Abstract:
The invention concerns a method for manufacturing an armature of an internal rotor type electric machine comprising a plurality of stator teeth, coils wound on the stator teeth and a stator yoke on the inner circumference of which the stator teeth are fixed. The stator teeth are attached radially to an outer circumference of a connecting disc, then the coils are wound on the stator teeth, then external edges of the stator teeth are fixed to an inner circumference of the stator yoke and then the connecting disc is removed from the stator teeth.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention concerns a method for manufacturing an armature of an internal rotor type electric machine being widely used in such as office apparatuses, electronic computer environmental apparatuses, home electric apparatuses, medical care appliances and factory automation machines.  
           [0003]    2. Description of the Prior Art  
           [0004]    In the prior art, an armature is constructed by winding coils on a plurality of stator magnetic pole teeth formed radially inside of a stator yoke. The winding of the coils is made manually through narrow gaps in the stator core, or by inserting a needle of a winding machine into the gap, or using an inserter. In the case of the manual winding of the coils, there is a problem that the skill is demanded of the operators. In the case of the needle winding machine, there is a problem that the amount of the coils to be wound is limited by the space required for the machine to move. Also in the case of using the inserter, there is still a problem that the space factor of the coils can not be raised.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the present invention to provide a method for manufacturing an armature of internal rotor type electric machine in which the winding of coils on stator cores can be made easily, that is excellent in production efficiency, by which the space factor can be raised, and that is applicable to such as a brushless motor or a stepping motor that is an internal rotor type electric machine.  
           [0006]    It is another object of the present invention to provide an armature of an internal rotor type electric machine manufactured by such method.  
           [0007]    To achieve the above objects, the present invention provides a method for manufacturing an armature of an internal rotor type electric machine comprising a plurality of stator teeth, coils wound on the stator teeth and a stator yoke on the inner circumference of which the stator teeth are fixed, wherein the stator teeth are attached radially to an outer circumference of a connecting disc, then the coils are wound on the stator teeth, then external edges of the stator teeth are fixed on the inner circumference of the stator yoke and then the connecting disc is removed from the stator teeth.  
           [0008]    Since the coils are wound on the stator teeth prior to be fixed to the stator york, the circumference of the stator teeth is left open, and the winding of the coils can be made easily. Moreover, either of a needle winding machine or a flyer winding machine can be used for winding the coils. Accordingly, armature of an internal rotor type electric machine of which the space factor of the coils and the production efficiency are raised can be provided.  
           [0009]    Further, armatures suitable to be applied for such as brushless motors, stepping motors or induction motors that are internal rotor type electric machines can be manufactured by the method for manufacturing an armature of an internal rotor type electric machine according to the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a plan view of a star-shaped core according to the present invention.  
         [0011]    [0011]FIG. 2 is a plan view of a stator yoke according to the present invention.  
         [0012]    [0012]FIG. 3 is a plan view of a connecting disc according to the present invention.  
         [0013]    [0013]FIG. 4 is an enlarged partial view of portion C in FIG. 3.  
         [0014]    [0014]FIG. 5 is a plan view of a stator tooth according to the present invention.  
         [0015]    [0015]FIG. 6 is a plan view of a laminated star-shaped core according to the present invention.  
         [0016]    [0016]FIG. 7 is a sectional view of the laminated star-shaped core according to the present invention.  
         [0017]    [0017]FIG. 8 is a plan view of another stator tooth according to the present invention.  
         [0018]    [0018]FIG. 9 is an enlarged partial view of a connecting disc for the stator tooth in FIG. 8, according to the present invention.  
         [0019]    [0019]FIG. 10 is a plan view of further another stator tooth according to the present invention.  
         [0020]    [0020]FIG. 11 is an enlarged partial view of a connecting disc for the stator tooth in FIG. 10, according to the present invention.  
         [0021]    [0021]FIG. 12 is a plan view of a laminated stator yoke according to the present invention.  
         [0022]    [0022]FIG. 13 is a sectional view of the laminated stator yoke according to the present invention.  
         [0023]    [0023]FIG. 14 is a sectional view of a bobbin coil according to the present invention.  
         [0024]    [0024]FIG. 15 is a sectional view of a star-shaped core to which the bobbin coils are attached according to the present invention.  
