Patent Publication Number: US-2022224183-A1

Title: Split-core assembly and stator including same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage application under 35 U.S.C. § 371 of International Application No. PCT/KR2019/006099, filed on May 21, 2019. The disclosure of the prior application is incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a split-core assembly and a state including the split-core assembly. The present disclosure, in more detail, relates to a split-core assembly that constitutes a concentrated type motor and includes a plurality of split cores, a coil coupled to each split core, and an insulator coupled between the split core and the coil, and a stator including the split-core assembly. 
     BACKGROUND 
     A brushless motor may include a stator and a rotor, where the stator may include a stator core on which a coil is wound. The stator core may be divided into a plurality of parts such as split cores arranged in the circumferential direction of the stator having a ring shape, where an insulator may be coupled between each of the split cores and a coil for insulation between the split core and the coil. 
     A motor may be classified into a concentrated type motor and a distributed type motor based on the winding type. For example, the concentrated type motor may be used as a driving motor of a hybrid vehicle or an electric vehicle. 
     In some cases, a driving motor of vehicles may include a conductive holder having accommodation grooves and a U-phase/V-phase/W-phase/N-phase conductive plates that are inserted and fixed in the accommodation grooves of the conductive holder. 
     For instance, each conductive plate may be bonded to the coil of a stator by welding, the conductive holder is made of a plastic material having non-conductivity, and the conductive plates may be accommodated in the conductive holder made of a copper material. 
     In some cases, a driving motor of vehicles may include a terminal assembly that includes a holder, a terminal, and a clip. 
     For instance, wiring may be provided between a wiring terminal of each terminal and a coil, the coils each may be made of a copper material and classified into a U-phase terminal, a V-phase terminal, a W-phase terminal, and an N-phase terminal, and an insulation distance may be maintained by the clip and the holder. 
     In some cases, several clips and holders may be provided to insulate the terminals, which may increase the number of parts of the assembly. In some cases, a specific assembly process such as bolting may be provided to fasten the conductive holder and the terminal assembly to the upper portion of the stator, which may lead to an increase of the manufacturing cost. 
     In some cases, a driving motor of vehicles may include a bobbin that includes a body, a coupling groove, and a terminal holder, where the terminal holder is integrated with the bobbin. 
     In some cases, when the terminal holder is integrated with the bobbin to manufacture a motor for a vehicle, the material cost may be reduced and the manufacturing process may be shortened. However, in some cases, when a plurality of bobbins are circumferentially arranged to form a stator, a gap may be generated between the terminal holders. In this case, the insulation effect of the terminal holders may be decreased and the possibility of current leakage may be increased. 
     SUMMARY 
     The present disclosure describes a stator and a split-core assembly in which the portion between a split core and a conductive plate can be effectively and stably shielded by an insulator (a nonconductor), where the stator or the split-core assembly includes an individual terminal holder for each split core. 
     The present disclosure further describes a stator and a split-core assembly in which terminals can effectively and stably overlap each other by providing the stator or the split-core assembly having an individual terminal holder for each split core. 
     The present disclosure also describes a stator and a split-core assembly in which a wire between a coil and a conductive plate is not exposed over a bobbin and a terminal holder by providing the stator or the split-core assembly having an individual terminal holder for each split core. 
     According to one aspect of the subject matter described in this application, a split-core assembly of a stator of a motor, where the stator includes a plurality of split-core assemblies that are arranged circumferentially about a central axis of the stator, includes a split core that includes a yoke and a tooth, the tooth extending from the yoke toward the central axis of the stator, a bobbin made of an insulator and coupled to an outer surface of the tooth, a coil wound around the bobbin, and a terminal holder made of an insulator and disposed on or above the yoke in an up-down direction along the central axis. The terminal holder defines a plurality of insertion grooves that are spaced apart from one another in a radial direction of the stator and configured to receive downward a plurality of conductive plates electrically connected to the coil. The terminal holder includes an insulating protrusion that protrudes from at least one surface of the terminal holder in a circumferential direction of the stator. The terminal holder is coupled to an adjacent terminal holder of another split-core assembly among the plurality of split-core assemblies, and the insulating protrusion overlaps with the adjacent terminal holder to thereby shield the split core from the plurality of conductive plates. 
     Implementations according to this aspect can include one or more of the following features. For example, the insulating protrusion can be disposed at each of the plurality of insertion grooves. In some examples, the terminal holder can include a plurality of insulating protrusions that protrude from the at least one surface of the terminal holder in the circumferential direction of the stator and that are arranged in the radial direction of the stator, where the plurality of insulating protrusions include the insulating protrusion. Circumferential lengths of the plurality of insulating protrusions in the circumferential direction can increase based on radial distances of the plurality of insulating protrusions away from the central axis. 
     In some implementations, the terminal holder can include a plurality of partition walls that include a plurality of middle partition walls that define boundaries of the plurality of insertion grooves, an outer partition wall that is located farther from an end of the coil than the plurality of middle partition walls and spaced apart from the plurality of middle partition walls, and an inner partition wall that is located closer to the end of the coil than the plurality of middle partition walls and spaced apart from the plurality of middle partition walls. The plurality of conductive plates can include a U-phase conductive plate, a V-phase conductive plate, a W-phase conductive plate, and an N-phase conductive plate that each include connection portions configured to connect to the coil, where each of the plurality of middle partition walls and the inner partition wall defines a three-phase terminal groove configured to receive one of the connection portions of the U-phase conductive plate, the V-phase conductive plate, or the W-phase conductive plate. The inner partition wall can further define a neutral terminal groove that receives the connection portion of the N-phase conductive plate. 
