Abstract:
A method of making an electric motor includes installing a plurality of hairpin coils in a plurality of slots, wherein the plurality of hairpin coils comprise a first hairpin coil and a second hairpin coil, the first hairpin coil comprising a first end and the second hairpin coil comprising a second end. The method further includes inserting the first and second ends into a void of an electrically conductive coupler to electrically connect the first and second ends; and placing the insulation cap over the coupler so as to protect the coupler from contacting other electric conductive materials.

Description:
CROSS-REFERENCE(S) TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Korean Patent Application No. 10-2012-0050649, filed on May 14, 2012, which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates to an electric rotary motor; and, particularly, to a method for binding stator winding coils. 
         [0004]    2. Discussion of the Related Technology 
         [0005]    In general, a motor necessarily includes a stator having coils wound therein, and the coils are inserted into slots of the stator. 
         [0006]    Recently, a demand for miniaturization and high efficiency of a motor has continuously increased. 
         [0007]    In order to realize the miniaturization and high efficiency of a motor according to such a demand, the slots of the stator include as many ring-shaped coils inserted therein as possible. 
         [0008]    However, because of a dead space formed between a ring-shaped coil and another adjacent ring-shaped coil and another dead space formed between the ring-shaped coil and a stator&#39;s teeth, the quantity of the inserted ring-shaped coils is inevitably limited. 
         [0009]    Examples of a winding method capable of accomplishing miniaturization and high efficiency of a motor by solving the above-described dead space problem may include a hairpin winding method. 
         [0010]    In the hairpin winding method, coils may be wound in slots of a stator without a dead space formed therein. Therefore, the hairpin winding method has an advantage in terms of miniaturization and efficiency. 
         [0011]    On the other hand, the hairpin winding method requires high-level manufacturing techniques such as coil forming, coil twisting, and coil welding, and a lot of problems occur during welding. 
         [0012]    In particular, when a welding defect occurs while a welding operation is performed or after a welding operation is completed, welded coils are removed, and the stator manufacturing process are performed again. In this case, the damage caused by the welding defect is inevitably high. 
         [0013]    Therefore, when the coil forming operation and the coil twisting operation of the hairpin winding method are more simplified, in particular, when the difficulties caused by the welding operation are removed, the advantage of the hairpin winding method in terms of miniaturization and efficiency may be maximized, and the merchantability of motors manufactured by the hairpin winding method may be improved. 
         [0014]    In the hairpin winding method, however, a welding operation is performed after the hairpin coils are wound. 
         [0015]    Because of the difficulties during the welding operation, coatings of the coils may be burned even though the coils are welded. Furthermore, since four layers are wounded adjacent to each other, coatings of first and second layers may be burned when third and fourth layers are welded, or coatings of the third and fourth layers may be burned when the first and second layers are welded. Furthermore, as primary-side copper loss increases due to an increase of contact resistance during partial welding, the efficiency may decrease at low speed. 
         [0016]    The disadvantages of the manufacturing process may include an additional coil process for welding, the use of expensive equipment for correctly performing a welding process and cooling down welding heat, and welding gas which may pollute a work place. 
         [0017]    In particular, attention is paid from the start to the end of the welding operation such that a welding defect does not occur. However, as the number of welding operations increases according to the number of stator slots, there is an inevitable limitation. 
         [0018]    For example, when the number of stator slots is 72, welding operations are performed 144 times. Therefore, when a welding defect occurs at the 144th welding operation even though the first to 143rd operations are normally performed, all of the welded hairpin coils are removed, and the same process is repeated. 
         [0019]    Therefore, the above-described patent document can hardly be free from various problems caused by welding, when manufacturing a motor according to the hairpin winding method which has an advantage in efficiency and output density because of the maximized space factor. 
       SUMMARY 
       [0020]    An embodiment of the present invention is directed to a method for binding a stator winding coil, which may bind hairpin coils wound in a stator through an operation of fitting a conductor to the hairpin coils such that problems caused by a welding defect during a welding operation do not occur, and may remove disadvantages in a manufacturing process caused by expensive welding equipment, and a rotary motor to which the method is applied. 
         [0021]    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 
         [0022]    One aspect of the invention provides a method of making an electric motor, comprising: installing a plurality of hairpin coils in a plurality of slots, wherein the plurality of hairpin coils comprise a first hairpin coil and a second hairpin coil, the first hairpin coil comprising a first end and the second hairpin coil comprising a second end; inserting the first and second ends into a void of an electrically conductive coupler to electrically connect the first and second ends; and placing the insulation cap over the coupler so as to protect the coupler from contacting other electric conductive materials. 
