JP2001280301A - Valve positioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve positioner for controlling a valve by automatically measuring the characteristics of portions to be controlled for automatic tuning. SOLUTION: The valve positioner comprises an input signal for setting the opening of a valve, a position sensor for detecting the opening of the valve, a control arithmetic part for performing control arithmetic operation corresponding to the input signal from a deviation between a valve opening signal obtained by the position sensor and the input signal to generate a control signal, an electropneumatic change mechanism part for generating an air flow rate in accordance with the control signal, and a pressure amplifier for supplying to the valve an air pressure based on the air flow rate generated by the electropneumatic change mechanism part. When portions to be controlled consisting of the electropneumatic change mechanism part, the pressure amplifier, the position sensor and the valve receive automatically setting signal, the characteristics of the portions to be controlled are automatically measured and tuning parameters for generating the control signal for the control arithmetic part are found with arithmetic operation from the characteristics of the portions to be controlled so as to be replaced with present tuning parameters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve positioner, and more particularly, to a valve positioner that receives an input signal and controls the valve opening of the valve to match the received input signal. A position sensor that detects the degree position and converts it to an electric signal, a control operation unit that performs control operation so that a signal from the position sensor matches an input signal, and a control signal calculated by the control operation unit for a valve. An electro-pneumatic conversion mechanism for converting into a drive signal, automatically measuring the characteristics of the control target portion composed of these components, automatically calculating the tuning parameters of the control calculation portion from the characteristics of the control target portion, and automatically The present invention relates to a valve positioner having a tuning function.

[0002]

2. Description of the Related Art A conventional valve positioner is
Since an arithmetic function (CPU or the like) is mounted inside, a control algorithm for controlling the valve opening degree of the valve can be realized by software. With this technology, complicated control calculations can be performed, so that the controllability of the valve is much improved compared to the mechanical valve positioner of the previous generation. On the other hand, with respect to the control algorithm, the use of an increased number of control parameters has made tuning more complicated, and the installation has required more man-hours. In order to solve this problem, some models have an automatic tuning function. In addition, the use of the calculation function has been extended to self-diagnosis, control valve diagnosis, and the like, in addition to control calculation.

However, one of the causes of difficulty in tuning the valve positioner is that the valve positioner cannot be specified because there are many types of valves that must be controlled. That is, since it is not possible to specify the characteristics of the valve to be combined with the valve positioner, the tuning has to be performed by repeating the cut-and-try operation. Accordingly, a valve positioner having a function of assisting a tuning operation or a valve positioner having an automatic tuning function has been developed.

As an automatic tuning method for realizing the automatic tuning function, there are a tuning assist type valve positioner and an automatic tuning type valve positioner.

[0005] A tuning assist type valve positioner is designed so that an operator inputs a model name, type and characteristics of a valve to be combined with the valve positioner to the valve positioner, and the valve positioner appropriately determines the type based on the data. This is a so-called semi-auto tuning method of selecting a proper tuning parameter.

An automatic tuning type valve positioner provides an automatic setting signal to a valve positioner.
This is a method in which characteristics such as valve size and hysteresis are measured, and a tuning set of control parameters is selected from a predetermined parameter table.

[0007]

However, as described in the above-mentioned prior art, it is difficult for the valve positioner to perform tuning for controlling the valve. There are an auxiliary valve positioner and an automatic tuning type valve positioner, but each has the following problems.

[0008] The problem with the automatic tuning method is that the operator requires some information and knowledge of the valve, and thus requires a certain degree of specialty. Therefore, since the information and characteristics of the valve must be input to the valve positioner, the input man-hour is increased and there is a risk that a human error such as an input error may occur.

The problem with the automatic tuning method is that, in order to perform accurate tuning with respect to valve characteristics in which countless combinations are conceivable, the amount of data in the parameter table that the valve positioner must have becomes enormous, and memory and the like become large. Hardware is required and costs increase. If an attempt is made to solve this problem by using a small number of parameter tables, there is a problem that tuning is coarse and tuning is inaccurate.

As described above, some of the elements of the valve positioner itself have non-linear characteristics having unique characteristics, and there is a problem that it is impossible to perform actual tuning reflecting these effects. This is because the control target of the valve positioner is not limited to the valve depending on the control device.Specifically, depending on the method of measuring the characteristics of the valve, accurate measurement cannot be performed or measurement takes time. However, there is a problem that the time required for tuning becomes longer.

Therefore, there is a problem that such a problem has to be solved and a method of performing simpler, more accurate, and faster automatic tuning of the valve has to be solved.

[0012]

In order to solve the above problems, a valve positioner according to the present invention has the following configuration.

(1) An input signal for setting the valve opening of a valve, a position sensor for detecting the valve opening of the valve, and a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal by performing a control operation so that the valve opening of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner comprising: a pressure amplifier that supplies air pressure based on an air flow rate generated in a conversion mechanism to the valve, wherein the control is configured by the electropneumatic conversion mechanism, a pressure amplifier, a position sensor, and a valve. When the target portion receives the automatic setting signal, a tuning parameter for generating a control signal of the control calculation portion is obtained by calculation by automatically measuring each characteristic of the control target portion. Rutotomoni, valve positioner, characterized in that it has to replace the current tuning parameters.

