| 摘要 |
PURPOSE:To reduce a speed when a shutter touches a ground at an unwinding period. CONSTITUTION:During unwinding of a shutter 11, a hydraulic pump 3 is driven through drive of a motor 1 and a delivery flow rate of the hydraulic pump 13 is accumulated in an accumulator 17. With the increase of a pressure accumulation amount, fluid resistance of the hydraulic pump 13 is increased and the rotation speed of the motor 1 is reduced. As a result, a speed when the shutter touches a ground is reduced. Meanwhile, when the shutter is rewound, pressure oil accumulated in the accumulator 17 is caused to flow reversely to the hydraulic pump 13. In this case, the load of the motor 1 is reduced and consumption energy of the motor 1 is saved. |
