Patent Publication Number: US-2023163651-A1

Title: Stator provided with insulating paper, motor having stator, and method for manufacturing motor

Description:
TECHNICAL FIELD 
     The present invention relates to a stator having an insulating paper, an electric motor having the stator, and a method for manufacturing the electric motor. 
     BACKGROUND ART 
     In the prior art, in an electric motor such as a three-phase rotating electric machine, in order to insulate coils having different phases from each other, it is well known to insert a phase-to-phase insulating paper between the coils (e.g., see Patent Literature 1 and 2). It is also well known to fix the phase-to-phase insulating paper with an adhesive tape, etc., in order to prevent the phase-to-phase insulating paper from being misaligned (e.g., see Patent Literature 3 to 6). 
     CITATION LIST 
     Patent Literature 
     [PTL 1] JP 2007-060819 A 
     [PTL 2] JP 2013-207820 A 
     [PTL 3] JP H09-131012 A 
     [PTL 4] JP 2008-131749 A 
     [PTL 5] JP 2007-104826 A 
     [PTL 6] JP 2005-312222 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     When the phase-to-phase insulating paper is too thick relative to the width of a slot of a stator core, it is difficult to insert it into the slot, and conversely, when it is too thin, it is easy for it to slip off. Further, in a conventional electric motor, it is difficult to provide a means for fixing the phase-to-phase insulating paper in the radial direction around the coil end. Therefore, there is also the problem that the position of the phase-to-phase insulating paper within the slot is easily offset together with the coil wound in the slot. 
     On the other hand, when the phase-to-phase insulating paper has a special shape corresponding to the shape of the coil and/or the slot pitch, etc., the manufacturing cost thereof increases, and in addition, such a phase-to-phase insulating paper cannot flexibly cope with various coil shapes and/or winding arrangements, etc. Further, it is necessary to perform shaping such as bending the coil end of the coil, depending on the shape of the phase-to-phase insulating paper. Therefore, when the phase-to-phase insulating paper protrudes from the stator core, the coil length becomes long. 
     Solution to Problem 
     One aspect of the present disclosure is a stator of an electric motor, comprising: a stator core having a plurality of slots; a plurality of coils positioned in the slots, each coil having a coil end positioned outside relative to an axial end of the stator core; at least one coil end insulating paper positioned between the coil ends so as to insulate the coil ends from each other; a plurality of coil-to-coil insulating papers positioned in the slots, each coil-to-coil insulating paper having a protruding portion which protrudes from at least one of both axial ends of the stator core; and a wedge insulating paper positioned in the slot where the coil is positioned, the wedge insulating paper positioned inside in a radial direction of the stator core relative to the coil, wherein each of the coil end insulating papers has an adhesive portion, and a plurality of the protruding portions are adhered to one coil end insulating paper. 
     Another aspect of the present disclosure is an electric motor having the above stator. 
     Still another aspect of the present disclosure provides a manifacturing method of a stator of an electric motor, comprising: inserting a plurality of coils into a plurality of slots of a stator core so that each coil has a coil end positioned outside relative to an axial end of the stator core; inserting a plurality of coil-to-coil insulating papers into the slots so that each coil-to-coil insulating paper has a protruding portion which protrudes from at least one of the two axial ends of the stator core; and positioning at least one coil end insulating paper having an adhesive portion at at least one of the two axial ends of the stator core so that each coil end insulating paper is positioned between the coil ends and a plurality of the protruding portions are adhered to each coil end insulating paper. 
     Advantageous Effects of Invention 
     According to the aspect of the present disclosure, the plurality of coil-to-coil insulating papers are fixed by at least one coil end insulating paper, more specifically, the coil-to-coil insulating papers are adhered to a plurality of portions of each coil end insulating paper. Therefore, the coil end insulating paper can be easily positioned and fixed. Further, the structure composed of such coil end insulating paper and coil-to-coil insulating paper can be applied to a stator of an electric motor having an arbitrary number of poles and slot arrangement. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a cross-sectional view showing a schematic configuration of an electric motor according to the present disclosure. 
         FIG.  2    is a perspective view showing a stator core according to a first embodiment. 
         FIG.  3    is a view showing a state in which a slot liner insulating paper is inserted into a slot of the stator core. 
