Patent Publication Number: US-2007114858-A1

Title: Rotor for use in motor with cooling function

Description:
FIELD OF THE INVENTION  
      The present invention relates to a rotor for use in a motor with a cooling function, and more particularly, to a rotor for use in a motor with a cooling function, wherein cooling blades of the rotor are formed through injection molding so as to achieve a simplified assembly process and improved durability of the rotor.  
     BACKGROUND OF THE INVENTION  
      In general, a motor is a device that converts electrical energy into mechanical energy to provide a rotational force. Motors are being widely applied to various industrial fields including electric home appliances and industrial machines. Motors can be largely divided into alternating current (AC) motors and direct current (DC) motors.  
      With reference to  FIG. 1 , a conventional motor will be descried hereinafter.  
       FIG. 1  illustrates a sectional view of a conventional motor  10 , particularly, an induction motor, which is one of AC motors. The conventional motor  10  includes a stator  11 , a rotor  12 , a shaft  13 , and cooling fans  15 . The stator  11  is affixed to a casing  14 , and the rotor  12  is installed to be rotatable by having a gap inside the stator  11 . The shaft  13  is pressed into a central part of the rotor  12  and rotates together with the rotor  12 . The cooling fans  15  are installed on both edge regions of the rotor  12 .  
      The stator  11  includes a coil  11   a  and a stator coil  11   b  of a magnetic substance. The coil  11   a  is supplied with AC current to generate a rotating magnetic field. The stator coil  11   b  generates flow paths of magnetic fluxes produced by the rotating magnetic field of the coil  11   a.    
      The stator coil  11   b  is formed by stacking a plurality of identically shaped silicon steel sheets over each other in an axial direction. Although not illustrated, a plurality of slots is radially spaced a certain distance apart from each other along the inner surface of the stator coil  11   b . The coil  11   a  is coiled around the slots using a distributional coiling method, a central coiling method, or a concentric coiling method.  
      The rotor  12  includes conductors (not shown) and a rotor core  12   b  of the magnetic substance. The conductors generate a torque by reciprocal reactions between the current provided by the coil  11   a  and the magnetic fluxes. The rotor core  12   b  has the conductors (not shown) installed therein and provides flow paths of the magnetic fluxes.  
      The conductors are formed of a metal such as aluminum or copper having high electrical conductivity, or magnets.  
      The rotor core  12   b  is formed by stacking a plurality of identically shaped silicon steel sheets in an axial direction. Although not illustrated, a plurality of slots is radially spaced a certain distance apart from each other in parallel to the axial direction on the outer surface or the inner side of the rotor core  12   b . As like the coil  11   a , the conductors of the rotor  12  are installed around the slots to run parallel to the axial direction.  
      The shaft  13  passes through the rotor core  12   b  to be affixed to the rotor  12  so as to rotate by means of holders  14   a  and bearings  14   b  disposed on both sides of the casing  14 .  
      The cooling fans  15  are formed through injection molding to be attached or affixed to the edge regions of the rotor  12 . Particularly, the cooling fans  15  are formed in a certain shape to produce a wind when rotating.  
      The conventional motor  10  operates as in the following.  
      When AC current is supplied to the coil  11   a , a magnetic field is generated in a vertical direction to the axis. As a result, the magnetic fluxes start rotating through the stator coil  11   b , and the rotating magnetic fluxes cross the conductors of the rotor  12  through the gap to thereby provide a certain amount of current to the conductors. The current provided to the conductors generates a torque in the rotor  12  according to the Fleming&#39;s left hand rule.  
      When the rotor  12  rotates, the cooling fans  15  also rotate to move air in from the outside and discharge the air to the inside of the casing  14  for air circulation. As a result, the motor  10  is cooled down.  
