Method of manufacturing stator coil

1. A method of manufacturing a stator coil that is comprised of a plurality of phase windings, the method comprising:

a shaping step for shaping electric wires to form a plurality of shaped wires;

an assembling step for assembling the plurality of shaped wires to form a wire assembly; and

a rolling step for rolling the wire assembly around a core member to form a rolled wire assembly,

characterized in that:

each of the shaped wires includes a plurality of straight portions, which extend parallel to each other and are arranged in a longitudinal direction of the wire assembly, and a plurality of turn portions that connect, alternately on opposite sides of the straight portions, adjacent ones of the straight portions;

the shaped wires have, in the longitudinal direction of the wire assembly, a plurality of straight superposed parts each of which is formed by superposing a pair of the straight portions of the shaped wires;

the rolled wire assembly obtained in the rolling step has, in a circumferential direction of the rolled wire assembly, a plurality of straight stacked parts each of which is formed by stacking a predetermined number of the straight superposed parts in a radial direction; and

in the rolling step, the wire assembly is rolled around the core member with aligning members being sequentially inserted into spaces formed between adjacent ones of the straight superposed parts of the wire assembly to secure the superposition of the straight portions in each of the straight superposed parts and make intervals between adjacent ones of the straight superposed parts even.

2. The method of manufacturing the stator coil as set forth in claim 1 , further characterized in that:

in the rolling step, the wire assembly is rolled around the core member by a plurality of turns to form the rolled wire assembly; and

the aligning members are stacked in each of the spaces in stages by inserting, from the radially outer side of the core member, one of the aligning members into each of the spaces for each turn of the rolling of the wire assembly.

3. The method of manufacturing the stator coil as set forth in claim 1 , further characterized in that:

in the rolling step, the wire assembly is rolled around the core member by a plurality of turns to form the rolled wire assembly; and

each of the aligning members is protruded, from the core member radially outward, into one of the spaces for each turn of the rolling of the wire assembly, thereby being inserted into the one of the spaces in stages.

4. The method of manufacturing the stator coil as set forth in claim 1 , further characterized in that:

each of the aligning members is made up of at least one aligning arrow that is protruded from an outer circumferential surface of the core member radially outward to abut that side surface of a corresponding one of the straight superposed parts which is on the backward side in the rolling direction of the wire assembly.

5. The method of manufacturing the stator coil as set forth in claim 1 , further characterized in that:

each of the aligning members is made up of a taper pin that is tapered so as to extend in width radially outward; and

the taper pin is protruded from the core member radially outward while rotating for each turn of the rolling of the wire assembly.

6. The method of manufacturing the stator coil as set forth in claim 1 , further characterized in that:

in the rolling step, when the wire assembly is on its way to be fed to the core member, a plurality of pre-aligning members are respectively inserted into consecutive ones of the spaces formed between adjacent ones of the straight superposed parts of the wire assembly to secure the superposition of the straight portions in each of those straight superposed parts which are each sandwiched by an adjacent pair of the pre-aligning members.

7. The method of manufacturing the stator coil as set forth in claim 6 , further characterized in that:

the rolling step is a continuous rolling step for rolling the wire assembly around the core member while continuously feeding the wire assembly to the core member; and

in the continuous rolling step, the pre-aligning members are advanced into and retreated out of the spaces while being moved in synch with the wire assembly.

8. The method of manufacturing the stator coil as set forth in claim 6 , further characterized in that:

the rolling step is a pitch-based rolling step for rolling the wire assembly around the core member while feeding the wire assembly to the core member by N times the interval between an adjacent pair of the straight superposed parts of the wire assembly at a time, where N is a natural number; and

in the pitch-based rolling step, a plurality of processes are repeated which include a pre-aligning member insertion process for inserting the pre-aligning members into the spaces of the wire assembly when the wire assembly is sopped,

an advancing process for advancing the wire assembly together with the pre-aligning members by N times the interval between an adjacent pair of the straight superposed parts of the wire assembly,

a pre-aligning member removal process for removing the pre-aligning members out of the spaces of the wire assembly, and

a retreating process for retreating the pre-aligning members by N times the interval between an adjacent pair of the straight superposed parts of the wire assembly.

9. The method of manufacturing the stator coil as set forth in claim 8 , further characterized in that:

in the pitch-based rolling process, a position keeping member insertion process is performed, following the advancing process, for inserting position keeping members into other ones of the spaces of the wire assembly than those of the spaces in which the pre-aligning members are inserted;

a position keeping member removal process is performed, following the pre-aligning member insertion process, for removing the position keeping members out of the other spaces of the wire assembly;

the pre-aligning member removal process, the retreating process, and the pre-aligning member insertion process are performed with the position keeping members inserted in the other spaces of the wire assembly; and

the advancing process is performed with the position keeping members removed out of the other spaces of the wire assembly.