     In some examples, the bobbin can include a winding portion around which the coil is wound, an outer flange that is disposed radially outward relative to the winding portion and protrudes from an outer edge of the winding portion, the outer flange being coupled to the terminal holder, and an inner flange that is disposed radially inward relative to the winding portion and protrudes from an inner edge of the winding portion. The outer flange can define a first groove that receives a first end of the coil coupled to the connection portion of the N-phase conductive plate and a second groove that that receives a second end of the coil coupled to one of the connection portions of the U-phase conductive plate, or the V-phase conductive plate, or the W-phase conductive plate. The first groove can be defined at an upper portion of the outer flange, and the second groove can be defined at the upper portion of the outer flange and spaced apart from the first groove. 
     In some implementations, the inner partition wall, the plurality of middle partition walls, and the outer partition wall can be arranged in the radial direction of the stator, where an upper end of the outer flange is located higher than upper ends of the plurality of middle partition walls and the inner partition wall in the up-down direction. A radial gap between the outer flange and the inner partition wall can be wider than a radial gap between the inner partition wall and an innermost middle partition wall among the plurality of middle partition walls. 
     In some implementations, the bobbin can include a first bobbin and a second bobbin that are coupled to each other and surround the tooth, where the first bobbin is coupled to an upper portion of the tooth, and the second bobbin is coupled to a lower portion of the tooth. The first bobbin can include a first winding portion around which an upper portion of the coil is wound, a first outer flange that is disposed radially outward relative to the first winding portion and protrudes from an outer edge of the first winding portion, where the first outer flange is coupled to the terminal holder, and a first inner flange that is disposed radially inward relative to the first winding portion and protrudes from an inner edge of the first winding portion. The first outer flange can define a first groove that receives a first end of the coil coupled to the connection portion of the N-phase conductive plate and a second groove that that receives a second end of the coil coupled to one of the connection portions of the U-phase conductive plate, the V-phase conductive plate, or the W-phase conductive plate. The first groove can be defined at an upper portion of the first outer flange, and the second groove can be defined at the upper portion of the first outer flange and spaced apart from the first groove. 
     In some implementations, the stator can include the plurality of split-core assemblies that include the split-core assembly described above and that are circumferentially coupled to one another other. 
     According to another aspect, a split-core assembly of a stator of a motor, where the stator includes a plurality of split-core assemblies that are arranged circumferentially about a central axis of the stator, includes a split core including a yoke and a tooth extending from the yoke toward the central axis, a bobbin made of an insulator and coupled to an outer surface of the tooth, a coil wound around the bobbin, and a terminal holder made of an insulator and disposed on or above the yoke in an up-down direction along the central axis. The terminal holder defines a plurality of insertion grooves that are spaced apart from one another in a radial direction of the stator and configured to receive downward a plurality of conductive plates electrically connected to the coil. The terminal holder includes a bottom plate that defines bottoms of the plurality of insertion grooves, an insulating protrusion that protrudes from a first end of the bottom plate in a circumferential direction of the stator, and an insulating groove that is defined at a second end of the bottom plate opposite to the first end of the bottom plate. The insulating protrusion is coupled to and seated in the insulating groove of another split-core assembly among the plurality of split-core assemblies located adjacent to the split-core assembly. 
     Implementations according to this aspect can include one or more of the following features. For example, the terminal holder can include a plurality of partition walls that are spaced apart from one another to thereby define the plurality of insertion grooves therebetween, where the insulating protrusion further protrudes from at least one of plurality of partition walls in the circumferential direction of the stator such that the insulating protrusion has an L shape. The insulating groove can be a stepped groove that is defined along the second end of the bottom plate and at least one of the plurality of partition wall such that the insulating groove has the L shape corresponding to the insulating protrusion. 
     In some implementations, the insulating protrusion and the insulating groove can be disposed at each of the plurality of insertion grooves. In some examples, the terminal holder can include a plurality of insulating protrusions that protrude from the first end of the bottom plate in the circumferential direction and that are arranged in the radial direction of the stator, where the plurality of insulating protrusions include the insulating protrusion. Circumferential lengths of the plurality of insulating protrusions in the circumferential direction can increase based on radial positions of the plurality of insulating protrusions away from the central axis. 
     In some implementations, the terminal holder can include a plurality of partition walls including a plurality of middle partition walls that define boundaries of the plurality of insertion grooves, an outer partition wall that is located farther from an end of the coil than the plurality of middle partition walls and spaced apart from the plurality of middle partition walls, and an inner partition wall that is located closer to the end of the coil than the plurality of middle partition walls and spaced apart from the plurality of middle partition walls. The plurality of conductive plates can include a U-phase conductive plate, a V-phase conductive plate, a W-phase conductive plate, and an N-phase conductive plate that each include connection portions configured to connect to the coil, where each of the plurality of middle partition walls and the inner partition wall defines a three-phase terminal groove configured to receive one of the connection portions of the U-phase conductive plate, the V-phase conductive plate, or the W-phase conductive plate. The inner partition wall can further define a neutral terminal groove that receives the connection portion of the N-phase conductive plate. 
     In some examples, the bobbin can include a winding portion around which the coil is wound, an outer flange that is disposed radially outward relative to the winding portion and protrudes from an outer edge of the winding portion, the outer flange being coupled to the terminal holder, and an inner flange that is disposed radially inward relative to the winding portion and protrudes from an inner edge of the winding portion. The outer flange can define a first groove that receives a first end of the coil coupled to the connection portion of the N-phase conductive plate, and a second groove that that receives a second end of the coil coupled to one of the connection portions of the U-phase conductive plate, the V-phase conductive plate, or the W-phase conductive plate. The first groove can be defined at an upper portion of the outer flange, and the second groove can be defined at the upper portion of the outer flange and spaced apart from the first groove. 
