Patent Publication Number: US-2009230808-A1

Title: Motor stator and motor stator manufacturing method

Description:
TECHNICAL FIELD 
     The present invention relates to a structure of a stator used in a motor and more particularly to a motor stator structure which uses laminated conductors. 
     BACKGROUND ART 
     Heretofore, mainstream stators for use in motors have been winding type stators in which enamel-coated copper wires are inserted into slots in an inner periphery of a stator core and an enamel-coated copper wire is wound around a teeth portion formed between slots. Recently, a stator using laminated conductors for the purposes of stator compactness and high power output as described in JP2001-178053A has also been proposed. 
     The stator using laminated conductors is more advantageous in two points than the winding type stator. The first advantage is that by adopting a method whereby laminated conductors inserted in slots are joined using an end connecting conductor formed of a laminate of thin plates, the thickness of coil end portions which would expand in the case of the winding type can be reduced, thereby contributing to stator size reduction. 
     The second advantage is as follows: in connection with higher motor power output, the winding type stator, in which an enamel-coated copper wire is wound around the teeth portion of the stator, must provide the minimum bending radius to prevent the enamel coating from cracking and thus has a limitation that the thickness of the winding itself cannot be larger than a given level. In contrast, the laminate type stator is so constructed as to use a connecting conductor as a separate member to connect the end portions, which means that the cross-section area of the inside of a slot can be larger and the space factor of conductors in the slot can be increased to increase the current density. 
       FIG. 21  is an exploded perspective view of a motor in JP2001-178053A disclosed as an example of the laminate type stator. 
     The motor of JP2001-178053A is constituted by combining a stator core  110  with laminated coil pieces  120 , an annular first connecting coil piece  130 , a second connecting coil piece  140  and a connecting ring  150 . Each laminated coil piece  120  is formed by integrally molding two sets of linear laminated thin plate conductors with an insulating resin. The first connecting coil piece  130  and the second connecting coil piece  140  are formed by integrally molding a laminated thin plate conductor with an insulating resin. The connecting ring  150  is formed by combining connecting wires for U, V and W phases and a neutral wire and arranging them in an annular pattern and integrally molding them with an insulating resin. 
     Then, a machined end portion of one laminated coil piece  120  which is inserted into a slot  114  of the stator core  110 , and an end portion of another laminate coil piece  120  inserted into another slot  114  are brought face-to-face with machined end portions of thin plates constituting the first connecting coil piece  130  and the second connecting coil piece  140  and joined by welding and electrically connected. 
     Since the laminate type stator is thus constructed by combining laminated conductors by resin molding and electrically connecting them by welding, the end portions of the stator are equivalent in size to the thicknesses of the first connecting coil piece  130 , the second connecting coil piece  140  and the connecting ring  150 , offering an advantage in making the stator compact. Also, each laminated coil piece  120  to be inserted into each slot  114  is made by laminating thin plates and thus the space factor of the slot  114  can be increased to increase the current density, offering an advantage in increasing the stator power output. 
     However, in manufacturing the motor stator as disclosed in JP2001-178053A, there should be as many as  400  joints between thin plates. Therefore, when joints between thin plates are welded as described in JP2001-178053A, even if a welding technique such as TIG welding or laser welding is employed, the position of a TIG welding torch or laser welding spot must be accurately adjusted to all joints, resulting in a long welding time and higher cost. 
     In addition, the heat generated during welding might burn the enamel covering the thin plates. Besides, since thin plate end portions are machined, machining cost is required; and also for welding, the laminated coil piece  120 , first connecting coil piece  130  and second connecting coil piece  140  have to be positioned with high accuracy. 
     To solve the problems which might be caused in JP2001-178053A, the present applicant has proposed a stator manufacturing method and a motor stator manufactured by the method in JP2005-137174A. This method uses a conductive adhesive agent to connect thin plates. More specifically, after thin plates are press molded, an end portion of at least one thin plate is coated with conductive adhesive and, after assembling, pressure is applied to join plates. According to this method, the time required for connection can be reduced. 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, the prior art JP2005-137174A has a problem about the assemblability of end portions. More specifically, when the connecting surface of one thin plate end portion is coated with conductive adhesive as suggested in JP2005-137174A, if an edge of the other thin plate scrapes the surface coated with conductive adhesive, the conductive adhesive might peel off. In order to avoid this, it is required to improve the component manufacturing accuracy and to assemble components so as to ensure that the components are in adequate relative positions. However, both requirements cause increase in cost. 
