Abstract:
In a stator and a rotating electric machine equipped with this stator, the insulation properties of a coil are ensured by suppressing lead wire stress generated during a stator assembly process. The stator has a stator core, a coil wound around the stator core, lead wires led out from the coil, and power lines provided between the lead wires and a connection terminal of an external circuit. The lead wires and the power lines are electrically connected with each other through an elastically deformable elastic bus bar. Even if a shift occurs in the relative position between the coil and the connection terminal during the assembly process of the stator, this configuration allows the elastic bus bar to absorb the shift and makes it possible to suppress the stress generated on the lead wires.

Description:
This is a 371 national phase application of PCT/JP2010/073693 filed 28 Dec. 2010, the contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a stator and a rotating electric machine equipped with this stator, and more specifically to improvement of a connecting structure between a coil and terminals of a stator. 
     BACKGROUND ART 
     A rotating electric machine has a rotor and a stator disposed around the rotor. The stator has a coil, and a current flowing through this coil generates a rotating magnetic field. Electromagnetic effects acting between this rotating magnetic field and the rotor cause the rotor to rotate. 
     Patent Literature 1 below discloses a stator having a stator core, a coil wound around this stator core, and a lead line extending from the coil. In such a stator, the coil is impregnated with varnish, such as high strength epoxy resin, to enhance mechanical strength of the coil and ensure insulation. 
     Patent Literature 2 below discloses a stator core, a coil wound around this stator core, a lead line of the coil, and a connection terminal connecting between the lead line and an external circuit. A curved bent portion is formed on the lead line. This bent portion absorbs stress caused on a lead wire due to changes in relative positions of the stator and the connection terminal, and prevents the lead wire from being damaged. 
     CITATION LIST 
     Patent Literature 
     
         
         
           
             [Patent Literature 1] JP 2004-350381 A 
             [Patent Literature 2] JP 2002-247811 A 
           
         
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     Patent Literature 1 and Patent Literature 2 above disclose an example of a stator in which a lead line of a coil is connected to a connection terminal of an external terminal via a power line which is a conductor such as copper. In order to assemble such a stator, before relative positions of the coil and the connection terminal are determined, one end of the power line is fixed to a tip of the lead line of the coil by welding. Then, another end of the power line is aligned to the connection terminal whose position has been determined, and fixed via a bolt, for example. Because the lead line is tensioned or compressed during this alignment of the power line upon fixation, stress is caused on this lead line. Due to stress caused on the lead line, coating of the coil, such as thermoplastic resin, which is affixed to varnish may be peeled from the coil disposed at the base end of the lead line, and insulation failure may be caused. 
     The object of the present invention is to provide a stator that reduces stress caused on the lead line of the coil during the stator assembly process to thereby ensure insulation of the coil, and provide a rotating electric machine having this stator. 
     Solution to Problem 
     A feature of the present invention is that, in a stator which has a stator core, a coil wound around the stator core, a lead line extending from the coil, and a power line disposed between the lead line and a connection terminal of an external circuit, the lead line and the power line are electrically connected via an elastically deformable elastic bus bar. 
     Further, a coil is a three-phase AC coil and is able to have a module member in which elastic bus bars of respective phases are integrated using an insulating member. 
     It is also preferable that the elastic bus bar is formed by bending a plate-like conductor. 
     It is further preferable that the module member includes a terminal bus bar which connects between terminals arranged on both sides of coil ends along the radial direction. 
     It is still further preferable that a rotating electric machine has the above-described stator. 
     Advantageous Effects of Invention 
     With a stator of the present invention and a rotating electric machine having this stator, it is possible to reduce stress caused on a lead line of a coil during the stator assembly process and ensure insulation of the coil. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a configuration of a rotating electric machine according to the present embodiment; 
         FIG. 2  shows a cross-section of the rotating electric machine taken along the line A-A of  FIG. 1 ; 
         FIG. 3  shows a partial detailed view of an end portion of a stator from the axis direction; 
         FIG. 4  shows a cross-section of the stator taken along the line B-B of  FIG. 3 ; and 
         FIG. 5  shows a cross-section of the stator taken along the line C-C of  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of a stator of the present invention and a rotating electric machine having this stator will be described hereinafter with reference to  FIGS. 1 and 2 .  FIG. 1  shows a configuration of a rotating electric machine according to the present embodiment, while  FIG. 2  shows a cross-section of a stator taken along the line A-A of  FIG. 1 . 
     A rotating electric machine  10  of the present embodiment is a three-phase AC rotating electric machine and is used as a motor for a vehicle, for example. The rotating electric machine  10  has a rotor  12 , a stator  14 , and a case for containing them (not shown). The stator  14  is disposed along the inner circumference of the case, and the rotor  12  is disposed inside this inner circumference of the stator  14  in a rotatable manner. 
     The rotor  12  is a cylindrical magnetic body that is concentric with a rotation shaft  16  and is formed by laminating, for example, electromagnetic steel plates along the axis direction. As shown in  FIG. 1 , in the rotor  12 , eight permanent magnets  18  are arranged along the circumferential direction. The number of the permanent magnets  18  is just one example. In the present embodiment, the permanent magnets  18  are embedded in holes formed in the rotor  12  so as to extend along the axis direction. However, this is not limiting, and the permanent magnets  18  may be disposed along the outer circumference of the rotor  12 . A rotation shaft  16  is rotatably supported by a bearing (not shown) disposed in the case. In addition, although, in the present embodiment, a case where the rotor  12  is formed by laminating the electromagnetic steel plates has been described, this configuration is not limiting, and the rotor  12  may be formed of dust core. 
     The stator  14  is disposed around the rotor  12  with a slight gap from the rotor  12 . The stator  14  has a hollow cylindrical stator core  20  and a cylindrical body  22  surrounding the stator core  20  and fixing the stator core  20 . 
     The stator core  20  is a magnetic body and is formed by laminating, for example, electromagnetic steel plates along the axis direction. More specifically, the stator core  20  is formed by pressing and punching thin plate-like electromagnet steel plates, laminating a predetermined number of punched electromagnetic steel plates along the axis direction, and applying, for example, pressing and compacting processing to a plurality of laminated electromagnetic steel plates to thereby integrate the plates. Although, in the present embodiment, a case where the stator core  20  is formed by laminating the electromagnetic steel plates has been described, this configuration is not limiting, and the stator core  20  may be formed of a dust core. 
     The stator core  20  has a ring-shaped yoke  20   a  and teeth  24  which protrude from the inner circumference of this yoke  20  toward the inside in the radial direction and are arranged along the circumferential direction with a predetermined interval in between. A conductor such as copper extends through a slot  26  which is a groove-like space between the teeth  24 . By extending this conductor through the slot  26  and winding it around the teeth  24 , a coil  28  (shown in  FIG. 2 ) is formed. In order to provide insulation, the surface of the conductor constituting the coil  28  is coated with thermoplastic resin such as polyphenylene sulfide resin (PPS). 
     The coil  28  has a portion referred to as a coil end  28   a  which serves to bridge the conductor from one slot  26  to another slot  26 . The coil end  28   a  is positioned so as to protrude from the end portion of the stator core  20  along the direction of the axis  30 , as shown in  FIG. 2 . By impregnating and filling the coil  28  with varnish from the coil end  28   a  side to the inside of the coil  28 , mechanical strength and insulation of the coil  28  are ensured. 
     A cylindrical body  22  has an approximate cylindrical shape and is formed such that the inner diameter of this shape is smaller than the outer diameter of the stator core  2 , in consideration of interference. The cylindrical body  22  fastens and fixes the stator core  22  by shrink fitting or press fitting. As shown in  FIG. 2 , a flange portion  32  extending to the outside along the radial direction is formed on the end portion along the direction of the axis  30 . This flange portion  32  is fixed to the case via a fastening member such as a bolt. 
     In the rotating electric machine configured in such a manner, by turning on the coil  28 , a rotating magnetic field is generated in the stator  14 , and a force to be absorbed by this rotating magnetic field is generated in the rotor  12  having the permanent magnets  18 , thereby causing the rotor  12  to rotate. 
     Next, a connecting structure between the coil  28  of the stator  14  and a connection terminal  34  will be described with reference to  FIGS. 3 to 5 .  FIG. 3  shows a partial detailed view of the end portion of the stator  14  from the direction of the axis  30 .  FIG. 4  shows a cross-section of the stator  14  taken along the line B-B of  FIG. 3 , while  FIG. 5  shows a cross-section of the stator  14  taken along the line C-C of  FIG. 3 . 
     The stator  14  has the connection terminal  34  for an external circuit, a lead line  36  extending from the coil  28 , and a power line  38  disposed between the connection terminal  34  and the lead line  36 . The lead line  36  and the power line  38  are electrically connected via an elastic bus bar  40  which is elastically deformable. The lead line  36 , the power line  38 , and the elastic bus bar  40  are all conductors. 
     The connection terminal  34  is a terminal for connecting between an external circuit connected to a power supply such as a battery and the coil  28 . The connection terminal  34  is provided on the case. The connection terminal  34  consists of three terminals: U-phase, V-phase, and W-phase terminals. 
     As shown in  FIG. 4 , the lead line  36  is extended from the coil end  28   a  located outside along the radial direction. The lead line  36  is formed such that its base end is affixed to the coil end  28   a  with varnish and its end segment  37  extends outside along the direction of the axis  30 . In order to correspond to the above-described connection terminals  34 , the lead line  36  includes three conductors: U-phase, V-phase, and W-phase conductors. 
     As shown in  FIG. 3 , the power line  38  has mounting brackets  38   a  which can be fixed to the connection terminals  34  via a securing member such as a bolt. In order to correspond to the above-described connection terminals  34 , the power line  38  also includes three conductors: U-phase, V-phase, and W-phase conductors. 
     The elastic bus bar  40  is formed by bending a conductor in an elastically deformable manner. More specifically, as shown in  FIG. 4 , the elastic bus bar  40  is formed to have a U-shaped cross-section. One end of the elastic bus bar  40  is connected to the end segment  37  of the lead line  36 , for example, by welding. Meanwhile, the other end of the elastic bus bar  40  is connected to the end segment  39  of the power line  38 , for example, by welding. The elastic bus bar  40  also includes three conductors: U-phase, V-phase, and W-phase conductors. 
     By causing the elastically deformable elastic bus bar  40  to electrically connect between the lead line  36  and the power line  38  in this way, it is possible to reduce stress caused on the lead line  36  during the assembly process of the stator  14  and ensure insulation of the coil  28 . 
     More specifically, in order to assemble the stator  14 , before the relative positions between the coil  28  and the connection terminal  34  are determined, the lead line  36 , the elastic bus bar  40 , and the power line  38  are connected by welding, respectively. Then, after the stator  14  is fixed to the case, and the relative positions of the stator  14  and the connection terminal  34  are determined, the mounting bracket  38   a  of the power line  38  is fixed to the connection terminal  34  via a bolt, for example. This alignment between the mounting bracket  38   a  of the power line  38  and the connection terminal  34  tensions or compresses the power line  38  upon fixation and causes stress on this power line  38 . Because, in the stator  14  according to the present embodiment, this stress on the power line  38  is absorbed by elastic deformation of the elastic bus bar  40 , stress caused on the lead line  36  is reduced. Accordingly, unlike the conventional art, coating of the base end of the lead line  36  is prevented from being peeled from the conductor serving as the body of the lead line  36 , and as a result, insulation of the coil  28  can be ensured. 
     Further, the stator  14  according to the present embodiment has a feature of having a module member  42  in which the elastic bus bars  40  of the respective phases are integrated using an insulating member. The insulating member is thermoplastic resin such as aromatic nylon (PA6T), and the module member  42  is formed by resin molding. 
     By integrating three elastic bus bars  40  using the insulating member in this manner, it becomes possible to further reduce stress caused on the lead line  36 . In other words, stress caused on at least one power line  38  during the assembly process of the stator  14  is absorbed by the elastic bus bar  40  connected to that power line  38  and reduced. Then, the stress that has not been absorbed is transmitted from that elastic bus bar  40  to other elastic bus bars  40  via the insulating member and absorbed there. In other words, the module member  42  can distribute the stress caused on the power line  38  and allow it to be absorbed by the three elastic bus bars  40 . Further, because the module member  42  includes thermoplastic resin, it is also possible for this resin to absorb the stress on the power line  38 . 
     Further, the module member  42  includes a terminal bus bar  46  connecting between terminals  44  arranged on both sides of the coil end  28   a  along the radial direction. The terminal  44  and the terminal bus bar  46  are both conductors. 
     As shown in  FIG. 5 , the terminals  44  extend from outside and inside of the coil end  28  along the radial direction, respectively. The base ends of the terminals  44  are affixed to the coil end  28   a  with varnish, and the tips of the terminals  44  are formed so as to extend to the outside along the direction of the axis  30 . The terminal  44  includes three conductors: U-phase, V-phase, and W-phase conductors. 
     The terminal bus bar  46  is formed by bending a conductor in an elastically deformable manner, like the elastic bus bars  40 . More specifically, as shown in  FIG. 5 , the terminal bus bar  46  is formed to have a U-shaped cross-section. One end of the terminal bus bar  46  is connected to the tip of the terminal  44  located outside along the radial direction by, for example, welding. Meanwhile, the other end of the terminal bus bar  46  is connected to the tip of the terminal  44  located inside along the radial direction by, for example, welding. The terminal bus bar  46  also includes three conductors: U-phase, V-phase, and W-phase conductors. 
     The module member  42  is formed by integrating, that is, resin molding, the terminal bus bars  46  of the respective phases using the insulating member. With such a configuration, it is possible to further reduce stress caused on the lead line  36 . More specifically, during the assembly processing of the stator  14 , stress on a power line  38  is transmitted from an elastic bus bar  40  connected to that power line  38  to the other elastic bus bars  40  via the insulating member, and also to the terminal bus bars  46  and absorbed there. In other words, it is possible for the module member  42  to distribute stress caused on the power line  38  to as many elastic bus bars  40  and  46  as possible and allow the stress to be absorbed there, thereby further reducing the stress caused on the lead line  36 . Further, with this configuration, it is also possible to distribute vibrations generated during operation of the rotating electric machine  10  to the respective bus bars  40  and  46  and absorb it there. As a result, stress caused on the lead line  36  can be reduced. 
     Further, by adopting such a module member  42 , alignment between the lead line  36  extending from the coil end  28   a  and the terminal  44 , more particularly, alignment between the tips of them, can be facilitated, and the steps of the assembly processing of the stator  14  can be reduced. 
     Industrial Applicability 
     Although, in the present embodiment, it has been described that the numbers of the connection terminals  34 , the lead lines  36 , the power lines  38 , the elastic bus bars  40 , the terminals  44 , and the terminal bus bars  46  correspond to the number of U-phase, V-phase, and W-phase, respectively, the present invention is not limited to this configuration, and it may further include a neutral point terminal or conductor. 
     Although, in the present embodiment, it has been described that the elastic bus bar  40  is formed to have a U-shaped cross-section, the present invention is not limited to this configuration. The elastic bus bar  40  may also be formed to have other shapes, such as an S-shaped cross-section, as long as it is an elastically deformable shape. 
     Although, in the present embodiment, it has been described that the terminal bus bar  46  is formed to have a U-shaped cross-section, the present invention is not limited to this configuration. The terminal bus bar  40  may also be formed to have other shapes as long as it is an elastically deformable shape. 
     Further, although, in the present embodiment, it has been described that the terminal bus bar  46  connects between the terminals  44  facing along the radial direction as shown in  FIG. 3 , the present invention is not limited to this configuration. The terminal bus bar  46  may also connect between two terminals  44  that do not face along the radial direction, that is, two terminals  44  that are arranged so as to be shifted along the circumferential direction. In this case, the terminal bus bar  46  is provided so as to extend along the circumferential direction in the insulating member of the module member  42 . 
     Reference Signs List 
       10  Rotating electric machine,  14  stator,  20  stator core,  28  coil,  28   a  coil end,  34  connection terminal,  36  lead line,  38  power line,  40  elastic bus bar,  42  module member,  44  terminal,  46  terminal bus bar.