Abstract: According to the present invention, foreign substances, such as external dust and the like, can be prevented from being introduced into a lubricating fluid inside a bearing, so that the extension of the durability life of a motor or fan motor can be expected and once the assembly of a rotor assembly is completed, an impeller and a stator assembly can be assembled even in a non-clean room environment, thereby reducing cost and time in an assembly process, and because a sealing protrusion can block external foreign substances in a state in which the sealing protrusion is located radially inside a sleeve than the outer diameter of the sleeve, the design of a stator core can be made more freely, and it can be applied in even a case where the inner diameter of the stator core is small and the thickness of the stator core is large.

Abstract: A brake apparatus stops a rotor of an external-rotor motor that drives the head or a joint of a home robot. Frictional torque is generated when a friction pad presses a rotor surface even when a power source is switched off. A posture of a moving part, such as the head, of the robot is not abruptly disturbed even though the power source is switched off. Since a light external force is applied to the moving part of the robot in the off state of the power source, a motion in a direction desired by the user takes places without being stiff. The motion of the head of the robot stops when the external force is removed. An intention of the user who touches the robot may be satisfied even when the power source of the robot is switched off.