      However, in the conventional motor  10 , since the rotor core  12   b  is formed by stacking the multiple silicon steel sheets having the same shape over each other, a structure for attaching the cooling fans  15  to the rotor  12  may be formed with some limitations. Thus, it is often required to form the cooling fans  15  in such a structure to be attached to the rotor core  12   b . Due to this structural burden, there may be a complication in implementing a desired structure and difficulties in miniaturization and a firm attachment of the cooling fans  15  to the rotor core  12   b . For instance, one of such motors is disclosed in U.S. Pat. No. 6,006,553, entitled “HEAT DISSIPATING BLADES FOR A MOTOR OF A WASHING MACHINE”.  
      Also, an assembly process is generally performed to attach the cooling fans  15  to the rotor core  12   b , and thus, the manufacturing process may become complex, resulting in decrease in productivity.  
     SUMMARY OF THE INVENTION  
      It is, therefore, an object of the present invention to provide a rotor for use in a motor with a cooling function, wherein cooling blades of the rotor are formed be integrated with the rotor so as to reduce a cost for manufacturing cooling fans, aid miniaturization of products and improve productivity through simplifying an assembly process.  
      In accordance with a preferred embodiment of the present invention, there is provided a rotor for use in a motor with a cooling function, the rotor including a main body formed by pressing soft magnetic powder, and a plurality of cooling blades formed to be integrated with the main body to produce a wind for cooling when the rotor rotates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:  
       FIG. 1  illustrates a sectional view of a conventional motor;  
       FIG. 2  illustrates a sectional view of a motor in accordance with a first embodiment of the present invention;  
       FIG. 3  illustrates a perspective view of a main body of a rotor for use in motor with a cooling function in accordance with the first embodiment of the present invention;  
       FIG. 4  illustrates a perspective view of the rotor for use in the motor with the cooling function in accordance with the first embodiment of the present invention;  
       FIG. 5  illustrates a sectional view of a motor in accordance with a second embodiment of the present invention;  
       FIG. 6  illustrates a perspective view of a main body of a rotor for use in the motor with a cooling function in accordance with a second embodiment of the present invention;  
       FIG. 7  illustrates a perspective view of the rotor for use in the motor with the cooling function in accordance with the second embodiment of the present invention;  
       FIG. 8  illustrates a sectional view of a motor in accordance with a third embodiment of the present invention;  
       FIGS. 9 and 10  illustrate top views of various types of rotors having a cooling function in accordance with the third embodiment of the present invention;  
       FIG. 11  illustrates a sectional view of a motor in accordance with a fourth embodiment of the present invention; and  
       FIG. 12  illustrates a top view of a rotor for use in the motor with a cooling function in accordance with the fourth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
      Referring now to  FIG. 2 , there is illustrated a sectional view of a motor  100  in accordance with a first embodiment of the present invention.  
      The motor  100  includes a rotor  110  having a cooling function. The rotor  110  includes a main body  111  and cooling blades  112 , and is molded by pressing soft magnetic powder. The main body ill is installed to be rotatable by having a gap inside a stator  130  affixed to a casing  120  and provides flow paths of magnetic fluxes. The main body  111  includes attachment reinforcing openings  111   a  on outer surface portions of the main body  110 . Each of the cooling blades  112  are formed to protrude through injection molding of the cooling blades  112  into the respective attachment reinforcing openings  111   a.    
      In the first embodiment of the present invention, the rotor  110  includes the cooling blades  112  on both upper and lower sides of the main body  111 . However, the cooling blades  112  may also be placed on one of the upper and lower sides.  
      A shaft cavity  111   b  is formed in a central region of the main body  111  to firmly hold a shaft  140 , and the attachment reinforcing openings  111   a  are formed on the upper and lower surfaces of the main body  110  for the injection molding of the cooling blades  112 .  
