Motor-incorporated hypocycloid-type speed reducer

A motor-incorporated hypocycloid-type speed reducer comprising:

• a case;
• a motor housed in the case and including:
• a motor core supported by a first bearing to be rotatable about a motor shaft and having an eccentric portion eccentric to the motor shaft at a predetermined degree;
• coils wound around the motor core;
• and
• a magnet arranged centering on the motor shaft;
• a first internal gear housed in the case and arranged to be coaxial with the motor shaft;
• a second internal gear arranged to be coaxial with the motor shaft and having a diameter being smaller than a diameter of the first internal gear;
• an output shaft rotatably supported by a second bearing and arranged to be coaxial with the motor shaft, the output shaft being provided with the second internal gear;
• and
• an external gear having a first external gear, of which teeth are meshed with teeth of the first internal gear, and a second external gear, of which teeth are meshed with teeth of the second internal gear, the first external gear and the second eternal gear being formed to be coaxial with each other, and the external gear being provided with a rotor receiving portion rotatable integrally with the eccentric portion of the motor core via a third bearing, the rotor receiving portion being coaxial with the first external gear and the second external gear.