     On the other hand, if the conductive adhesive coated on the connecting surface of the thin plate end portion should peel off, the contact area would decrease and thus the resistance in the contact surface might become larger. If the resistance in the contact surface is larger, the motor will generate more heat. 
     Particularly, driving motors for hybrid vehicles are required to provide higher power output and higher density than conventional motors. If a high voltage current flows through a high-density motor stator, the motor would generate more heat, posing a problem with the durability of the motor or the like. 
     In the technique described in JP2001-178053A, each laminated coil piece  120  is formed by integrally molding two sets of linear laminated conductors with an insulating resin. Molding components integrally in this way is an additional molding step, posing a problem of cost rise. 
     The present invention has been made in view of the above circumstances and has an object to provide a motor stator allowing assembly with high efficiency and at low cost and a manufacturing method for the motor stator. 
     Means for Solving the Problems 
     To achieve the above object, the present invention provides the following configurations.
     (1) A stator for motor, comprises: a stator core formed with a plurality of slots in an inner periphery thereof; a plurality of laminated conductors each including a plurality of thin plates, each laminated conductor being inserted in each slot; and an end connecting conductor including a plurality of laminated connecting thin plates each having a connecting portion for connecting an end portion of one of the laminated conductors to an end portion of another laminated conductor; wherein the end portion of each thin plate and the connecting portion of each connecting thin plate are tapered in thickness.   (2) In the stator for motor (1), the end portion of each thin plate and the connecting portion of each connecting thin plate are tapered in thickness to have slanted surfaces on one sides, the end portion of each thin plate and the connecting portion of each connecting thin plate are provided with an insulating layer on a non-slanted surface, and an adhesive is applied in a layer on at least one of the slanted surface of the connecting portion of the connecting thin plate of the connecting conductor and the slanted surface of the end portion of the thin plate of each laminated conductor.   (3) A stator for motor, comprises: a stator core formed with a plurality of slots in an inner periphery thereof; a first laminated conductor and a second laminated conductor, each of which includes a plurality of laminated thin plates, inserted in the same slot; wherein the first and second laminated conductors are encased in an insulating case while an insulating plate is interposed between the first and second laminated conductors.   

     According to another aspect, the present invention provides the following configurations.
     (4) A method of manufacturing a stator for motor comprises: a stator core formed with a plurality of slots in an inner periphery thereof a plurality of laminated conductors each having a plurality of thin plates, each laminated conductor being inserted in each slot; and an end connecting conductor including a plurality of laminated connecting thin plates each having a connecting portion for connecting an end portion of one of the laminated conductors to an end portion of another laminated conductor; wherein the end portion of each thin plate and the connecting portion of each connecting thin plate are tapered in thickness, the plurality of thin plates have different thickness from each other, the plurality of connecting thin plates has the same thickness, and the manufacturing method comprises a step of adjusting positions of the connecting thin plates to between the thin plates of one of the laminated conductor and between the thin plates of another laminated conductor to be connected to the former one by use of a guide, and assembling the end connecting conductor to the laminated conductors.   

     The functions and advantages of the motor stator configured as above are explained below. 
     According to the configuration (1), the end portion of each thin plate and the connecting portion of each connecting thin plate are both tapered in thickness. Accordingly, in the process of assembling the end connecting conductor including the plurality of laminated connecting thin plates to the laminated conductors each including the plurality of thin plates inserted in different slots to connect the end portions of the different laminated conductors, the slanted surfaces of the tapered portions are unlikely to contact with each other up to a final stage of assembly. Thus, an adhesive layer or others on each tapered portion is unlikely to peel off. 
     According to the configuration (2), the end portion of each thin plate and the connecting portion of each connecting thin plate are tapered in thickness to have slanted surfaces on one sides, and the end portion of each thin plate and the connecting portion of each connecting thin plate are provided with an insulating layer on a non-slanted surface, and an adhesive is applied in a layer on at least the slanted surface of the connecting portion of the connecting thin plate. Accordingly, the area of the slanted surface can be larger to allow the adhesive to be applied wider, leading to a reduction in the contact resistance at joints between the conductors. Further, the insulating layer is formed on the non-slanted surface, so that insulation between the thin plates of each laminated conductor can be easily ensured. 
