inlets  112  may be provided on both sides of the frame  110  to form a passage through which ambient air is introduced in an axial direction of the stator S and the rotor R as described hereinafter. 
     The stator S may include an iron stator core  122  fixed within the frame  110  and a stator coil  126  wound around the iron stator core  122 . 
     In an exemplary embodiment, as illustrated in  FIG. 2 , the iron stator core  122  may have a radial duct hole. 
     Also, in an exemplary embodiment, a plurality of duct holes may be provided to be spaced apart from one another in the axial direction of the iron stator core  122 . 
     The duct holes may extend outwardly from the iron stator core  122  to form a path for air introduced to an inner side of the iron stator core  122  to pass through the interior of the iron stator core  122  and be subsequently discharged outwardly. 
     The iron stator core  122  may be cooled by air flowing in the duct holes. 
     The rotor R is disposed in the hollow of the cylindrical stator S and rotates through magnetism generated by the stator coil  126 . 
     The rotor R may include a rotational shaft  130 , an iron rotor core  140 , a rotor coil  150 , and a duct plate  160 . 
     The rotational shaft  130  is rotatably supported by bearings  114  provided on both sides of the frame  110 , and extends such that at least one end thereof is exposed outwardly from the frame  110 , to transmit rotary power to an external element. 
     A plurality of iron rotor cores  140  may be stacked in an axial direction of the rotational shaft  130  and coupled to the rotational shaft  130 . Each of the iron rotor cores  140  may have a disk shape, and a plurality of iron rotor cores may be stacked to form a cylindrical iron core. 
     As illustrated in  FIG. 3A , the iron rotor cores  140  may include a plurality of air holes  144  penetrating through the body in a width direction. 
     The air holes  144  may form a path allowing air to flow in the axial direction of the rotational shaft  130  at an inner side of the plurality of stacked iron rotor cores  140 . 
     Coil coupling holes  142  may be provided on the edge portion of the iron rotor core  140 , through which the coil  150  is wound. 
     In an exemplary embodiment, the iron rotor core  140  may be formed through aluminum die casting having high precision, high strength at high temperatures, and high abrasion resistance, but the present disclosure is not limited thereto. 
     The rotor coil  150  may be wound around the plurality of iron rotor cores  140  through the coil coupling holes  142  provided in the plurality of iron rotor cores  140 . 
     The rotor coil  150  is wound around the iron rotor core  140 , and when a current flows in the rotor coil  150 , the rotor coil  150  generates magnetism to magnetize the iron rotor cores  140 . 
     The duct plates  160  may be formed as d-shaped members stacked between the stacked iron rotor cores  140 , so a rotation behavior of the duct plates  160  is consistent with that of the iron rotor cores  140 . 
     The duct plates  160  may outwardly discharge air at the inner side of the iron rotor cores  140 . 
     Namely, the duct plates  160  may discharge air flowing in the air holes  144  of the iron rotor cores  140  outwardly of the iron rotor cores  140 . 
     To this end, in an exemplary embodiment, the duct plates  160  may each include a blade portion  162 , a duct slit portion  164 , and a slit extending portion  168 . 
     As illustrated in  FIG. 3B , the blade portion  162  corresponds to a portion radially extending from the center of a body of the duct plate  160 . 
     A coil coupling hole  166  corresponding to the coil coupling hole  142  provided in the iron rotor core  140  may be provided in an end portion of the blade portion  162 . 
     The duct slit portions  164  are formed between the plurality of blade portions  162  and provided as a flow path along which air flows. 
     Namely, the duct slit portion  164  may correspond to a space between the blade portions  162 . 
     The duct slit portion  164 , having a structure extending and cut outwardly of the iron rotor cores  140 , may form a path allowing air flowing to the air holes  144  of the iron rotor cores  140  to be discharged outwardly of the iron rotor cores  140 . 
     In an exemplary embodiment, the duct slit portions  164  may correspond to the plurality of air holes  144  provided in the iron rotor cores  140 , respectively, and may be radially formed outwardly in the duct plate  160 . 
     As illustrated in  FIG. 4 , when the iron rotor core  140  and the duct plate  160  overlap, the duct slit portions  164  of the duct plate  160  may communicate with the air holes  144  of the iron rotor core  140 . 
     When the duct slit portions  164  and the air holes  144  communicate, a partial amount of air flowing to the air holes  144  may be discharged outwardly of the iron rotor core  1400  and the duct plate  160  through the duct slit portions  164 . 