     In some implementations, the inner partition wall, the plurality of middle partition walls, and the outer partition wall can be arranged in the radial direction of the stator, where an upper end of the outer flange is located higher than upper ends of the plurality of middle partition walls and the inner partition wall in the up-down direction. A radial gap between the outer flange and the inner partition wall can be wider than a radial gap between the inner partition wall and an innermost middle partition wall among the plurality of middle partition walls. 
     In some implementations, the bobbin can include a first bobbin and a second bobbin that are coupled to each other and surround the tooth, where the first bobbin is coupled to an upper portion of the tooth, and the second bobbin is coupled to a lower portion of the tooth. The first bobbin can include a first winding portion around which an upper portion of the coil is wound, a first outer flange that is disposed radially outward relative to the first winding portion and protrudes from an outer edge of the first winding portion, where the first outer flange is coupled to the terminal holder, and a first inner flange that is disposed radially inward relative to the first winding portion and protrudes from an inner edge of the first winding portion. The first outer flange can define a first groove that receives a first end of the coil coupled to the connection portion of the N-phase conductive plate, and a second groove that that receives a second end of the coil coupled to one of the connection portions of the U-phase conductive plate, the V-phase conductive plate, or the W-phase conductive plate. The first groove can be defined at an upper portion of the first outer flange, and the second groove can be defined at the upper portion of the first outer flange and spaced apart from the first groove. 
     In some implementations, the stator includes the plurality of split-core assemblies that include the split-core assembly described above and are circumferentially coupled to one another other. 
     According to another aspect, a split-core assembly of a stator of a motor is described. The stator includes a plurality of split-core assemblies that include the split-core assembly and are arranged circumferentially about a central axis of the stator. The split-core assembly includes a split core, a coil wound around the split core, a bobbin made of an insulator and positioned between the split core and the coil, and a terminal holder made of an insulator, where the terminal holder defines a plurality of insertion grooves configured to receive a plurality of conductive plates that are electrically connected to the coil, respectively. The terminal holder includes a bottom plate that defines portions of the plurality of insertion grooves, an insulating protrusion that protrudes from a first end of the bottom plate in a circumferential direction of the stator, and an insulating groove that is defined at a second end of the bottom plate opposite to the first end of the bottom plate. The insulating protrusion is coupled to and seated in the insulating groove of another split-core assembly among the plurality of split-core assemblies located adjacent to the split-core assembly. 
     Implementations according to this aspect can include one or more of the following features. For example, the terminal holder can include a plurality of partition walls including an inner partition wall that faces the bobbin, an outer partition wall that is spaced apart from the inner partition wall in a radial direction of the stator, and a plurality of middle partition walls that are disposed between the outer partition wall and the inner partition wall and define the plurality of insertion grooves. The plurality of conductive plates can include a U-phase conductive plate, a V-phase conductive plate, a W-phase conductive plate, and an N-phase conductive plate that each include connection portions configured to connect to the coil, where each of the plurality of middle partition walls and the inner partition wall defines a three-phase terminal groove configured to receive one of the connection portions of the U-phase conductive plate, the V-phase conductive plate, or the W-phase conductive plate. The inner partition wall can further define a neutral terminal groove that receives the connection portion of the N-phase conductive plate. 
     In some implementations, the insulating protrusion can be disposed at a first end portion of at least one of the plurality of middle partition walls or the outer partition wall, and the insulating groove can be defined at a second end portion of the at least one of the plurality of middle partition walls or the outer partition wall. 
     In some implementations, since the split-core assembly includes a split core, a bobbin, a coil, and a terminal holder and the terminal holder has an insulating protrusion that protrudes along a certain surface crossing the central axis of a stator, when two split-core assemblies are coupled to each other, it can be possible to effectively and stably shield between the split core and the conductive plate. 
     In some implementations, since the terminal holder has a bottom plate, an insulating protrusion, and an insulating groove, and when two split-core assemblies are coupled to each other, the insulating protrusion of any one terminal holder is seated in the insulating groove of the other terminal holder, it can be possible to effectively and stably overlap the terminal holders and shield between the split core and the conductive plates. 
     In some implementations, a plurality of insulating protrusions are formed at one terminal holder and protrude from a bottom plate and each partition wall and the number and shape of insulating grooves correspond to those of the insulating protrusions, so insulation between the conductive plate, insulation between the conductive plates and the split core, and coupling of terminal holders can be stably made. 
     In some implementations, the protruding degree of the insulating protrusion is increased as it goes away from the central axis of the stator, it can be possible to more effectively prevent a gap between two terminal holders. 
     In some implementations, since the coil and the conductive plates are connected in the space between the outer flange and the inner partition wall, it can be possible to provide a stator and a split-core assembly in which the wires between the coil and the conductive plates are not exposed over the bobbin and the terminal holder. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing an example of a stator including a plurality of split-core assemblies. 
         FIG. 2  is a perspective view showing an example of the split-core assembly shown in  FIG. 1 . 
         FIG. 3  is a perspective view separately showing examples of a split core, a bobbin, and a terminal holder of the split-core assembly shown in  FIG. 2 . 
         FIG. 4  is an exploded perspective view showing the stator shown in  FIG. 1  and an example of conductive plates coupled to the stator. 
         FIG. 5  is a partial enlarged plan view showing an example state in which the stator and the conductive plates are coupled. 
         FIG. 6  is a perspective cross-sectional view taken along line A-A′ of  FIG. 5 . 