     In particular, the end portion of each thin plate and the connecting portion of each connecting thin plates are wholly tapered in thickness to have a slanted surface. This makes it possible to reduce the range where the slanted surfaces contact with each other. 
     According to the configuration (3), the stator for motor comprises the stator core formed with the plurality of slots in an inner periphery thereof and the first and second laminated conductors, each of which includes the plurality of laminated thin plates, inserted in the same slot. The first and second laminated conductors are encased in the insulating case while the insulating plate is interposed between the first and second laminated conductors. Accordingly, the first and second laminated conductors can be integrally combined by a simple assembling work without needing a molding process, while insulation is ensured therebetween. 
     The functions and advantages of the method of manufacturing the stator for motor, described in (4) are explained below. 
     Both end portions of each thin plate of the laminated conductor and both connecting portions of each connecting plate of the end connecting conductor are tapered in thickness. The plurality of thin plates is gradually different in thickness from one thin plate placed at one end in the direction of lamination to another thin plate placed at the other end. 
     On the other hand, the plurality of connecting thin plates has the same thickness, and thus it is difficult to assemble the end connecting conductor to the laminated conductor as compared with the case where the connecting thin plates have the same thickness. 
     Further, if the plurality of thin plates is different in width from one another, the thin plates can have the same cross-sectional area. 
     According to the present invention, in assembling the end connecting conductor to the different laminated conductors, the guide is used to adjust the positions of the connecting thin plates to between the thin plates of the different laminated conductors. Accordingly, the slanted surfaces of the tapered portions are unlikely to contact with each other up to a final stage of assembly. Thus, an adhesive layer or others on each tapered portion is unlikely to peel off. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a perspective view showing the shapes of a first laminated conductor, a second laminated conductor, and an end connecting conductor; 
         FIG. 2  is perspective view of a stator core in which the first and second laminated conductors are fitted; 
         FIG. 3  is a perspective view of an assembly of  FIG. 2  to which the end connecting conductor is assembled; 
         FIG. 4  is a perspective view of an assembly of  FIG. 3  to which a connecting terminal, U-,V-,W-phases terminals, and a neutral terminal are connected; 
         FIG. 5  is a perspective view of the first laminated conductor; 
         FIG. 6  is a perspective view showing a configuration that the first and second laminated conductors are placed interposing therebetween a plate-like insulating resin insulator; 
         FIG. 7  is a perspective view showing a configuration that the first and second laminated conductors interposing the insulating plate are covered with a insulating case; 
         FIG. 8  is a perspective view of the stator core; 
         FIG. 9A  is a schematic front view showing a device for inserting connecting plates of the end connecting conductor into the first laminated conductor; 
         FIG. 9B  is a schematic right side view showing the device for inserting the connecting plates of the end connecting conductor into the first laminated conductor; 
         FIG. 10  is a perspective view showing another example of the first and second laminated conductors; 
         FIG. 11  is a schematic diagram showing a first state in a process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 12  is a schematic diagram showing a second state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 13  is a schematic diagram showing a third state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 14  is a schematic diagram showing a fourth state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 15  is a schematic diagram showing a fifth state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 16  is a schematic diagram showing a sixth state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 17  is a schematic diagram showing a seventh state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 18  is a schematic diagram showing an eighth state in the process for assembling the end connecting conductor to the first and second laminated conductors; 
         FIG. 19  is a perspective view of a stator core assembled with a U-shaped laminated conductor in a second embodiment; 
         FIG. 20  is a perspective with of the assembly of  FIG. 19  to which an end connecting conductor is connected; and 
         FIG. 21  is an exploded perspective view showing a configuration of a stator core in a prior art. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A motor stator of a first embodiment of the present invention will be described in detail referring to accompanying drawings. It is to be noted that the number of components and the size of each component in the following explanations are merely examples and may be changed appropriately.  FIG. 2  is a perspective view of a stator core  10  in which a first laminated conductors  11  and a second laminated conductors  12  are fitted. 
