Abstract:
Provided are: a rotating-electrical-machine stator in which the height of coil ends of a stator coil is suppressed, while interference between adjacent conductors at the coil ends is avoided; and a rotating electrical machine provided with same. The rotating-electrical-machine stator is provided with: a stator core provided with a plurality of slots; and a stator coil inserted into the slots. The rotating-electrical-machine stator is characterized in that: the stator coil is provided with at least two conductors which are disposed in the same layer as a first conductor, and which are inserted into the slots adjacent to the first conductor; and the shapes of coil protrusions protruding radially outwards are configured so as to form arcs.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a stator of a rotating electric machine such as a motor and a generator, and a rotating electric machine including the stator. 
       BACKGROUND ART 
       [0002]    JP 2011-234482 A (PTL 1) discloses a background art of the present technical field. The publication discloses that “there is provided a stator of a rotating electric machine that can reduce damage to an insulation film of a conductor that forms a stator coil while suppressing enlargement of a coil end of the stator coil. A turn portion of the conductor is formed of a protruding portion that protrudes from a first slot in a direction parallel to an axial direction of a stator core, a slope portion that diagonally extends at an angle of less than 90 degrees toward a kth slot (another slot), which is separated from the first slot at a predetermined interval (one magnetic pole pitch) via a first bent portion bent in a circumferential direction from a tip of the protruding portion, and a second bent portion bent in a direction parallel to the axial direction of the stator core from a tip of the slope portion, and connected to a slot housing portion housed in the kth slot. Therefore, the turn portion includes two bent portions, and is formed in an asymmetric shape in a circumferential direction. 
       CITATION LIST 
     Patent Literature 
       [0003]    PTL 1: JP 2011-234482 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    However, in the technique disclosed in PTL 1, enlargement of a wire diameter of a stator coil causes coils adjacent to each other to easily interfere therewith when shifting from a first slot to a second slot. In order to avoid the interference therebetween, many parts of a conductor need to be bent at the time of slot shift; however, the risk of damaging an insulation film that covers a coil surface increases. Making the insulation film thick as a countermeasure against the above causes a problem of decreasing a space factor of the conductor in the slot and thus, lowering the efficiency. In addition, it becomes difficult to reduce the height of the coil end due to the interference between the adjacent conductors. 
         [0005]    Accordingly, an object of the present invention is to provide a stator of a rotating electric machine in which the height of a coil end of a stator coil is reduced while interference between adjacent conductors at the coil end is avoided, and to provide a rotating electric machine including the stator. 
       Solution to Problem 
       [0006]    In order to solve the problem described above, configurations described in claims are adopted, for example. 
         [0007]    The present application includes a plurality of methods to solve the problem described above. An example of such methods is a stator of a rotating electric machine, including a stator core that has a plurality of slots, and a stator coil inserted into the slot. In addition, the stator coil includes two or more conductors disposed in the same layer as a first conductor and inserted into the slots adjacent to the first conductor, and a shape of a coil-protruding portion protruding to an outer diameter is an arc-like shape. 
       Advantageous Effects of invention 
       [0008]    The present invention can provide a stator of a rotating electric machine in which the height of a coil end of a stator coil is reduced while interference between adjacent conductors at the coil end is avoided, and a rotating electric machine including the stator. 
         [0009]    Other problems, structures, and effects that are not described above will be apparent from the following description of the embodiment. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a block diagram of a hybrid electric vehicle. 
           [0011]      FIG. 2  is a cross-sectional view of a rotating electric machine according to an embodiment of the present invention. 
           [0012]      FIG. 3  a is an external view of a stator of the rotating electric machine. 
           [0013]      FIG. 4  is a schematic view of a coil inserted into one slot. 
           [0014]      FIG. 5  is a view of a stator core with the coil inserted therein as viewed from the side of an inner diameter. 
           [0015]      FIG. 6  is an external view of the stator of the rotating electric machine according to the embodiment of the present invention. 
           [0016]      FIG. 7  is an external view of a conventional stator of a rotating electric machine. 
           [0017]      FIG. 8  is a view of the stator of the present embodiment as viewed vertically relative to an axial direction. 
           [0018]      FIG. 9  is a view illustrating a conventional stator coil. 
           [0019]      FIG. 10  is a perspective view illustrating the stator coil of the embodiment. 
           [0020]      FIG. 11  is a view illustrating the stator coil of the embodiment 
           [0021]      FIG. 12  is a view illustrating a combination of the stator coils of the embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0022]    Hereinafter, an embodiment of the present invention will be described. 
