JPS59113385A - Method of controlling valve - Google Patents

Abstract

PURPOSE:To secure the control of a sluice valve, by detecting the pressure of a pressure accumulator and the back pressure of a servomotor which is under the action of a self-shutting force and by comparing the detected values with each other so that oil returned to a chamber open to the servomotor is transferred to a pressure oil tank. CONSTITUTION:A changeover valve 101 is provided to switch a passage so that oil drained to a chamber 62 open to a servomotor is transferred to an oil collecting tank 51 or to a pressure oil tank 55. A pressure pipe 102 from the chamber 62 and a pressure pipe 103 from the pressure tank 55 are connected to the pilot pressure chambers of the changeover valve 101. When the pressure of the chamber 62 open to the servomotor has become higher than that of the tank 55, the oil returned to the chamber 62 is transferred to the tank 55. For that reason, the capacity of the pressure oil tank 55 can be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a pressure accumulator for valve operation, which enables the valve to be operated a certain number of times even if the supply of energy for valve operation from the outside is cut off. The present invention relates to a valve control system having a valve control system, and particularly relates to a valve control system suitable for reducing the capacity of a pressure oil accumulator for valve operation.

[Prior art]

Water control valves for hydroelectric power plants are installed to reliably cut off waterways in the event of an accident involving hydraulic machinery, power generation equipment, or the power transmission system. They are also required to have the ability to operate the water control valve a certain number of times.

For this reason, hydraulically operated type water control valves as shown in Fig. 1 are widely used as conventional water control valves, and hydraulic pressure is supplied by installing a pressure oil tank that performs a pressure accumulation function. To explain the conventional system in Figure 1, there is an oil collection tank 1, an oil pump 2, a pump drive electric motor 3, and an air compressor 1? &4, Pressure oil tank 5 that performs pressure accumulation function
, safety valve 6, these are the components of a typical main pressure oil system. The water control valve control oil is supplied from the oil pump 2 and air from the air compressor 4 to the pressure oil tank 5, respectively,
It generates and maintains pressure by compressing air.

The water utilization valve control mechanism includes a hydraulic supply pipe 7, an operation valve 8, and a valve opening pipe 9.
, valve closed side pipe 10, servo motor 11, open (chamber III 1
2. Closed side chamber 13, flow rate adjustment valves 14, 15 for setting operation time
, an oil drain pipe 16 to the oil collection tank, and a water control valve 17. Valve stem 1
8. A piston rod 2o of a servo motor and a piston 2°-1 are connected to the operating lever 19. In this control system, when opening the water utilization valve, an open side command for the operation valve 8 is given to the operation command part 8-1 of the operation valve 8, and when closing it, the
-2, the water utilization valve is opened and closed.

Also, in the figure, the bypass valve 21 and the guide vane of the hydraulic machine are 22.

Butterfly valves or rotary valves are generally widely used as water utilization valves for hydroelectric power plants, and these valves have a self-closing force.

In normal operation, the water control valve operates by first opening the bypass valve 21 with the guide vane 22 of the hydraulic equipment closed in order to reduce the operating force of the valve, and then increasing the pressure 2 ri and P2 before and after the water control valve.
After the water is almost balanced, the water control valve is opened.
In addition, when closing, there is a method of closing the guide vane 22, closing the water utilization valve, and finally closing the bypass valve 21, and the method of closing the hydraulic equipment, power transmission system, etc. in the event of an accident (electrical equipment and machinery become inoperable at the same time). In the event of an emergency when the guide vane 22 cannot be closed due to the operation of the guide vane 22, the water utilization valve is closed without waiting for the guide vane 22 to close in order to cut off the power generation water and stop the power generation machine for the safety of one device. There are two ways to do this. When this water flow is cut off, the pressure P2 on the downstream side of the valve becomes low as the flow rate decreases as the valve closes.
As the pressure 'pt-P2 acting on the valve increases, the operating force of the valve also increases.In general, the closing ability of a water control valve is determined by the capacity of the servo motor to enable the above-mentioned "water cutoff". ,
The required operating torque for the valve is shown in FIG. In the figure, curve A is the torque diagram required for normal valve opening and closing, which is due to the water control valve's own weight and friction of rotating parts such as the valve stem, and is approximately the same at the valve rotation angle. is the value of The curved opening in the middle is the torque required to close the "flow water cutoff" valve, and the closing force must be applied by the servo motor from the fully open point A to BA, but from the point B to the 0 point, the torque is applied toward the valve. The self-closing force is created by the unbalanced force caused by the flowing water, and there is no need to close the servo motor; on the other hand, the servo motor acts as a brake. From point 0 to point D, the thrust force due to the pressure upstream of the valve that acts on the valve increases as the valve approaches full closure, and this is the friction torque generated on the valve stem at this time, and the maximum value E at the fully closed point. becomes.

