Stator, electric motor, compressor, refrigerating and air conditioning apparatus, and method for manufacturing stator
A stator includes a yoke portion, and a tooth portion located inside the yoke portion in a radial direction. A fracture surface ratio of an inner surface of the tooth portion in the radial direction is lower than a fracture surface ratio of a side surface of the yoke portion.
1. A stator comprising:
a yoke portion; and
a tooth portion located inside the yoke portion in a radial direction,
wherein at least a part of an inner surface of the tooth portion in the radial direction is a surface formed by etching,
a fracture surface ratio of the inner surface is lower than a fracture surface ratio of a side surface of the yoke portion,
the fracture surface ratio of the inner surface is a ratio of an area of a fracture surface formed on the inner surface to a total area of a distal end of the tooth part, the fracture surface being a surface formed by brittle fracture, and
the fracture surface ratio of the side surfaces of the yoke portion is a ratio of an area of a fracture surface formed on the side surfaces to a total area of the side surfaces, the fracture surface being a surface formed by brittle fracture.
2. The stator according to claim 1 , wherein a dislocation density of the inner surface of the tooth portion is lower than a dislocation density of the side surface of the yoke portion.
3. The stator according to claim 1 , wherein the inner surface of the tooth portion is formed of a corrosion surface.
4. The stator according to claim 1 , wherein a silicon concentration of the tooth portion is higher than a silicon concentration of the yoke portion.
5. The stator according to claim 1 , wherein Vickers hardness of the tooth portion is higher than Vickers hardness of the yoke portion.
6. The stator according to claim 1 , wherein
the yoke portion includes a first sheet, and
the tooth portion includes a second sheet.
7. The stator according to claim 6 , wherein the second sheet is mounted at an inner end of the first sheet in the radial direction.
8. The stator according to claim 6 , wherein materials of the first sheet and the second sheet are different from each other.
9. The stator according to claim 6 , wherein the first sheet is made of an electrical steel sheet.
10. The stator according to claim 6 , wherein the second sheet is made of an amorphous material.
11. The stator according to claim 6 , wherein a thickness of the first sheet is 0.20 mm to 0.50 mm.
12. The stator according to claim 6 , wherein a thickness of the second sheet is 10 μm to 100 μm.
13. The stator according to claim 6 , wherein the yoke portion is formed by press working.
14. A stator comprising:
a yoke portion; and
a tooth portion located inside the yoke portion in a radial direction, wherein
a fracture surface ratio of an inner surface of the tooth portion in the radial direction is lower than a fracture surface ratio of side surfaces of the yoke portion,
the fracture surface ratio of the inner surface is a ratio of an area of a fracture surface formed on the inner surface to a total area of a distal end of the tooth part, the fracture surface being a surface formed by brittle fracture, and
the fracture surface ratio of the side surfaces of the yoke portion is a ratio of an area of a fracture surface formed on the side surfaces to a total area of the side surfaces, the fracture surface being a surface formed by brittle fracture.
15. An electric motor comprising:
a stator; and
a rotor provided inside the stator,
the stator comprising:
a yoke portion formed of at least one first sheet; and
a tooth portion formed of at least one second sheet and located inside the yoke portion in a radial direction,
wherein at least a part of an inner surface of the tooth portion in the radial direction is a surface formed by etching,
a fracture surface ratio of the inner surface is lower than a fracture surface ratio of side surfaces of the yoke portion,
the fracture surface ratio of the inner surface is a ratio of an area of a fracture surface formed on the inner surface to a total area of a distal end of the tooth part, the fracture surface being a surface formed by brittle fracture, and
the fracture surface ratio of the side surfaces of the yoke portion is a ratio of an area of a fracture surface formed on the side surfaces to a total area of the side surfaces, the fracture surface being a surface formed by brittle fracture.
16. The electric motor according to claim 15 , wherein the rotor includes:
a magnet insertion hole;
a permanent magnet inserted in the magnet insertion hole; and
a slit formed outside the magnet insertion hole in the radial direction.
17. The electric motor according to claim 16 , wherein the permanent magnet is magnetized in the radial direction.
18. A compressor comprising:
an electric motor;
a compression mechanism driven by the electric motor; and
a housing covering the electric motor and the compression mechanism,
the electric motor comprising:
a stator; and
a rotor provided inside the stator,
the stator comprising:
a yoke portion formed of at least one first sheet; and
a tooth portion formed of at least one second sheet and located inside the yoke portion in a radial direction,
wherein at least a part of an inner surface of the tooth portion in the radial direction is a surface formed by etching,
a fracture surface ratio of the inner surface is lower than a fracture surface ratio of a side surface of the yoke portion,
the fracture surface ratio of the inner surface is a ratio of an area of a fracture surface formed on the inner surface to a total area of a distal end of the tooth part, the fracture surface being a surface formed by brittle fracture, and
the fracture surface ratio of the side surfaces of the yoke portion is a ratio of an area of a fracture surface formed on the side surfaces to a total area of the side surfaces, the fracture surface being a surface formed by brittle fracture.
19. The compressor according to claim 18 , wherein the stator is fixed in the housing by press fitting or shrinkage fitting.
20. A refrigerating and air conditioning apparatus comprising:
an indoor unit; and
an outdoor unit including the compressor according to claim 18 and connected to the indoor unit.
21. A method for manufacturing a stator including a yoke portion and a tooth portion located inside the yoke portion in a radial direction, the method comprising:
forming a plurality of sheets into shapes of the yoke portion and the tooth portion;
stacking the plurality of sheets; and
forming at least a part of an inner surface of the tooth portion in the radial direction by etching so that a fracture surface ratio of the inner surface is lower than a fracture surface ratio of a side surface of the yoke portion,
wherein
the fracture surface ratio of the inner surface is a ratio of an area of a fracture surface formed on the inner surface to a total area of a distal end of the tooth part, the fracture surface being a surface formed by brittle fracture, and
the fracture surface ratio of the side surfaces of the yoke portion is a ratio of an area of a fracture surface formed on the side surfaces to a total area of the side surfaces, the fracture surface being a surface formed by brittle fracture.
22. A method for manufacturing a stator including a yoke portion and a tooth portion located inside the yoke portion in a radial direction, the method comprising:
forming a plurality of sheets into a shape of the yoke portion by press working;
forming the plurality of sheets into a shape of the tooth portion;
stacking the plurality of sheets; and
forming at least a part of an inner surface of the tooth portion in the radial direction by etching so that a fracture surface ratio of the inner surface is lower than a fracture surface ratio of a side surface of the yoke portion,
wherein
the fracture surface ratio of the inner surface is a ratio of an area of a fracture surface formed on the inner surface to a total area of a distal end of the tooth part, the fracture surface being a surface formed by brittle fracture, and
the fracture surface ratio of the side surfaces of the yoke portion is a ratio of an area of a fracture surface formed on the side surfaces to a total area of the side surfaces, the fracture surface being a surface formed by brittle fracture.