| 摘要 |
PURPOSE: To prevent a cage from the trouble of upward travelling in driving a hydraulic elevator with raised oil temperature. CONSTITUTION: The rotational speed of a hydraulic pump 3 is changed by controlling an electric motor so that pressurized oil is supplied to and discharged from a hydraulic jack 1 to vertically move a cage 2. During the stoppage of the cage 2, a third switch 21 is opened through a solenoid valve 25 and working oil is sent from a second main circuit 20 to an oil tank 8 to perform the drive with raised oil temperature. In this case, the rotational speed of the motor 4 is controlled so that the pump pressure is at predetermined pressure under jack pressure. Also, when the pump pressure exceeds the jack pressure, the power supply of the motor 4 is shut off. |
