| 摘要 |
PURPOSE:To compensate the slipping-off of the center of rotation of an electric motor, and prevent an electric motor from the generation of abnormal sound and vibration by a method wherein the amount of a looseness in deflective direction of one side bearing of the electric motor for driving of a ventilating fan is made larger than that of the other side bearing. CONSTITUTION:When an electric motor 8 is driven, the turning effort of a rotor 26 is generated caused by the rotatable supporting of the electric motor 8, a stator 22 is rotated in reverse direction by the reaction force. A wire 35 is reeled up with a reeling shaft 28 by the rotating reaction force of the stator 22, a connecting rod 4 is drawn down, a shutter 3 is opened. A bearing 30 of which looseness is approximately zero is used for the rotatable supporting of a cylinder shaft 27 located at the side to which a rotating shaft 9 of the electric motor 8 is protruded, and a bearing 31 of which looseness is larger than that of the bearing 30 is used for the rotatable supporting of a rotatable supporting reeling shaft 28, thus, the slipping off of the axis can be compensated, and the generation of abnormal sound and abnormal vibration can be prevented.
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