         [0025]    [0025]FIG. 16 is a sectional view of a star-shaped core to which the bobbin coils are attached and that is connected by the stator yoke according to the present invention.  
         [0026]    [0026]FIG. 17 is a sectional view of an armature of an internal rotor type electric machine according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    Embodiments of the present invention are explained referring to the attached drawings.  
         [0028]    [0028]FIG. 1 is a plan view of a star-shaped core  10  for an internal rotor type electric machine according to the present invention. FIG. 2 is a plan view of a stator yoke  31  according to the present invention.  
         [0029]    The star-shaped core  10  comprises stator teeth  11  to  18  and a connecting disc  21 . Later on, the stator teeth  11  to  18  are connected to the stator yoke  31  to form a stator core.  
         [0030]    The star-shaped core  10  and the stator yoke  31  are made by punching and lamination using a press.  
         [0031]    Then, an electrical insulation process is applied to the star-shaped core  10 . After that, coils are wound on the magnetic pole teeth  11  to  18 . Since the circumference of the star-shaped core  10  is opened, winding of the coils can be easily made by a needle winding machine or a flyer winding machine and the space factor of the coils can be raised. Further, bobbins on which coils are wound can also be attached to the magnetic pole teeth  11  to  18  without difficulty.  
         [0032]    The star-shaped core  10  on which coils are wound is pushed into an inside of the stator yoke  31  to be connected with the latter. Then, the connecting disc  21  is removed and an armature of an internal rotor type electric machine is completed.  
         [0033]    [0033]FIG. 3 is a plan view of the connecting disc  21 . The connecting disc  21  shown in the figure as an example is provided with eight protruding portions  41  to  48  placed at regular intervals on the circumference. Further, four lamination dowels  51  to  54  are also provided.  
         [0034]    [0034]FIG. 4 is an enlarged partial view of portion C in FIG. 3. Width a of each of the protruding portions  41  to  48  corresponds to an interval A (see FIG. 1) between two tooth edge portions  61  (see FIG. 5) of the stator teeth  11  to  18 . Also, height c of each of the protruding portions  41  to  48  corresponds to a height B (see FIG. 1) of each of the tooth edge portions  61 . Additionally, as shown in FIG. 4, the width a at the top of each of the protruding portions  41  to  48  is made larger than the width b at the root of the protruding portions. That is, the width of the protruding portion increases from the root toward the top.  
         [0035]    [0035]FIG. 5 is a plan view showing in detail an example of the stator tooth  11 . The stator tooth  11  comprises a tooth edge portion  61 , a magnetic route portion  62  and a yoke connecting portion  63 , and provided with holding grooves  64 , 65  and lamination dowels  66 , 67 .  
         [0036]    [0036]FIG. 6 is a plan view of a laminated star-shaped core  70  according to the present invention. The laminated star-shaped core  70 , shown as an example, comprises a laminated connecting disc  71  and eight laminated stator teeth  81  to  88  connected to the laminated connecting disc  71 .  
         [0037]    The connection of the eight laminated stator teeth  81  to  88  to the laminated connecting disc  71  is made automatically by a punching machine for the stator core. The punching and the lamination are made simultaneously.  
         [0038]    The lamination process is carried out as follows.  
         [0039]    [0039]FIG. 7 is a sectional view of the laminated star-shaped core  70  along E-E′ line shown in FIG. 6. In an example shown in the drawing, five sheets of silicon steel plates a are laminated.  
         [0040]    Two adjacent silicon steel plates in five silicon steel plates α composing the laminated connecting disc  71  are laminated with each other by each of five lamination dowels  91  wedged by half thickness of each of the adjacent steel plates.  
         [0041]    Also, two adjacent silicon steel plates in five silicon steel plates β composing the laminated stator tooth  81  connected to the external circumference portion of the laminated connecting disc  71  are laminated with each other by each of five lamination dowels  111  also wedged by half thickness of each of the adjacent silicon steel plates.  
         [0042]    The stator teeth  82  to  88  are also laminated in the same manner and connected to the external circumference portion of the laminated connecting disc  71 .  
         [0043]    Form of the tooth edge portion  61  of the stator tooth  11  shown in FIG. 5 as an example differs according to the uses, that is, for an induction motor, for a brushless motor or for a stepping motor.  
