Motor

A motor comprising:

• a rotor including a shaft with a vertically extending central axis as a center, a rotor magnet that rotates together with the shaft, a sensor yoke disposed axially upward from the rotor magnet to rotate together with the shaft, a sensor magnet supported by the sensor yoke, and an input gear including a gear portion that transmits torque generated by the rotor magnet to outside;
• an armature disposed radially outward of the rotor magnet;
• a bearing mechanism that supports the rotor to be rotatable with respect to the armature;
• a housing that covers the armature, the rotor, and the bearing mechanism;
• and
• a rotation detection sensor facing the sensor magnet to detect rotation of the rotor;
• wherein
• the bearing mechanism includes a first bearing disposed axially upward from the rotor magnet and a second bearing disposed axially downward from the rotor magnet;
• the housing includes a housing main body including a bottom axially facing a lower end of the shaft to support the second bearing and the armature, and a bearing holder that supports the first bearing at a center thereof;
• the rotation detection sensor is disposed at an upper side of the bearing holder;
• the shaft includes an upper surface disposed axially upward and radially inward from the gear portion and an exposed portion that is exposed in regions axially downward from the gear portion and axially upward from the sensor yoke;
• and
• the exposed portion and an inner peripheral surface of the sensor magnet radially face each other.

A method of manufacturing a motor including a rotor including a shaft with a central axis as a center, an upper surface disposed axially upward and radially inward from a gear portion, and an exposed portion that is exposed in regions axially downward from the gear portion and axially upward from a sensor yoke, a rotor magnet rotatable together with the shaft, the sensor yoke disposed axially upward from the rotor magnet, a sensor magnet supported by the sensor yoke, and an input gear including the gear portion to transmit torque generated by the rotor magnet to an outside;

• an armature disposed radially outward of the rotor magnet;
• a bearing mechanism that supports the rotor to be rotatable with respect to a stator and includes a first bearing disposed axially upward from the rotor magnet and a second bearing disposed axially downward from the rotor magnet;
• a housing that covers the stator, the rotor, and the bearing mechanism and includes a housing main body including a bottom and a bearing holder to support the first bearing at a radially inner side thereof;
• and a rotation detection sensor at an upper side of the bearing holder to face the sensor magnet to detect rotation of the rotor, the method comprising:
• (a) attaching the armature to the housing main body;
• (b) preparing a rotor assembly including the rotor, the bearing mechanism, and the bearing holder;
• and
• (c) attaching the rotor assembly to the housing by gripping the rotor assembly at the exposed portion and pressing the upper surface of the shaft axially downward.