       FIG. 8  is a perspective view of the stator core  10 . The stator core  10  is a laminate of plural flat electromagnetic steel plates, taking the form of a hollow cylinder. Eighteen slots  24  and eighteen teeth portions  25  each formed between slots  24  are provided in an inner periphery of the stator core  10 . The stator core  10  has three bolt holes  26 . 
       FIG. 5  shows a perspective view of a second laminated conductor  12  formed in such a way that nine thin plates  31  each having both end portions tapered in side view (in thickness) with slanted surfaces  31   a  whereby the thickness of each end portion becomes gradually smaller toward the outermost end. Each slanted surface  31   a  forms an angle of 6 degrees with respect to a flat surface of the end portion. The thin plates  31  are all copper plates with a thickness of 0.5 mm. Each thin plate  31  includes an insulating layer  31   b  on the surface where the slanted surface  31   a  is not formed. The process of forming the insulating layer  31   b  is explained below. Thermosetting adhesive is applied to one side of insulating tape made of polyimide or amidoimide. A heat roller is then made to run over it with the adhesive-coated surface stuck to the thin plate  31  to let the thermosetting adhesive set, so that the insulating tape serving as the insulating layer  31   b  is attached to one surface of the thin plate  31 . The first laminated conductor  11  is structurally the same as the second laminated conductor and a detailed description thereof is omitted here. 
     As shown in  FIG. 6 , the first laminated conductor  11  and the second laminated conductor  12  are arranged with am insulating plate  23  made of resin (insulating material) interposed therebetween. They are encased in an insulating case made of resin (insulating material) as shown in  FIG. 7 . As shown in  FIG. 6 , the insulating plate  23  has a thin middle portion and thicker end stepped portions  23   b  at both ends. A notch  30   c  is formed in the side of the end portion of the thin plate  30 . By engaging this notch  30   c  with the stepped portion  23   b  of the insulating plate  23 , the first laminated conductor  11  and the second laminated conductor  12  are longitudinally positioned in place. The insulating case  28  is formed with a flange  28   a  at one end. 
     A set of the first laminated conductor  11  and the second laminated conductor  12 , encased in the insulating case  28  with the insulating plate  23  interposed therebetween as shown in  FIG. 7 , is inserted into each of the slots  24 . At this time, the flange  28   a  comes into contact with an end face of the stator core  10  so that the insulating case  28  is positioned in place. On the other hand, the positions of the first laminated conductor  11 , second laminated conductor  12 , and insulating plate  23  are not determined relative to the insulating case  28 . However, as shown in  FIG. 2 , the positions of the first laminated conductor  11  and second laminated conductor  12  are determined relative to an end face of the stator core  10  in the height direction by a jig (not shown). In other words, the height of the first laminated conductor  11  and second laminated conductor  12  from the end face of the stator core  10  is fixed. 
     Next, referring to  FIG. 1 , how to connect thin plates  30  of the first laminated conductor  11  inserted in one slot  24  and thin plates  31  of one second laminated conductor  12  inserted in an adjacent  24  slot will be explained. 
     Firstly, an end connecting conductor  13  is comprised of nine connecting thin plates  32  which are laminated. Each connecting thin plate  32  has connecting portions  13   a  at both ends each being tapered downward in thickness to have a slanted surface  32   a  on one side. The inclination angle of the slanted surface  32   a  is 6 degrees relative to the vertical plane (the surface opposite the slanted surface  32   a ). In other words, the angle of the slanted surface  32   a  of the end connecting conductor  13  is different in direction from the angle of the slanted surface  30   a  of the thin plate  30  of the first laminated conductor  11  but the same in absolute value. An adhesive layer  27  is coated on each slanted surface  32   a.    
     Next, how to form the adhesive layer  27  will be explained. 
     The adhesive layer  27  is formed by evenly applying particulate silver (in a gel state) dissolved in an organic solvent with a thickness of 10 μm by screen printing. More specifically, a gel silver solvent is applied with a mesh (mesh pitch: 200 μm) placed over a target area of the slanted surface  32   a.  At this time, a raised portion is formed around the target area by scribing in order to prevent the silver solvent from overflowing. Then, the silver solvent on the mesh is scraped off by a scraper. Then the mesh is removed. Consequently, a gel layer with a thickness of 10 μm is formed. The solvent is then evaporated and dried by heating. After drying, a silver paste coating is left, which does not easily come off even if slightly touched or rubbed, but would come off if rubbed with a sharp edge. Such rubbing should be avoided as far as possible in order to ensure stability in product performance. 