         [0023]    In the foregoing method, the coupler may surround the first and second ends. The first hairpin coil may comprise another end configured to be connected to a terminal of an electric source. The plurality of hairpin coils may comprise a third hairpin coil and a fourth hairpin coil, the third hairpin coil comprising a third end and the fourth hairpin coil comprising a fourth end; wherein the method may further comprise inserting the third and fourth ends into a void of an additional electrically conductive coupler to electrically connect the third and fourth ends; and wherein the insulation cap may be further placed over the additional coupler so as to protect the additional conductor from contacting the other electric conductive materials. The coupler and the additional coupler may be insulated from each other by the cap. 
         [0024]    In accordance with an embodiment of the present invention, a method for binding a stator winding coil includes: inserting four hairpin coils, of which each two hairpin coils form a pair, into each of a plurality of slots formed radially in a stator, wherein portions of the hairpin coils inserted into the stator are exposed from one side of the stator and ready to be connected to a terminal for supplying electricity and the other portions of the hairpin coils are exposed from the other side of the stator and ready to be electrically connected; and connecting the other portions of the hairpin coils through a conductor, and fitting a cap to insulate the conductor after the conductor is connected. 
         [0025]    Each of the hairpin coils may be manufactured using a raw coil coated with a coating and having a predetermined diameter and length, and may have a connection portion and portions which are not connected to each other but extended from the connection portion so as to face each other. 
         [0026]    When two hairpin coils forming a pair among the four hairpin coils are inserted into one slot, the other two hairpin coils forming a pair may be inserted adjacent to the two hairpin coils. 
         [0027]    The hairpin coils may be twisted in such a manner that the portions thereof are exposed from the one side of the stator and ready to be connected to the terminal for supplying electricity and the other portions thereof are exposed from the other side of the stator and ready to be electrically connected. 
         [0028]    The portions of the hairpin coils may correspond to the connection portions of the hairpin coils inserted into the one slot, the other portions of the hairpin coils may correspond to the portions extended from the connection portions of the hairpin coils inserted into the one slot and facing each other, and the other portions of the twisted hairpin coils may correspond to adjacent portions of two hairpin coils inserted into the one slot. 
         [0029]    The connection portions of the hairpin coils may be cut off before the hairpin coils are twisted, and coatings of the portions extended from the connection portion and facing each other may be removed to form ends. 
         [0030]    The conductor may connect the two hairpin coils inserted into the one slot such that the hairpin coils electrically conduct. 
         [0031]    The conductor may have an opening through which the two adjacent hairpin coils are fitted. 
         [0032]    The cap may have an opening through which the conductor is fitted. 
         [0033]    The cap may be fitted to insulate the conductor for electrically connecting the two adjacent hairpin coils and another conductor for electrically connecting other two adjacent hairpin coils at the same time. 
         [0034]    In accordance with another embodiment of the present invention, a rotary motor to which a method for binding a stator winding coil is applied includes: a plurality of stators each having a plurality of slots which are formed in a radial manner and into which four hairpin coils each two forming a pair are inserted; a conductor coupled to the hairpin coils exposed from onside of the stator so as to electrically connect the hairpin coils, in a state where the hairpin coils are inserted to the stator; a cap formed of an insulator and fitted to the conductor to insulate the conductor. 
         [0035]    The conductor may connect two adjacent hairpin coils inserted into one slot, and the cap may be fitted to insulate the conductor for electrically connecting the two adjacent hairpin coils and another conductor for electrically connecting two other adjacent hairpin coils at the same time. 
         [0036]    The conductor may have an opening through which the two adjacent hairpin coils are fitted, and the cap may have an opening through which the conductor is fitted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]      FIG. 1  shows a process for manufacturing a rotary motor, in which ends of coils wound in a stator are bound according to a non-welding method. 
           [0038]      FIGS. 2 to 5  are diagrams illustrating a state in which the rotary motor is manufactured according to the manufacturing process of  FIG. 1 . 
           [0039]      FIG. 6  illustrates the rotary motor which is manufactured by applying a method for binding a stator winding coil in accordance with an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0040]    Embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the 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 present invention to those skilled in the art. Throughout the disclosure, like reference numerals refer to like parts throughout the various figures and embodiments of the present invention. 
         [0041]      FIG. 1  shows a process for manufacturing a rotary, electric motor, in which ends of coils wound in a stator are bound according to a non-welding method. 