      In case where the multiple cooling blades  112  exist, as illustrated in  FIG. 3 , the attachment reinforcing openings  111   a  are formed in one integral opening by including first openings  111   c  and second openings  111   d . The first openings  111   c , as shown, are formed on those points where the respective cooling blades  112  are placed, and the second openings  111   d  connect the first openings  111   c  individually with each other. Alternatively, the attachment reinforcing openings  111   a  may be formed in multiple numbers of the openings corresponding to the respective cooling blades  112 . In addition to these mentioned structures, the attachment reinforcing openings  111   a  can be formed in various structures.  
      The attachment reinforcing openings  111   a  allow the cooling blades  112  to be firmly affixed to the main body  111  by increasing the attachment surface of the attachment reinforcing openings  111   a  with a material to be molded by injection and a bonding force to the cooling blades  112  obtained after the injection molding.  
      The cooling blades  112  are injected into the respective attachment reinforcing openings  111   a  to protrude so as to generate a wind for cooling when the main body  111  rotates.  
      As illustrated in  FIG. 4 , the cooling blades  112  are formed in a half-diameter direction, i.e., toward the outer side from the shaft cavity  111   b , which is the center of the rotation, and arranged around the center of the rotation. As illustrated, the multiple cooling blades  112  exist.  
      As illustrated in the first embodiment of the present invention, the cooling blades  112  may be formed such that the cooling blades  112  are formed in the shape of a straight line when viewed from the top. Alternatively, the cooling blades  112  may be formed in a curvature shape from the top view.  
      As described above, the main body  111  is formed by pressing the soft magnetic powder, and thus, forming the attachment reinforcing openings  111   a  into which the cooling blades  112  are injected and molded. The soft magnetic power includes iron-based particles, each coated with a certain material to be electrically insulated from each other.  
      For the press molding of the main body  111 , a molding space having substantially the same shape as the main body  111  is prepared in a press molding machine, and then filled with the soft magnetic powder. Then, a press member such as a punch is used to press the soft magnetic powder to form the attachment reinforcing openings  111   a  in the main body  111 . At this time, a lubricating agent and/or a binding agent may be added to the soft magnetic powder and pressed together.  
      The main body  111  includes a three-dimensional soft magnetic composite (SMC) due to the aforementioned press process on the soft magnetic powder. As compared with the conventional process of using the silicon steel sheets, the main body  111  is allowed to have an increased degree of freedom. Thus, different from the conventional stack structure of the silicon steel sheets having the same shape, this SMC allows the formation of the attachment reinforcing openings  111   a  in various shapes.  
      The main body  111  is installed into an injection molding machine to form the cooling blades  112  on the respective attachment reinforcing openings  111   a . Also, an injection molding material such as synthetic resin is injected into a molder having a space for forming the cooling blades  112 , and molded to form the cooling blades  112  integrated with the main body  111 .  
      Although the implementation of the rotor  110  in the motor  100 , more particularly, the induction motor  100 , is exemplified in the first embodiment, the rotor  110  can also be implemented in other types of motors such as AC motors and DC motors, which usually require the cooling. In the first embodiment of the present invention, as the rotor  110  is implemented in the induction motor  100 , although not illustrated, conductors for providing a certain amount of current to a target are placed around slots formed on the outer surface or the inner side of the main body  111 .  
      The rotor  110  having the cooling function in accordance with the first embodiment of the present invention operates as follows.  
      When AC current is supplied to a coil  131  of the stator  130 , rotating magnetic fluxes are produced through a stator core  132 . This rotating magnetic fluxes cross the conductors (not shown) of the rotor  110 , placed on the outer surface or the inner side of the main body  111 , through the gap to provide a certain amount of current to the conductors (not shown), so that the rotor  110  produces a torque.  
      Due to the torque, the rotor  110  rotates, and the cooling blades  112  rotating along with the main body  111  to produce a wind, which causes air to be moved in from the outside of the casing  120  and discharged to the inside thereof. As a result, the inner side of the casing  120  is cooled down.  
