Patent GB-927623-A (GB)
Title: Adjusting devices for the guide blading of water turbines
IPC: F03B3/18
Filed: 1959-10-15
Abstract: 927,623. Hydraulic turbines. ESCHER WYSS A.G. Oct. 15, 1959 [Oct. 16, 1958], No. 34987/59. Class 110 (3). In an adjusting device for the guide blades of a water turbine, a fluid-pressure ram is connected to the guide blading by an adjusting linkage which comprises a toggle lever mechanism which in the closed position of the guide blading reaches at least the dead-centre position so that the guide blading will remain in its closed position even when pressure is no longer applied to the ram. In Fig. 1, the guide blades 1, for example of a Kaplan turbine, are shown in their closed position in which each blade abuts against the trailing portion 2 of an adjacent blade. Each blade is rotatably mounted by a pivot-pin 13 and a lever 12 is rigidly secured thereto. The lever 12 is connected by a link 11 to a projection 10 on a regulating ring 9, the pivotal points being indicated at 15 and 14 respectively and the parts 11 and 10 form a toggle lever mechanism. The regulating ring 9 is moved angularly by means of a fluid pressure ram 4 disposed in a cylinder 3 to which pressure fluid is applied through lines 5 and 6. The ram 4 is secured to a pistonrod 7 which is connected to the regulating ring by a rod 8. When the ram is in the position 4<SP>1</SP> indicated by dotted lines, the links 11, 12 are in the positions 11<SP>1</SP>, 12<SP>1</SP>, indicated by dotted lines and the pivots 14, 15 are in the positions 14<SP>1</SP>, 151, the guide blades 1 being in the open position. As the ram is moved to the lefthand end of the cylinder, the linkage is moved so that the pivot 14 moves to the position 14<SP>11</SP> which is almost the dead-centre position, the guide blades 1 then being in the closed, abutting position shown. The ram is moved still further to the left so that the pivot 14 reaches the deadcentre position 14<SP>111</SP>, the pivot point 15 being then displaced slightly outwardly by reason of elastic deformation of the lever 12. In this position in which the link 11 is disposed radially of the axis of the ring 9, the blades will remain in the closed position even when pressure fluid is no longer applied to the ram. Actually, in the final position of the ram at the left-hand end of the cylinder, the pivot point 14 is at the position 14 which lies beyond the dead-centre position 14<SP>111</SP> so that restoring forces on the blades will tend to move the regulating ring still further in the closing direction. In Fig. 2, the toggle linkage is disposed between the fluid pressure ram 17, 18 and the regulating ring 19 and comprises links 21, 22, 23 which are pivotally connected as shown at points 26, 27, 28 and 31, the pivot point 31 being fixed. The regulating ring 19 is connected to the guide blades 16 by links 24, 25. When the blades are in the open position, the ram and links are in the positions indicated in dotted lines. As the ram is moved upwardly, the pivot point 27 moves from position 27<SP>1</SP> to the position 27 which is just over the dead-centre position, i.e. just beyond the straight line connecting the pivot points 28, 31, the blades then being in the closed position. In Fig. 3, a fluid pressure ram 37, 38, is associated with each guide blade 35, the ram and the adjusting links 40, 42, 43, 44 being in the positions shown in dotted lines when the blade is in the open position. As the ram 38 is moved downwardly to the position shown in full lines, the links 42, 43 reach and then pass through the dead-centre position as shown in full lines, the pivot point 46 then lying beyond the straight line connecting the pivot points 41, 47. The guide blade is then in the closed position and cannot be displaced therefrom by forces acting on the blade even when pressure fluid is no longer applied to the ram.