SQUIRREL-CAGE ROTOR

PURPOSE:To prevent separation of a conductor due to a centrifugal force and to improve an exciting current, a power factor, an efficiency by providing a groove on the outer periphery of a core, burying the conductor in the groove, and engaging a thin-wall pipe of a magnetic element with the outer periphery of the core. CONSTITUTION:A rectangular groove 32 is provided on the outer periphery of a columnar core 31 integral with the shaft 31a of a magnetic element supported by bearings 39a, 39b, and a soft copper conductor 33 is buried from its radial outside. A thin-wall pipe 35 of a magnetic element is engaged with the outer periphery of the core 31 in which the conductor 33 is buried in the groove 32. According to this structure, the conductor 33 is burdened with centrifugal force generated by a high speed rotation on the thin-wall pipe 35 to eliminate a fear of separation of the conductor 33, and the bending rigidity of a squirrel-cage rotor 30 is increased by the pipe 35. The groove 32 is closed by the pipe of the magnetic element to reduce a magnetic resistance of an air gap between stators, to improve an exciting current, a power factor, an efficiency, and to particularly suppress temperature rise of a light load. Thus, even if it is left to stand in a working field as a concrete vibrator with the switch remaining closed, fear of burning can be avoided.