         [0023]    In the following description, a rotating electric machine for a hybrid electric vehicle is used as an example of a rotating electric machine. In addition, in the following description, an “axial direction” refers to a direction along a rotation axis of the rotating electric machine. A circumferential direction refers to a direction along a rotation direction of the rotating electric machine. A “radial direction” refers to a radius vector direction (radial direction) when the rotation axis of the rotating electric machine is regarded as a center. An “inner periphery side” refers to an inner side (inner diameter side) in the radial direction, and an “outer periphery side” refers to the opposite direction, that is, an outer side (outer diameter side) in the radial direction. 
         [0024]    First, an outline of the embodiment will be described. 
         [0025]    The embodiment described herein relates to a coil structure of the stator of the rotating electric machine. The rotating electric machine mainly includes a cylindrical stator, and a rotor disposed on an inner periphery side of the stator at a predetermined distance from the stator. 
         [0026]    The stator has a plurality of magnetic poles arranged such that the polarity alternates in a rotation direction, and includes a cylindrical stator core, and a plurality of stator coils wound around the stator core. The stator core includes a plurality of slots that are formed to penetrate the stator core in the axial direct on and arranged circumferentially to accommodate the stator coils. Each stator coil is formed by electrically connecting a number of conductors disposed in the respective slots. The coil extends axially in the slot, while a lead-out line portion led out from one axial end of the slot extends over multiple slots arranged at predetermined circumferential pitches to correspond to the plurality of magnetic poles. The stator coils each include a crank portion that shifts in layer as the coils are separated from each other at predetermined circumferential pitches. The stator coils are configured such that the coils led out from the adjacent slots do not interfere with each other. 
         [0027]    In the present embodiment, there is also provided a bent portion that is bent back from the outer side in the radial direction toward the inner side in the radial direction, in addition to the crank portion for layer shift in the plurality of phases of stator coils. The bent portion that is bent back can increase the distance for avoiding interference between the adjacent coils, thus decreasing the axial height of the coils. Therefore, t s possible to reduce the height of the coil ends, and to secure a gap from other devices such as a mission portion. 
         [0028]    Next, the embodiment will be described in detail with reference to the drawings. 
         [0029]      FIG. 1  is a block diagram of a hybrid electric vehicle in which a rotating electric machine according to an embodiment of the present invention is installed. A vehicle  1  includes an engine  2  used as a power source for the vehicle, and a rotating electric machine  3 . Alternatively, two rotating electric machines having different functions may be used. In such a case, one of the rotating electric machines performs both power generation and vehicle driving, while the other rotating electric machine performs vehicle driving. 
         [0030]    Rotating torque generated by the engine  2  and the rotating electric machine  3  is transmitted to wheels (driving wheels)  6  via a transmission  4 , such as a stepless transmission or a stepped automatic transmission, and a differential gear  5 . The rotating electric machine  3  is installed between the engine  2  and the transmission  4 , or in the transmission  4 . Thus, the rotating electric machine  3  needs to have a small size and a high output in order to minimize an influence of space on the vehicle  1 . 
         [0031]      FIG. 2  is a partial cross-sectional view simply illustrating the rotating electric machine  3 , in which the left part from a shaft  201  is illustrated as a cross-sectional view and the right part is illustrated as a side view. The rotating electric machine  3  is accommodated and disposed inside a case  7 . In a case where the rotating electric machine  3  is disposed between the engine  2  and the transmission  4  as illustrated in  FIG. 1 , the case  7  is formed using the case of the engine  2  or the case of the transmission.  4 . In a case where the rotating electric machine  3  is installed inside the transmission  4 , the case  7  is formed using the case of the transmission  4 . 
         [0032]    The rotating electric machine  3  includes a stator  100  and a rotor  200 . The rotor  200  is disposed on the inner periphery side of the stator  100  via a gap  11 . The rotor  200  is fixed to the shaft  201  and rotates integrally with the shaft  201 . Both ends of the shaft  201  are rotatably supported by the case  7  by bearings  202 A and  202 B. The outer periphery side of the stator  100  is fixed on the inner periphery side of the case  7  with a bolt  12  or the like. The rotating electric machine  3  is a three-phase synchronous electric motor using a permanent magnet as the rotor  200 , and functions as an electric motor when a large three-phase alternate current (e.g., about 300 A) is supplied to the stator  100 . 
         [0033]      FIG. 3  is a perspective view illustrating the stator  100  alone of the rotating electric machine  1 .  FIG. 4  is a cross-sectional view illustrating the inside of respective slots  105 . 
