Patent ID: 7102259

Claim:
A rotor of a synchronous induction electric motor comprising: a slot for generating induction torque, and a slit for generating reluctance torque, wherein the slot and the slit are filled up with aluminum which is short-circuited by an end-ring at each of both ends of the rotor, and the rotor includes a gas vent hole penetrating in a direction of a rotational axis, wherein the gas vent hole has a cross-section shape with a short axis and a lone axis, and wherein the long axis extends in a direction of a d-axis of the rotor and extends in a radial direction of the rotor, and wherein the gas vent hole is wholly open at an entrance side of a gas flow, and the gas vent hole has a flow-restricting portion at an outer circumferential side of the rotor at an exit side of the gas flow.