Generally, the required closing torque when shutting off the water flow is as large as four times or more when normally opening and closing the valve.

In addition, curves C and 2 are the servo motor output at the minimum allowable operating oil pressure of the pressure oil device that satisfies the required maximum closing torque E when water is cut off, and E and H are the servo motor output at the normal hydraulic pressure of the pressure oil device. It is torque.

On the other hand, the operating oil pressure at the time of this "water cutoff" is the residual pressure in the pressure oil tank 5 when no energy is applied from the outside to the pump drive electric motor 3 in the pressure oil device of the operation system. This is the minimum allowable operating force. This allowable minimum operating pressure is based on the relationship between the amount of oil consumed by the water control valve servo motor and the amount of oil and air in the pressure oil tank. The operating pressure is set, and generally the minimum allowable operating oil pressure is 60 to 70% of the normal maximum pressure.

That is, if the allowable minimum operating oil pressure is lowered, the amount of air in the hydraulic tank is reduced and the size of the hydraulic tank is reduced, but the capacity of the servo motor of the water utilization valve is required to be large. If the allowable minimum operating oil pressure is set high, the pressure oil tank will become larger and the water control valve servo motor will become smaller. Therefore, consider the dimensions and costs of both the pressure oil system and the water control valve servo motor. Its optimum value can be determined.

As mentioned above, in the conventional control system of the water utilization valve, the required output of the operating servo motor is the maximum value of the required closing torque for "water cutoff" under the above-mentioned emergency conditions, that is, the point in Figure 2. Based on section E, the pressure in the pressure oil tank 5 is determined by the amount of pressure oil caused by the operation of the water control valve servo motor when there is no operating power source for the oil pump drive S electric motor 3, that is, when there is no oil replenishment from the oil pump. It is necessary to design with the minimum allowable operating pressure of the hydraulic pressure reduced after consumption, and the extra operating force due to the difference between the normal operating pressure and the allowable minimum operating pressure, and the servo motor operating force in the self-closing range when water is cut off. This becomes unnecessary, and the servo motor capacity increases accordingly.As a result, it has the following unreasonable drawbacks.

(1) The oil collection tank 1, pressure oil tank 5, oil pump, air compressor 4, and other control equipment are large in size and require a large installation space.

(2) Since a large amount of operating oil is always stored, maintenance work including fire prevention becomes complicated.

In addition, in order to avoid the above-mentioned drawbacks, the operating condition is such that the water flow is cut off in advance, so that the supply of operating oil from the pressure oil tank is stopped when the valve is opened at a certain degree, and the open and closed sides of the servo motor are communicated. However, in this case, when the flow rate passing through the valve changes and self-closing temporarily disappears, the operating hydraulic pressure is cut off and the valve cannot close. There is.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the unreasonable drawbacks of the prior art described above and to provide an effective valve control method.

[Summary of the invention]

The feature of the present invention is that in the prior art, the back pressure in the servo motor opening side chamber 12 generated when the water control valve shuts off the water flow is
Focusing on the fact that the internal pressure is higher than the internal pressure of the pressure oil tank 5, when this condition occurs, the oil in the servo motor open side chamber 12 is automatically reduced.
In other words, the amount of oil returned from the servo motor open side chamber, which consumes a large amount of oil, is guided to the pressure oil tank 5, and the amount of oil in the pressure oil tank is increased and pressure is applied to the pressure tank.As a result, the capacity of the pressure oil device is increased. When the water control valve shuts off the flow of water in the event of a power generation equipment accident, the water control valve, its hydraulic oil system, and control can be safely and reliably maintained even when the supply of energy from the outside is cut off and the water control valve is completely independent. This closes the valve.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to three diagrams of the sheath. Oil collecting tank 51, oil pump 52, pump driving electric motor 53, air compressor 54, pressure oil tank 55 for accumulating pressure. safety valve 5
6 constitutes the main part of the pressure oil system. As a control mechanism of the water control valve, a pressure oil supply pipe 57, an operation valve 58, and an opening operation command section 58-
1. Closing operation command unit 58-2, valve opening side pipe 59, valve closing side pipe 6
0, servo motor 61, open side chamber 62, close side chamber 63, flow rate adjustment valves 64, 65 for setting operation time, oil drain pipe 66 to the oil collecting tank, and communication between the servo motor open side chamber and the pressure oil tank, which is a feature of the present invention. The communication pipe 100 switches the drained oil from the servo motor open side chamber to the oil collecting tank 51 and the pressure oil tank 55? A switching valve 101 that operates the switching valve, a pressure pipe 102 from the open side chamber of the servo motor that operates the switching valve, and a pressure pipe 10 from the pressure oil tank.
3. A flow rate adjustment valve 104 for adjusting the operating time of the servo motor when introducing oil into the pressure oil tank 55, a check valve 105, and a safety valve 106 that operates at a lower value than the safety valve 56 described above are arranged.

The above control system includes a water control valve 67, a valve shaft 68, and an operation lever 69.
, servo motor piston wood 70, piston 70
-1 is connected, a bypass valve 72 is attached to the water control valve, and a hydraulic mechanical guide vane 73 is attached downstream of the valve.

In the above configuration, during normal opening and closing operations of the water control valve,
Due to the operation of the opening operation command unit 58 - 1 of the operating valve 58 , the pressure in the pressure oil tank 55 is transferred through the pressure oil supply pipe 57 , the open side of the operating valve 58 , and the valve opening side pipe 59 to the open side chamber 62 of the servo motor 61 .
The water utilization valve is opened, and the servo motor closes the side chamber 6.
3 passes through the valve-closing side pipe 60, the closed side of the operation valve 58, and the flow rate adjustment valve 64, and is drained into the oil collecting tank 51. Also, during the normal closing operation, the closing operation command section 58- of the operating valve 58 is activated in the above manner.
By the operation 2, the pressure oil in the pressure oil tank 55 is introduced to the closed side of the operation valve 58, causing the valve to operate.

In this normal state, the oil in the servo motor open side chamber 63 passes through the flow rate adjustment valve 65, but this pressure is lower than the internal pressure of the pressure oil tank, and the pressure in the pressure pipe 102 is lower than the pressure in the pressure pipe 102.
Since the pressure at 03 is high, the switching valve 101 does not operate, and the oil is drained into the oil collecting tank 51 as in the conventional system. When the water control valve shuts off the flow of water, the pressure in the servo motor open side chamber 62 is increased by the self-closing force caused by the flow of water from valve opening point B to point C, as shown by the curved line in FIG. The torque in the closing direction applied to the water control valve 67 rotates the valve shaft 68 and the operating lever 69 in the closing direction, pushing the piston rod 70 and the piston 70-1 in the closing direction, and adjusts the flow rate for adjusting the closing time of this valve. The flow rate is suppressed by the throttling action of the valve 65, and the pressure in the servo motor closed side chamber 62 is increased.As a result, the pressure in the pressure pipe 102 becomes higher than the pressure in the pressure pipe 103 due to the operating setting force of the switching valve 101, and the switching valve 101 is operated. When the force becomes larger than the set value, the switching valve 101 operates, and the drain oil from the servo motor closing side chamber is drained through the flow regulating valve 104 for adjusting the closing time and the check valve 1osft.
The oil is then withdrawn to the pressure oil tank 55. In this case, if the pressure oil tank is not refilled with oil from the oil pump and the hydraulic pressure is close to the allowable minimum operating pressure, the oil for the servo motor operation from point F to point G in curve 2 in Figure 2 is in the pressure oil tank. 55 to prevent pressure drop inside the tank.

In addition, when the pressure inside the pressure oil tank is close to normal pressure, the pressure for the servo motor operation from point H to point 1 on the curve in Figure 2 is returned to the pressure oil tank 55, but only oil is released from the safety valve 106. To prevent the pressure inside the tank from rising abnormally without causing sudden pressure fluctuations in the tank.

Below, an example of the effect obtained by comparing the capacity of the oil tank of the conventional improved type and the capacity of the oil tank according to the present invention will be shown. The specifications of the water control valve and servo motor in this case are as follows.

Valve diameter 1) = 200 crn, valve upstream pressure P t =
50 kg/cm” Valve stem diameter d = 80 cm
+ Valve stem friction coefficient μ = 0.2 Servo motor diameter Ds =
67 crn + piston rod diameter dr = 2 & an lever radius R = 111 crn, lever closing angle θ = 30' Servo motor stroke 5 o = 157 crr 1 ° Range of self-closing force generation when water is cut off S 1 = S o/3 Required torque for valve closing when water is cut off Maximum value of = TE normal operating oil pressure P
o = 70 kg/cnF Allowable minimum operating oil pressure when water is cut off PE = 45 kg/crn" Servo motor closing operation oil consumption amount Vs: V s = -(Ds -d
r") X5o='(67"-28") 1574
4 =456855・4cW1' The required torque TE when shutting off the flowing water is d π 'l'E=-D2XPIX-Xμ=-(200") x
50 x 'LC' x O, 24242 = 12566400kg-cm Servo motor output torque Ts is Ts = -(Da"-d") XPEXRxco
s=i(67”-28”)X45X111XCO830
=12587296kg-α Therefore, the servo motor is capable of shutting off the running water.

1. The capacity of the pressure oil tank using the conventional O improved method is: Tank internal pressure after the valve closes once without replenishing the oil pump.
In order to achieve the allowable minimum operating pressure PE = 45 kg/crl, the tank air amount VA is determined by Boyle's law, the oil consumption amount for closing operation when water is cut off is 273 of Vs, and VAXPO = (VA + V8X2/31xPE2, in the present invention. The capacity of the pressure oil tank is VAt? - The homotor oil consumption is increased by the volume of the piston rod dr from the open side of the servo motor, so VAtXPO = (VAt + VsX2/3 - hdr ”)
X5OX2/a)XPE! ! -(d rT)XSOX
z7g=B (28”) 157 X2/1=6444
8. 11) VA, -PE Therefore, according to the present invention, compared to the conventional improvement plan, the air amount is sufficient at 78.8% (VA), which is a reduction of 21.2%. Become.

〔Effect of the invention〕

According to the present invention, if the water control valve operates to cut off the water flow,
The self-closing force generated during automatic valve closing is used as a pressure source by the servo motor to increase the pressure, and the amount of oil consumed by the servo motor during that time is returned to the pressure oil tank.As a result, the pressure oil is increased. It becomes possible to reduce the capacity of the device and obtain effective and economical control of the water control valve.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing the control system of a conventional water control valve and pressure oil device, Fig. 2 is a water control valve required operating torque curve, and Fig. 3 is a water control valve showing an embodiment of the present invention. FIG. 3 is a system diagram showing the control system of the pressure oil device. 1.51...Oil tank, 2,52...Oil pump, 3.
53...Electric motor, 4.54...Air compressor, 5,5
5... Pressure oil tank, 17.67... Water control valve, 58-
1... Open command section, 58-2... Close command section.

Claims (1)

[Claims] 1. When a valve shuts off fluid, the action of the self-closing force is Detects the back pressure of the servo motor and the pressure of the pressure accumulator, and directs the liquid on the servo motor back pressure side in the range where the servo motor back pressure is higher than the pressure of the pressure accumulator to the pressure accumulator using the pushing force of the self-closing force. Characteristic valve control method.