JPH10103313A - Runaway preventing device for valve drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent runaway of a valve drive device through detection of abnormality of a signal. SOLUTION: A signal proper decision circuit 18 comprises a differential circuit 19 to detect that a value of an opening signal shows a tendency to increase a comparing circuit 20 to detect that a value of an opening signal is higher compared with an opening closing indication signal; a deviation circuit 21 to detect that a difference between the values of the opening signal and the opening closing indication signal exceeds an allowable value; an amplifier trouble detecting circuit 22 to output a cut-off indication signal when an output signal from the differential circuit 19, an output signal from a comparing circuit 20, and an output signal from a deviation circuit 21 are all a positive value; and an opening sensor reverse connection detecting circuit 23 to output a cutoff indication signal when an output signal from the differential circuit 19 and a output signal from the comparing circuit 20 are a negative value and an output signal from the deviation circuit 21 is a positive value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slide valve and the like interposed in a flow path for flowing a high-temperature fluid in, for example, a petroleum refining plant, and more particularly to a device for preventing runaway of a valve driving device.

[0002]

2. Description of the Related Art Conventionally, in this type of valve driving device,
A servo valve is provided in the hydraulic supply circuit to the cylinder device that opens and closes the valve, and the amount of movement of the cylinder device is controlled by adjusting the drive current supplied to the servo valve to control the valve opening. . For this purpose, the current opening of the valve detected by the valve opening sensor is input to the control circuit as a valve opening sensor signal, and the newly-opened opening is input as an opening / closing instruction signal, and both signals are input to the servo valve. Supply appropriate drive current to servo valve by comparing with amplifier for
The valve is controlled to open and close.

[0003]

In the above configuration, if the current opening is erroneously transmitted to the servo valve amplifier due to an abnormality of the opening sensor, the valve driving device will open the opening different from the instructed opening. There is a danger of runaway toward and the valve may be fully opened. Particularly, in a petroleum plant or the like, the full opening of the valve causes a runaway of the process in the plant and may cause serious damage to the entire apparatus, and a reliable preventive measure is required. However, the servo valve amplifier is provided with a circuit that detects when a signal in the circuit is abnormal, but when the opening sensor is abnormal, the servo valve amplifier is used by the opening sensor. No abnormality can be recognized in the signal input to the microcomputer itself, and no abnormality can be detected in the servo valve amplifier.

[0004]

In order to solve the above-mentioned problems, a runaway prevention device for a valve drive device according to the present invention is provided with a hydraulic pressure for a cylinder for driving a valve body to be opened and closed by a cylinder device and supplying hydraulic pressure to the cylinder device. A servo valve amplifier is provided in the middle of the circuit to supply a drive current to the servo valve, and a servo valve amplifier is provided to the servo valve amplifier.
A valve driving device that inputs an opening / closing instruction signal indicating a new opening and an opening signal indicating a current opening detected by an opening sensor, and compares the two openings to control a driving current to a servo valve. In the middle of the cylinder hydraulic circuit, an operation check valve that receives a control signal pressure and opens the hydraulic pressure input / output path from the cylinder device is interposed, and an electromagnetic check valve is provided in the middle of the signal pressure circuit that supplies the control signal pressure. An on-off valve is interposed and an on-off valve relay that cuts off the drive current in response to a shut-off instruction signal is provided in the middle of the electric circuit that supplies drive current to the electromagnetic on-off valve, and supplies drive current to the servo valve In the middle of the electric circuit, a relay for servo valve that intercepts the drive current in response to the shutoff instruction signal is interposed, and a signal appropriate judgment circuit that inputs the shutoff instruction signal to the on-off valve relay and the servo valve relay is provided. The appropriateness judgment circuit increases the value of the opening signal A differentiating circuit for outputting an output signal of positive value when in the direction, a comparator circuit for outputting an output signal of positive value when compared to the switching instruction signal is a large value of the opening signal,
A deviation circuit that outputs a positive value output signal when a difference between the value of the opening signal and the value of the opening / closing instruction signal is equal to or greater than a certain value; and a difference circuit output signal, a comparison circuit output signal, and a deviation circuit output signal. An amplifier failure detection circuit that outputs a shutoff instruction signal when any of them is a positive value, an output signal of a differentiating circuit and an output signal of a comparing circuit are negative values, and an output signal of a deviation circuit is a positive value. And an opening degree sensor reverse connection detection circuit for outputting a cutoff instruction signal to the circuit.

