| 摘要 |
<p>The present invention relates to a door opening and closing device capable of automatically and manually opening and closing a door. The present invention is improved to more smoothly open and close the door without an effort since the device is operated by a no-load state when the door is manually opened and closed. The present invention comprises: a forward motor (10) having a motor gear (11); a deceleration gear means (20) receiving a rotational force of the motor gear (11) to reduce the speed of the device; a chain gear (30) receiving power from the deceleration gear means (20); a chain (40) engaged with the chain gear (30) to be horizontally moved to open and close the door (1); and a power transmission reservation means (50) enabling power to be transmitted to an idle gear (52) linked with the gear (21′) of the deceleration gear means (20) and transmitting the power toward the chain (40) after the idle gear (52) idles a plurality of times to reserve transmission of the power.</p> |
