Abstract:
An armature includes a plurality of equalizing connectors for permanently electrically connecting pairs of commutator segments that should have the same electric potential, so that each of the pairs of the commutator segments that should have the same electric potential has a substantially equal electrical potential. In one embodiment, at least one pair of adjacent coil portions share a common slot.

Description:
That is a continuation of application Ser. No. 09/266,606 (confirmation No; Unassigned) filed Mar. 11, 1999, now abandoned, the disclosure of which is incorporated herein by reference 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an armature for a dynamo-electric machine in which side portions of adjacent coil portions, etc., share a slot. 
   2. Description of the Related Art 
     FIG. 11  is a side elevation of an armature  1  for a conventional motor. The armature  1  is disposed so as to be freely rotatable within a stator (not shown) having four poles. The armature  1  comprises: a motor shaft  2 ; a core  3  secured to the motor shaft  2  having slots  4  extending in the axial direction; a coil  6  composed of wires  5  coated with enamel wound around the core  3 ; and a commutator  8  secured to the motor shaft  2  at one end of the core  3 . 
   The commutator  8  has twenty-one segments  11 ; insulating segments  10  electrically insulating the segments  11  from each other; and hooks  12  disposed so as to protrude from each of the segments  11  which are electrically connected to the wires  5 . 
     FIG. 12  is a front elevation of the core  3 . Twenty-one slots  4  are formed in the core  3  spaced equidistantly in the circumferential direction and teeth  9  are disposed between the slots  4 . The coil  6  is composed of wires  5  wound onto the core by so-called “lap winding”. 
     FIGS. 13  to  15  are diagrams explaining the winding of the wires  5  onto the core  3  by the lap winding method. 
     FIG. 13  is a diagram showing the wires  5  being simultaneously supplied from the nozzles of a winding device (not shown) which winds the wires  5  onto the core  3 , simultaneously forming a first coil portion A  30 , a first coil portion B  31 , and a first coil portion C  32 , respectively. The first coil portion A  30  is formed by winding a wire  5  supplied from a first nozzle, for example, ten or so turns around tooth No.  2  of the teeth  9  and tooth No.  6  of the teeth  9  which are separated by four slots  4 . The first coil portion B  31  is formed by winding a wire  5  supplied from a second nozzle, for example, ten or so turns around tooth No.  9  of the teeth  9  and tooth No.  13  of the teeth  9  which are separated by four slots  4 . The first coil portion C  32  is formed by winding a wire  5  supplied from a third nozzle, for example, ten or so turns around tooth No.  16  of the teeth  9  and tooth No.  20  of the teeth  9  which are separated by four slots  4 . 
     FIG. 14  is a diagram showing wires  5  continuing to be supplied from the nozzles of the winding device (not shown) after engaging the hooks  12 , additionally forming a second coil portion A  36 , a second coil portion B  37 , and a second coil portion C  38 , respectively. 
     FIG. 15  is a diagram showing the completed winding of the wires  5  between the teeth  9  of the core  3 . A third coil portion A  42 , a fourth coil portion A  45 , a fifth coil portion A  48 , a sixth coil portion A  51 , and a seventh coil portion A  54  are additionally and continuously formed by the wire  5  supplied from the first nozzle. A third coil portion B  43 , a fourth coil portion B  46 , a fifth coil portion B  49 , a sixth coil portion B  52 , and a seventh coil portion B  55  are additionally and continuously formed by the wire  5  supplied from the second nozzle. 
   In the above motor, the armature  1  is rotated about the motor shaft  2  by electromagnetic action by supplying an electric current to the coil  6  from outside by means of brushes (not shown) which contact the segments  11 . The segments  11  contacted by the brushes are switched in succession, switching the direction of the current supplied to the coil  6 , so that whatever rotational position the armature  1  is in, the rotating force on the armature  1  is in a specific direction. 
   In the conventional (but not prior art) armature  1  described above, there are twenty-one slots  4  in total and three nozzles, the total number of slots  4  being evenly divisible by the number of nozzles, and the wires  5  are wound uniformly in each of the coil portions, making the impedance substantially the same in adjacent coils portions. 
   However, if, for example, the number of slots is increased from twenty-one to twenty-two in order to increase torque, and four nozzles are used to wind the wires onto such a core, as shown in  FIG. 17 , adjacent coil portions must share a slot along one side. 
     FIG. 17  is a diagram showing wires being simultaneously supplied to the core from four nozzles of a winding device (not shown) having two rotational angles, 98.2 degrees and 81.8 degrees, as shown in  FIG. 16 , simultaneously forming a first coil portion A  108 , a first coil portion B  109 , a first coil portion C  110 , and a first coil portion D  111 , respectively. 