         FIG. 7A  is an enlarged perspective view showing an example portion of the bobbin and the terminal holder shown in  FIG. 3 . 
         FIG. 7B  is a perspective view showing the portion of the bobbin and the terminal holder shown in  FIG. 7A  in another direction. 
         FIG. 8  is a plan view showing the bobbin and the terminal holder shown in  FIG. 3 . 
         FIG. 9  is a plan view showing an example of a bobbin and a terminal holder. 
     
    
    
     DETAILED DESCRIPTION 
     Hereafter, one or more implementations of the present disclosure are described in detail with reference to the accompanying drawings to describe the present disclosure in more detail. Like reference numerals indicate the same components throughout the detailed description. 
       FIG. 1  is a perspective view showing an example of a stator  1 . 
     In some implementations, a concentrated type motor can include the stator  1 , and the stator  1  can include a split-core assembly  10 . 
     The split-core assembly  10  can include a plurality of parts. For example, the split-core assemblies  10  can be circumferentially arranged around a central axis S of the stator  1 . That is, a plurality of split-core assemblies  10  can be circumferentially arranged around the central axis S. The stator  1  shown in  FIG. 1  can be formed by combining the plurality of split-core assemblies  10 . 
     In some examples, a motor including the stator  1  can be a 3-phase motor, and the number of the split-core assemblies  10  forming one stator  1  can be a multiple of 3. For example, as shown in  FIG. 1 , the number of the split-core assemblies  10  of one stator  1  can be 24. 
     In the present disclosure, the direction that is parallel with the direction of the central axis S of the stator  1  is defined as an up-down direction. The circumferential direction in the present disclosure refers to a circumferential direction around the central axis S, and the radial direction refers to the radial direction from the central axis S unless stated otherwise. 
     In some implementations, the plurality of split-core assemblies  10  can be arranged such that both ends are in close contact with each other in the circumferential direction. The split-core assemblies  10  can be coupled to each other by their own parts, or can be coupled to each other through other parts. As for the former, for example, the split-core assemblies  10  can be fitted or locked to each other, and as for the latter, for example, the split-core assemblies  10  can be inserted and coupled to each other in the housing of a motor. 
     The stator  1  to which the split-core assemblies  10  are coupled can have a ring shape. In some examples, where the stator  1  is included in a concentrated type motor, a rotor can be positioned in the central space B of the stator  1  and can be rotated about the central axis S. 
       FIG. 2  is a perspective view showing the split-core assembly  10  shown in  FIG. 1 ,  FIG. 3  is a perspective view separately showing a split core  100 , a bobbin  200 , and a terminal holder  400  of the split-core assembly shown in  FIG. 2 ,  FIG. 4  is an exploded perspective view showing the stator  1  shown in  FIG. 1  and conductive plates  20 ,  30 ,  40 , and  50  coupled to the stator  1 ,  FIG. 5  is a partial enlarged plan view showing the state in which the stator a and the conductive plates  20 ,  30 ,  40 , and  50  are coupled, and  FIG. 6  is a perspective cross-sectional view taken along line A-A′ of  FIG. 5 . 
     The split-core assembly  10  can include a split core  100 , a bobbin  200 , a coil  300 , and a terminal holder  400 . 
     The split core  100  can be made of conductive metal. The split core  100  can be formed by stacking several metal plates (core plates) in the up-down direction, in which the metal plates can have the same shape and size. 
     The split core  100  can have a yoke  110  and a tooth  120  extending close to the central axis S from the yoke  110 . 
     The yoke  110  is the portion that is relatively far from the central axis S and the tooth  120  is the portion that is relatively close to the central axis S. The yoke  110  has a circumferential with, as compared with the tooth  120 . 
     The inner surface  121  of the tooth  120  can be a curved surface and faces the central axis S of the stator  1 . 
     When split-core assemblies  10  are coupled to each other, any one split core  100  and the other split core  100  can be in close contact with each other, and in this case, the yokes  110  of the split cores  100  can be in close contact with each other. 
     In order to stably bring the split cores  100  in close contact with each other and in order to stably couple the split cores  100 , a protrusion  111  that circumferentially protrudes can be formed on any one side of the yoke  110  and a concave groove  112  can be formed on the other side so that the protrusion  111  is inserted therein. The protrusion  111  and the groove  112  can be fitted to each other. That is, the protrusion  111  and the groove  112  can be located at opposite sides in the circumferential direction and can have corresponding shapes and sizes (see  FIG. 3 ). 
     The bobbin  200  can be made of an insulator and can be coupled to the outer side of the split core  100 . The bobbin  200  can be made of plastic. The bobbin  200  can surround at least a portion of the tooth  120 . 
     The bobbin  200  is provided for insulation between the split core  100  and a coil  300  when the coil  300  is wound around the split core  100 . The bobbin  200  is positioned between the split core  100  and the coil  300  and surrounds the tooth  120  of the split core  100 . The bobbin  200  can be formed in a tube shape, and in this case, the axis thereof can be defined in the radial direction of the stator  1 . 
     In some implementations, the bobbin  200  can have a winding portion  210 , an outer flange  220 , and an inner flange  230 . 
     The coil  300  can be wound on the outer surface of the winding portion  210 . 
     The winding portion  210  can be formed in a tube shape, and in this case, the axis of the winding portion  210  can face the radial direction of the stator  1 , and the cross-section of the winding portion  210  can be a rectangle. 