         [0034]    As illustrated in  FIGS. 3 and 4 , the stator  100  includes a stator core (also referred to as a stator iron core)  101  in which a plurality of slots  105  is formed on the inner periphery side of the stator, and three stator coils  102  wound around the stator core  101  and corresponding to U-phase, V-phase, and W-phase, respectively. The slots  105  are formed to pass through in the axial direction and arranged at equal intervals from each other at a predetermined circumferential pitch in the circumferential direction. A slit  108  is opened to extend axially on the inner periphery side. 
         [0035]    Each stator coil  102  includes a number of conductors  106  that are inserted into and held in the slots  105 , as will be described later. The conductors  106 , which are provided adjacent to each other in the same slot  105 , are welded together at a welding portion  104  formed at one axial end side (lower end side of  FIG. 3 ) of the stator core  101 . Thus, an elongated stator coil  102  in which the conductors  106  are electrically connected to each other at the welding portion  104  is formed. Insulating paper  103  is inserted into each slot  105  to insulate between a linear portion that passes through the slot  105  of the conductor  106  and the stator core  101 . As illustrated in  FIG. 4 , the insulating paper  103  is provided to bundle two adjacent conductors  106  out of the four conductors  106  arranged in each slot  105 . That is, two pieces of insulating paper  103  are provided in each slot  105 . 
         [0036]    Each stator coil  102  extends over multiple slots  105  arranged apart from each other at predetermined circumferential pitches, by a substantially U-shaped or V-shaped lead-out line portion  107  that is led out from one axial end of the slot  105 . The plurality of stator coils  102  generates a plurality of magnetic poles whose polarity alternates in the rotation direction. 
         [0037]    As illustrated in  FIG. 4 , the four conductors  106   a,    106   b,    106   c,  and  106   d  inserted into the slot  105  are arranged in a row in the radial direction of the stator core  101  so as to form concentric layers. The positions of the conductors  106   a,    106   b,    106   c,  and  106   d  inserted into the slot  105  are referred to as a first layer, a second layer, a third layer, and a fourth layer respectively, in order from the inner side in the radial direction. That is, the conductor  106   a  is arranged at and inserted into the first layer, the conductor  106   b  at the second layer, the conductor  106   c  at the third layer, and the conductor  106   d  at the fourth layer. 
         [0038]    In the present embodiment illustrated in  FIGS. 3 and 4 , the stator coil  102  includes a crank portion  109  that is twisted when shifting from the first layer to the second layer, and from the third layer to the fourth layer. Note that this twist in shift between the layers is not essential. 
         [0039]      FIG. 5  is a view illustrating the coil inserted into the stator core, as viewed from the inner diameter side. 
         [0040]    Each conductor  106  that constitutes the stator coil  102 , as illustrated in  FIGS. 4 and 5 , is a coil having a rectangular cross-section. Each conductor  106  has a linear portion  110  axially penetrating the slot  105 , while one lead-out line portion  107  led out from one axial end (upper end of  FIG. 3 ) of the slot  105  is in the U-shape or the V-shape, and made of a copper wire having joint portions  104  on both ends. A portion of the conductor  106  that is led out from the slot  105  and constitutes the coil end portion is referred to as a coil-end conductor portion  300 . A detailed structure of the coil-end conductor portion  300  will be described later. 
         [0041]    A segment coil may al so be used as the conductor  106 . In this case, before the segment coil is inserted into the slot  104 , it is possible to form, in advance, coil ends located at both axial ends that are further outside from the ends of the stator core  101 , and to easily provide an appropriate insulating distance between different phases or identical phases. 
         [0042]      FIG. 6  is an external view of the stator of the present embodiment, and  FIG. 7  is an external view of the conventional stator. 
         [0043]    When the stator  100  is viewed from the axial direction, the conductor  106  is disposed on a circumference having a predetermined radius R. As illustrated in  FIG. 6 , the outer circumference of the conductor  106  in the present embodiment has a molded shape that traces a smooth arc. As illustrated. in  FIG. 7 , the outer circumference of the conventional conductor  106  has a wavelike molded shape W with respect to the outer diameter line. Furthermore, the conductor  106  is formed such that a gap  111  generated between adjacent crossing conductors has the shape of a parallelogram. As a result, the gap between adjacent conductors can be sufficiently secured even in the case where the wire diameter is large, making it possible to ensure an appropriate insulating distance. 
         [0044]      FIG. 6  is a view of the stator  100  of the present embodiment as viewed in a direction perpendicular to the axial direction. The conductor  106  led out from the stator core extends in the outer diameter direction (left-right direction n  FIG. 8 ) while forming a substantially trapezoidal shape in parallel with the axial direction (up-down direction in  FIG. 8 ). As a result, it is possible to minimize the protrusion in the outer diameter direction at the coil end portion, and to achieve downsizing and space saving of the rotating electric machine. In order to cool the electric motor, direct cooling by transmission oil, or indirect cooling of the housing assembled outside the stator by the flow of water or air is performed. By providing a flat shape  112  to the coil end in the outer diameter direction, the flow of the cooling member and the cooling effect can be enhanced. 
         [0045]      FIG. 9  illustrates a conventional configuration of the coil-end conductor portion  300  in the conductor  106  constituting the stator coil  102 , and  FIGS. 10 to 12  are diagrams illustrating the coil-end conductor portion  300  in the present embodiment. As illustrated in  FIGS. 9 and 10 , each of the coil-end conductor portions  300  includes, at both ends thereof, the linear portions  110  extending in the axial direction from the slot, forms the bent portions  302  connected to respective inclined portions  301  in the axial direction, and forms the crank portion  303  for layer shift at the vertex of the inclined portions. In  FIG. 9 , the width corresponding to the wire diameter or more does not protrude in the outer diameter direction at a portion from the inclined portion  301  to the crank portion  302 . In  FIG. 10  illustrating the present embodiment, there are provided the bent portions  305  that bend back from the outer diameter to the inner diameter or from the inner diameter to the outer diameter while shifting in the radial direction by the width corresponding to the wire diameter, at a portion from the inclined portion  301  to the crank portion  303 . 
         [0046]    As illustrated in  FIG. 11 , an axial connection angle  304  formed between the linear portion  110  penetrating in the ax direction of the conductor  106  and the inclined portion  301  is the same at both ends when the crank portion  303  is set as the center, and the coil-end conductor portion  300  has a shape with no bent portion in the axial direction from the inclined portion  301  to the crank portion  303  at the vertex of the inclined portion. 
         [0047]    As illustrated in  FIG. 12 , the coil-end conductor portion  300  has the inclined portions  301  varying in axial height, and the radial bent portion  305  provided in the middle of the inclined portion  301  is radially adjacent to the inclined portion  301  of another adjacent coil-end conductor portion  300 . 
         [0048]    Consequently, while minimizing the protrusion of the coil end portion in the outer diameter direction of the stator core, it is possible to avoid the interference between the adjacent stator coils, which in turn can reduce the height of the coil ends regardless of the wire diameter. 
         [0049]    As described above, according to the present invention, the bent portions which are provided in the axial direct on in the segment coil in the stator of the rotating electric machine for a vehicle include one at the vertex and two at slot root portions. At the same time, the bent portions include the first bent portion that is provided and bent in the outer diameter direction of the stator core, and the second or more bent portions that are bent back from the outer diameter direction to the inner diameter direction. With this configuration, it is possible to minimize the protrusion of the coil end portion in the outer diameter direction of the core and to avoid the interference between the adjacent coils. Therefore, it is possible to provide a stator structure of the rotating electric machine, in which the height of the coil ends can be reduced regardless of the wire diameter. 
         [0050]    The present invention is not limited to the above-mentioned examples, and includes a variety of modifications. For example, the examples described above have been described in detail in order to describe the present invention for easy understanding, and are not necessarily limited to those including all the configurations described above. In addition, some configurations in the examples can be deleted or replaced by another configuration, or another configuration can be added thereto. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  vehicle 
           2  engine 
           3  rotating electric machine 
           4  transmission 
           5  differential gear 
           6  wheel 
           7  case 
           100  stator 
           101  stator core 
           102  stator coil 
           103  insulating paper 
           104  welding portion of conductor 
           105  slot 
           106 ,  106   a - d  conductor 
           107  U-shaped or V-shaped conductor lead-out portion 
           108  slit portion provided in slot 
           109  crank portion 
           110  linear portion of conductor in slot 
           111  gap generated between crossing conductors 
           112  flat shape of coil end outer diameter 
           200  rotor 
           201  shaft 
           202 A,  202 B bearing 
           300  coil-end conductor portion 
           301  inclined portion 
           302  bent portion between inclined portion and linear portion of conductor 
           303  crank portion for layer shift of stator coil 
           304  connection angle of bent portion between inclined portion and linear portion of conductor 
           305  radially bent portion provided in inclined portion