   The first coil portion A  108  in  FIG. 17  is formed by winding a wire supplied from a first nozzle, for example, ten or so turns around tooth No. 4 of the teeth  107  and tooth No.  22  of the teeth  107  which are separated by four slots  102 . The first coil portion B  109  is formed by winding a wire supplied from a second nozzle, for example, ten or so turns around tooth No.  5  of the teeth  107  and tooth No.  9  of the teeth  107  which are separated by four slots  102 . The first coil portion C  110  is formed by winding a wire supplied from a third nozzle, for example, ten or so turns around tooth No.  11  of the teeth  107  and tooth No.  15  of the teeth  107  which are separated by four slots  102 . The first coil portion D  111  is formed by winding a wire supplied from a fourth nozzle, for example, ten or so turns around tooth No.  16  of the teeth  107  and tooth No.  20  of the teeth  107  which are separated by four slots  102 . 
   In this case, the slot  102  between tooth No.  4  of the teeth  107  and tooth No.  5  of the teeth  107  is shared by a side portion of the first coil portion A  108  and a side portion of the first coil portion B  109 , and the slot  102  between tooth No.  15  of the teeth  107  and tooth No.  16  of the teeth  107  is shared by a side portion of the first coil portion C  110  and a side portion of the first coil portion D  111 . 
   For that reason, differences in impedance arise between the coil portions  108  to  111  in the slots  102  shared by the coil portions  108  to  111  because the wires are wound under conditions in which the coil portions  108  to  111  interfere with each other, leading to the following problems: 
   Differences in induced voltage arise in the coil portions  108  to  111  and unbalanced currents flow through the brushes, and as a result, the rectifying action of the brushes deteriorates, the temperature in the brushes and the commutator increases together with the increase in sparks generated by the brushes, the life of the brushes and the commutator is reduced, torque ripples increase, and the operating noise of the motor increases markedly due to the combined effects of the above. 
   SUMMARY OF THE INVENTION 
   The present invention aims to solve the above problems and an object of the present invention is to provide an armature for a dynamo-electric machine capable of preventing the occurrence of unbalanced currents flowing through the brushes and of reducing operating noise while maintaining the rectifying effect of the brushes, and to provide a method of manufacture therefore. 
   To this end, according to the present invention, there is provided an armature for a dynamo-electric machine comprising: a shaft; a core secured to the shaft having a plurality of slots extending in the axial direction formed on the outer circumferential surface thereof; a coil composed of a plurality of coil portions formed by winding wires a plurality of turns around a pair of the slots separated by a predetermined number of the slots and offsetting each of the coil portions one slot at a time in the circumferential direction of the core; and a commutator secured to the shaft having a plurality of segments; adjacent the coil portions sharing one of the slots along one side thereof, wherein the segments which should have the same electric potential are electrically connected by means of equalizing connectors. 
   According to another aspect of the present invention, there is provided an armature for a dynamo-electric machine comprising: a shaft; a core secured to the shaft having a plurality of slots extending in the axial direction formed on the outer circumferential surface thereof; a coil composed of a plurality of coil portions formed by winding wires a plurality of turns around a pair of the slots separated by a predetermined number of the slots and offsetting each of the coil portions one slot at a time in the circumferential direction of the core; and a commutator secured to the shaft having a plurality of segments; the number of vacant slots between adjacent the coil portions being nonuniform, wherein the segments which should have the same electric potential are electrically connected by means of equalizing connectors. 
   According to another aspect of the present invention, there is provided an armature for a dynamo-electric machine comprising: a shaft; a core secured to the shaft having a plurality of slots extending in the axial direction formed on the outer circumferential surface thereof; a coil composed of a plurality of coil portions formed by winding wires a plurality of turns around a pair of the slots separated by a predetermined number of the slots and offsetting each of the coil portions one slot at a time in the circumferential direction of the core for a plurality of laps; and a commutator secured to the shaft having a plurality of segments; the number of turns of the wires in the coil portions differing in the initial lap and the subsequent laps, wherein the segments which should have the same electric potential are electrically connected by means of equalizing connectors. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a winding diagram for an armature according to Embodiment 1 of the present invention; 
       FIG. 2  is a diagram showing coil portions wound on a core during the winding of wires by lap winding; 
       FIG. 3  is a diagram showing a coil wound on a core upon completion of the winding of wires by lap winding; 
       FIG. 4  is a winding diagram for an armature according to Embodiment 2 of the present invention; 
       FIG. 5  is a winding diagram for an armature according to Embodiment 3 of the present invention; 
       FIG. 6  is a diagram showing wires being wound by lap winding onto the core in  FIG. 5 ; 
       FIG. 7  is a diagram showing wires being wound by lap winding onto the core in  FIG. 5 ; 
       FIG. 8  is a diagram showing a coil body wound on the core in  FIG. 5  during the winding of wires by lap winding; 
       FIG. 9  is a diagram showing a coil wound on the core in  FIG. 5  upon completion of the winding of wires by lap winding; 
       FIG. 10  is a diagram showing coil portions wound on the core of an armature according to Embodiment 4 of the present invention during the winding of wires by lap winding; 
       FIG. 11  is a side elevation of a conventional (but not prior art) armature; 
       FIG. 12  is a front elevation of the core in  FIG. 11 ; 
       FIG. 13  is a diagram showing coil portions wound on the core in  FIG. 12  during the winding of wires by lap winding; 
       FIG. 14  is a diagram showing coil portions wound on the core in  FIG. 12  during the winding of wires by lap winding; 
       FIG. 15  is a diagram showing a coil wound on the core in  FIG. 12  upon completion of the winding of wires by lap winding; 
       FIG. 16  is a front elevation showing another example of a core; and 
       FIG. 17  is a diagram showing wires being wound by lap winding onto the core in FIG.  16 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiment 1 
     FIG. 1  is a winding diagram for an armature  100  of a motor which is a dynamo-electric machine according to Embodiment 1 of the present invention and shows the winding of wires  103  onto a core  101  having four poles and twenty-two slots  102  using four nozzles of a winding device (not shown) simultaneously. The diagram shows the enamel-coated wires  103  being wound by lap winding across a plurality of slots  102 , simultaneously forming a first coil portion A  108 , a first coil portion B  109 , a first coil portion C  110 , and a first coil portion D  111 , respectively. A commutator  105  has twenty-two segments  104 , segments  104  which should have the same electric potential being electrically connected by means of equalizing connectors  106 . For example, the first segment  104  is connected to the twelfth segment  104 , the second segment  104  is connected thirteenth segment  104 , etc. 
     FIG. 2  is a diagram showing wires  103  being supplied from each of the nozzles of the winding device and wound onto the core  101  and shows the formation of a second coil portion A  112 , a second coil portion B  113 , a second coil portion C  114 , and a second coil portion D  115 , respectively, after the engagement of hooks on the segments  104 . Moreover, the initial formation of coil portions  108  to  111  on the core  101  by wires  103  supplied from each of the nozzles is the same as in FIG.  17 . 
     FIG. 3  is a front elevation of the armature  100  with a coil  116  completely formed thereon by continuing to wind the wires  103  while offsetting one slot at a time. 
   In the armature  100  having the above construction, since segments  104  which should have the same electric potential are electrically connected by means of the equalizing connectors  106 , although the wires are wound with the side portions of adjacent coil portions  108  to  115  sharing slots  102  and the coil portions  108  to  115  interfering with each other, unbalanced currents do not flow through the brushes due to differences in induced voltage arising in the coil portions. As a result, inconveniences such as the rectifying action of the brushes deteriorating, the temperature in the brushes and the commutator increasing together with increases in sparks generated by the brushes, the life of the brushes and the commutator being reduced, torque ripples increasing, or the operating noise of the motor increasing markedly due to the combined effects of the above, do not occur. 
   Embodiment 2 
     FIG. 4  is a winding diagram for an armature  300  of a motor according to Embodiment 2 of the present invention and shows the winding of wires  103  onto a core  101  having twenty-two slots  102  using three nozzles of a winding device (not shown) simultaneously. In this embodiment, wires  103  are simultaneously supplied and wound onto the core  101  from a plurality of nozzles of a winding machine whose number does not evenly divide the number of slots  102 , giving rise to vacant slots A between adjacent coil portions  301 ,  302 ,  303 . The number of vacant slots may be one or two and their distribution is nonuniform. In this case, the wires  103  are not wound uniformly onto the core  101  and there is a risk that differences in induced voltages may occur between the coil portions  301 ,  302 ,  303 . However, in this case also, the flowing of unbalanced currents through the brushes is prevented by electrically connecting segments which should have the same electric potential by means of equalizing connectors. 
   Embodiment 3 
     FIG. 5  is a winding diagram for an armature  200  of a motor according to Embodiment 3 of the present invention and shows wires  103  being simultaneously supplied from two nozzles of a winding device (not shown), simultaneously forming a first coil portion A  201  and a first coil portion B  202 , respectively. Segments  104  which should have the same electric potential are electrically connected by means of equalizing connectors  106 . For example, the first segment  104  is connected to the twelfth segment  104 , the second segment  104  is connected thirteenth segment  104 , etc.  FIG. 6  is a front elevation of the core  101  at that time. 
     FIG. 7  is a diagram showing wires  103  continuing to be supplied from the two nozzles and shows the additional formation of a second coil portion A  203  and a second coil portion B  204 , respectively, after the engagement of hooks on the segments  104 . 
     FIG. 8  is a front elevation of the core  101  with a coil body  205  formed thereon by continuing to wind the wires  103  for a total of eleven slots while offsetting one slot at a time.  FIG. 9  shows the formation of a coil  206  upon completion of a winding in which the wires  103  in the core portion up to the point in  FIG. 8  were wound, for example, six turns, and after that were wound, for example, seven turns. 
