| 摘要 |
PROBLEM TO BE SOLVED: To exert a force sufficiently powerful to release a door by predominating over the attraction force of a magnet used in a door packing and to enable release of a door at a speed approximately equal to a natural speed and at the same degree as a speed at which a door is opened by a user's hand. SOLUTION: When a signal for releasing the door is applied by a switch, an electromagnetic solenoid 13 is excited, and a plunger 13A is withdrawn. Through movement of the plunger 13A, a rod 16 is moved forward through a coupling plate 14 and a block 17 for fixing. A coil spring 22 is compressed. By pressing an operating body 26 by a rod head 25, and pressing a heat insulating door 4 by the operating body 26, it predominates over the attraction force of the magnet of the door packing 8, and the heat insulation door 4 is started to release. In this case, a coil spring 27 is stretched to the same extend as a moving amount of a rod 16. The coil spring 27 is further stretched, and its energizing force is added to an inertia force in the release direction of the heat insulation door 4. The inertia force overcomes the closing force of a door catcher to push out the operating body 26, and the heat insulation door 4 is completely released.
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