| 摘要 |
PURPOSE:To obtain a lightweight, small-sized and inexpensive driving device of a valve by increasing the open/close stroke of the valve without changing the length of the isometric link or the shift stroke. CONSTITUTION:When a handle 22 is rotated clockwise, shift members 17, 17' are shifted so as to approach together due to the screwing relation between male thread sections 20, 20' and female thread sections 16, 16' with different thread directions. Pantographs A, B are extended, a valve bar 7 is moved downward, and the valve port 3 is closed by a valve body 2. VS=nVdcotalpha where, alpha is an angle formed by a line parallel to the axis of a drive shaft 19 and a link 14 at a pin 8, (n) is the number of steps of all links, Vd is the speed of the shift members 17, 17', and VS is the speed of the valve bar 7. As the shift members 17, 17' approach together, alpha is gradually increased and VS is decreased, thereby the valve body slowly closes the valve port 3 near the close position of the valve and the water hammer is prevented from occurring. |