With the above configuration, during normal operation, the control signal pressure acts on the operation check valve through the electromagnetic on-off valve to open the operation check valve. This is performed by adjusting the value of the drive current supplied from the amplifier to the servo valve and operating the servo valve.

During this time, an open / close instruction signal and an opening signal are input to the servo valve amplifier,
Both signals are input to a signal appropriateness determination circuit, and the amplifier failure detection circuit and the opening degree sensor reverse connection detection circuit determine the appropriateness of each signal.

For example, the opening state of the valve element is detected in a differentiating circuit, the fact that the current opening degree of the valve element exceeds the indicated opening degree by the opening / closing instruction signal is detected in the comparing circuit, and the indicated opening degree is determined in the deviation circuit. When detecting that the opening of the present opening exceeds the allowable value set in advance, the amplifier failure detecting circuit corrects the valve opening transmitted by the open / close instruction signal due to the failure of the amplifier for the servo valve. However, it is determined that the valve body is open despite the fact that the closing operation is instructed by the opening / closing instruction signal, and a shutoff instruction signal is output. The servo valve relay and the on / off valve relay that have received the cutoff instruction signal respectively cut off the drive current, and the servo valve and the electromagnetic on / off valve close their respective hydraulic circuits. As a result, the operation check valve whose control signal pressure has been released by closing the electromagnetic on-off valve shuts off the flow of hydraulic pressure to and from the cylinder device, immediately stops driving the cylinder device, and prevents runaway of the valve drive device.

The differential circuit detects the closing state of the valve element, the comparison circuit detects that the current opening degree of the valve element is smaller than the instruction opening degree according to the opening / closing instruction signal, and the deviation circuit detects the present opening degree and the current opening degree. When it is detected that the opening of the opening exceeds a preset allowable value, the opening sensor reverse connection detection circuit detects that the opening of the opening sensor is reversely connected, and the valve opening is correctly adjusted by the amplifier for the servo valve. And outputs a cutoff instruction signal. As a result, the drive of the cylinder device stops immediately, preventing runaway of the valve drive device.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, the slide valve 1 is used in a petroleum refining facility or the like. In order to prevent a malfunction from causing an explosion or the like, it is required to prevent runaway of the valve driving device.

In the cylinder device 2, a piston 3 is connected to the valve body 1a of the slide valve 1, and a front oil chamber 4a and a rear oil chamber 4b are formed in the cylinder chamber with the piston 3 as a boundary. The front oil chamber 4a and the rear oil chamber 4b communicate with a cylinder hydraulic circuit composed of a hydraulic supply system 7 and a hydraulic discharge system 8 via cylinder check valves 5, 5 and a servo valve 6, respectively. .

The hydraulic supply system 7 includes a pump 10, an accumulator 11, and a sub-operation check valve 12 between the tank 9 and the servo valve 6, and includes cylinder operation check valves 5, 5 and a sub-check. A signal pressure circuit 13 for supplying a control signal pressure to the valve 12 includes an electromagnetic on-off valve 14.

