JP2543706Y2 - Electric positioner - Google Patents

Description

[Detailed description of the invention] A. Industrial application field The invention relates to an electric positioner used for flow control and the like.

B. Outline of the Invention The present invention is based on the opening signal and the opening setting signal in an electric positioner that opens and closes the electric valve in relation to the opening signal of the motorized valve, the opening setting signal, and the neutral zone setting signal. By controlling the motor-operated valve based on the calculated opening degree setting signal, dead zone operation signal, and a parallel movement amount operation signal for translating the opening degree setting signal and the dead zone operation signal in parallel with respect to the opening degree signal, high performance is achieved. Enables control of motorized valves.

C. Prior Art As shown in FIG. 6, an electric positioner is used in an automatic control system of a water treatment process. An electric positioner outputs an opening degree setting signal which is an output of a controller to an electric valve which is an operation terminal. This is converted into a signal to be operated.

That is, FIG. 6 shows an automatic control system of the water treatment process, wherein 1 is a water tank, 2 is a flow meter, 3 is an electric valve, 4 is an electric motor, 5 is an opening meter, 6 is a flow setting device, 7 is Butt circuit,
8 is a controller, 9 is a relay, and 10 is an electric positioner.

In the automatic control system shown in FIG. 6, the amount of effluent from the water tank 1 is measured by the flow meter 2, and the detection signal is compared with the setting signal of the flow setting device 6 in the matching circuit 7. The deviation signal obtained by the matching circuit 7 is input to a controller 8, and the controller 8 inputs an opening setting signal to an electric positioner 10.

Further, an opening signal of the electric valve 5 is input from the opening meter 5 to the electric positioner 10. The electric positioner 10 outputs an open / close signal based on the opening signal of the opening meter 5 and the opening setting signal of the controller 8, controls the relay 9 to control the motor 4, and thereby controls the motor-operated valve 3. To adjust the water flow.

FIG. 7 shows such a conventional electric positioner.
11 is a matching circuit that receives the opening setting signal and the opening signal as inputs.
12 is an amplifier that amplifies the deviation signal of the matching circuit 11, 13 is a comparator that compares the output signal of the amplifier 12 with the neutral band setting signal of the neutral band setting circuit 16, and 14 is an open command signal according to the output signal of the comparator 13. An open output circuit for outputting, a closed output circuit 15 for outputting a close command signal in response to an output signal of the comparator 13, and a power supply circuit 17 are also provided.

D. Problems to be Solved by the Invention According to the electric positioner of FIG. 7, as shown in FIG. 8, when the difference between the opening degree setting signal and the opening degree signal deviates from the neutral zone, an open or close signal is output. Things. The neutral zone is provided for the inertia of the operation of the motor-operated valve and takes into account the amount of overshoot due to the inertia until the motor-operated valve stops, and is fixedly set regardless of the magnitude of the opening degree setting signal. It is a dead zone.

However, in general, the characteristics of the motor-operated valve are non-linear as shown in FIG. 9, and it is difficult to optimally adjust the entire control range including that the entire control system is a delay system. there were. In particular, when the number of times of operation of the motor-operated valve is increased, the life of the motor-operated valve and the switch that operates the motor-operated valve may be reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object the purpose of setting a constant band regardless of the magnitude of the opening setting signal, that is, a neutral band where the opening signal is 0 with respect to the opening setting signal. By setting a second dead band set in accordance with the magnitude of the opening setting signal in addition to the first dead band and by moving the neutral band and the second dead band in parallel, high-performance operating characteristics are obtained. It is to provide an electric positioner.