     Also, as illustrated in the partially enlarged view of  FIG. 3B , the slit extending portion  168  corresponds to a portion in which the end of the blade portion  162  is tapered to increase the width of the outer end portion of the duct slit portion  164 . 
     Namely, the slit extending portion  168  may include sloped surfaces formed on both sides of the ends of the blade portion  162 . 
     The slit extending portion  168  allows air discharged through the duct slit portion  164  to be smoothly discharged in a circumferential direction of the iron rotor core  140  through the sloped surfaces at the ends of the blade portion  162  when the rotor R rotates at a high speed. 
     Since air resistance of the blade portion  162  that rotates at a high speed is reduced through the slit extending portion  168 , efficiency of the motor may be increased and operating noise may be reduced. 
     In an exemplary embodiment, the duct plate  160  described above may be disposed in a position not aligned with the duct hole  123  of the iron stator core  122  with respect to the axial direction of the rotational shaft  130  as illustrated in  FIG. 1 . 
     Accordingly, air discharged through the duct slit portion  164  may be introduced to the space between the iron rotor core  140  and the iron stator core  122  to cool the iron rotor core  140  and the iron stator core  122  and subsequently flow into the duct hole  123 , rather than being immediately discharged through the duct hole  123  of the iron stator core  122 . 
     The air guide  170  may be provided on both sides within the frame  110  and guide air introduced through the air inlet  112  of the frame  110  toward the rotor R. 
     In an exemplary embodiment, the air guide  170  may be configured in the form of a funnel extending from the air inlet  112  toward the rotor R. 
     Hereinafter, an air cooling operation of the open-type induction motor  100  according to an exemplary embodiment of the present disclosure as described above will be described. 
     As illustrated in  FIG. 5 , when the open-type induction motor  100  according to an exemplary embodiment of the present disclosure is driven and the rotor R rotates, air accommodated in the air holes  144  of the iron rotor core  140  moves outwardly of the duct plate  160  through the duct slit portion  164  by centrifugal force according to the rotation of the iron rotor core  140 . 
     In this case, the blade portion  162  of the duct plate  160  may serve as a blade pushing air to exert centrifugal force on the air accommodated in the duct slit portion  164 . 
     The air which has moved through the duct slit portion  164  is discharged outwardly of the duct plate  160  and introduced to the space between the iron rotor core  140  and the iron stator core  122 . 
     The air accommodated in the space between the iron rotor core  140  and the iron stator core  122  is forced in a direction outward from the iron stator core  122  through air pressure generated due to the rotation of the iron rotor core  140  so as to be introduced to the duct hole  123  provided in the iron stator core  122 . 
     The air introduced to the duct hole  123  cools the iron stator core  122  within the iron stator core  122 , is discharged outwardly of the iron stator core  122 , and subsequently moves to the interior of the frame  110 . 
     Meanwhile, when the air accommodated within the air hole is released due to the rotation of the iron rotor core  140 , atmospheric pressure in the air holes  144  is lowered, and thus, ambient air of the frame  1210  is introduced into the air holes  144  through the air inlet  112 . 
     The air guide  170  guides the air introduced through the air inlet  112  toward the rotor R, so that the air may be moved to the air holes  144  of the iron rotor core  140 . 
     In the open-type induction motor  100  according to an exemplary embodiment of the present disclosure, air is introduced to the interior of the iron rotor core  140  and the iron stator core  122  to increase the area in which the rotor R and the stator S are in contact with air, and thus, cooling efficiency of the rotor R and the stator S is enhanced. 
     Also, in the open-type induction motor  100  according to an exemplary embodiment of the present disclosure, since air is automatically introduced to the interior of the rotor R through rotation of the duct plate  160 , an additional fan for introducing ambient air to the rotor is not required, reducing manufacturing costs of the device and preventing the generation of mechanical loss according to driving of the fan. 
     As set forth above, according to exemplary embodiments of the present disclosure, cooling efficiency of the rotor and the stator may be enhanced by air. 
     In addition, according to exemplary embodiments of the present disclosure, since an additional fan for introducing ambient air is not required and ambient air is automatically introduced to the rotor and the stator according to rotation of the rotor, the configuration of the device may be simplified, manufacturing costs of the device may be reduced, and mechanical loss is not generated. 
     While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present invention as defined by the appended claims.