     All the nine thin plates  32  constituting the end connecting conductor  13  have the same thickness t (0.5 mm in the present embodiment). 
     On the other hand, as shown in  FIG. 1 , when the thin plates  30  and thin plates  31 , which constitute the first laminated conductor  11  and second laminated conductor  12  respectively, have the same thickness (T=0.5 mm) as that of the thin plate  32 , the thin plates  30 ,  31  can be engaged directly with the thin plates  32  of the end connecting conductor  13  because the array pitch of the thin plates  30  and  31  is the same as the array pitch of the thin plates  32 . 
     However, in order to increase the power output of the motor, it is necessary to improve the conductor space factor in a slot. For this reason, generally, thin plates  30  and thin plates  31  arranged in one slot  24  are gradually wider in width from the inner periphery side to the outer periphery side of the slot  24  (i.e., in a radially outward direction of the stator core  10 ) so as to match the shape of the slot  24  of which width is larger on its outer periphery side. 
     Simultaneously, as shown in  FIG. 10 , the innermost thin plates  30 ,  31  are different in thickness from the outermost thin plates  30 ,  31 . More specifically, the thin plates  30 ,  31  are gradually smaller in thickness from the innermost one to the outermost one. Thus, the outermost thin plates  30 ,  31  are the thinnest. Since the thickness is different in the above manner, the sectional area of the innermost thin plates  30 ,  31  and that of the outermost thin plates  30 ,  31  are made equal in a direction perpendicular to the height direction. 
     In other words, the thickness of the innermost thin plates  30 ,  31  is larger than that of the outermost thin plates  30 ,  31 . This means that the slanted surfaces  30   a  and  31   a  of the first laminated conductor  11  and second laminated conductor  12  are not arranged with a constant pitch. 
     In contrast, the connecting thin plates  32  of the end connecting conductor  13  are all arranged with a constant pitch. If an attempt is made to directly insert the thin plates  32  between the thin plates  30  or  31 , tips of some plates of the first laminated conductor  11  and second laminated conductor  12  might scrape the adhesive layers  27  of the end connecting conductor  13  and peel the adhesive layers  27 . 
     While the width of the thin plates  30 ,  31  are larger toward the outer periphery side of the slot  24 , the slanted surfaces  32   a  of the thin plates  32  of the end connecting conductor  13  is designed to be fixed and also equal to the width of the outermost thin plates  30 ,  31 . 
     There is substantially no difficulty in assembling the end connecting conductor  13  to the first laminated conductor  11  and second laminated conductor  12  as shown in  FIG. 1  using the thin plates  30 ,  31  with the same thickness. Therefore, how to assemble the end connecting conductor  13  to the first laminated conductor  11  and second laminated conductor  12  as shown in  FIG. 10  using the thin plates  30 ,  31  of different thicknesses will be described below. 
     Specifically, to avoid a problem which tends to occur in such configuration, a guide member is used to determine the positions of the thin plates  32  of the end connecting conductor  13  relative to the thin plates  30  of the first laminated conductor  11  and the thin plates  31  of the second laminated conductor  12  so that the thin plates  32  are appropriately inserted between the thin plates  30  or  31 . An inserting manner using the guide member will be explained referring to  FIGS. 9A and 9B  and  FIGS. 11 to 18 . 
       FIGS. 9A and 9B  show a device for inserting the thin plates  32  of the end connecting conductor  13  into a first laminated conductor  11 .  FIG. 9A  is a front view and  FIG. 9B  is a right side view. The device for inserting the thin plates  32  into a second laminated conductor  12  is symmetrical to that of  FIGS. 9A and 9B , and therefore the device and the second laminated conductor  12  are not shown and their explanations are omitted. 