E. Means for Solving the Problems A neutral signal for stopping the motor-operated valve opening / closing signal in relation to a deviation signal between the motor-operated valve opening signal and the valve opening setting signal and an excessive amount of inertia until the motor-operated valve stops. A neutral position setting circuit for setting a first dead band, which is a band, compares the neutral band setting signal with a neutral band setting signal, and opens and closes the electric valve in accordance with the compared deviation signal. Opening range setting circuit for linearly approximating the degree characteristics and determining the opening range of each linear portion, and a variation calculation circuit for calculating a dead band command signal by calculating based on the variation of the opening setting signal Calculating a plurality of second dead zones based on the opening, an opening range setting signal of the opening range setting circuit, and a dead zone command signal of the change amount calculation circuit.
Outside at least one second dead zone is the first dead zone.
A dead band operation circuit for setting the at least one second dead band to be smaller than the first dead band, and the opening degree based on a change amount signal of the change amount calculation circuit. A high-performance electronic positioner is configured by a parallel movement amount calculation circuit that calculates the movement amount of the second dead band with respect to the signal.

F. Action A second dead zone is provided in addition to the first neutral zone, and the width of the second dead zone is automatically determined according to the magnitude of the opening signal.

By linearly approximating the valve opening characteristics, the opening ranges of the linear portions are specified, and the width of the dead zone in the specified opening ranges becomes stepwise.

The neutral zone and the dead zone automatically move in parallel depending on the amount of change in the opening setting signal. However, the widths of the neutral zone and the dead zone do not change.

The magnitude of the parallel movement is substantially proportional to the magnitude of the variation of the opening degree setting signal. If the state in which the amount of change in the opening degree setting signal is almost negligible continues for a certain period of time, the dead zone is set to 0 to minimize the steady-state deviation.

G. Embodiment An embodiment of the present invention will be described below with reference to FIGS.

In the present embodiment, as shown in FIG. 1, an opening range setting circuit 18 for setting an opening range of a motor-operated valve, and a change for calculating an amount of change of the opening setting signal when an opening setting signal is input. A second dead zone is calculated by inputting the amount operation circuit 19, the opening signal of the electric valve, the opening range setting signal from the opening range setting device 18 and the change amount signal from the change amount calculation circuit 19, and A dead zone calculation circuit 20 for inputting the second dead zone calculation signal to the comparator 13 is provided, and a parallel movement parameter setting circuit 21 and an output signal of the parallel movement parameter setting circuit 21 and an output signal of the change amount calculation circuit 19 are input. And a translation amount calculating circuit 22 for calculating the translation amount is provided.

According to the electric positioner having the above configuration, a deviation signal between the opening signal and the opening setting signal is obtained in the matching circuit 11, and this deviation signal is input to the comparator 13. The opening range setting circuit 18 sets the opening range of the motor-operated valve, and inputs the opening range setting signal to the dead zone calculation circuit 20. The change amount calculation circuit 19 performs calculation processing based on the opening degree setting signal of the electric valve to calculate a change amount of the opening degree setting signal, and inputs a dead zone command signal to the dead zone operation circuit 20. The dead zone command signal is a command to set the dead zone to 0 when there is almost no change in the opening degree setting signal or when a predetermined time has elapsed. The dead band calculation circuit 20 performs a calculation process based on the opening signal, the opening range setting signal, and the dead band command signal, and inputs a dead band calculation signal to the comparator 13.

The parallel movement parameter setting circuit 21 sets a parallel movement amount, and inputs the parallel movement amount setting signal to the parallel movement amount calculation circuit 22. The parallel movement amount calculation circuit 22 performs a calculation process based on the parallel movement amount setting signal and the calculation signal of the change amount calculation circuit 19, and inputs the parallel movement amount signal to the comparator 13. The comparator 13 performs a comparison process based on the opening deviation signal, the dead zone calculation signal, the parallel movement amount signal, and the neutral band setting signal from the neutral band setting circuit 16, and operates the open output circuit 14 and the closed output circuit 15 based on the output signal. Let it.

More specifically, as shown in FIG. 2, the opening range setting circuit 18 linearly approximates the opening characteristics of the motor-operated valve, and determines the opening range of each linear portion.