         FIG.  4    is a view showing. a state in which a coil of a first phase is inserted into the slot. 
         FIG.  5    is a view showing a state in which a. first coil-to-coil insulating paper is inserted into the slot. 
         FIG.  6    is a view showing a state in which a first coil end insulating paper is adhered to a protruding portion of the first coil-to-coil insulating paper. 
         FIG.  7    is a view showing a state in which the coil end insulating paper is adhered to all of the protruding portions. 
         FIG.  8    is a view showing a state in which a coil of a second phase is inserted into the slot. 
         FIG.  9    is a view showing a state in which a second coil-to-coil insulating paper is inserted into the slot. 
         FIG.  10    is a view showing a state in which a second coil end insulating paper is adhered to a protruding portion of the second coil-to-coil insulating paper. 
         FIG.  11    is a view showing a state in which a coil of a third phase is inserted into the slot. 
         FIG.  12    is a view showing a state in which a wedge insulating paper is inserted into the slot. 
         FIG.  13    is a view showing a state in which a first coil end insulating paper is adhered to a protruding portion of the first coil-to-coil insulating paper, in a stator according to a second embodiment. 
         FIG.  14    is a view showing a state in which a wedge insulating paper is inserted into the slot. 
         FIG.  15    is a view schematically showing a positional relationship between the coil and the insulating paper in the slot. 
         FIG.  16    is a view schematically showing a positional relationship between the coil and the coil end insulating paper. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG.  1    is a radial cross-sectional view showing a schematic structure of an electric motor  10  according to a preferred embodiment of the present invention. The motor  10  is a three-phase AC motor having ten poles and thirty-six slots, and has: a rotor  12  having a plurality of pairs of magnetic poles; a plurality of slots  16  extending in the direction of a rotation axis  14  of the rotor  12  and arranged in the circumferential direction of the rotation axis  14 ; a stator  18  radially opposed to the rotor  12 ; a plurality of windings inserted into the slot  16  and wound around the stator  18 ; and a sheet-shaped insulator positioned adjacent to the windings (described later). However, the present disclosure is not limited to this, and there are no particular restrictions on, for example, the number of poles of the motor, the number of slots, or the shape or the number of phases of the coil. 
     The rotor  12  includes a plurality of (in this case, ten) (permanent) magnets  20 , a rotor core  22 , and a rotor shaft  24 , and rotates about the rotation axis  14 . The present disclosure is mainly characterized by the configuration of a sheet-shaped insulator (hereinafter referred to as insulating paper) arranged in or near the slot  16  formed in a stator core  26  of the stator  18 . Therefore, description of the rotor  12  will be omitted hereafter. 
     First Embodiment 
     Next, the structure and a manufacturing method of the stator  18  will be described with reference to  FIGS.  2  to  12   . Here, an example in which a three-phase (U, V, W) coils are arranged in the stator core  26  having thirty-six slots  16  will be described. 
     First, as shown in  FIG.  2   , the stator core  26  having a plurality of slots  16  (thirty-six in the illustrated example) is provided, and then a slot liner insulating paper  30  is positioned in each slot  16 , as shown in  FIG.  3   . In the illustrated example, the slot liner insulating paper  30  is inserted into all of the slots  16 . However, when there is a slot in which the winding (coil) described later is not inserted at all, it is not necessary to arrange the slot liner insulating paper  30  and a wedge insulating paper  62  as described later in that slot. 
     Next, as shown in  FIG.  4   , a coil  32  of a first phase (for example, the U phase) is inserted into some of the plurality of slots  16  (here, the slot  16   a ). Specifically, the slot liner insulating paper  30  is configured and positioned so as to electrically insulate between the stator core  26  and the coil in the slot. 
     Next, as shown in  FIG.  5   , a vertically long first coil-to-coil insulating paper (phase-to-phase insulating paper)  34  (elongated in the axial direction of the stator core  26 ) is inserted into a slot  16   a  into which the U-phase coil  32  is inserted. The first coil-to-coil insulating paper  34  is configured and positioned so as to have a protruding portion  38  which axially protrudes from at least one of two axial ends  36  of the stator core  26 . Preferably, the first coil-to-coil insulating paper  34  is longer in length than the axial length of the stator core  26 , and is positioned in the slot  16   a  so as to project axially from both ends  36  as shown in  FIG.  5   . 
     Next, as shown in  FIG.  6   , a plurality of first coil end insulating papers  40 , each having an adhesive portion  42 , are arranged so that one coil-end insulating paper  40  is adhered to the plurality of protruding portions  38 . In the illustrated embodiment, the strip-shaped first coil end insulating paper  40  extends in the circumferential direction near the end surface  36  of the stator core  26 , and the adhesive portions  42  provided at least at both ends of the insulating paper  40  are adhered to and overlapped with the protruding portion  38  of the first coil-to-coil insulating paper  34 . In this regard, the first coil end insulating paper  40  may have the adhesive portion  42  on the entirety of one side thereof, and may be adhered to the protruding portion  38  and also to a coil end  44  of the coil  32 . 
     Herein, a wire rod such as a copper wire or a bundle of the wire rods, through which an electric current flows, is referred to as a “winding wire”, and, a ring shape (including a figure of eight shape) in Which the winding wire is closed is referred to as a “coil”. Further, the “coil end” refers to a portion of the coil which is not inserted into the slot of the stator core, i.e., a portion which exists axially outside the axial end of the stator core. A plurality of (in-phase) coils may be electrically connected to each other by a wire rod or a winding wire called “a connecting line” (see  FIG.  16    below). 
     Next, as shown in  FIG.  7   , the operation described with reference to  FIG.  6    is repeated so that all of the protruding portions  38  are adhered to either of the plurality of first coil end insulating papers  40 . In this regard, it is preferable that the coil end  44  of the (preferably all) U-phase coils  32  is also adhered to (the adhesive portion  42  of) the first coil end insulating paper  40 . Further, as illustrated, the plurality of strip-shaped coil end insulating papers  40  can he adhered to each other at their longitudinal end portions to form a single ring shape as a whole, but this treatment may not be performed. The first coil end insulating paper  40  is configured and positioned so that the coil end  44  of the U-phase coil  32  and a coil end  56  of a V-phase coil  46  described later do not come into contact with each other (i.e., they are electrically insulated). 
     Next, as shown in  FIG.  8   , similarly to the process of  FIG.  4   , the coil  46  of the second phase (for example, a V-phase) is inserted into some of the plurality of slots  16  (here, slots  16   b ). In this regard, the V-phase coil  46  may be inserted into the slot  16   a  into which the U-phase coil  32  is inserted. In that case, in the slot  16   b  ( 16   a ), the first coil-to-coil insulating paper  34  is inserted between the U-phase coil  32  and the V-phase coil  46 . In other words, the first coil-to-coil insulating paper  34  is configured and positioned so as to electrically insulate between the two coils haying different phases. 
     In addition, in an electric motor in which the number of current phases and the number of layers of the coil end are different from those in the first embodiment, the number of executions of the operations shown in  FIGS.  5  to  8    changes. For example, in the manufacturing process of a stator of an electric motor in which the number of current phases and the number of layers of a coil end are larger than those in the first embodiment, the number of operations shown in  FIGS.  5  to  8    is increased by that amount. 
     Next, as shown in  FIG.  9   , similarly to the process of  FIG.  5   , a vertically long second coil-to-coil insulating paper (phase-to-phase insulating paper)  48  is inserted into the slot  16   b  in which the V-phase coil  46  is inserted. Similar to the first coil-to-coil insulating paper  34 , the second coil-to-coil insulating paper  48  is configured and positioned so as to have a protruding portion  50  which axially protrudes from at least one of the two axial ends  36  of the stator core  26 . Preferably, the second coil-to-coil insulating paper  48  is longer in length than the axial length of the stator core  26  and is positioned in the slot  16   b  so as to project axially from both ends  36  as shown in  FIG.  9   . The second coil-to-coil insulating paper  48  may have the same shape, dimensions and material as the first coil-to-coil insulating paper  34 . 
     Next, as shown in  FIG.  10   , similarly to the process of  FIG.  6   , a plurality of second coil end insulating papers  52 , each haying an adhesive portion  54 , are arranged so that one coil end insulating paper  52  is adhered to the plurality of protruding portions  50 . In the illustrated embodiment, similarly to the first coin end insulating paper  40 , the strip-shaped second coil end insulating paper  52  extends in the circumferential direction near the end surface  36  of the stator core  26 , and the adhesive portions  54  provided at least at both ends of the insulating paper  52  are adhered to and overlapped with the protruding portion  50  of the second coil-to-coil insulating paper  48 . In this regard, the second coil end insulating paper  52  may have the adhesive portion  54  on the entirety of one side thereof, and may be adhered to the protruding portion  50  and also to a coil end  56  of the coil  46 . 
     Next, as shown in  FIG.  10   , the operation described with reference to  FIG.  9    is repeated so that all of the protruding portions  50  are adhered to either of the plurality of second coil end insulating papers  52 . In this regard, it is preferable that the coil end  56  of the (preferably all) V-phase coils  46  is also adhered to (the adhesive portion  54  of) the second coil end insulating paper  52 . Further, as illustrated, the plurality of strip-shaped coil end insulating papers  52  can be adhered to each other at their longitudinal end portions to form a single ring shape as a whole, but this process may not be performed. The second coil end insulating paper  52  is configured and positioned so that the coil end  56  of the V-phase coil  46  and a coil end  60  of a W-phase coil  58  described later do not come into contact with each other (i.e., they are electrically insulated). 
     Next, as shown in  FIG.  11   , similarly to the processes of  FIGS.  4  and  8   , the winding wire (coil)  58  of the third phase (for example, W-phase) is inserted into some of the plurality of slots  16  (here, slots  16   c ). In this regard, the W-phase coil  58  may be inserted into the slot  16   a  into which the U-phase coil  32  is inserted or the slot  16   b  into which the V-phase coil  46  is inserted. In that case, in the slot  16   c  ( 16   a  or  16   b ), the first coil-to-coil insulating paper  34  or the second coil-to-coil insulating paper  48  is inserted between the U-phase coil  32  or the V-phase coil  46  and the W-phase coil  58 . Specifically, the first coil-to-coil insulating paper  34  is configured and positioned so as to electrically insulate between the two coils (here, the U-phase coil  32  and the W-phase coil  58 ) having different phases, and similarly, the second coil-to-coil insulating paper  48  is configured and positioned so as to electrically insulate between the two coils having different phases. 
     Finally, as shown in  FIG.  12   , a wedge insulating paper  62  is inserted into the slots  16   a  to  16   c  into which at least either of the coils is inserted, or into all the slots  16 . More specifically, the wedge insulating paper  62  has a length substantially equal to the axial length of the stator core  26  and a wedge-shaped cross-sectional shape. The wedge insulating paper  62  is positioned inside the stator core  26  in the radial direction with respect to the coils positioned in each slot, and has a function of holding the coil so that the coil does not shift in the slot or does not fall out of the slot. 
     Any of the steps shown in  FIGS.  2  to  12    can he automated using well-known machinery and equipment, but some or all of them can also be performed manually. Further, in the first embodiment, the structure and arrangement of the coil end and/or the insulating paper at one end (upper end) in the axial direction of the stator  18  have been mainly described, whereas the lower end of the stator  18  may have the same structure and arrangement as the upper end, as shown in  FIG.  12    as a part thereof. 
     Second Embodiment 
       FIG.  13    is similar to  FIG.  7    and shows one step of the method for manufacturing the stator of the electric motor according to the second embodiment. In the first embodiment, the plurality of strip-shaped first coil-end insulating papers  40  are attached to the protruding portions  38  of the first coil-to-coil insulating paper  34  ( FIG.  6   ), and then the first coil end insulating papers  40  are connected to each other to form one ring-shaped member ( FIG.  7   ). On the other hand, in the second embodiment, a first coil end insulating paper  40 ′ formed in advance in a roll shape or a ring shape is prepared, and the first coil end insulating paper  40 ′ is attached to all the protruding portions  38  protruding from any of the axial ends (preferably the both ends) of the stator core. Since the other components of the second embodiment may be the same as those of the first embodiment, the same reference numerals as those of the first embodiment are added and detailed description thereof will be omitted. 