     Since the thin plates  32  of the end connecting conductor  13  all have the same thickness and shape, many ones can be housed in a cartridge  42  and to be supplied to a manufacturing line. The thin plates (nine plates in the present embodiment)  32  are separated by a shutter  41  and moved down. Just under them, the first laminated conductor  11  fitted in one slot  24  of the stator core  10  is located. A separator  43  provided with a guide member  33  including four guide pieces  33   a,    33   b,    33   c ,  33   d  is interposed between the end connecting conductor  13  and the first laminated conductor  1 . The guide pieces  33   a,    33   b,    33   c  and  33   d  are made of super steel and polished and held in such a manner as to be easily deformable toward clearance so that even if a guide surface of each guide piece touches and rubs the adhesive layer  27 , it does not affect the adhesive layer  27  seriously. The upper end of each guide piece  33   a,    33   b ,  33   c,    33   d  is rounded to prevent the upper end from scraping the adhesive layer  27 . 
     Each guide piece  33   a,    33   b,    33   c,    33   d  covers not the whole area of the adhesive layer  27  but almost half of the same in its width direction as shown in  FIG. 9A . This is intended to minimize the possibility of the adhesive layer  27  being rubbed by the guide pieces  33   a,    33   b,    33   c,    33   d . Although each guide piece  33   a,    33   b,    33   c,    33   d  covers almost half of the adhesive layer  27  in this embodiment, the guide pieces may be designed to have a smaller width to cover a smaller area of adhesive layer  27  in the width direction. 
     In  FIG. 11 , the right hand side of the first laminated conductor  11  corresponds to the outer periphery side of the stator core  10  and the left hand side corresponds to the inner periphery side. The figure shows that the thin plates  30  placed on the left side are thicker than those on the right side. When the end connecting conductor  13  is to be assembled to the first laminated conductor  11 , it is less difficult to directly insert the thin plates  32  of the end connecting conductor  13  into the plates  30  if they are thinner. On the other hand, if the plates  30  are thicker, the tips of the plates  30  are likely to scrape the adhesive layers  27  of the thin plates  32  of the end connecting conductor  13 . Hence, the guide member  33  is used mainly in guiding left-hand thin plates  30  of the first laminated conductor  11 . 
       FIG. 12  shows that the shutter  41  is slightly down. The top end of the guide piece  33   a  located at the highest. position enters the space between the third and fourth ones of the nine connecting thin plates  32  from the left end. As the shutter  41  further goes down, the guide piece  33   a  fully enters the space between the third and fourth thin plates  32  from the left end. Accordingly, the thin plates  32  are completely divided into two groups, three on the left and six on the right, as shown in  FIG. 13 . 
       FIG. 15  shows that the shutter  41  has further moved down. The guide piece  33   b  whose upper end is at the second highest position enters the space between the second and third thin plates  32  from the left end. The guide piece  33   c  whose upper end is at the third highest position enters the space between the fourth and fifth thin plates  32  from the left end. The guide piece  33   d  whose upper end is at the lowest position enters the space between the first and second thin plates  32  from the left end. 
     As the shutter  41  is moved down further, the four guide pieces  33   a,    33   b,    33   c,    33   d  increase the space between the first and second plates, the space between the second and third plates, the space between the third and fourth plates, and the space between the fourth and fifth plates as shown in  FIG. 16 , respectively. Accordingly, the thin plates  32  of the end connecting conductor  13  are positioned so that, even when the thin plates  32  are inserted between the thin plates  30  of the first laminated conductor  11 , the tips of the thin plates  30  do not touch the adhesive layers  27  of the thin plates  32 . 
     In this state, the nine connecting thin plates  32  are inserted between the nine thin plates  30  as shown in  FIGS. 17 and 18 . Thus, the tips of the thin plates  30  are unlikely to rub the adhesive layers  27  of the slanted surfaces  32   a  of the connecting thin plates  32 , whereby the adhesive layers  27  are unlikely to be peel off. 
     After the end connecting conductor  13  is assembled to the first laminated conductor  11  in one slot  24  and the second laminated conductor  12  in an adjacent slot  24 , the first laminated conductor  11  and the end connecting conductor  13  are heated together under pressure from both sides in the direction of a row of the thin plates  30  and the connecting thin plates  32  alternately arranged. This heats the silver paste of the adhesive layer  27  partially in a concentrated manner, making silver soldering of the laminated conductor  11  and the end connecting conductor  13 . This silver soldering is similarly performed on the second laminated conductor  12  and the end connecting conductor  13 . 
