Rotating electric machine and manufacturing method thereof

1. A rotating electric machine comprising:

a stator and a rotor that is rotatably provided through a rotary gap with respect to the stator, wherein

the rotor includes a rotor core in which rotor plates punched from roll formed magnetic steel plate are laminated, and a spider that retains the rotor core;

the rotor plates and the rotor core include a plurality of keys arranged in their inner circumference contacting with the spider;

the spider includes a plurality of keyways arranged in its outer circumference contacting with the rotor;

a plurality of keys of the rotor core and a plurality of keyways of the spider are formed in such a manner that they fit with each other; and

the plurality of keys of the rotor core and the plurality of keyways of the spider fit in a combination that renders a weight imbalance of the rotor core due to lamination of the rotor plates and a weight imbalance of the spider cancel each other.

2. A rotating electric machine according to claim 1 , wherein:

at least one of the plurality of keyways of the spider is formed as a small width keyway which has a smaller width than other keyways, and

among the plurality of keys of the rotor core, a rotor core minimum mass key, which shows that a mass of the rotor core in a direction in which the rotor minimum mass key exists is minimum, is fitted into the small width keyway.

3. A rotating electric machine according to claim 2 , wherein:

in position of the rotor core minimum mass key, among the plurality of keys of the rotor plates, a rotor plate minimum mass key, a rotor plate minimum mass key, which is a key indicating a part of the rotor plate where the rotor plate have less thickness than other part is piled up.

4. A rotating electric machine according to claim 2 , wherein:

an identification marking is provided in a vicinity of the rotor core minimum mass key.

5. A rotating electric machine according to claim 2 , wherein:

the rotor core is provided with lamination of the rotor plates, wherein the rotor plates are rotary laminated as needed, so that a part of a rotor core in a position of the rotor core minimum mass key is smaller in mass than any other part located in positions of other keys.

6. A rotating electric machine according to claim 2 , wherein:

the rotor core is provided by rotationally stacking an odd number of blocks, wherein in each block a rotor plate minimum mass key, which is a key indicating a part of the rotor plate where the rotor plate have less thickness than other part, is piled up.

7. A rotating electric machine according to claim 1 , wherein:

a rotating electric machine is an induction motor wherein holes into which conductors are inserted are formed in the rotor core and aluminium or copper is inserted into the holes by die-casting.

8. A rotating electric machine according to claim 1 , wherein:

the rotor core is fitted into the spider by shrink-fitting, whereby the rotor core is fitted into the spider in such a manner that the keys and the keyways are fitted together.

9. A rotating electric machine according to claim 1 , wherein:

magnet insertion holes are formed in the rotor core, and magnets are respectively inserted into the magnet insertion holes.

10. A rotating electric machine according to claim 1 , wherein:

a shaft is fitted into the spider and as well a ring plate is fitted into the spider, and a balance adjustment hole, through which a weight imbalance that is left behind after weight imbalance cancellation by a combination of the rotor core and the spider is complementary cancelled, is formed in the ring plate.

11. A rotating electric machine according to claim 2 , wherein:

the keyways are formed into a depth in which a weight imbalance due to lamination of the rotor plates and a weight imbalance of the spider cancel each other.