In this stator, a first coil portion, a second coil portion, a third coil portion, and a fourth coil portion each include a one-side coil part that is disposed so as to extend over a first slot and a third slot, and an other-side coil part that is disposed so as to extend over a second slot and a fourth slot.

An arm of a coil segment having an approximate U shape is placed in a slot of a stator core, and a portion protruding from the slot is bent in a circumferential direction. An arm is bent in a direction of an arrow A, and another arm positioned at an inner side in the radial direction in relation to this arm is bent in a direction of an arrow B. The arm positioned at the outer side has at least a part of a bending inner side surface of a bent portion hardened by pressurization.

An arm of a coil segment having an approximate U shape is placed in a slot of a stator core, and a portion protruding from the slot is bent in a circumferential direction. An arm is bent in a direction of an arrow A, and another arm positioned at an inner side in the radial direction in relation to this arm is bent in a direction of an arrow B. The arm positioned at the outer side has at least a part of a bending inner side surface of a bent portion hardened by pressurization.

First receiving recesses for receiving distal end portions of slot insertion portions of normal coil segments, and second receiving recesses for receiving distal end portions of long slot insertion portions of variant coil segments are formed at circumferential intervals on outer peripheral surface of an inner twisting jig corresponding to the innermost layer. In a state where the distal end portions of the long slot insertion portions before being twisted are inserted into the second receiving recesses, the first receiving recesses are at positions displaced in the circumferential direction with respect to the distal end portions to be housed therein. Primary twisting is performed by rotating the inner twisting jig in this state, and then the distal end portions of the normal coil segments are inserted into the first receiving recesses and the secondary twisting is performed with a rotational amount larger than that of the primary twisting.

First receiving recesses for receiving distal end portions of slot insertion portions of normal coil segments, and second receiving recesses for receiving distal end portions of long slot insertion portions of variant coil segments are formed at circumferential intervals on outer peripheral surface of an inner twisting jig corresponding to the innermost layer. In a state where the distal end portions of the long slot insertion portions before being twisted are inserted into the second receiving recesses, the first receiving recesses are at positions displaced in the circumferential direction with respect to the distal end portions to be housed therein. Primary twisting is performed by rotating the inner twisting jig in this state, and then the distal end portions of the normal coil segments are inserted into the first receiving recesses and the secondary twisting is performed with a rotational amount larger than that of the primary twisting.

A slot includes a coil housing portion having first and second side portions and a bottom portion. A first straight line connects first and second points which are boundaries between the bottom portion and the side portions. A slot opening has third and fourth points closest to the first and second side portions. A second straight line connects the first and third points. A third straight line connects the second and fourth points. A first region is surrounded by the first straight line and the bottom portion. A second region is surrounded by the second straight line and the first side portion, and is surrounded by the third straight line and the second side portion. A third region is surrounded by the three straight lines. Areas A1, A2 and A3 of the three regions and total cross-sectional areas S1, S2, S3 of coils therein satisfy (S1/A1)>(S2/A2)>(S3/A3).

A rotating electrical machine stator and a method for manufacturing a rotating electrical machine stator with high productivity. A rotating electrical machine stator includes a stator core having a slot; and a coil having a leg part including a held-in-slot part held in the slot and a portion extending from the held-in-slot part, and a resin foam is provided between an inner surface of the slot and an outer surface of the held-in-slot part facing the inner surface of the slot. The coil is formed by joining together a plurality of segment conductors each having a joint part, and a conductive joint material is disposed between a pair of joint parts facing each other in the slot.

A rotating electrical machine stator and a method for manufacturing a rotating electrical machine stator with high productivity. A rotating electrical machine stator includes a stator core having a slot; and a coil having a leg part including a held-in-slot part held in the slot and a portion extending from the held-in-slot part, and a resin foam is provided between an inner surface of the slot and an outer surface of the held-in-slot part facing the inner surface of the slot. The coil is formed by joining together a plurality of segment conductors each having a joint part, and a conductive joint material is disposed between a pair of joint parts facing each other in the slot.

A rotary electric machine armature that includes a cylindrical armature core and a coil wound around the armature core, wherein: the coil is formed by joining a plurality of segment conductors to each other; the segment conductors have respective conductor side portions that extend along the axial direction; the conductor side portions are provided with respective joint portions; the joint portions have respective facing surfaces; the joint portions of a pair of the segment conductors are joined to each other with the facing surfaces of the joint portions facing each other; and a facing surface of the facing surfaces is formed so as to have a portion that faces a radial direction and so as not to have portions that overlap each other as viewed in the radial direction over the entire facing surface.

A rotary electric machine armature that includes a cylindrical armature core and a coil wound around the armature core, wherein: the coil is formed by joining a plurality of segment conductors to each other; the segment conductors have respective conductor side portions that extend along the axial direction; the conductor side portions are provided with respective joint portions; the joint portions have respective facing surfaces; the joint portions of a pair of the segment conductors are joined to each other with the facing surfaces of the joint portions facing each other; and a facing surface of the facing surfaces is formed so as to have a portion that faces a radial direction and so as not to have portions that overlap each other as viewed in the radial direction over the entire facing surface.