     The outer flange  220  can be integrated with the winding portion  210  and formed such that the diameter increases at a position that is farther from the central axis S than the winding portion  210 . That is, the outer flange  220  is formed such that the edge opens outward at the winding portion  210 . The outer flange  220  can form the outer end of the bobbin  200  in the radial direction of the stator  1 . The outer flange  220  can form the boundary of the region in which the coil  300  is wound when the coil  300  is wound on the winding portion  210 . 
     In the split-core assemblies  10  and the stator  1 , the outer flange  220  can be integrated with the terminal holder  400 . That is, the terminal holder  400  can be integrated with the bobbin  200 . 
     The inner flange  230  can be integrated with the winding portion  210  and formed such that the diameter increases at a position that is closer to the central axis S than the winding portion  210 . That is, the inner flange  230  is formed such that the edge opens outward at the winding portion  210 . The inner flange  230  can form an end of the bobbin  200  at the opposite side to the outer flange  220 . That is, the inner flange  230  can form the inner end of the bobbin  200  in the radial direction of the stator  1 . The inner flange  230  can form the boundary of the region in which the coil  300  is wound when the coil  300  is wound on the winding portion  210 . 
     A first groove  221  and a second groove  222  can be formed at the upper portion of the outer flange  220 . 
     The first groove  221  is formed to be concave downward from the upper end of the outer flange  220  and the outer flange  220  is radially pierced by the first groove  221 . An end  310  of the coil  300  to which A connection portion  21  of an N-phase conductive plate  20  of the conductive plates is coupled is inserted in the first groove  221 . 
     The second groove  222  is spaced apart from the first groove  221  and is formed to be concave downward from the upper end of the outer flange  220 , and the outer flange  220  is pierced by the second groove  222 . An end  320  of the coil  300  that is coupled to one of a connection portion  31  of a U-phase conductive plate  30 , a connection portion  42  of a V-phase conductive plate  40 , and a connection portion  51  of a W-phase conductive plate  50  is inserted in the second groove  222 . 
     In some implementations, the bobbin  200  can include a first bobbin  200   a  and a second bobbin  200   b.    
     The first bobbin  200   a  is a part coupled to the upper portion of the tooth  120  and the second bobbin  200   b  is a part coupled to the lower portion of the tooth  120 . The second bobbin  200   b  is coupled to the first bobbin  200   a , thereby surrounding the tooth  120 . 
     The first bobbin  200   a  has a first winding portion  210   a , a first outer flange  220   a , and a first inner flange  230   a.    
     The first winding portion  210   a , which is the portion on which the coil  300  is wound, forms the upper portion of the winding portion  210 . 
     The first outer flange  220   a  is formed such that the diameter increases at a position farther from the central axis S than the first winding portion  210   a , and forms the upper portion of the outer flange  220 . 
     In some implementations, when the bobbin  200  is divided into the first bobbin  200   a  and the second bobbin  200   b , the first groove  221  and the second groove  222  can be formed at the first outer flange  220   a.    
     The first inner flange  230   a  is formed such that the diameter increases at a position closer to the central axis S than the first winding portion  210   a , and forms the upper portion of the inner flange  230 . 
     The second bobbin  200   b  can have a second winding portion  210   b , a second outer flange  220   b , and a second inner flange  230   b.    
     The second winding portion  210   b , which is the portion on which the coil  300  is wound, forms the lower portion of the winding portion  210 . 
     The second outer flange  220   b  is formed such that the diameter increases at a position farther from the central axis S than the second winding portion  210   b , and forms the lower portion of the outer flange  220 . 
     The second inner flange  230   b  is formed such that the diameter increases at a position closer to the central axis S than the second winding portion  210   b , and forms the lower portion of the inner flange  230 . 
     The lower portion of the first bobbin  200   a  and the upper portion of the second bobbin  200   b  can be formed such that any one thereof is fitted in the other one. That is, the lower portion of the first bobbin  200   a  and the upper portion of the second bobbin  200   b  can overlap each other. The portion of the first bobbin  200   a  that overlaps the second bobbin  200   b  is a first overlap portion  240 , and the portion of the second bobbin  200   b  that overlaps the first bobbin  200   a  is a second overlap portion  250 . The first overlap portion  240  can be formed at the lower ends of the first winding portion  210   a , the first outer flange  220   a , and the first inner flange  230   a , and the second overlap portion  250  can be formed at the upper ends of the second winding portion  210   b , the second outer flange  220   b , and the second inner flange  230   b.    
     Accordingly, when the first bobbin  200   a  and the second bobbin  200   b  are coupled, relative movement in the circumferential direction and the radial direction between the first bobbin  200   a  and the second bobbin  200   b  is restricted, whereby they can be stably coupled. 
     The coil  300  is made of conductive metal and can be made of copper, and is repeatedly wound on the outer surface of the winding portion  210  of the bobbin  200 . A first end  310  that is any one end of the coil  300  can be fitted in the first groove  221  of the outer flange  220  and positioned toward the terminal holder  400 . Further, a second end  320  that is the other end of the coil  300  can be fitted in the second groove  222  of the outer flange  220  and positioned toward the terminal holder  400 . 
     In some implementations, the terminal holder  400  can be made of an insulator. In some examples, the terminal holder  400  can be integrated with the bobbin  200 . When the bobbin  200  is divided into the first bobbin  200   a  and the second bobbin  200   b , the terminal holder  400  can be integrated with the first bobbin  200   a . In some examples, the terminal holder  400  can be at least partially disposed on the yoke  110 . 
     A plurality of insertion grooves  401 ,  402 ,  403 , and  404  in which the plurality of conductive plates  20 ,  30 ,  40 , and  50  electrically connected to the coil  300  are inserted, respectively, can be sequentially formed at the terminal holder  400 . 
     A motor including the split-core assemblies  10  and the stator  1  can be a 3-phase motor, and in this case, the conductive plates  20 ,  30 ,  40 , and  50  and the coil  300  can be connected to make Y-wiring. 
     The conductive plates  20 ,  30 ,  40 , and  50  coupled to the stator  1  can be four conductive plates. The N-phase conductive plate  20  that forms a neutral point, and the U-phase conductive plate  30 , V-phase conductive plate  40 , and W-phase conductive plate  50  that form 3 phases each can be connected to the terminal holder  400 . The four conductive plates  20 ,  30 ,  40 , and  50  can be coaxially arranged (around the central axis S). 
     Four insertion grooves  401 ,  402 ,  403 , and  404  can be formed at the terminal holder  400  such that the four conductive plates  20 ,  30 ,  40 , and  50  are inserted therein, respectively. The insertion grooves  401 ,  402 ,  403 , and  404  are narrow and long grooves and are elongated in the circumferential direction of the stator  1 . 
     The terminal holder  400  has a plurality of partition walls  441 ,  442 ,  443 ,  444 , and  445  spaced apart from each other to form the insertion grooves  401 ,  402 ,  403 , and  404 . 
     In some implementations, the partition walls  441 ,  442 ,  443 ,  444 , and  445  can be radially spaced apart from each other. That is, the partition walls  441 ,  442 ,  443 ,  444 , and  445  can be spaced apart from each other in a direction perpendicular to the central axis S. In some implementations, the partition walls can be spaced apart from each other in a direction not perpendicular to the central axis S or can be spaced apart from each other in a direction inclined a predetermined angle from the central axis S. 
     It is assumed in the following description that the partition walls  441 ,  442 ,  443 ,  444 , and  445  are spaced apart from each other in a radial direction of the central axis S. 
     The terminal holder  400  has a bottom plate  430  and a plurality of partition walls  441 ,  442 ,  443 ,  444 , and  445  such that the insertion grooves  401 ,  402 ,  403 , and  404  can be formed. 
     The bottom plate  430  connects the lower ends of the plurality of partition walls  441 ,  442 ,  443 ,  444 , and  445  to each other. The bottom plate  430  can form the innermost surfaces of the insertion grooves  401 ,  402 ,  403 , and  404 , and the top of the bottom plate  430  can be the bottoms  401   a ,  402   a ,  403   a , and  404   a  of the insertion grooves  401 ,  402 ,  403 , and  404 . 
     The bottom plate  430  can form a portion of a fan shape in a plane. That is, the bottom plate  430  can be formed such that the circumferential width increases as it goes away from the central axis S, and both edges of the bottom plate  430  can be arranged in the radial direction of the stator  1 . 
     The terminal holder  400  has five partition walls  441 ,  442 ,  443 ,  444 , and  445  to form the four insertion grooves  401 ,  402 ,  403 , and  404 . 
     The four insertion grooves  401 ,  402 ,  403 , and  404  can be formed in the radial direction of the stator  1 , can form a portion of a coaxial circle, and can be spaced apart from each other with the same intervals by the partition walls  441 ,  442 ,  443 ,  444 , and  445 . 
     The insertion grooves  401 ,  402 ,  403 , and  404  of the terminal holder  400  are open upward, and the conductive plates  20 ,  30 ,  40 , and  50  are inserted downward in the insertion grooves  401 ,  402 ,  403 , and  404 . 
     The up-down heights of the partition walls  441 ,  442 ,  443 ,  444 , and  445  (the up-down heights of the insertion grooves  401 ,  402 ,  403 , and  404 ) are larger than the up-down heights of the conductive plates  20 ,  30 ,  40 , and  50 . 
     The partition walls  441 ,  442 ,  443 ,  444 , and  445  can be formed such that the widths (circumferential lengths) thereof are sequentially increased as they go away from the central axis S. 
     The partition walls  441 ,  442 ,  443 ,  444 , and  445  can be formed circumferentially throughout the entire region of the bottom plate  430 . That is, the circumferential lengths of the partition walls  441 ,  442 ,  443 ,  444 , and  445  can be the same as the circumferential length of the bottom plate  430  at the positions where the partition walls  441 ,  442 ,  443 ,  444 , and  445  are connected. 
     The partition walls can be classified into middle partition walls  441 ,  442 , and  443 , an outer partition wall  444 , and an inner partition wall  445 . That is, the terminal holder  400  can have middle partition walls  441 ,  442 , and  443 , an outer partition wall  444 , and an inner partition wall  445 . 
     The middle partition walls  441 ,  442 , and  443  form the boundaries of the plurality of insertion grooves  401 ,  402 ,  403 , and  404 , and can be provided as a plurality of pieces. When four insertion grooves  401 ,  402 ,  403 , and  404  are provided, three middle partition walls  441 ,  442 , and  443  are provided. The middle partition walls  441 ,  442 , and  443  can all have the same height. 
     The outer partition wall  444  can be farther from the ends  310  and  320  of the coil  300  than the middle partition walls  441 ,  442 , and  443 , and can be spaced apart from the middle partition walls  441 ,  442 , and  443 . 
     The outer partition wall  444  can be positioned outside the middle partition wall  443  (far from the central axis S) which is farthest from the central axis S in the radial direction. The height of the outer partition wall  444  can be larger than the height of the middle partition walls  441 ,  442 , and  443 . 
     The inner partition wall  445  can be closer to the ends  310  and  320  of the coil  300  than the middle partition walls  441 ,  442 , and  443 , and can be spaced apart from the middle partition walls  441 ,  442 , and  443 . 
     The inner partition wall  445  can be positioned inside the middle partition wall  441  (close to the central axis S) which is closest to the central axis S in the radial direction. The height of the inner partition wall  445  can be the same as the height of the middle partition walls  441 ,  442 , and  443 . 
     In some implementations, 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a  can be formed at the middle partition walls  441 ,  442 , and  443  and the inner partition wall  445 . The 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a  can be formed downward from the upper ends of the middle partition walls  441 ,  442 , and  443  and the inner partition wall  445 . The upper portions of the middle partition walls  441 ,  442 , and  443  and the inner partition wall  445  are radially pierced by the 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a.    
     The length (height) from the lower ends of the 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a  to the top (the bottoms  401   a ,  402   a ,  403   a , and  404   a ) of the bottom plate  430  can be larger than or the same as the up-down length (height) of the 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a.    
     The 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a  can be arranged straight at the terminal holder  400 . 
     The connection portion  31  of the U-phase conductive plate  30 , the connection portion  41  of the V-phase conductive plate  40 , and the connection portion  51  of the W-phase conductive plate  50  are individually fitted in the 3-phase terminal grooves  441   a ,  442   a ,  443   a , and  445   a , respectively. 
     In some implementations, a neutral terminal groove  445   b  can be defined at the inner partition wall  445 . For example, the neutral terminal groove  445   b  can be recessed downward from the upper end of the inner partition wall  445 . The upper portion of the inner partition wall  445  is radially pierced by the neutral terminal groove  445   b.    
     The length (height) from the lower end of the neutral terminal groove  445   b  to the top (the bottoms  401   a ,  402   a ,  403   a , and  404   a ) of the bottom plate  430  can be larger than or the same as the up-down length (height) of the neutral terminal groove  445   b.    
     The connection portion  21  of the N-phase conductive plate  20  is fitted in the neutral terminal groove  445   b.    
     In some implementations, when the inner partition wall  445 , the middle partition walls  441 ,  442 , and  443 , and the outer partition wall  444  are formed in the radial direction of the stator  1 , the upper end of the outer flange  220  can be higher than the upper ends of the middle partition walls  441 ,  442 , and  443  and the inner partition wall  445 , and the gap between the outer flange  220  and the inner partition wall  445  can be larger than the gaps between the partition walls  441 ,  442 ,  443 ,  444 , and  445 . 
     In some implementations, the ends  310  and  320  of the coil  300  and the connection portions  21 ,  31 ,  42 , and  51  of the conductive plates  20 ,  30 ,  40 , and  50  can be easily coupled in a space  405  between the outer flange  220  and the inner partition wall  445 . In some examples, the ends  310  and  320  of the coil  300  and the connection portions  21 ,  31 ,  42 , and  51  of the conductive plates  20 ,  30 ,  40 , and  50  can be coupled without being exposed over the upper ends of the bobbin  200  and the terminal holder  400 . In some examples, the connection portions  21 ,  31 ,  42 , and  51  can include a strip or bar of a conductor that includes an end hook connected to the end  320  of the coil  300 . 
       FIG. 7A  is an enlarged perspective view showing a portion of the bobbin  200  and the terminal holder  400  shown in  FIG. 3 ,  FIG. 7B  is a perspective view showing the portion of the bobbin  200  and the terminal holder  400  shown in  FIG. 7A  in another direction, and  FIG. 8  is a plan view showing the bobbin  200  and the terminal holder  400  shown in  FIG. 3 . 
     In some implementations, insulating protrusions  411 ,  412 ,  413 , and  414  can be integrally formed at the terminal holder  400 . In some implementations, insulating grooves  421 ,  422 ,  423 , and  424  can be formed at the terminal holder  400 . 
     The insulating protrusions  411 ,  412 ,  413 , and  414  can protrude toward a certain surface crossing the central axis S, at the terminal holder  400 . 
     The insulating protrusions  411 ,  412 ,  413 , and  414  can protrude in the circumferential direction of the terminal holder  400 . 
     Accordingly, in some implementations, when two terminal holders  400  are coupled to each other, the insulating protrusions  411 ,  412 ,  413 , and  414  of any one terminal holder  400  can overlap the other terminal holder  400 , and it can be possible to shield between the split core  100  and the conductive plates  20 ,  30 ,  40 , and  50 . 
     The insulating protrusions  411 ,  412 ,  413 , and  414  can protrude in the circumferential direction of the stator  1  from an end of the bottom plate  430 . The insulating protrusions  411 ,  412 ,  413 , and  414  can protrude in the circumferential direction of the stator  1  from an end of any one or more of the partition walls  441 ,  442 ,  443 ,  444 , and  445 . Since the insulating protrusions  411 ,  412 ,  413 , and  414  protrude from the bottom plate  430  and any one of the partition walls  441 ,  442 ,  443 ,  444 , and  445 , the insulating protrusions  411 ,  412 ,  413 , and  414  can have a      or      shape, e.g., an L shape. That is, the cross-section of the insulating protrusions  411 ,  412 ,  413 , and  414  can have a      or      shape, e.g., an L shape. 
     The insulating protrusions  411 ,  412 ,  413 , and  414  can be formed at the insertion grooves  401 ,  402 ,  403 , and  404 , respectively. In this case, the insulating protrusions  411 ,  412 ,  413 , and  414  can be formed radially throughout the insertion grooves  401 ,  402 ,  403 , and  404  and can be formed throughout the insertion grooves  401 ,  402 ,  403 , and  404  in the up-down direction. 
