| 摘要 |
PURPOSE:To prevent the burning of an electric motor when hydraulic oil is low in temperature by providing the device with a means detecting oil temperature within an oil tank or a hydraulic cylinder, and thereby controlling the speed of an elevator to be decreased when oil temperature is lower than a specified value. CONSTITUTION:In a hydraulic elevator, a pulley is rotatably supported at the upper end section of the plunger 3 of a hydraulic cylinder 2, and a cage 1 is moved up and down via a rope 4 which is installed on the pulley so as to be wound. And a three phase induction motor 6 driving a hydraulic pump 5 is controlled through an inverter by a control means 12 to which pulse signals generated by a first encoder ENC 1 as the cage 1 is moved, are inputted. In this case, an oil tank 7 is provided with an oil temperature sensor 100, when oil is less than a specified value in temperature, and is great in density, the speed of the elevator is made low by lowering the speed command outputted by the control means 12. And when the current value of the electric motor 6 is equal to or more than a specified value, the speed of the elevator is so constituted as to be decreased with the speed command lowered in a similar way. |