     In the above way, all the end connecting conductors  13  to the corresponding laminated conductors  11  and  12 . In the present embodiment, as shown in  FIG. 3 , on one end face (an upper face in the figure) of the stator core  10 , eighteen end connecting conductors  13  are assembled and silver-soldered to the first laminated conductors  11  and second laminated conductors  12  inserted in eighteen slots  24 . 
     Successively, the stator core  10  with the end connecting conductors  13  silver-soldered to the first laminated conductors  11  and second laminated conductors  12  is turned over, and end connecting conductors  13  are assembled and silver-soldered to the first laminated conductors  11  and second laminated conductors  12  on an opposite end face (a lower face in the figure) of the stator core  10 . This process is almost the same as the abovementioned and hence only a difference will be described and the same points will not be repeated. 
     The difference is that the first thin plate  30  of the first laminated conductor  11  is connected with the second thin plate  31  of the second laminated conductor  12  as shown in  FIG. 20 . In this way, the n-th thin plate  30  of the first laminated conductor  11  and the (n+1)-th thin plate  31  of the second laminated conductor  12  are connected sequentially. Such connection between the first laminated conductor  11  in one slot  24  and the second laminated conductor  12  in an adjacent slot  24  makes a loop between the first thin plate  31  of the second laminated conductor  12  and the ninth thin plate  30  of the first laminated conductor  11 . The ninth thin plate  30  of the first laminated conductor  11  and the first thin plate  31  of the second laminated conductor are unconnected. 
     Next, connecting terminals  20 ,  21 , and  22  (see  FIG. 4 ) for constituting three phases U, V, and W respectively are connected sequentially. More specifically, the unconnected ninth thin plate  30  of the first laminated conductor  11  is connected with the first thin plate  31  of a second conductor  12  of the third phase next one (next but two) and such connections are made sequentially. Consequently, a U-phase coil, a V-phase coil and a W-phase coil are formed on the whole circumference of the stator core  10 . 
     Then, a U-phase terminal  14  and a neutral line terminal  17  are connected to an end of the U-phase coil. A V-phase terminal  15  and a neutral line terminal  18  are connected to an end of the V-phase coil. A W-phase terminal  16  and a neutral line terminal  19  are connected to an end of the W-phase coil. 
     Next, though not shown, the stator core  10 , end connecting conductors  13 , first laminated conductors  11  and second laminated conductors  12  and so on are covered are covered by insert molding using a die while only the U, V and W phase terminals  14 ,  15 ,  16  and neutral line terminals  17 ,  18 ,  19  are left outside the die. A stator is thus completed. 
     As detailed above, the motor stator in the present embodiment includes: the stator core  10  with the plurality of slots  24  in an inner periphery, the first laminated conductors  11  each having the plurality of laminated thin plates  30  to be inserted into each slot  24 , the second laminated conductors  12  each having the plurality of laminated thin plates  31  to be inserted into each slot  24 , and the end connecting conductors  13  each having the plurality of laminated connecting thin plates  32  for connecting a first laminated conductor  11  in one slot  24  to a second laminated conductor  12  in another slot  24 . The end portions of thin plates  30  and  31  and the connecting portions  13   a  of the thin plates  32  are tapered in thickness. Thus, when the adhesive layers  27  are coated on the slanted surfaces, the adhesive layers  27  are unlikely to be damaged in the process of assembling the end connecting conductor  13  to the first and second laminated conductors  11  and  12  without causing an increase in the resistance at joints, leading to less heat generation. 
     In addition, the end portion of each thin plate  30 ,  31  and the connecting portion of each thin plate  32  are formed with the slanted surfaces  30   a,    31   a  and  32   a  on one side respectively. Further, the insulating layers  30   b,    31   b  are formed on the non-slanted surfaces of the thin plates  30 ,  31 , opposite to the slanted surfaces  30   a,    31   a.  The adhesive layers  27  are formed on the slanted surfaces  32   a  of the connecting portions  13   a  of the thin plates  32 . Accordingly, the area of a slanted surface can be larger to allow adhesive to be coated wider, leading to a reduction in the contact resistance at joints between conductors. Besides, since the insulating layers are formed on non-slanted surfaces, insulation between the thin plate conductors can be easily assured. 
     Furthermore, since the connecting surface is wholly slanted, the following advantage can be obtained. Even if only the end portions of the connecting surfaces of the thin plates are slanted, it is possible to prevent the adhesive layers from being scraped off by an end portion edge. However, when the connecting surfaces are wholly slanted as above, the range of rubbing by contact between the slanted surfaces can be reduced. Also, if only the end portions should be slanted, a space with no mutual contact would be generated there; however, since more current flows in the shortest distance area as a current flows from a laminated conductor to a connecting conductor, if there should be a space around the root of the joint of the laminated conductor, the problem of increased contact resistance would arise. This problem can be avoided by the connecting surfaces in the present embodiment which are wholly slanted. 
     Furthermore, the motor stator of the present embodiment includes the stator core  10  with the slots  24  in an inner periphery, and a set of the first and second laminated conductors  11  and  12  inserted in the same slot  24 , each conductor having plural laminated thin plates  30  or  31 . The first laminated conductor  11  and the second laminated conductor  12 , with the insulating plate  23  interposed therebetween, are encased in the insulating case  28 . Therefore, the first and second laminated conductors  11  and  12  are united only by simple assembling work while assuring insulation without any molding process. 
     According to the manufacturing method of the present embodiment for a motor stator which includes the stator core  10  with the slots  24  in an inner periphery, the first and second laminated conductors  11  and  12 , each having the plurality of laminated thin plates  30  or  31 , and the end connecting conductor  13  having the plurality of laminated connecting thin plates  32  for connecting the end portions of the first laminated conductor  11  in one slot  24  and the end portions of the second laminated conductor  12  in another slot  24 , the end portions of thin plates  30 ,  31  and the connecting portions  13   a  of connecting thin plates  32  are all tapered; the plural thin plates  30 ,  31  are gradually different in thickness and the connecting thin plates  32  are the same in thickness; and, in assembling the end connecting conductor  13  to the first laminated conductor  11  and the second laminated conductor  12 , the guide pieces  33   a ,  33   b,    33   c ,  33   d  are used to adjust the positions of the connecting thin plates to the positions between the thin plates of the laminated conductors so that no contact between slanted portions occurs before the final stage of assembly in which slanted surfaces contact each other, and thus adhesive layers  27  coated on the slanted surfaces are unlikely to peel off. 
     A second embodiment of the present invention will be described referring to  FIGS. 19 and 20 . The lower end portions of a first laminated conductor  11  and a second laminated conductor  12  are connected with a U-shaped laminated conductor  50 . This is equivalent to the first embodiment in which the end portions of the first laminated conductor  11  and the second laminated conductor  12  are connected by the end connecting conductor  13  on only one side of the stator core  10 . 
     As shown in  FIG. 20 , neighboring U-shaped laminated conductors  50  are connected by a connecting conductor  13 . The end portions of thin plates constituting each U-shaped laminated conductor  50  have the same slanted surfaces as the end portions of the first laminated conductor  11  and the second laminated conductor  12 . The end connecting conductor  13  is the same as that in the foregoing embodiment. 
     The assembling process in the present embodiment is performed in the same manner as the connecting process after the step of turning over the stator core  10  in the first embodiment. More specifically, by connecting the n-th thin plate  30  of the first laminated conductor  11  in one slot  24  and the (n+1)-th thin plate of the second laminated conductor  12  in an adjacent slot  24  sequentially, the first laminated conductor  11  and second laminated conductor  12  make a loop between the first thin plate  31  of the second laminated conductor  12  and the ninth thin plate  30  of the first laminated conductor  11 . A detailed description is omitted here. 
     According to this embodiment, only one end portions (upper end portions in the figure) are connected using the connecting conductors  13 , so that production efficiency can be improved. 
     The present invention is not limited to the foregoing embodiments and may also be embodied by partially modifying the configuration without departing from the scope of the invention. 
     For instance, the adhesive layer  27  is formed on the slanted surface  32   a  of the connecting thin plate  32  in the above embodiments. As an alternative, it may be formed on the slanted surfaces  30   a  and  31   a  of thin plates  30  and  31  or it also may be formed on the slanted surfaces of both the connecting thin plate  32  and the thin plates  30 ,  31 . 
     Further, although silver paste is used as an adhesive in the above embodiment, another type of soldering paste may be used instead.