MOTOR ROTOR STRUCTURE FOR ELECTRIC TURBOCHARGER, AND METHOD FOR INSTALLING SAME

An object of the invention is to provide a motor rotor structure for an electric turbo charger which can be manufactured at a low cost while ensuring the assembly quality of a motor rotor for an electric turbo charger by fixedly fitting, over a shaft, a rotor core having electromagnetic steel sheets pre-formed as an integrated stack in such a manner as to prevent the rotor core from rotating relative to the shaft. The motor rotor structure for an electric turbo charger is characterized by including: a rotor core 2 which is rotated by a magnetic field formed by a stator placed in a housing; a shaft 4 configured to rotate a compressor impeller 3 and the rotor core 2 together; and a bearing which supports the shaft 4 rotatably, wherein the motor rotor includes: the rotor core 2 which has electromagnetic steel sheets previously integrated as a stack; a stopper portion 48 which is formed at an intermediate portion of the shaft 4 in the thrust direction of the shaft 4 to restrict axial movement of the rotor core 2; and a pressing unit which presses the rotor core 2 fitted over the shaft 4 against the stopper portion 28, the pressing unit preventing a circumferential phase shift between the shaft 4 and the rotor core 2 by a pressing force thereof.