         [0044]    [0044]FIG. 8 shows an example of a form of stator tooth for a two-phase induction motor. In general, an inner portion tooth width D is less than an outer tooth width E. In order to connect the stator tooth  11  having such form to the connecting disc  21  with a sufficient connection strength, tooth edge pressing bosses  131 ,  132 , . . . are provided with protruding portions of the connecting disc  21 , since an inner connecting width d is less than an outer connecting width e as shown in FIG. 9. When connected, the inner portion tooth width D coincides with the inner connecting width d and the outer tooth width E coincides with the outer connecting width e. Consequently, the laminated stator teeth  81  to  88  as shown in FIG. 6 are not separated outwardly from the laminated connecting disc  71 .  
         [0045]    [0045]FIG. 10 is a plan view of further another stator tooth, in which an inner portion tooth width F is larger than an outer tooth width G. The corresponding form of the connecting disc is shown in FIG. 11, in which an inner connecting width f corresponding to the inner portion tooth width F is larger than an outer connecting width g corresponding to the outer tooth width G. Consequently, the laminated stator teeth  81  to  88  as shown in FIG. 6 are not separated outwardly from the laminated connecting disc  71 .  
         [0046]    [0046]FIG. 12 is a plan view of a laminated stator yoke  150  according to the present invention. In an inner circumferential portion of the laminated stator yoke  150 , grooves  161  to  168  for inserting the york connection portions of the laminated stator teeth  81  to  88  are provided. Also, lamination dowels  171  to  178  are provided with the laminated stator yoke  150 .  
         [0047]    [0047]FIG. 13 is a sectional view of the laminated stator yoke along B-B′ line in FIG. 12. Each of five lamination dowels  171  is successively wedged by half thickness of each of adjacent steel plates of the stator yoke by a press machine to laminate the adjacent steel plates. Thus, the stator yoke is laminated.  
         [0048]    [0048]FIG. 14 is a sectional view of a bobbin coil according to the present invention. Coils  201  are wound on the bobbin coil  191 . The bobbin coils  181  of the same number to the laminated stator teeth  81  to  88  are prepared.  
         [0049]    [0049]FIG. 15 is a sectional view of a laminated star-shaped core  210  on which the bobbin coils  181  of the same number to the laminated stator teeth  81  to  88  are attached to the laminated stator teeth  81  to  88  as shown in FIG. 6.  
         [0050]    Thus, since the circumference of the laminated stator teeth  81  to  88  according to the present invention is left open, the bobbin coils  181  can be attached easily to the laminated stator teeth  81  to  88 . Additionally, although the above explanation is made for the case in which the bobbin coils  181  are used, winding of coils directly on the laminated stator teeth  81  to  88  is also can be made easily using either of a needle winding machine or a flyer winding machine. Accordingly, the space factor of the coils, and consequently the power of the motor, can be raised.  
         [0051]    [0051]FIG. 16 is a sectional view of a laminated stator core  230  connected to the laminated stator yoke  150 , according to the present invention. The laminated stator core  230  is formed by pushing the laminated star-shaped core  210 , on which the bobbin coils  181  are attached as shown in FIG. 15, into the laminated stator yoke  150  as shown in FIG. 12. The positioning of the laminated star-shaped core  210  with the laminated stator yoke  150  is made using a matchmark  220  formed on the inner circumference of the laminated connecting disc  71  and another matchmark  179  formed on the outer circumference of the laminated stator yoke  150 . In this manner, each of the grooves  161  to  168  of the laminated stator yoke  150  perfectly coincides with each of the yoke connecting portions  63  of the laminated stator teeth  81  to  88  and a connection with high accuracy can be made.  
         [0052]    [0052]FIG. 17 is a sectional view of an armature  260  of an internal rotor type electric machine according to the present invention. The armature  260  is completed by pressing the surface of the laminated connecting disc  71  to remove the laminated connecting disc  71  from the laminated stator core  230  shown in FIG. 16.  
         [0053]    In the above description of the embodiment according to the present invention, the explanation is made for a case in which eight stator teeth are formed as an example. It is quite apparent that the number of the teeth is not limited to eight but it can be arbitrary chosen at need. Also, the explanation is made for a case in which five sheets of silicon steel plates are laminated. It is also quite apparent that the number of the silicon steel plates is not limited to five but it can be arbitrary chosen at need.