| 摘要 |
PURPOSE:To stabilize a torque during operation and also to prevent a magnetic noise due to groove higher harmonics by a construction wherein rotor grooves are provided in two steps, main grooves on the lower part are formed at regular intervals and auxiliary grooves on the upper part are formed at irregular intervals. CONSTITUTION:When a cage type rotor is obtained through building up steel sheets axially to a given thickness, providing a plurality of grooves axially and applying a cage winding thereon, said axial grooves are arranged in two steps consisting of auxiliary grooves 4a on the upper part and main grooves 4b on the lower part. Then, the auxiliary grooves 4a coming near to the outer peripheral surface of a core are formed in a small sectional area and at irregular intervals, and the main grooves 4b coming near to the center are formed in a large sectional area and at regular intervals. This way of constitution may suppress an electromagnetic noise and also minimize a torque pulsation. |
