| 摘要 |
PURPOSE: To reduce shock at the time of lowering an elevator by rotating an oil pump and a motor by working fluid returning to an oil tank in lowering the elevator, taking a signal of a rotation number of the motor by a detector installed on the motor, and rotating the motor at the same rotation number as this based on the signal. CONSTITUTION: A rotation number of a motor 1 at a time at a specified time after starting lowering an elevator is set as an output signal of an inverter control power source 11. In this condition, an inverter control device 13 is actuated when a signal of a rotation number taken by a rotation number detector 14 becomes equal to the set rotation number, so the inverter control power source 11 is operated to rotate the motor 1 at the set rotation number. By thus speed-controlling the motor 1 by the inverter control power source 11 to achieve a speed synchronized with the rotation number based on the signal from the rotation number detector 14, the hydraulic elevator can be smoothly accelerated and lowered till it is lowered at its full speed, thereby shock is reduced. |
