Abstract:
A fluid container associated with the wicket gate operating ring to receive fluid from a source so as to add an emergency counterweight to the gate operating ring upon failure of the gate operating ring servomotors.

Description:
BACKGROUND OF THE INVENTION 
     Normally it is required that the forces acting on the gate operating ring of a horizontal turbine machine be equally distributed. However, there has been a demand for a counterweight arrangement for providing a closing force if fluid pressure to the gate ring operator of a bulb turbine is lost. In providing an effective counterweight for the gate ring, the large weight destroys the equal distribution of forces on the particular gate operating ring. 
     Turbine machine size has increased with a corresponding increase in the size of the gate operating ring having a much larger radius. Thus, a greater unequal distribution of forces are applied to the bulb turbine gate ring. The greater unequal distribution of forces upon the gate ring requires that gate ring servomotors must be oversized to counteract the increase in the weight of the counterweight in an opening movement. 
     SUMMARY OF THE INVENTION 
     In resolving the problem, it was conceived that if the counterweight was available only when needed, such as at the time of loss of fluid pressure to the servomotors, then the unequal distribution of forces to the gate operating ring would not be a problem. In other words, by providing an emergency closure device which would act on the gate ring only when needed, a reduction in servomotor size would result and a balance of forces on the gate ring will be possible. 
     It is a general object of the invention to provide a counterweight system which is only active in an emergency situation. 
     Another object of the invention is to provide a counterweight system which is automatically activated when required and deactivated when not required. 
     Still another object of the invention is to provide a counterweight system which utilizes a flow of water to provide the necessary weight for a counterweight system when needed. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view partly in section and partly in elevation through a penstock showing a bulb turbine therein having the counterweight system of the present invention; 
     FIG. 2 is an enlarged sectional view through the bulb turbine taken in a plane represented by the lines II--II in FIG. 1, showing the gate ring, operating servomotors and the counterweight system of the present invention; and, 
     FIG. 3 is an enlarged fragmentary view of a gate linkage connecting the wicket gate to the gate operating ring. 
    
    
     DESCRIPTION OF THE INVENTION 
     As shown in FIG. 1, a bulb turbine generator unit 10 is supported by upper and lower stay columns 11 and 12, respectively. The machine includes a bulb portion 16 which is supported on a center pier 17 within the intake section 18 of a dam 19. Forward of the bulb 16 the machine includes a runner cone 21 located within the discharge ring 22 of the draft tube 23. A runner hub assembly 26 operatively supports a plurality of angularly adjustable runner blades 27 which radiate from the hub 26. A plurality of adjustable wicket gates 31 are supported by an inner gate barrel 32 and an outer gate barrel 33. 
     The angularly adjustable wicket gates 31 which control the flow of water to the runner blades 27 are positionable by operation of a gate operating ring 36. The gate operating ring 36 is movably supported on the outer gate barrel 33. The wicket gates 31 are operably connected in a well known manner to the gate operating ring 36 as shown in FIG. 3. As there shown, wicket gates 31 are provided with a stem 34 which receive a spacer hub 42. A lever arm 43 is keyed to the extending end of the gate stem and has its free end pivotally connected to a link 44. Link 44, in turn, has its opposite end secured to the gate operating ring 36. Thus, rotation of the ring 36 in a counterclockwise direction as viewed in FIG. 2 will serve to move the wicket gates 31 to closed positions. On the other hand, movement of the gate ring 36 in a clockwise direction as viewed in FIG. 2, will serve to open the gates. 
     Operation of the gate operating ring 36 is accomplished by means of a pair of servomotors 51 and 52 which are supported on brackets that are attached to the sidewalls 53 and 54 of the turbine gallery. As shown in FIG. 2, the gate operating ring 36 is positioned so that the wicket gates 31 will all be open. When the gates 31 are to be closed a signal will be obtained to cause the servomotors 51 and 52 to be energized to effect a retraction of their associated piston rods 56 and 57 within their associated cylinders 58 and 59. This will cause the gate operating ring 36 to be rotated in a counterclockwise direction, as viewed in FIG. 2, to thereby move the wicket gates to closed positions. 
     For emergency operation, in the event that fluid pressure to the servomotors 51 and 52 fail, or if the servomotors become inoperative for any reason, there is provided a counterweight system 60. 
     As shown in FIG. 2, the counterweight system 60 includes a fluid tank member 61. Tank 61 is suspended from a bracket 62 that is attached to the gate operating ring 36 by means of a rod 63. The tank 61 is provided with a fluid fill line 66 which communicates with the interior of the tank. (A control valve 67 is provided which may be a solenoid actuated valve for automatic operation or manual actuated valve.) A supply line 68 is connected to the inlet side of valve 67 for supplying fluid to the tank 61 when the valve is opened. At the lower end of the tank 61 there is provided a drain line 71 which is connected to a flow control valve 72. The outlet of the control valve 72 is in communication with a drain line 73. 
     In operation a loss of fluid pressure in the servomotors 51 and 52 will be detected by an alarm system (not shown). This will result in a signal being generated to energize the solenoid of valve 67 to open the valve. As a result, fluid will flow into the tank 61 filling the tank. As the fluid flows into tank 61, the weight of the fluid will effect rotation of the gate operating ring 36 in a counterclockwise direction, thereby effecting the movement of the wicket gates 31 to a closed position. With the gates closed, the solenoid of valve 67 will be deenergized to condition the valve to stop fluid flow to tank 61. After the emergency has been corrected, the solenoid of valve 72 will be energized by another signal and valve 72 will be energized to condition the valve to open allowing the tank to drain. After the tank has drained another signal is obtained to deenergize the solenoid of valve 72 to condition the valve to a closed position and the emergency cycle is complete. 
     With the present invention, a constant unequal force of a counterweight is not applied to the gate operating ring 36. Thus, the ring structure need not be oversized to accept such unequal force nor do the servomotors need to be oversized to counteract the constant applied counterweight mass. The counterweight herein disclosed is only applied to the gate operating ring 36 in response to an energency.