         [0042]    When the method for binding a stator winding coil is applied, rectangular copper wires come out of first and second layers of a hairpin coil and third and fifth layers of another hairpin coil adjacent to the hairpin coil, respectively, and a ring-shaped conductor coupler connects two rectangular copper wires among the rectangular copper wires without welding the respective copper wires, and is covered by a cap formed of an insulator. Accordingly, the method may satisfy effects of welding and insulating at the same time. 
         [0043]    The method will be described in detail through steps S 10  to S 70 . 
         [0044]    Step S 10  is to process a coil formed of a conductor into a U-shaped hairpin coil.  FIG. 2  illustrates the process of step S 10 . 
         [0045]    Referring to  FIG. 2 , in embodiments, a raw coil  1  coated with a coating and having a predetermined diameter and length is prepared, and then processed into a hairpin coil  2  by a coil processor  10 . The hairpin coil  2  has a connection portion and portions extended from the connection portion, and the extended portions are set to face each other, thereby forming a U-shape. 
         [0046]    Four hairpin coils  2  are inserted into one slot of the stator, and are referred to as coil elements  2   a,    2   b,    2   c,  and  2   d,  respectively. 
         [0047]    Therefore, the number of hairpin coils  2  to be manufactured is set four times larger than the number of slots of the stator. 
         [0048]    Step S 20  is to insert a hairpin coil  2  having four coil elements  2   a  to  2   d  into each slot  20   a  of the stator. 
         [0049]    During this process, an insulation paper is inserted between the hair pin coils  2 . 
         [0050]    The plurality of slots are formed radially in the stator, and the stator is typically manufactured by stacking stator cores. 
         [0051]    Accordingly, the first and second coil elements  2   a  and  2   b  and the third and fourth coil elements  2   c  and  2   d  are aligned in a state where they are sequentially arranged in a circumferential direction of the slot  20   a.  Through this process, the hairpin coil  2  having four coil elements  2   a  to  2   d  is inserted in each of the slots  20   a  formed in the stator  20 . 
         [0052]    Step S 40  is to cut the connection portions of the coil elements  2   a  to  2   d  and remove the coatings such that ends K are formed at the cut portions, after the hairpin coils  2  are inserted into all of the slots  20   a  of the stator  20 . 
         [0053]    Typically, the formation of the ends K is performed after the hairpin coils  2  are inserted into all of the slots of the stator  20 , but may be performed while the raw coil  1  is processed into the hairpin coil  2 . 
         [0054]    In this state, the ends K of the first and second coil elements  2   a  and  2   b  are not adjacent to each other, and the ends K of the third and fourth coil elements  2   c  and  2   d  are not adjacent to each other. 
         [0055]    Step S 50  is to twit upper and lower end portions of the hairpin coils  2  inserted into all of the slots  20   a  of the stator  20  such that the hairpin coils  2  are deformed. 
         [0056]    The twisting operation is performed by a bender  30 . Referring to  FIG. 3  illustrating the twisting operation, the bender  30  sequentially twists the upper and lower end portions of the hairpin coils  2 , exposed from the stator  20 . 
         [0057]    Accordingly, the respective ends K of the first and second coil elements  2   a  and  2   b  are adjacent to form a pair, and the respective ends K of the third and fourth coil elements  2   c  and  2   d  are adjacent to form a pair. 
         [0058]    The hairpin coils  2  inserted into all of the slots  20   a  of the stator  20  are set in such a state. 
         [0059]    Through the twisting operation, the hairpin coil  2  exposed upward from the stator  20  is ready to be connected to a terminal (for example, U and U′, V and V′, W and W′, X and X′, and Z and Z′ in the case of a three-phase motor), and the hairpin coil  2  exposed downward from the stator  20  is ready to be electrically conducted. 
         [0060]    Step S 60  is to connect the hairpin coils  2  inserted into all of the slots  20   a  of the stator  20  such that the hairpin coils  2  are electrically conducted. This process does not require a welding operation, because conductors or electrically conductive couplers  40  are used. 
         [0061]    Typically, each of the conductors  40  includes a first conductor element  40   a  to connect the first and second coil elements  2   a  and  2   b  and a second conductor element  40   b  to connect the third and fourth coil elements  2   c  and  2   d.    
         [0062]    Therefore, the number of conductors  40  to be manufactured is set to a half of the number of hairpin coils  2 . 
         [0063]    The conductor  40  has a rectangular shape of which one side is opened, and is fitted through the opening. 
         [0064]    Referring to  FIG. 4 , step S 60  may be completed by a simple operation of fitting the first conductor element  40   a  to the ends K of the first and second coil elements  2   a  and  2   b  and fitting the second conductor element  40   b  to the ends K of the third and fourth coil elements  2   c  and  2   d.    
         [0065]    The above-described operation of fitting the conductor  40  to the ends K is performed on the hairpin coils  20   a  inserted into all of the slots  20   a  of the stator  20 , and all of the hairpin coils  2  are switched to a state in which they are electrically connected through the conductors  40 . 
         [0066]    Accordingly, the hairpin coils  2  may be manufactured without a welding operation which causes burning damage due to a welding defect and makes the manufacturing process difficult. In particular, it is possible to overcome the difficulties in acquiring the hairpin coil welding technique and the loss of cost competitiveness caused by expensive welding equipment. 
         [0067]    Step S 70  is to insulate the conductor  40  after the conductor  40  is coupled to the hairpin coil  2  inserted into each of the slots  20   a  of the stator  20 . 
         [0068]    This process is performed using a cap  50  formed of an insulator. Since the electrically insulating cap  50  covers the first and second conductor elements  40   a  and  40   b  together, the number of caps to be manufactured is set to a half of the number of conductors  40 . 
         [0069]    The cap  50  has a rectangular shape of which one side is opened, and is fitted through the opening. 
         [0070]    Referring to  FIG. 5 , the process may be completed by a simple operation of aligning the first conductor element  40   a  fitted to the adjacent ends K of the first and second coil elements  2   a  and  2   b  and the second conductor element  40   b  fitted to the adjacent ends K of the third and fourth coil elements  2   c  and  2   d,  and then fitting the cap  50  to the first and second conductor elements  40   a  and  40   b.    
         [0071]    As the above-described operation of fitting the cap  50  is performed on all of the hairpin coils  2  coupled to the first and second conductor elements  40   a  and  40   b,  the hairpin coils  2  are connected through the conductors  40 . Then, the hairpin coils  2  not only are electrically connected, but also maintain the insulation state. 
         [0072]    Therefore, the operation of electrically connecting the hairpin coils  2  and the operation of insulating the hairpin coils  2  may be performed in one place at the same time. Accordingly, it is possible to overcome the inconvenience and merchantability loss when the electrical connection operation is performed by welding. Specifically, the inconvenience and merchantability loss may occur because the electrical connection operation and the insulation operation are not performed at the same time and are performed in different places. 
         [0073]      FIG. 6  illustrates the rotary motor manufactured by the method for binding a stator winding coil in accordance with the embodiment of the present invention. 
         [0074]    In the above-described method for binding a stator winding coil in accordance with the embodiment of the present invention, four hairpin coils  2  of which each two hairpin coils form a pair are inserted into the stator  20  through each of the slots  20   a  formed in a radial shape, portions of the hairpin coils  2  inserted into the stator  20  are exposed from one side of the stator  20  and ready to be connected to a terminal for supplying electricity, the other portions of the hairpin coils  2  are exposed from the other side of the stator  20  and connected to the conductors  40  so as to electrically conduct, and the conductors  40  are insulated by the caps  50 . Therefore, the electrical connection operation and the insulation operation may be performed in one place at the same time during the hairpin coil winding operation. Accordingly, the method does not require a welding operation which causes burning damage due to a welding defect and makes the manufacturing process difficult. 
         [0075]    In accordance with the embodiment of the present invention, as a welding operation is removed during the process of manufacturing a rotary motor having hairpin coils wound therein, it is possible to exclude problems caused by a welding defect during a welding operation. Furthermore, the disadvantages of the manufacturing process caused by expensive welding equipment may be overcome. Accordingly, the cost and the working environment may be significantly improved. 
         [0076]    Furthermore, the operation of binding the hairpin coils wound in the stator is performed by the fitting operation using the conductor. Therefore, it is possible to significantly simplify the complex process in which the number of welding operations increases according to the number of slots of the stator. Furthermore, as the hairpin coils are completely bound through the conductor after the binding operation, contact resistance and copper loss are reduced, which makes it possible to significantly improve the motor efficiency. 
         [0077]    Furthermore, the conductor to connect the hairpin coils wound in the stator is insulated by an operation of fitting the cap to the conductor. Therefore, the insulation operation is easily performed. As the conductor is separately insulated by the cap, the insulation performance is improved, which makes it possible to significantly increase the lifetime of the motor. 
         [0078]    While embodiments of the present invention have been described, it will be apparent to 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.