| 摘要 |
PURPOSE:To prevent the overspeed rotation of a windmill, by controlling the hydraulic pressure of a hydraulic cylinder with the use of an electo-magnetically proportional relief valve. CONSTITUTION:When a windmill catches the wind so that the rotating torque exceeds the load side torque, the maximum current runs through an electro-magnetically proportional relief valve 13 which is therefore fully closed. If a solenoid valve 12 is opened for Tsec, oil is fed into a hydraulic cylinder 7 which moves a pitch drive rod 5 rightward so that the pitch angle of blades 3 is started to be shifted to its starting pitch. Simultaneously, the rotational speed of a windmill shaft 1 is started to be accelerated. The hydraulic pressure increases as the rotational speed increases so that the pitch drive rod 5 is further pushed and then is stopped by a mechanical stopper 18. With this arrangement the shift from the starting pitch to the running pitch is completed. |