     Since the insulating protrusions  411 ,  412 ,  413 , and  414  are formed at the insertion grooves  401 ,  402 ,  403 , and  404 , respectively, when four insertion grooves  401 ,  402 ,  403 , and  404  are provided, four insulating protrusions  411 ,  412 ,  413 , and  414  can be provided. When a plurality of insulating protrusions  411 ,  412 ,  413 , and  414  are provided at one terminal holder  400 , the insulating protrusions  411 ,  412 ,  413 , and  414  can be formed in the same shape. 
     The thickness of the insulating protrusions  411 ,  412 ,  413 , and  414  can be smaller than the thicknesses of the bottom plate  430  and the partition walls  441 ,  442 ,  443 ,  444 , and  445 . For example, the thickness of the insulating protrusions  411 ,  412 ,  413 , and  414  can be about ½ of the thicknesses of the bottom plate  430  and the partition walls. 
     The insulating grooves  421 ,  422 ,  423 , and  424  are formed opposite the insulating protrusions  411 ,  412 ,  413 , and  414  at the terminal holder  400 . That is, at the terminal holder  400 , the insulating grooves  421 ,  422 ,  423 , and  424  and the insulating protrusions  411 ,  412 ,  413 , and  414  are formed at both circumferential ends. 
     The insulating grooves  421 ,  422 ,  423 , and  424  can be concave grooves or stepped grooves formed at an end of the bottom plate  430 . 
     In some implementations, when two terminal holders  400  are coupled to each other, the insulating protrusions  411 ,  412 ,  413 , and  414  of any one terminal holder  400  can be seated in the insulating grooves  421 ,  422 ,  423 , and  424  of the other terminal holder  400 . 
     The insulating grooves  421 ,  422 ,  423 , and  424  can be formed to be concave and can be stepped in the circumferential direction of the stator  1  at a circumferential end of the partition walls. Since the insulating grooves  421 ,  422 ,  423 , and  424  are formed at the bottom plate  430  and any one of the partition walls  441 ,  442 ,  443 ,  444 , and  445 , the insulating grooves  421 ,  422 ,  423 , and  424  can make a      or      shape, e.g., an L shape. The insulating grooves  421 ,  422 ,  423 , and  424  can have a shape and a size that correspond to those of the insulating protrusions  411 ,  412 ,  413 , and  414 . 
     The insulating grooves  421 ,  422 ,  423 , and  424  may be formed at the insertion grooves  401 ,  402 ,  403 , and  404 , respectively. In this case, the insulating grooves  421 ,  422 ,  423 , and  424  may be formed radially throughout the insertion grooves  401 ,  402 ,  403 , and  404  and can be formed throughout the insertion grooves  401 ,  402 ,  403 , and  404  in the up-down direction. 
     Since the insulating grooves  421 ,  422 ,  423 , and  424  are formed at the insertion grooves  401 ,  402 ,  403 , and  404 , respectively, when four insertion grooves  401 ,  402 ,  403 , and  404  are provided, four insulating grooves  421 ,  422 ,  423 , and  424  are provided. When a plurality of insulating grooves  421 ,  422 ,  423 , and  424  are provided at one terminal holder  400 , the insulating grooves  421 ,  422 ,  423 , and  424  may be formed in the same shape. 
     As described above, the terminal holder  400  has the bottom plate  430 , the insulating protrusions  411 ,  412 ,  413 , and  414 , and the insulating grooves  421 ,  422 ,  423 , and  424 . Further, when two split-core assemblies  10  are coupled to each other, the insulating protrusions  411 ,  412 ,  413 , and  414  of any one terminal holder  400  are inserted or seated in the insulating grooves  421 ,  422 ,  423 , and  424  of the other terminal holder  400 . Accordingly, it is possible to effectively and stably overlap the terminal holders  400  and shield between the split core  100  and the conductive plates  20 ,  30 ,  40 , and  50 . 
       FIG. 9  is a plan view showing an example of a bobbin  200  and a terminal holder  400 . 
     In some implementations, the protruding degrees (e.g., circumferential lengths) of the insulating protrusions  411 ,  412 ,  413 , and  414  can be increased as they go away from the central axis S. 
     When a plurality of insulating protrusions  411 ,  412 ,  413 , and  414  are formed at one terminal holder  400 , the insulating protrusions  411 ,  412 ,  413 , and  414  that are relatively far from the central axis S can further protrude than the insulating protrusions  411 ,  412 ,  413 , and  414  that are relatively close to the central axis S. 
     In this case, the insulating grooves  421 ,  422 ,  423 , and  424  can also formed to corresponding to the protruding degrees of the insulating protrusions  411 ,  412 ,  413 , and  414 , respectively. 
     When a plurality of split-core assemblies  10  are circumferentially coupled to each other, the gap between the terminal holders  400  can be increased as it goes away from the central axis S. In some examples, the protruding degrees of the insulating protrusions  411 ,  412 ,  413 , and  414  are increased as they go away from the central axis S, to thereby effectively reduce or prevent a gap between the terminal holders  400 . 
     Although a specific implementation of the present disclosure was described above with reference to drawings, the present disclosure is not limited thereto and it should be understood that the present disclosure can be changed and modified by those skilled in the art in various ways through more detailed implementations without departing from the spirit and scope of the present disclosure. Accordingly, the range of the present disclosure should be defined not by the implementations described above, but by the spirit described in claims. 
     In the split-core assembly and a stator including the split-core assembly, insulating protrusions are formed at a terminal holder, and when two split-core assemblies are coupled to each other, the insulating protrusions of any one terminal holder overlap the other terminal holder. Accordingly, it can be possible to prevent or reduce a gap between the split-core assemblies, and the present disclosure has sufficient industrial applicability because a portion between the split core and the conductive plates is shielded.