Miniature electric motor having bearing unit

Abstract

A miniature motor having a rotor arranged within a casing within which a stator is mounted, and a rotary shaft of the rotor is supported by bearing units mounted on both ends of the casing. One of the bearing units is provided with a thrust receiving member for supporting an end portion of the rotary shaft in a thrust direction, and a bearing for supporting the rotary shaft in a radial direction within a rotary shaft insertion hole. The thrust receiving member having a dimension that is equal to or smaller than an inner diameter of a bottomed recess formed in the casing is laid on a flat bottom surface of the bottomed recess. The bearing is securely fixed within the bottomed recess and contacted against the thrust receiving member. The rotary shaft insertion hole is in fluid communication with a through-hole formed in a bottom plate of the bottomed recess. Thus, it is possible to shorten an axial length of the motor and to stably support the rotary shaft while preventing any deformation of the thrust receiving member. It is also possible to ventilate air entrained in the insertion hole when the rotary shaft is inserted into the insertion hole of the bearing impregnated with lubricating oil.