Rotary electric machine, electric power steering device, and method of manufacturing a rotary electric machine

A rotary electric machine, comprising:

• a rotor;
• and
• a stator including a stator core, the stator core including a core back portion having an annular shape and a plurality of tooth portions arranged at an interval in a circumferential direction of the stator to extend from the core back portion in a radial direction of the stator, the stator core having a slot portion formed between the plurality of tooth portions being adjacent to each other in the circumferential direction, the stator being arranged with respect to the rotor through a magnetic air gap portion therebetween,
• wherein each of the plurality of tooth portions includes a distal end being an end located on a side of the each of the plurality of tooth portions that is closer to the rotor,
• wherein the stator core further includes a connecting portion made of a magnetic material, which is formed at the distal end of each of the plurality of tooth portions and projects from the distal end of the each of the plurality of tooth portions in the circumferential direction to connect the plurality of tooth portions being adjacent to each other in the circumferential direction,
• wherein the connecting portion has a cutout portion formed on a side of the connecting portion that is closer to the magnetic air gap portion,
• wherein the connecting portion includes a slot portion-side thin connecting portion formed so as to be closer to the slot portion than the cutout portion,
• wherein a portion of the connecting portion that is shifted in the circumferential direction from a portion of the connecting portion in which the slot portion-side thin connecting portion is formed has formed therein a slot projecting portion projecting from the slot portion toward the magnetic air gap portion with respect to the slot portion-side thin connecting portion,
• wherein the connecting portion further includes:
• a magnetic air gap portion-side thin connecting portion formed so as to be closer to the magnetic air gap portion than a position at which the slot projecting portion is formed;
• and
• a radial thin connecting portion, which connects the slot portion-side thin connecting portion and the magnetic air gap portion-side thin connecting portion to each other,
• wherein the slot projecting portion is arranged on each of circumferential sides of the cutout portion, or the cutout portion is arranged on each of circumferential sides of the slot projecting portion,
• wherein the stator core further includes:
• a stator core inner diameter portion including the plurality of tooth portions and the connecting portion;
• and
• a stator core outer diameter portion including the core back portion,
• wherein the stator core inner diameter portion is to be fitted inside the stator core outer diameter portion, and as a result of fitting the stator core inner diameter portion inside the stator core outer diameter portion, a radially inward force is applied to the stator core inner diameter portion, the radially inward force being translated into a deforming circumferentially compressing force on to the connecting portion,
• wherein, when the slot projecting portion is arranged on each of the circumferential sides of the cutout portion, the radial thin connecting portion is deformed so that a circumferential width of the cutout portion on the side closer to the magnetic air gap portion is reduced when the deforming circumferentially compressing force is applied to the connecting portion,
• wherein, when the cutout portion is arranged on each of the circumferential sides of the slot projecting portion, the radial thin connecting portion is deformed so that a circumferential width of the slot projecting portion on the side closer to the slot portion is reduced when the deforming circumferentially compressing force is applied to the connecting portion,
• wherein each of the plurality of tooth portions has a tooth cutout portion formed therein on a side of the each of the plurality of tooth portions that is closer to the magnetic air gap portion, and
• wherein θ1/θ2≤1.7 is satisfied, where θ1 represents an angle of the tooth cutout portion that is formed in the circumferential direction with an axial center being a center, and θ2 represents an angle of the cutout portion that is formed in the circumferential direction with the axial center being the center.

A method of manufacturing a rotary electric machine, comprising:

• providing a rotor;
• providing a stator including a stator core, the stator core including a core back portion having an annular shape and a plurality of tooth portions arranged at an interval in a circumferential direction of the stator to extend from the core back portion in a radial direction of the stator, the stator core having a slot portion formed between the plurality of tooth portions being adjacent to each other in the circumferential direction;
• arranging the stator with respect to the rotor through a magnetic air gap portion therebetween;
• forming each of the plurality of tooth portions to include a distal end being an end located on a side of the each of the plurality of tooth portions that is closer to the rotor;
• providing the stator core to include a connecting portion made of a magnetic material, which is formed at the distal end of each of the plurality of tooth portions and projects from the distal end of the each of the plurality of tooth portions in the circumferential direction to connect the plurality of tooth portions being adjacent to each other in the circumferential direction,
• forming the connecting portion with a cutout portion formed on a side of the connecting portion that is closer to the magnetic air gap portion, the connecting portion including a slot portion-side thin connecting portion formed so as to be closer to the slot portion than the cutout portion, a portion of the connecting portion that is shifted in the circumferential direction from a portion of the connecting portion in which the slot portion- side thin connecting portion having formed therein a slot projecting portion projecting from the slot portion toward the magnetic air gap portion with respect to the slot portion-side thin connecting portion, the connecting portion further including:
• a magnetic air gap portion-side thin connecting portion formed so as to be closer to the magnetic air gap portion than a position at which the slot projecting portion is formed;
• and a radial thin connecting portion, which connects the slot portion-side thin connecting portion and the magnetic air gap portion- side thin connecting portion to each other, the slot projecting portion being arranged on each of circumferential sides of the cutout portion, or the cutout portion being arranged on each of circumferential sides of the slot projecting portion, the stator core further including:
• a stator core inner diameter portion including the plurality of tooth portions and the connecting portion;
• and a stator core outer diameter portion having the core back portion, inside of which the stator core inner diameter portion is to be fitted to apply a radially inward force to the stator core inner diameter portion;
• and
• fitting the stator core inner diameter portion inside of the stator core outer diameter portion,
• wherein, as a result of fitting the stator core inner diameter portion inside of the stator core outer diameter portion, a radially inward force is translated into a deforming circumferentially compressing force on to the connecting portion,
• wherein, when the slot projecting portion is arranged on each of the circumferential sides of the cutout portion, the radial thin connecting portion is deformed so that a circumferential width of the cutout portion on the side closer to the magnetic air gap portion is reduced when the deforming circumferentially compressing force is applied to the connecting portion,
• wherein, when the cutout portion is arranged on each of the circumferential sides of the slot projecting portion, the radial thin connecting portion is deformed so that a circumferential width of the slot projecting portion on the side closer to the slot portion is reduced when the deforming circumferentially compressing force is applied to the connecting portion,
• wherein the stator core includes a plurality of kinds of stator-core core sheets laminated one on another, and
• wherein the cutout portion or the slot projecting portion formed in one of the plurality of kinds of stator-core core sheets being laminated one on another is arranged so as to be shifted in the circumferential direction from the cutout portion or the slot projecting portion formed in another of the plurality of kinds of stator-core core sheets.