       FIG.  14    shows a state in which the wedge insulating paper  62  is inserted into the slot  16  in a stator  18 ′ of the electric motor according to the second embodiment. In the first embodiment, the plurality of strip-shaped second coil-end insulating papers  52  are adhered to the protruding portions  50  of the second coil-to-coil insulating paper  48 , and then the second coil end insulating papers  52  are connected to each other to form one ring-shaped member ( FIG.  10   ). On the other hand, in the second embodiment, a second coil end insulating paper  52 ′ formed in advance in a roll shape or a ring shape is prepared, and the second coil end insulating paper  52 ′ is adhered to all the protruding portions  50  protruding from any of the axial ends (preferably both ends) of the stator core. Since the other components of the second embodiment may be the same as those of the first embodiment, the same reference numerals as those of the first embodiment are added and detailed description thereof will be omitted. 
     The manufacturing steps of the stator according to the second embodiment can also be automated using well-known machinery and equipment, but some or all of them can also be performed manually. Further, also in the second embodiment, the structure and arrangement of the coil end and/or the insulating paper may have the same structure and arrangement at the axial upper and lower ends of the stator  18 . 
     Among the four types of insulating papers in the first and second embodiments, the shapes of the slot liner insulating paper and the wedge insulating paper may be the same as those used for the stator core of the conventional electric motor. Suitable materials for the slot liner insulating paper, the wedge insulating paper and coil-to-coil (phase-to-phase) insulating paper include a PPS film, a PET film, PEN film, a paper made of aramid fibers such as a Nomex (registered trademark) paper, a PPS, a multilayer mixed film containing an adhesive layer and a PET, and a multilayer film containing a paper made of aramid fibers and a PET film. 
     Suitable materials for the coil end insulating paper include a Nomex (registered trademark) paper coated with an acrylic adhesive to form an insulating adhesive tape, and a polyester film base material reinforced with epoxy resin coated with thermosetting rubber-based adhesive material to form an insulating adhesive tape. In particular, some of the latter have a very high elongation rate as a mechanical property of about 120%, which is particularly preferable for the following reasons. 
     In the actual manufacturing process of (the stator of) the electric motor, after all the coils are inserted into the slots as shown in  FIG.  12    or  FIG.  14   , in order to adjust the shape of the coil end, a step of pressing both ends of the stator with a force of, for example, 1 to 5 tons to compress the coil end may be added. In the step of pressing, the coil end insulating paper adhered to the coil end expands or contracts, so if the elongation rate of the coil end insulating paper is relatively low, the coil end insulating paper may break and the insulation between the coil ends haying different phases may be impaired. In order to avoid such a problem, the elongation rate as a mechanical property of the coil end insulating paper is preferably 50% or more, more preferably 80% or more, and further preferably 100% or more, considering the amount of deformation of the coil end due to general pressing. 
       FIG.  15    shows the positional relationship between the coil and the insulating paper in the slot  16  of the stator core  26 . The slot  16  is a space defined between a plurality of tooth portions  64  of the stator core  26 . In the illustrated embodiment, the slot liner insulating paper  30 , the U-phase coil  32 , the first coil-to-coil insulating paper  34 , the V-phase coil  46  and the wedge insulating paper  62  are positioned in the slot  16 . 
     The slot liner insulating paper  30  is shaped along the internal shape of the slot  16  and has a function of insulating the stator core  26  from the coils  32  and  46 . Further, the wedge insulating paper  62  closes the opening (slit) of the slot  16  so as to partially hold the V-phase coil  46  (mainly inside in the radial direction), so that the coil in the slot  16  is not displaced in the slot  16  and does not fall from the slot  16 . 
     The first coil-to-coil insulating paper  34  has a function of partially surrounding the U-phase coil  32  (mainly inside in the radial direction) and insulating the U-phase coil  32  and the V-phase coil  46 . In other words, when the two coils having different phases are inserted in the same slot, the first coil-to-coil insulating paper  34  is positioned between the coils and functions as the phase-to-phase insulating paper which insulates the coils from each other. This is also applicable to the second coil-to-coil insulating paper  48 . When the three (three-phase) coils are inserted in one slot, the two coil-insulating papers are used to insulate the three coils from each other. 
     As described above, when the plurality of coils haying different phases are inserted in one slot, the coil-to-coil insulating paper is positioned between the coils and functions as the phase-to-phase insulating paper which insulates the coils from each other. However, the coil-to-coil insulating paper may be inserted into the slot in which no coil is inserted, or may be inserted into the slot in which only one coil is positioned. In this regard, when the coil-to-coil insulating paper is to be inserted into the slot in which one coil is positioned, the coil-to-coil insulating paper is inserted after the coil is inserted. As such, the coil-to-coil insulating paper may not have the function as the phase-to-phase insulating paper, but even in that case, the coil-to-coil insulating paper functions as a member for easily and surely positioning and fixing the coil end insulating paper. 
       FIG.  16    is a schematic view for explaining mainly the function of the coil end insulating paper, and here, the first coil end insulating paper  40  will be described as an example. Herein, it is assumed that the plurality of U-phase coils  32  and the plurality of V-phase coils  46  are inserted in the slot  16 , the U-phase coils  32  are connected to each other by a connecting line  66 , and the V-phase coils  46  are connected to each other by a connecting line  68 . 
     As illustrated, in case that the coil end  44  of the U-phase coil  32  and the coil end  56  of the V-phase coil  46  overlap with each other when viewed in the radial direction of the stator. The first coil end insulating paper  40  is arranged between the coil ends so that the coil ends having different phases do not come into contact with each other or so that the connecting lines  66  and  68  do not come into contact (conduct) with each other. As such, the coil end insulating paper is a sheet-like member which insulates between the plurality of coil ends having different phases of flowing currents or the plurality of connecting lines, in the region outside the axial end surface  36  of the stator core. 
     The coil end insulating paper may be adhered to the coil end in order to prevent misalignment with the coil end, but this is not essential. In other words, the coil end insulating paper may be of any shape and material, as long as it is adhered to the plurality of coil-to-coil insulating papers and can physically separate the coil ends having different phases. 
     In the first and second embodiments, since the coil-to-coil insulating paper and the coil end insulating paper are both sheet-like members, they can be adhered to each other with a relatively high adhesive force. On the other hand, since the coil end is a bundle of windings, the adhesive strength with the coil end insulating paper is relatively low, the coil end insulating paper and the coil end may be separated from each other after the stator is manufactured or during the use of the electric motor, However, as described above, the coil end insulating paper only needs to be able to physically separate the coil ends having different phases, and thus there is no problem in the performance of the electric motor. Further, since the coil end insulating paper is a flexible sheet-like member such as paper or film, it easily follows the shape of the coil end, and thus it is not necessary to lengthen the coil end (coil length). 
     In the above embodiments, the coil-to-coil insulating paper can be automatically inserted into the slot, and can be inserted by the same device and method as the wedge insulating paper. Further, the coil end insulating paper (for example, adhesive tape) having the adhesive portion is suitable for automation in its arrangement because it is easy to be positioned. In particular, as in the first embodiment, when arranging the coil end insulating paper as the plurality of strip-shaped members at each end of the stator core, automation is facilitated by forming a mount adhered to the adhesive portion in a predetermined shape in advance. Further, if the coil end insulating paper is also adhered to the coil end when the coil end insulating paper is adhered to the protruding portion of the coil-to-coil insulating paper, positioning and fixing in the radial direction becomes easy. As such, in the present disclosure, the simple strip-shaped coil-to-coil insulating paper and the strip-shaped or ring-shaped coil end insulating paper can be used to insulate the coils with an inexpensive and simple structure. Further, even if the number of poles and/or the winding arrangement is different, it is not necessary to prepare coil-to-coil insulating paper and the coil-end insulating paper having different shapes. 
     REFERENCE SIGNS LIST 
     
         
           10  three-phase AC motor 
           12  rotor 
           14  rotation axis 
           16 ,  16   a,    16   b,    16   c  slot 
           18 ,  18 ′ stator 
           20  magnet 
           22  rotor core 
           24  shaft 
           26  stator core 
           30  slot liner insulating paper 
           32 ,  46 ,  58  coil 
           34 ,  48  coil-to-coil insulating paper 
           36  end surface 
           38 ,  50  protruding portion 
           40 ,  40 ′,  52 ,  52 ′ coil end insulating paper 
           42 ,  54  adhesive portion 
           44 ,  56 ,  60  coil end 
           62  wedge insulating paper 
           64  tooth portion 
           66 ,  68  connecting line