Since the steady-state error may increase due to the addition of the second dead zone, the change amount calculation circuit 19 keeps the change amount of the opening degree setting signal small for a predetermined time as shown in FIG. Then, the second dead zone is set to 0 to eliminate the steady-state error. As shown in FIG. 4, the dead zone calculation circuit 20 sets a dead zone outside the neutral zone, and its width is determined stepwise within the above-mentioned opening range. In this case, assuming that the opening range of X in the opening ranges X, Y, and Z shown in FIG. 2 = the opening range of A and Y = B and the opening range of Z = C, then B>A> C. .
The second dead zone operates only when the switching signal is output when the vehicle deviates from the neutral zone, and the output of the switching signal is stopped within the neutral zone.

As shown in FIG. 5, the parallel movement amount calculating circuit 22
It is set by moving in parallel from the state shown in the figure. Here, the neutral zone and the dead zone are translated in accordance with the magnitude of the change amount {(previous value) − (current value)} of the opening degree setting signal. The amount of parallel movement is proportional as shown in FIG.
The width of the dead zone and the width of the second dead zone do not change. When the opening degree setting signal changes, the first and second directions move in the same direction according to the amount of change.
The second dead zone is translated.

H. Effects of the Invention The invention is as described above, and has the following excellent advantages.

(1) By providing the dead zone function, it is possible to stabilize the entire control range and reduce the number of opening / closing operations. Further, the width of the dead zone is automatically adjusted according to the magnitude of the opening signal, so that the problem due to the non-linearity of the valve opening characteristics can be solved and optimized.

(2) Since the neutral zone and the dead zone are proportionally moved in parallel according to the magnitude of the change in the opening degree setting signal, feedforward control is performed, so that the number of opening / closing operations can be further reduced.

(3) If a state in which the amount of change of the opening degree setting signal hardly changes is continued for a certain period of time, the dead zone is set to 0, thereby minimizing the steady-state deviation due to the dead zone.

As described above, since the number of times of opening / closing operations can be significantly reduced without lowering the control accuracy, the shortening of the life of the motor-operated valves and the switches that operate them can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electric positioner according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of a flow rate with respect to an opening of a motorized valve of the electric positioner of FIG. 1, and FIG. 3 is an operation of the electric positioner of FIG. FIG. 4 is an operation characteristic diagram of the electric positioner of FIG. 1, FIG. 5 is an operation characteristic diagram of the electric positioner of FIG. 1, FIG. 6 is a block diagram of a water treatment process using the electric positioner, FIG. 7 is a block diagram of a conventional electric positioner, FIG. 8 is a characteristic diagram of a motor-operated valve, and FIG. 9 is a characteristic diagram of the electric positioner of FIG. 10 ... electric positioner, 11 ... matching circuit, 12 ... amplifier, 13 ... comparator, 14 ... open output circuit, 15 ... closed output circuit, 16 ... neutral band setting circuit, 17 ... power supply circuit, 18
…… Opening range setting circuit, 19 …… Change amount calculation circuit, 20 ……
Dead zone setting circuit, 21: Parallel movement parameter setting circuit, 22: Parallel movement calculation circuit.

Claims (1)

(57) [Scope of request for utility model registration] 1. A neutral band for stopping a motor-operated valve opening / closing signal in relation to a deviation signal between the motor-operated valve opening signal and the valve opening setting signal and an excessive amount of inertia until the motor-operated valve stops. A neutral position setting circuit for setting a dead band of 1 in a neutral position setting signal, and an electric positioner for opening and closing the electric valve in accordance with the compared deviation signal; An opening range setting circuit that approximates and determines an opening range of each linear portion; a change amount calculation circuit that calculates a dead band command signal by calculating based on a change amount of the opening degree setting signal; At least one second dead band outside the first dead band by calculating based on an opening range setting signal of the opening range setting circuit and a dead band command signal of the change amount calculation circuit. The second dead zone is the first dead zone. Larger than the band and at least one second dead band of the first
A dead band operation circuit that is set to be smaller than the dead band; and a parallel movement amount calculation circuit that calculates a movement amount of the second dead band with respect to the opening degree signal based on a change amount signal of the change amount calculation circuit. An electric positioner characterized by comprising: