Patent Publication Number: US-2015061433-A1

Title: Electricity collection and distribution ring

Description:
The present application is based on Japanese patent application No. 2013-175264 filed on Aug. 27, 2013, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electricity collection and distribution ring for collecting and distributing electricity from/to multi-phase windings. 
     2. Description of the Related Art 
     An electricity collection and distribution ring is known that supplies motor current to U-, V- and W-phase wirings of a three-phase AC motor (see JP-B-3902219). 
     The electricity collection and distribution ring (or centralized power distribution member) disclosed in JP-B-3902219 has four annular conductors each formed in an annular shape and respectively corresponding to U-, V-, W- and neutral phases, plural holding members for fixing the four annular conductors to each other in an axially-aligned state, and plural junction terminals for connecting each annular conductor to the windings. 
     Each holding member has first and second housing grooves which open respectively at both ends in the axial direction of the holding member. Some of the plural annular conductors are held in the first housing groove and the remaining annular conductors are held in the second groove. In addition, an attachment groove for connecting the junction terminal to the annular conductor is formed on the holding member. The position of the attachment groove differs depending on the axial position of the annular conductor to which the junction terminal is connected. That is, in this electricity collection and distribution ring, the bus rings are electrically and mechanically connected to the windings by the junction terminals and several types of holding members having the attachment groove at a different position. 
     SUMMARY OF THE INVENTION 
     The fixing member disclosed in JP-B-3902219 requires several types of molds to mold the holding members since several types of holding members having the attachment groove at a different position are used and it is thus difficult to reduce the cost. In addition, rigidity of holding the annular conductors may be reduced since the attachment groove for attaching the junction terminal is formed on the holding member. 
     It is an object of the invention to provide an electricity collection and distribution ring that needs no attachment grooves for attaching terminals so as to allow the reduced cost and the improved rigidity thereof.
     (1) According to one embodiment of the invention, an electricity collection and distribution ring comprises:
       a plurality of annular conductors respectively connected to the multi-phase windings according to the phases of electric current; and   a plurality of fixing members for fixing the plurality of annular conductors to each other,   wherein the annular conductor comprises a plurality of connecting portions connected to end portions of the windings at a plurality of positions in a circumferential direction, and   wherein the plurality of fixing members are disposed between a pair of the plurality of connecting portions adjacent along a circumferential direction of the plurality of annular conductors.   
       

     Effects of the invention 
     According to one embodiment of the invention, an electricity collection and distribution ring can be provided that that needs no attachment grooves for attaching terminals so as to allow the reduced cost and the improved rigidity thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Next, the present invention will be explained in more detail in conjunction with appended drawings, wherein: 
         FIG. 1  is an explanatory schematic diagram illustrating a rough configuration example of an electric motor which is provided with an electricity collection and distribution ring in a first embodiment of the present embodiment; 
         FIG. 2  is an appearance diagram illustrating a configuration example of the electricity collection and distribution ring in the first embodiment of the invention; 
         FIG. 3  is an appearance diagram illustrating a state in which the electricity collection and distribution ring in the first embodiment of the invention is mounted on a stator; 
         FIG. 4  is a plan view showing the stator and first to third bus rings as viewed from a central axis direction thereof; 
         FIG. 5  is a perspective view showing the first to third bus ring; 
         FIG. 6A  shows a connecting portion of the first bus ring,  FIG. 6B  shows a connecting portion of the second bus ring and  FIG. 6C  shows a connecting portion of the third bus ring; 
         FIG. 7A  is a perspective view showing an appearance of a fixing member,  FIG. 7B  is a side view showing the fixing member and  FIG. 7C  is a top view showing the fixing member; 
         FIG. 8A  is a plan view showing a portion of the electricity collection and distribution ring as viewed from an axial direction thereof in a state that the fixing members are detached and  FIG. 8B  is a diagram illustrating a state in which the fixing members are attached to the electricity collection and distribution ring of  FIG. 8A ; 
         FIG. 9  is a side view showing a fixing member in a second embodiment of a invention; and 
         FIG. 10  is an appearance diagram illustrating a configuration example of the electricity collection and distribution ring in a third embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     General Configuration of Electric Motor 
       FIG. 1  is a schematic diagram of an electric motor  1  for explaining a function of an electricity collection and distribution ring  4  in the first embodiment of the invention. 
     The electric motor  1  is provided with a rotor  2 , a stator  3  and the electricity collection and distribution ring  4  composed of first to fourth bus rings  41  to  44 . 
     The rotor  2  has a shaft  21  and a cylindrical magnet  22 . The shaft  21  is rotatably supported by a non-illustrated bearing and is located coaxially with the stator  3 . The magnet  22  is fixed to an outer peripheral surface of the shaft  21  and has plural magnetic poles. 
     The stator  3  is provided with multi-phase windings  32  respectively wound around outer peripheries of plural annularly-arranged cores  31 , and insulators  33  described later (shown in  FIG. 3 ). In the first embodiment, twenty-four cores  31  are arranged along a circumferential direction of the stator  3 . The twenty-four cores  31  are categorized into U-phase cores  31 U, V-phase cores  31 V and W-phase cores  31 W according to the positions thereof and are arranged such that the V-phase core  31 V is next to the U-phase core  31 U, the W-phase core  31 W next to the V-phase core  31 V and the U-phase core  31 U next to the W-phase core  31 W along a rotational direction R of the rotor  2  shown in  FIG. 1 . 
     The windings  32  wound around the U-phase cores  31 U are U-phase windings  32 U, the windings  32  wound around the V-phase cores  31 V are V-phase windings  32 V and the windings  32  wound around the W-phase cores  31 W are W-phase windings  32 W. The U-phase windings  32 U collect and distribute electricity (power collection and power distribution) via the first bus ring  41 . The V-phase windings  32 V collect and distribute electricity via the second bus ring  42 . The W-phase windings  32 W collect and distribute electricity via the third bus ring  43 . 
     An end portion  321 U, which is one of both end portions of the U-phase winding  32 U, is electrically connected to the first bus ring  41  and another end portion  322 U is electrically connected to the fourth bus ring  44 . An end portion  321 V, which is one of both end portions of the V-phase winding  32 V, is electrically connected to the second bus ring  42  and another end portion  322 V is electrically connected to the fourth bus ring  44 . In addition, an end portion  321 W, which is one of both end portions of the W-phase winding  32 W, is electrically connected to the third bus ring  43  and another end portion  322 W is electrically connected to the fourth bus ring  44 . 
     The first bus ring  41  is one aspect of a first annular conductor of the invention and the second bus ring  42  is one aspect of a second annular conductor of the invention. In addition, the third bus ring  43  is one aspect of a third annular conductor of the invention. The fourth bus ring  44  serves as a neutral-phase bus ring. 
     Power supply terminals  410 ,  420  and  430  are respectively connected to the first to third bus rings  41  to  43 . Drive currents having sine waveforms 120 degrees out of phase with each other are supplied from a non-illustrated inverter via the power supply terminals  410 ,  420  and  430 . A rotating magnetic field is created in the stator  3  by the drive currents, the magnet  22  receives a torque generated by an attractive force and a repulsive force caused by the rotating magnetic field and thus rotates the shaft  21 . The first to third bus rings  41  to  43  are fixed to each other by below-described fixing members  5  (shown in  FIG. 2 ). 
       FIG. 2  is a perspective view showing an appearance of the electricity collection and distribution ring  4  in the first embodiment.  FIG. 3  is a perspective view showing a state in which the electricity collection and distribution ring  4  is mounted on the stator  3 .  FIG. 4  is a plan view showing the stator  3  shown in  FIG. 3  and the first to third bus rings  41  to  43  as viewed from a central axis direction thereof.  FIG. 5  is a perspective view showing the first to third bus rings  41  to  43 . An axial direction, a radial direction and a circumferential direction of the first to third bus rings  41  to  43  are sometimes simply mentioned as “the axial direction”, “the radial direction” and “the circumferential direction” in the following description. 
     The electricity collection and distribution ring  4  is provided with the first to third bus rings  41  to  43  respectively connected to the multi-phase (U-, V- and W-phase) windings  32 U,  32 V and  32 W according to the phases of electric current, and plural fixing members  5  (twenty-four, in the first embodiment) for fixing the first to third bus rings  41  to  43  to each other. 
     In the first bus ring  41 , connecting portions  41   a  for connection to the end portions  321 U of the U-phase windings  32 U are provided at plural circumferential positions and each supported portion  41   b  located between a pair of adjacent connecting portions  41   a  is held by the fixing members  5 . In the second bus ring  42 , connecting portions  42   a  for connection to the end portions  321 V of the V-phase windings  32 V are provided at plural circumferential positions and each supported portion  42   b  located between a pair of adjacent connecting portions  42   a  is held by the fixing members  5 . In the third bus ring  43 , connecting portions  43   a  for connection to the end portions  321 W of the W-phase windings  32 W are provided at plural circumferential positions and each supported portion  43   b  located between a pair of adjacent connecting portions  43   a  is held by the fixing members  5 . 
     In the first embodiment, the connecting portions  41   a ,  42   a ,  43   a  of eight each are respectively provided on the first to third bus rings  41  to  43  at equal intervals. In addition, the first to third bus rings  41  to  43  are fixed to the fixing members  5  in a state of being concentrically aligned along the axial direction. The detailed configuration of the fixing member  5  will be described later. 
     The stator  3  is composed of plural core assemblies  30  in each of which the insulator  33  is attached to the core  31  formed by laminating plural electromagnetic steel sheets  310  and the winding  32  is wound around the outer periphery of the core  31  with the insulator  33  interposed therebetween. In the first embodiment, the stator  3  has a ring shape formed by annularly arranging twenty-four core assemblies  30 . 
     Meanwhile, the electricity collection and distribution ring  4  is arranged on the outer peripheral side of the stator  3  with respect to the windings  32  ( 32 U,  32 V,  32 W) and the end portions  321 U,  321 V and  321 W of the windings  32  extending outward in the radial direction are respectively connected to the connecting portions  41   a ,  42   a  and  43   a  of the first to third bus rings  41  to  43 . The other end portions  322 U,  322 V and  322 W of the windings  32  extending inward in the radial direction are connected to the fourth bus ring  44  (shown in  FIG. 1 ). 
     Configuration of First to Third Bus Rings  41  to  43   
     As shown in  FIG. 5 , each of the first to third bus rings  41  to  43  is formed by bending an insulated wire in which a center conductor (metal conductor)  400  formed of a highly conductive such as copper is covered with a resin insulation  401 . The center conductor  400  is exposed from the insulation  401  at both ends of each of the first to third bus rings  41  to  43  and the power supply terminal  410 ,  420  or  430  is connected to the exposed center conductor  400  by pressure bonding or crimping. 
       FIG. 6A  shows the connecting portion  41   a  and the supported portion  41   b  of the first bus ring  41 ,  FIG. 6B  shows the connecting portion  42   a  and the supported portion  42   b  of the second bus ring  42  and  FIG. 6C  shows the connecting portion  43   a  and the supported portion  43   b  of the third bus ring  43 . 
     The connecting portion  41   a  integrally has a U-shaped portion  411  formed by bending the center conductor  400  into a U-shape and a pair of extension portions  412  radially extending between both end portions of the U-shaped portion  411  and the supported portions  41   b . Likewise, the connecting portion  42   a  integrally has a U-shaped portion  421  formed by bending the center conductor  400  into a U-shape and a pair of extension portions  422  radially extending between both end portions of the U-shaped portion  421  and the supported portions  42   b . In the same way, the connecting portion  43   a  integrally has a U-shaped portion  431  formed by bending the center conductor  400  into a U-shape and a pair of extension portions  432  radially extending between both end portions of the U-shaped portion  431  and the supported portions  43   b.    
     In such a configuration, the first bus ring  41  and the U-phase windings  32 U are electrically connected at the connecting portions  41   a  in a state that the end portions  321 U of the windings  32 U are inserted into the U-shaped portions  411 . Likewise, the second and third bus rings  42  and  43  and the V- and W-phase windings  32 V and  32 W are electrically connected respectively at the connecting portions  42   a  and  43   a  in a state that the end portions  321 V and  321 W of the windings  32 V and  32 W are inserted into the U-shaped portions  421  and  431 . 
     The U-shaped portion  411  of the first bus ring  41  is composed of an arc portion  411   a  having an arc shape and a pair of shaft portions  411   b ,  411   c  which face each other in the circumferential direction with the arc portion  411   a  in-between and extend in the axial direction. Likewise, the U-shaped portion  421  of the second bus ring  42  is composed of an arc portion  421   a  having an arc shape and a pair of shaft portions  421   b ,  421   c  which face each other in the circumferential direction with the arc portion  421   a  in-between and extend in the axial direction. In the same way, the U-shaped portion  431  of the third bus ring  43  is composed of an arc portion  431   a  having an arc shape and a pair of shaft portions  431   b ,  431   c  which face each other in the circumferential direction with the arc portion  431   a  in-between and extend in the axial direction. 
     Arc-shaped protrusions  411   d  and  411   e  are formed respectively on the opposing portions of the paired shaft portions  411   b  and  411   c  of the first bus ring  41  so as to have a curvature which is larger than that of the outer peripheral surface of the center conductor  400  at the supported portion  41   b  and at the extension portion  412 . Surfaces of the paired shaft portions  411   b  and  411   c  opposite to the protrusions  411   d  and  411   e  are formed as flat side surfaces  411   f  and  411   g  which are orthogonal to the circumferential direction of the first bus ring  41 . 
     As show in  FIGS. 6B and 6C , arc-shaped protrusions  421   d ,  421   e ,  431   d  and  431   e  and flat side surfaces  421   f ,  421   g ,  431   f  and  431   g  are also formed on the pair of shaft portions  421   b ,  421   c  of the second bus ring  42  and the pair of shaft portions  431   b ,  431   c  of the third bus ring  43  in the same manner as the pair of shaft portions  411   b ,  411   c  of the first bus ring  41 . 
     The shaft portions  411   b  and  411   c  of the U-shaped portion  411  of the first bus ring  41  are shorter than the shaft portions  421   b  and  421   c  of the U-shaped portion  421  of the second bus ring  42 , and the shaft portions  431   b  and  431   c  of the U-shaped portion  431  of the third bus ring  43  are longer than the shaft portions  421   b  and  421   c  of the U-shaped portion  421  of the second bus ring  42 . This absorbs a difference of axial positions of the first to third bus rings  41  to  43  and end portions of the windings  32  on one side (the end portions  321 U,  321 V and  321 W) are thus inserted into the U-shaped portions  411 ,  421  and  431  in the vicinity of the arc portions  411   a ,  421   a  and  431   a.    
     Configuration of Fixing Member  5   
       FIG. 7A  is a perspective view showing an appearance of the fixing member  5 ,  FIG. 7B  is a side view showing the fixing member  5  and  FIG. 7C  is a top view showing the fixing member  5 . 
     Each fixing member  5  has a main body portion  50  and guide portions  51 ,  52  formed at both circumferential ends of the main body portion  50 . First to third recessed portions  500   a ,  500   b  and  500   c  which can partially house the first to third bus rings  41  to  43  are formed on the main body portion  50 . 
     The main body portion  50  is slightly curved along the circumferential direction so as to match the circumferential curvature of the supported portions  41   b ,  42   b  and  43   b  of the first to third bus rings  41  to  43 . 
     The main body portion  50  has a plate-like base portion  500  having a predetermined thickness in the radial direction, and an upper wall  501 , a first middle wall  502 , a second middle wall  503  and a lower wall  504  which are formed in a row along the axial direction so as to radially protrude from the base portion  500 . The first recessed portion  500   a  is formed between the upper wall  501  and the first middle wall  502 , the second recessed portion  500   b  is formed between the first middle wall  502  and the second middle wall  503  and the third recessed portion  500   c  is formed between the second middle wall  503  and the lower wall  504 . 
     The first to third recessed portions  500   a ,  500   b  and  500   c  are formed to extend along the circumferential direction and open in the radial direction. In the first embodiment, the first to third recessed portions  500   a ,  500   b  and  500   c  are formed to be recessed radially inward and to open radially outward. In addition, bottom surfaces  50   a ,  50   b  and  50   c  of the first to third recessed portions  500   a ,  500   b  and  500   c  are formed in an arc shape which matches the curvature of the outer peripheral surfaces of the first to third bus rings  41  to  43  (see  FIG. 2 ). 
     The guide portions  51  and  52  are formed respectively at both circumferential ends of the main body portion  50  so as to extend continuously from the bottom surfaces  50   a ,  50   b  and  50   c  of the first to third recessed portions  500   a ,  500   b  and  500   c  toward the inside in the radial direction. A pair of guide portions  51 ,  52  is formed so that outer surfaces continuous from the bottom surfaces  50   a ,  50   b  and  50   c  of the first to third recessed portions  500   a ,  500   b  and  500   c  are gently curved and a circumferential distance between the guide portions  51  and  52  increases toward the winding  32  (shown in  FIG. 3 ) which are located radially inward. 
     As shown in  FIG. 7B , the supported portion  41   b  is held in the first recessed portion  500   a  and the first bus ring  41  is thereby fixed to the fixing member  5 . The supported portion  42   b  is held in the second recessed portion  500   b  and the second bus ring  42  is thereby fixed to the fixing member  5 . Also, the supported portion  43   b  is held in the third recessed portion  500   c  and the third bus ring  43  is thereby fixed to the fixing member  5 . 
     An opening width W 1  of the first recessed portion  500   a  is smaller than the diameter of the supported portion  41   b  of the first bus ring  41 . Likewise, an opening width W 2  of the second recessed portion  500   b  and an opening width W 3  of the third recessed portion  500   c  are smaller than the diameters of the supported portions  42   b  and  43   b  of the second and third bus rings  42  and  43 . Thus, the supported portions  41   b ,  42   b  and  43   b  of the first to third bus rings  41  to  43  are compressively deformed in the axial direction and press-fitted. 
     Here, press-fitting is to compress the first to third bus rings  41  to  43  toward the bottom surfaces  50   a ,  50   b  and  50   c  of the first to third recessed portions  500   a ,  500   b  and  500   c . In more detail, it is compression by a force with which the first to third bus rings  41  to  43  compressed into the first to third recessed portions  500   a ,  500   b  and  500   c  do not easily fall out of the first to third recessed portions  500   a ,  500   b  and  500   c  (e.g., do not fall out due to own weight of the first to third bus rings  41  to  43 ). 
     As shown in  FIGS. 3 and 4 , plural fixing members  5  are attached to the first to third bus rings  41  to  43  at intervals along the circumferential direction, and pairs of extension portions  412 ,  422  and  432  of the first to third bus rings  41  to  43  are arranged between pairs of fixing members  5  adjacent in the circumferential direction of the first to third bus rings  41  to  43  so as to protrude in a direction of inserting the supported portions  41   b ,  42   b  and  43   b  into the first to third recessed portions  500   a ,  500   b  and  500   c.    
     In the first embodiment, since the supported portions  41   b ,  42   b  and  43   b  of the first to third bus rings  41  to  43  are inserted into the first to third recessed portions  500   a ,  500   b  and  500   c  in a radially inward direction, the connecting portions  41   a ,  42   a  and  43   a  are arranged to protrude inward toward the windings  32  between the pairs of adjacent fixing members  5 . Thus, when the electricity collection and distribution ring  4  is attached to the stator  3 , the U-shaped portions  411 ,  421  and  431  are positioned at locations of the end portions  321 U,  321 V and  321 W of the windings  32 U,  32 V and  32 W. 
     Meanwhile, a distance between a pair of circumferentially adjacent fixing members  5  is a distance corresponding to a circumferential width of a pair of connecting portions  41   a  of the first bus ring  41 , a circumferential width of a pair of connecting portions  42   a  of the second bus ring  42  and a circumferential width of a pair of connecting portions  43   a  of the third bus ring  43 . Here, “a corresponding distance” means to have a dimensional relationship which causes the pairs of extension portions  412 ,  422  and  432  to come into contact with the guide portions  51  and  52  of the fixing members  5  when fixing the first to third bus rings  41  to  43  to each other using the fixing members  5  and allows the pairs of connecting portions  41   a ,  42   a  and  43   a  to be arranged at equal intervals in the circumferential direction. In addition, this restricts relative movement of the first to third bus rings  41  to  43  in the circumferential direction. 
       FIG. 8A  is a plan view showing a portion of the electricity collection and distribution ring  4  as viewed from the axial direction. In the first embodiment, a circumferential width W U  between a pair of extension portions  412  of the first bus ring  41 , a circumferential width W V  between a pair of extension portions  422  of the second bus ring  42  and a circumferential width W W  between a pair of extension portions  432  of the third bus ring  43  are the same width. The widths W U , W V  and W W  shown in  FIG. 8A  are circumferential widths between middle portions of the extension portions  412 ,  422  and  432 . 
       FIG. 8B  is a plan view showing a state in which the fixing members  5  are attached to the first to third bus rings  41  to  43  of  FIG. 8A . A distance D between a pair of fixing members  5  adjacent in the circumferential direction of the first to third bus rings  41  to  43  (a distance between the guide portion  52  of one of the pair of fixing members  5  and the guide portion  51  of the other fixing member  5 ) is slightly larger than the widths W U , W V  and W W . The distance D is, e.g., not less than 1.01 and not more than 1.1 times the widths W U , W V  and W W . The distance D shown in  FIG. 8B  is a distance between portions of the fixing members  5  facing the middle portions of the extension portions  412 ,  422  or  432  shown in  FIG. 8A . 
     Functions and Effects of the First Embodiment 
     The following functions and effects are obtained in the first embodiment. 
     (1) Since the first to third bus rings  41  to  43  respectively have the connecting portions  41   a ,  42   a  and  43   a , holding rigidity of the fixing member  5  can be increased as compared to the case where the first to third bus rings  41  to  43  are fixed to each other by, e.g., holding members having attachment grooves for attaching junction terminals, and it is thus possible to increase rigidity of the electricity collection and distribution ring  4 . 
     (2) The fixing members  5 , which are the same single type and thus have the same shape, are used to fix the first to third bus rings  41  to  43 . Therefore, it is possible to mold the fixing members  5  by one set of molds and the number of types of components can be also reduced, which allows the manufacturing cost of the electricity collection and distribution ring  4  to be reduced. 
     (3) Since the supported portions  41   b ,  42   b  and  43   b  of the first to third bus rings  41  to  43  are inserted into the first to third recessed portions  500   a ,  500   b  and  500   c  by press fitting, the fixing members  5  once fixed are less likely to be detached from the first to third bus rings  41  to  43  and this makes assembly easy. 
     (4) Each of the first to third bus rings  41  to  43  is formed by bending one insulated wire to have the U-shaped portions  411 ,  421 ,  431 , the extension portions  412 ,  422 ,  432  and the supported portions  41   b ,  42   b ,  43   b , and the end portions  321 U,  321 V and  321 W of the U-, V- and W-phase windings  32 U,  32 V and  32 W are electrically connected to the first to third bus rings  41  to  43  in a state of being inserted into the U-shaped portions  411 ,  421  and  431 . Therefore, it is not necessary to use, e.g., connecting terminals to connect the first to third bus rings  41  to  43  to the U-, V- and W-phase windings  32 U,  32 V and  32 W and this allows production efficiency to be improved and the manufacturing cost of the electricity collection and distribution ring  4  to be reduced. 
     (5) The first to third bus rings  41  to  43  are fixed to the fixing members  5  at intervals along the circumferential direction. This allows the connecting portions  41   a ,  42   a  and  43   a  to protrude radially inward from between the pairs of circumferentially adjacent fixing members  5  and thus to be easily connected the end portions  321 U,  321 V and  321 W of the windings  32 U,  32 V and  32 W. 
     (6) Since the distance between the fixing members  5  adjacent in the circumferential direction of the first to third bus rings  41  to  43  corresponds to the circumferential width between the pair of extension portions  412 ,  422 ,  432  of the first to third bus rings  41  to  43 , the connecting portions  41   a ,  42   a  and  43   a  are arranged at equal distances when using the fixing members  5  to fix the first to third bus rings  41  to  43  to each other. This allows the U-shaped portions  411 ,  421  and  431  to be positioned at locations of the end portions  321 U,  321 V and  321 W of the windings  32 U,  32 V and  32 W when assembling the electricity collection and distribution ring  4  to the stator  3 . 
     Second Embodiment 
     Next, the second embodiment of the invention will be described. 
       FIG. 9  is a side view showing the fixing member  5  in the second embodiment. The fixing member  5  in the second embodiment is the same as the fixing member  5  in the first embodiment except the shape. Therefore, the same constituent elements as those described in the first embodiment are denoted by the same reference numerals as those used in the first embodiment and the overlapped explanation thereof will be omitted. 
     In the second embodiment, locking portions  501   a ,  502   a  and  503   a  for locking the first to third bus rings  41  to  43  are provided on the main body portion  50  of the fixing member  5  to prevent the first to third bus rings  41  to  43  from falling out of the first to third recessed portions  500   a ,  500   b  and  500   c.    
     The first recessed portion  500   a  for fixing the supported portion  41   b  (indicated by a dashed-two dotted line in  FIG. 9 ) of the first bus ring  41  is formed between the upper wall  501  and the first middle wall  502  and the locking portion  501   a  is formed to protrude from a front end portion of the upper wall  501  toward the first middle wall  502 . 
     Meanwhile, the second recessed portion  500   b  for fixing the supported portion  42   b  (indicated by a dashed-two dotted line in  FIG. 9 ) of the second bus ring  42  is formed between the first middle wall  502  and the second middle wall  503  and the locking portion  502   a  is formed to protrude from a front end portion of the first middle wall  502  toward the second middle wall  503 . 
     Furthermore, the third recessed portion  500   c  for fixing the supported portion  43   b  (indicated by a dashed-two dotted line in  FIG. 9 ) of the third bus ring  43  is formed between the second middle wall  503  and the lower wall  504  and the locking portion  503   a  is formed to protrude from a front end portion of the second middle wall  503  toward the lower wall  504 . 
     An opening width W A  (a distance between the locking portion  501   a  and the first middle wall  502 ) of the first recessed portion  500   a  is smaller than the diameter of the supported portion  41   b  of the first bus ring  41 . Likewise, an opening width W B  (a distance between the locking portion  502   a  and the second middle wall  503 ) of the second recessed portion  500   b  and an opening width W C  (a distance between the locking portion  503   a  and the lower wall  504 ) of the third recessed portion  500   c  are smaller than the diameters of the supported portions  42   b  and  43   b  of the second and third bus rings  42  and  43 . Thus, the first to third bus rings  41  to  43  are inserted into the first to third recessed portions  500   a ,  500   b  and  500   c  of the fixing member  5  by press-fitting while elastically deforming the upper wall  501 , the first middle wall  502  and the second middle wall  503 . 
     In the second embodiment, the locking portions  501   a ,  502   a  and  503   a  prevent the first to third bus rings  41  to  43  from falling out of the first to third recessed portions  500   a ,  500   b  and  500   c  more reliably than the first embodiment. 
     Third Embodiment 
     Next, the third embodiment of the invention will be described. 
       FIG. 10  is a perspective view showing a configuration example of the electricity collection and distribution ring  4  in the third embodiment. The electricity collection and distribution ring  4  in the third embodiment is the same as the first embodiment except the shapes of the connecting portions  41   a ,  42   a  and  43   a  of the first to third bus rings  41  to  43 . Therefore, the same constituent elements as those described in the first embodiment are denoted by the same reference numerals as those used in the first embodiment and the overlapped explanation thereof will be omitted. 
     The connecting portion  41   a  of the first bus ring  41  integrally has a U-shaped portion  411 A protruding radially inward of the first bus ring  41  and the extension portions  412 . That is, a protruding direction of the U-shaped portion  411 A of the connecting portion  41   a  in the third embodiment is different from that of the U-shaped portion  411  in the first embodiment. 
     Likewise, the connecting portions  42   a  and  43   a  of the second and third bus rings  42  and  43  respectively integrally have U-shaped portions  421 A,  431 A protruding radially inward of the second and third bus rings  42  and  43  and the extension portions  422 ,  432 . 
     The U-shaped portion  421 A of the second bus ring  42  is inclined in the axial direction so that the axial position of the tip end portion thereof is arranged at the same level as the position of the tip end portion of the U-shaped portion  411 A of the first bus ring  41 . Likewise, the U-shaped portion  431 A of the third bus ring  43  is inclined in the axial direction so that the axial position of the tip end portion thereof is arranged at the same level as the position of the tip end portion of the U-shaped portion  411 A of the first bus ring  41 . 
     This absorbs a difference of axial positions of the first to third bus rings  41  to  43  and the end portions  321 U,  321 V and  321 W (shown in  FIG. 3 ) of the windings  32  (shown in  FIG. 3 ) are thus inserted into the U-shaped portions  411 A,  421 A and  431 A when the electricity collection and distribution ring  4  is attached to the stator  3 . 
     In the third embodiment described above, it is possible to obtain the same functions and effects as the first embodiment. In addition, the first to third bus rings  41  to  43  can be made differently only by changing an inclination angle of the U-shaped portions  421 A and  431 A. 
     Although the embodiments of the invention have been described above, the invention according to claims is not to be limited to the embodiments. Further, all combinations of the features described in the embodiments are not always needed to solve the problem of the invention. 
     For example, the first to third bus rings  41  to  43  may be fixed such that the connecting portions  41   a ,  42   a  and  43   a  of the first to third bus rings  41  to  43  protrude radially outward from between the pairs of circumferentially adjacent fixing members  5  and the supported portions  41   b ,  42   b  and  43   b  of the first to third bus rings  41  to  43  are inserted into the first to third recessed portions  500   a ,  500   b  and  500   c  toward the outside in the radial direction. 
     SUMMARY OF THE EMBODIMENTS  
     Technical ideas understood from the embodiments will be described below citing the reference numerals, etc., used for the embodiments. However, each reference numeral described below is not intended to limit the constituent elements in the claims to the members, etc., specifically described in the embodiments. 
     [1] An electricity collection and distribution ring ( 4 ) for collecting and distributing electricity from/to multi-phase windings ( 32 ) respectively wound around a plurality of annularly-arranged cores ( 31 ), comprising: a plurality of annular conductors ( 41  to  43 ) respectively connected to the multi-phase windings ( 32 ) according to the phases of electric current; and a plurality of fixing members ( 5 ) for fixing the plurality of annular conductors ( 41  to  43 ) to each other, wherein the annular conductor ( 41 ,  42 ,  43 ) comprises a plurality of connecting portions ( 41   a ,  42   a ,  43   a ) connected to end portions of the windings ( 32 ) at a plurality of positions in a circumferential direction, and the plurality of fixing members ( 5 ) are arranged between pairs of the connecting portions ( 41   a ,  42   a ,  43   a ) adjacent along a circumferential direction of the plurality of annular conductors ( 41  to  43 ). 
     [2] The electricity collection and distribution ring ( 4 ) described in the [1], wherein the fixing member ( 5 ) comprises a plurality of recessed portions ( 500   a ,  500   b  and  500   c ) for respectively housing portions of the plurality of annular conductors ( 41  to  43 ), and supported portions ( 41   b ,  42   b  and  43   b ) of the plurality of annular conductors ( 41  to  43 ) to be held by the fixing member ( 5 ) are inserted into the recessed portions ( 500   a ,  500   b  and  500   c ) by press-fitting. 
     [3] The electricity collection and distribution ring ( 4 ) described in the [1] or [2], wherein locking portions ( 501   a ,  502   a  and  503   a ) are provided on the fixing member ( 5 ) to lock the plurality of annular conductors ( 41  to  43 ) and thus to prevent the annular conductors ( 41  to  43 ) from falling out of the recessed portions ( 500   a ,  500   b  and  500   c ). 
     [4] The electricity collection and distribution ring described in any of the [1] to [3], wherein the connecting portion ( 41   a ,  42   a ,  43   a ) integrally comprises a U-shaped portion ( 411 ,  421 ,  431 ) formed by bending into a U-shape and extension portions ( 412 ,  422 ,  432 ) radially extending between both end portions of the U-shaped portion ( 411 ,  421 ,  431 ) and the supported portions ( 41   b ,  42   b ,  43   b ) to be held by the fixing member ( 5 ), and the annular conductors ( 41  to  43 ) are electrically connected to the windings ( 32 ) in a state that the end portions of the windings ( 32 ) are inserted into the U-shaped portions ( 411 ,  421 ,  431 ). 
     [5] The electricity collection and distribution ring described in any of the [1] to [4], wherein the plurality of recessed portions ( 500   a ,  500   b  and  500   c ) are aligned in an axial direction of the annular conductor ( 41 ,  42 ,  43 ) and open in a radial direction of the annular conductor ( 41 ,  42 ,  43 ), and the connecting portions ( 41   a ,  42   a ,  43   a ) of the plurality of annular conductors ( 41  to  43 ) protrude from between pairs of the adjacent fixing members ( 5 ) in a direction of inserting the supported portions ( 41   b ,  42   b  and  43   b ) into the recessed portions ( 500   a ,  500   b  and  500   c ). 
     [6] The electricity collection and distribution ring described in the [5], wherein a distance between a pair of the fixing members ( 5 ) adjacent in a circumferential direction of the plurality of annular conductors ( 41  to  43 ) corresponds to a distance between a pair of the extension portions ( 412 ,  422 ,  432 ).