The servo valve 6 includes a control circuit 15 shown in FIG.
It operates in response to a drive current supplied from a servo valve amplifier provided in the inside thereof, and switches the hydraulic supply system 7 and the hydraulic discharge system 8 and stops the supply of hydraulic pressure to control the opening of the valve element. Things. The servo valve amplifier of the control circuit 15 inputs an opening / closing instruction signal A indicating a new opening and an opening signal B indicating a current opening detected by an opening sensor (not shown). The drive current to the servo valve 6 is controlled by comparing the opening degrees. The valve operating device cylinder operation check valves 5 and 5 and the sub check valve 12 receive the control signal pressure and maintain the open state, and the solenoid on-off valve 14 receives the drive current from the control circuit 15 and receives the drive current. It operates to open and close the signal pressure circuit 13.

As shown in FIG. 2, an on-off valve relay 16 for intercepting a drive current in response to a shut-off instruction signal is provided in the middle of an electric circuit for supplying a drive current to the electromagnetic on-off valve 14. In the middle of the electric circuit that supplies the drive current to the servo valve 6, a servo valve relay 17 that receives the cutoff instruction signal and cuts off the drive current is provided.

The signal suitability judging circuit 18 inputs a shut-off instruction signal to the on-off valve relay 16 and the servo valve relay 17, and outputs a positive value output signal when the value of the opening signal B is increasing. , A comparator circuit 20 that outputs a positive output signal when the value of the opening signal B is larger than the opening / closing instruction signal A, and a value of the opening signal B and the opening / closing instruction signal A. And a deviation circuit 21 for outputting a positive output signal when the difference between the two signals is equal to or greater than a predetermined value. The output signal of the differentiation circuit 19, the output signal of the comparison circuit 20, and the deviation circuit 2
1 is a positive value, an amplifier failure detection circuit 22 that outputs a cutoff instruction signal, an output signal of a differentiating circuit 19 and an output signal of a comparing circuit 20 are negative values, and a deviation circuit 21 is provided. And an opening degree sensor reverse connection detection circuit 23 that outputs a shutoff instruction signal when the output signal of the above is a positive value. The amplifier failure detection circuit 22 and the opening sensor reverse connection detection circuit 23 are formed by AND circuits, and the output signal of the differentiating circuit 19 and the output signal of the comparison circuit 20 are inverted in the opening sensor reverse connection detection circuit 23. You are typing.

The operation of the above configuration will be described below. During normal operation, the control signal pressure is applied to the cylinder operation check valves 5, 5
And act on the sub-operation check valve 12, and each check valve 5, 5, 5,
12 is open. In this state, the control of the hydraulic pressure for the cylinder device 2 is performed by adjusting the value of the drive current supplied from the servo valve amplifier of the control circuit 15 to the servo valve 6, and operating the servo valve 6,
The valve body 1a is driven by the cylinder device 2 to control the opening thereof.

During this time, an open / close instruction signal A and an opening signal B are supplied to the servo valve amplifier of the control circuit 15.
Are input to the signal appropriateness determination circuit 18, and the amplifier failure detection circuit 22 and the opening degree sensor reverse connection detection circuit 23 determine the appropriateness of each signal.

For example, the servo valve amplifier malfunctions, the drive current to the servo valve 6 has an error, and the valve body 1a opens despite the closing instruction being given by the open / close instruction signal A. Assume that a situation has occurred.

At this time, since the opening degree is increased in the differentiating circuit 19, the open state of the valve body 1a is detected. In the comparing circuit 20, the current opening degree of the valve body 1a exceeds the opening degree indicated by the opening / closing instruction signal A. When the deviation circuit 21 detects that the difference between the designated opening and the current opening exceeds a preset allowable value (deviation value 2%), the amplifier failure detection circuit 22 The valve opening transmitted by the opening / closing instruction signal A is not correctly transmitted to the servo valve 6 due to the failure of the amplifier, and the valve body 1a opens even though the closing operation is instructed by the opening / closing instruction signal A. And outputs a cutoff instruction signal.

Servo valve relay 1 which has received a cutoff instruction signal
7 and the on / off valve relay 16 respectively cut off the drive current, and the servo valve 6 and the electromagnetic on / off valve 14 close the respective hydraulic circuits. As a result, the cylinder operation check valves 5 and 5 and the sub-check valve 12 whose control signal pressure is released by closing the electromagnetic on-off valve 14 block the flow of hydraulic pressure into and out of the cylinder device 2 and drive the cylinder device 2. Stops immediately, preventing runaway of the valve drive.

As another example, the opening signal of the opening sensor is not affected by the wrong polarity when connecting the opening sensor during maintenance or the like, even though the valve 1a is open. It is assumed that a situation occurs in which an input is made so as to be closed.

In this case, the differentiating circuit 19 detects the closed state of the valve 1a, and the comparing circuit 20 detects the valve 1a.
It is detected that the current opening of “a” is smaller than the instruction opening by the opening / closing instruction signal A, and the deviation between the instruction opening and the current opening in the deviation circuit 21 exceeds a preset allowable value (deviation value 2%). Is detected, the opening sensor reverse connection detection circuit 23
Determines that the valve opening is not correctly input to the servo valve amplifier of the control circuit 15 due to the reverse connection of the opening sensor, and outputs a shutoff instruction signal. As a result, the driving of the cylinder device 2 is immediately stopped, and runaway of the valve driving device is prevented.

[0022]

As described above, according to the present invention, the open / close instruction signal and the opening signal are input to the signal appropriateness judgment circuit,
The amplifier failure detection circuit and the opening sensor reverse connection detection circuit judge the appropriateness of each signal, so it detects the failure of the servo valve amplifier and the reverse connection of the opening sensor,
The drive of the cylinder device is immediately stopped, and runaway of the valve drive device can be prevented.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a signal appropriateness determination circuit according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slide valve 2 Cylinder device 5 Cylinder operation check valve 6 Servo valve 7 Hydraulic supply system 8 Hydraulic discharge system 12 Sub-operation check valve 13 Signal pressure circuit 14 Electromagnetic on-off valve 15 Control circuit 16 On-off valve relay 17 For servo valve Relay 18 Signal appropriate judgment circuit 19 Differentiator circuit 20 Comparison circuit 21 Deviation circuit

Claims (1)

[Claims] 1. A valve body is driven to open and close by a cylinder device,
A servo valve is interposed in the middle of the cylinder hydraulic circuit that supplies hydraulic pressure to the cylinder device, and a servo valve amplifier that supplies drive current to the servo valve is provided. The servo valve amplifier shows a new opening. In a valve drive device that inputs an opening / closing instruction signal and an opening signal indicating a current opening detected by an opening sensor, and compares both openings to control a drive current to a servo valve, a hydraulic circuit for a cylinder In the middle of the process, an operation check valve for opening a passage for hydraulic pressure from the cylinder device in response to the control signal pressure is interposed, and an electromagnetic on-off valve is interposed in the signal pressure circuit for supplying the control signal pressure. In the middle of an electric circuit that supplies a drive current to an electromagnetic on-off valve, an on-off valve relay that cuts off the drive current in response to a cutoff instruction signal is provided in the middle of an electric circuit that supplies a drive current to a servo valve, Receiving the shutdown instruction signal A signal validity judgment circuit is provided that interposes a servo valve relay that cuts off the drive current, and that inputs a shutoff instruction signal to the on-off valve relay and the servo valve relay. A differentiating circuit that outputs a positive value output signal when there is an increasing tendency, a comparison circuit that outputs a positive value output signal when the opening signal value is larger than the opening / closing instruction signal, and an opening signal and opening / closing A deviation circuit that outputs a positive output signal when the difference between the instruction signal and the value is equal to or greater than a certain value, and all of the output signals of the differentiating circuit, the comparing circuit, and the deviation circuit are positive. An amplifier failure detection circuit that outputs a shutoff instruction signal when the output signal of the differential circuit and the output signal of the comparison circuit are negative, and the shutoff instruction signal is output when the output signal of the deviation circuit is a positive value. Output opening sensor reverse connection detection circuit A runaway prevention device for a valve drive device, comprising: