Patent ID: 7884516

Claim:
A motor comprising: a rotor which is provided with a rotor shaft; a stator which is disposed on an outer peripheral side of the rotor; a cylindrical bearing, which is made of resin material, comprising: a first end face which is formed with a circular recessed and bottomed part as a bearing part for rotatably supporting a shaft end of the rotor shaft; a second end face which is an opposite end face to the first end face in an axial direction of the rotor shaft; and a side wall part which forms an outer peripheral face between the first end face and the second end face; and a bearing holder which is provided with a through-hole into which the side wall part of the cylindrical bearing is slidably inserted; wherein the first end face is formed to be perpendicular to the side wall part of the cylindrical bearing and the circular recessed and bottomed part is formed with a cylindrical inner wall face which is cylindrically recessed from the first end face; wherein the first end face of the cylindrical bearing is formed with a ring-shaped groove which is recessed from the first end face at a position between the circular recessed and bottomed part and the side wall part so as to surround the circular recessed and bottomed part; and wherein a depth from the first end face of the ring-shaped groove is substantially equal to or larger than a depth from the first end face of the circular recessed and bottomed part wherein a thickness (D 1 ) between the ring-shaped groove and the side wall part of the cylindrical bearing is thinner than a width of the ring-shaped groove and a thickness (D 2 ) between the ring-shaped groove and the cylindrical inner wall face of the circular recessed and bottomed part is thinner than the width of the ring-shaped groove; thereby both of cylindricality of the side wall part and cylindricality of the cylindrical inner wall face of the cylindrical bearing are improved for improving concentricity of the rotor shaft and the cylindrical bearing which is slidably inserted into the through-hole of the bearing holder.