       FIG. 5  illustrates a sectional view of a motor  200  in accordance with a second embodiment of the present invention. As similar to the first embodiment of the present invention, it is exemplified in the second embodiment that a rotor  210  is installed in the motor  200 , more particularly, the induction motor. The rotor  210  includes a main body  211  and cooling blades  212 , and is molded by pressing soft magnetic powder. The main body  211  is installed to be rotatable by having a gap inside a stator  230  affixed to a casing  140 , and provides flow paths of magnetic fluxes. The main body  211  includes attachment reinforcing openings  211   a  on certain outer surface portions of the main body  211 . The cooling blades  212  are formed to protrude through injection molding into the respective attachment reinforcing openings  211   a  of the main body  211 . Those parts of the motor  200  different from the motor  100  described in the first embodiment of the present invention will be described in detail.  
      As illustrated in  FIG. 6 , the attachment reinforcing openings  211   a  may be formed as many as the cooling blades  212  and placed on given regions corresponding to the cooling blades  212 . In addition, the cooling blades  212  may be formed in an integral structure along the outer surface of the main body  211 , or in other various shapes and structures.  
      The cooling blades  212  are formed on the given outer surface portions of the main body  211  to run parallel to a shaft  240 , which is a central rotation axis. As illustrated in  FIG. 7 , the cooling blades  212  are formed to protrude through the injection molding into the respective attachment reinforcing openings  211   a , and spaced a certain distance apart from each other along the outer surface of the main body  211 . As illustrated in the second embodiment of the present invention, the cooling blades  212  may be formed in the shape of a straight line. Instead of this shape, the cooling blades  212  may also be formed in other shapes including curvature.  
      The rotor  210  having the cooling function operates as follows.  
      When the rotor  210  rotates by the driving of the motor  200 , e.g., the induction motor, the cooling blades  212  also rotates to produce a wind, which causes air to be moved in from the outside of the casing  140  and discharged to the inside thereof. As a result, the inner side of the casing  140  is cooled down.  
       FIG. 8  illustrates a sectional view of a motor  300  in accordance with a third embodiment of the present invention. In the motor  300 , a rotor  310  having a cooling function includes a main body  311  and cooling blades  312 , and is molded by pressing soft magnetic powder. The main body  311  of the motor  300  is installed to be rotatable by having a gap inside a stator  330 , which is affixed to a casing  320 , and provides flow paths of magnetic fluxes. A shaft  340  passes through a central region of the main body  311  to be affixed to the main body  311 . The cooling blades  312  are formed to be integrated with the main body  311 .  
      As illustrated in FIGS.  8  to  10 , a plurality of the cooling blades  312  are arranged individually on both upper and lower surfaces of the main body  311  along the center of rotation, i.e., around the shaft  340 . Each of the cooling blades  312  are formed in a half-diameter direction, i.e., toward the outer side from the center of the rotation.  
      As illustrated in  FIG. 9 , the cooling blades  312  are formed to be in the shape of a straight line from a top view so as to be easily manufactured. Also, as illustrated in  FIG. 10 , the cooling blades  312  may be formed in a curved shape, so that the wind can be produced more efficiently.  
      As described above, the rotor  310  is formed by pressing the soft magnetic powder, and thus, the cooling blades  312  are formed to be integrated with the main body  311 . The soft magnetic powder usually includes iron-based particles, each coated with a certain material to be electrically insulated from each other.  
      For the press molding of the rotor  310 , a molding space having substantially the same shape as the rotor  310  is prepared in a press molding machine, and then filled with the soft magnetic powder. Then, a press member such as a punch is used to press the soft magnetic powder to form the cooling blades  312  integrated with the main body  311 . At this time, a lubricating agent and/or a binding agent may be added to the soft magnetic powder and pressed together.  
      The rotor  310  includes a SMC having a three-dimensional shape due to the aforementioned press process on the soft magnetic powder. As compared with the conventional process of using the silicon steel sheets, the rotor  310  is allowed to have an increased degree of freedom. Thus, different from the conventional stack structure of the silicon steel sheets having the same shape, this SMC allows the formation of the cooling blades  312 .  