   By making six turns of the wires  103  in the initial lap and seven in the subsequent laps in this manner, the wires  103  have the equivalent of 6.5 turns, facilitating the modification of motor performance and increasing the degree of design freedom. There is a risk that in this condition differences in impedance between the coil portions may arise due to the differences in the number of turns of the wires  103 , and unbalanced currents may flow through the brushes due to differences in induced voltage arising in the coil portions. However, in this embodiment, as with Embodiments 1 and 2, since segments  104  which should have the same electric potential are electrically connected by means of the equalizing connectors  106 , unbalanced currents do not flow through the brushes. 
   Embodiment 4 
     FIG. 10  is a diagram showing a case in which the wires  103  are wound seven turns in the initial lap. In this case the shaded portions E of the slots  102  are completely covered by a first coil portion A  211  and a first coil portion B  212 , and the area of the shaded portions E is greater than in Embodiment 3 (see FIG.  6 ). As a result, the cross-sectional area of the slots  102  is reduced and wind ability is less favorable than in Embodiment 3, but by winding more turns in the initial lap when the diameter of the coil portions is small and winding less turns in the subsequent laps when the diameter of the coil portions is large, the difference in impedance between the initial lap and the subsequent laps is reduced. 
   Each of the above embodiments of the present invention has been explained using a motor as an example of a dynamo-electric machine, but the present invention can also be applied to a generator. Furthermore, the number of equalizing connectors  106  in each of the embodiments is eleven, but of course they are not limited to this number. 
   As explained above, the armature for a dynamo-electric machine according to one aspect of the present invention comprises: a shaft; a core secured to the shaft having a plurality of slots extending in the axial direction formed on the outer circumferential surface thereof; a coil composed of a plurality of coil portions formed by winding wires a plurality of turns around a pair of the slots separated by a predetermined number of the slots and offsetting each of the coil portions one slot at a time in the circumferential direction of the core; and a commutator secured to the shaft having a plurality of segments; adjacent the coil portions sharing one of the slots along one side thereof, wherein the segments which should have the same electric potential are electrically connected by means of equalizing connectors. Therefore, operating noise can be reduced while maintaining the performance of the dynamo-electric machine and the rectifying effect of the brushes. 
   According to another aspect of the present invention, the armature for a dynamo-electric machine comprises: a shaft; a core secured to the shaft having a plurality of slots extending in the axial direction formed on the outer circumferential surface thereof; a coil composed of a plurality of coil portions formed by winding wires a plurality of turns around a pair of slots separated by a predetermined number of the slots and offsetting each of the coil portions one slot at a time in the circumferential direction of the core; and a commutator secured to the shaft having a plurality of segments; the number of vacant slots between adjacent the coil portions being nonuniform, wherein the segments which should have the same electric potential are electrically connected by means of equalizing connectors. Therefore, operating noise can be reduced while maintaining the performance of the dynamo-electric machine and the rectifying effect of the brushes. 
   According to still another aspect of the present invention, the armature for a dynamo-electric machine comprises: a shaft, a; core secured to the shaft having a plurality of slots extending in the axial direction formed on the outer circumferential surface thereof; a coil composed of a plurality of coil portions formed by winding wires a plurality of turns around a pair of the slots separated by a predetermined number of the slots and offsetting each of the coil portions one slot at a time in the circumferential direction of the core for a plurality of laps; and a commutator secured to the shaft having a plurality of segments; the number of turns of the wires in the coil portions differing in the initial lap and the subsequent laps, wherein the segments which should have the same electric potential are electrically connected by means of equalizing connectors. Therefore, operating noise can be reduced while maintaining the performance of the dynamo-electric machine and the rectifying effect of the brushes. 
   According to one form of the armature for a dynamo-electric machine, the number of turns of the wires in the coil portions in the initial lap may be less than the number of turns of the wires in the coil portions in the subsequent laps. Therefore, the modification of torque and revolution performance can be facilitated and the degree of design freedom of the dynamo-electric machine increased, while maintaining the rectifying effect of the brushes and with the operating noise reduced, even when the number of turns of the wires in the coil portions in the initial lap is less than the number of turns of the wires in the coil portions in the subsequent laps. 
   According to another form of the armature for a dynamo-electric machine, the number of turns of the wires in the coil portions in the initial lap may be greater than the number of turns of the wires in the coil portions in the subsequent laps. Therefore, differences in impedance between the coil portions in the initial lap and the coil portions in the subsequent laps are small even when the number of turns of the wires in the coil portions in the initial lap is greater than the number of turns of the wires in the coil portions in the subsequent laps, enabling operating noise to be reduced while maintaining the performance of the dynamo-electric machine and the rectifying effect of the brushes.