| 摘要 |
PROBLEM TO BE SOLVED: To provide a motor-driven opening/closing device for a building, to be used together with a spring, which can detect an obstacle or a limit position by detecting mechanical load applied from a motor to a driven part. SOLUTION: An endless drive chain 12 is extended over the output side sprocket 15 and the drive side sprocket 8 of a motor. The motor is mounted on a movable plate 11, which is energized in the direction in which tension is applied to the drive chain 12 by an adjusting spring 13. During the normal rise and fall of a shutter curtain, the spring constant of the adjusting spring 13 is adjusted to be greater than a mutually pulling force between the output side sprocket 15 and the drive side sprocket 8, so that the movable plate 11 does not move. At an obstacle or a limit position, overload is applied and the movable plate 11 slides to actuate a microswitch 10 to stop the motor 9.
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