      Although the implementation of the rotor  310  in the motor  300 , more particularly, the induction motor  300 , is exemplified in the third embodiment, the rotor  310  can also be implemented in other types of motors such as AC motors and DC motors, which usually require the cooling. In the third embodiment of the present invention, as the rotor  310  is implemented in the induction motor  300 , although not illustrated, conductors for providing a certain amount of current to a target are placed around slots formed on the outer surface or the inner side of the main body  311 .  
      The rotor  310  having the cooling function in accordance with the third embodiment of the present invention operates as follows.  
      When AC current is supplied to a coil  331  of the stator  330 , rotating magnetic fluxes are produced through a stator core  132 . This rotating magnetic fluxes cross the conductors (not shown) of the rotor  310 , placed on the outer surface or the inner side of the main body  311 , through the gap to provide a certain amount of current to the conductors (not shown), so that the rotor  310  produces a torque.  
      Due to the torque, the rotor  310  rotates, and the cooling blades  312  integrated with the main body  311  produces a wind, which causes air to be moved in from the outside of the casing  320  and discharged to the inside thereof. As a result, the inner side of the casing  320  is cooled down.  
       FIG. 11  illustrates a sectional view of a motor in accordance with a fourth embodiment of the present invention. As similar to the above described embodiments, it is exemplified in the fourth embodiment that a rotor  410  is installed in the motor  400 , more particularly, the inductor motor. The rotor  410  having a cooling function includes a main body  411  and cooling blades  412 , and is molded by pressing soft magnetic powder. The main body  411  of the motor  400  is installed to be rotatable by having a gap inside a stator  430 , which is affixed to a casing  420 , and provides flow paths of magnetic fluxes. A shaft  440  passes through a central region of the main body  411  to be affixed to the main body  411 . The cooling blades  412  are formed to be integrated with the main body  411 . Hereinafter, those parts of the rotor  410  different from the rotor  110 ,  210  or  310  will be described in detail.  
      In the rotor  410 , the cooling blades  412  are formed on given outer surface portions of the main body  411  in parallel to a central rotation axis, i.e., the shaft  440 . As substantially the same as the arrangement illustrated in  FIG. 12 , the cooling blades  412  are arranged a certain distance apart from each other along the outer surface of the main body  411 .  
      As similar to the previous embodiments, the rotor  410  is molded by pressing the soft magnetic powder, and thus, the cooling blades  412  can be formed on the given outer surface portions of the main body  411  in the shape of a straight line or in a curved shape. Since the cooling blades  412  are also formed using the soft magnetic powder, the cooling blades  412  can provide flow paths of the rotating magnetic fluxes produced toward the stator  430 . As a result, a certain amount of current can be provided to conductors (not shown), installed on the outer surface or the inner side of the main body  411 , and the rotor  410  can also produce a torque.  
      The rotor  410  of the motor  400  in accordance with the fourth embodiment of the present invention operates as follows.  
      When the rotor  410  rotates by the driving of the motor, i.e., the inductor motor  400 , the cooling blades  412  also rotate to produce a wind, which causes air to be moved in from the outside of the casing  420  and discharge the air to the inside thereof. As a result, the inner side of the casing  420  is cooled down.  
      On the basis of various embodiments of the present invention, the cooling blades that produce a wind for cooling when the rotor rotates are formed through injection molding. Thus, durability and miniaturization of products can be achieved as well as an assembly process can be simplified. The simplified assembly process contributes to improvement in productivity.  
      In another embodiment of the present invention, the rotor is manufactured by pressing soft magnetic powder, the cooling blades are additionally prepared to be integrated with the rotor and have a certain structure for bonding to a target. Hence, the motor can be miniaturized, and a manufacturing process can be simplified, thereby improving productivity.  
      While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.