(2) An input signal for setting the valve opening of the valve, a position sensor for detecting the valve opening of the valve, and a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal by performing a control operation so that the valve opening of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner comprising: a pressure amplifier that supplies air pressure based on an air flow rate generated in a conversion mechanism to the valve, wherein the control is configured by the electropneumatic conversion mechanism, a pressure amplifier, a position sensor, and a valve. The target part, when receiving the automatic setting signal, automatically measures the response speed of the control target part, and generates a control signal of the control operation unit based on the parameter of the automatically measured response speed. Valve positioner, characterized in that for calculating the training parameters. (3) In the valve positioner of the above (2), the automatic measurement of the response speed of the controlled object part is to saturate the output of the electro-pneumatic conversion mechanism and measure the response speed of the valve at that time. Characterized valve positioner. (4) In the valve positioner according to the above (2), the automatic measurement of the response speed of the control target portion is performed by keeping a constant change speed of the output of the electropneumatic conversion mechanism,
A valve positioner characterized by measuring a response speed of a valve at that time. (5) In the valve positioner according to the above (3) or (4), the response speed of the valve is measured by the first position.
A valve positioner characterized by measuring a time when the valve opening changes from a second valve opening to a second valve opening. (6) In the valve positioner according to the above (3) or (4), the response speed of the valve is measured by the first position of the valve.
A valve positioner characterized by measuring a valve opening signal after a certain unit time after passing a valve opening signal obtained by detecting the valve opening in the position sensor by the position sensor. (7) In the valve positioner of the above (4), the rate of change of the output of the electro-pneumatic conversion mechanism is kept constant by utilizing a dead zone caused by the structure of the electro-pneumatic conversion mechanism. A valve positioner characterized in that:

(8) An input signal for setting the valve opening of the valve, a position sensor for detecting the valve opening of the valve, and a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal by performing a control operation so that a valve opening signal of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A pressure amplifier that supplies air pressure to the valve based on the air flow rate generated in the air conversion mechanism unit, wherein the control operation unit is
In the control calculation, at least one integrator is used to detect that the deviation between the valve opening signal and the input signal falls within a preset range, and output from the control calculation unit at that time. A valve positioner, wherein a control signal is used as an operation start reference signal and stored in a predetermined storage unit. (9) In the valve positioner according to (8), the operation start reference signal stored in the storage unit is used as a reference point of a control signal output from the control operation unit.

(10) An input signal for setting the valve opening of the valve, a position sensor for detecting the valve opening of the valve, and a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal by performing a control operation so that the valve opening of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner including a pressure amplifier that supplies air pressure based on an air flow rate generated in a conversion mechanism to a valve, and a control target including the electropneumatic conversion mechanism, a pressure amplifier, a position sensor, and a valve. Upon receiving the automatic setting signal, the part automatically measures the hysteresis of the control target part, and controls the control signal generated by the control calculation unit based on the automatically measured hysteresis parameters. Valve positioner, characterized in that for calculating the training parameters. (11) In the valve positioner according to the above (10), the automatic measurement of the hysteresis of the control target part includes a sensor for detecting a drive signal supplied to the valve, and the input / output characteristic of the valve is determined based on the detection of the sensor. The valve positioner is characterized in that the valve hysteresis is obtained by calculation by measuring the hysteresis. (12) In the valve positioner (10), the automatic measurement of the hysteresis of the control target part is performed by a control algorithm using at least a comparator in the control calculation of the control calculation unit, and the input signal is changed by changing the input signal. The valve opening signal of the valve is monitored, the input signal SP1 when the valve opening signal reacts is stored, and then the direction of change of the input signal is reversed, and the valve opening signal of the valve is reversed. A valve positioner storing an input signal SP2 at the time of a reaction, and calculating and measuring a hysteresis of the control target portion from a difference between the stored input signals SP1 and SP2. (13) In the valve positioner according to the above (12), the calculation of the hysteresis of the control target portion uses a value obtained by multiplying a difference between the input signals SP1 and SP2 by a loop gain of a stem of the valve. Valve positioner.

(14) An input signal for setting the valve opening of the valve, a position sensor for detecting the valve opening of the valve, and a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal by performing a control operation so that the valve opening of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner including a pressure amplifier that supplies air pressure based on an air flow rate generated in a conversion mechanism to a valve, and a control target including the electropneumatic conversion mechanism, a pressure amplifier, a position sensor, and a valve. The part measures a slip width of a slip phenomenon that occurs when the valve opening starts moving from a stationary state when the automatic setting signal is received, and a parameter including the measured slip width is measured. Valve positioner, characterized by calculating tuning parameters of the control signal generated by the control arithmetic unit by. (15) In the valve positioner of (14), when measuring the slip width, it is confirmed that the valve opening signal of the valve is stationary, the valve opening PV1 at that time is stored, and the control is performed. The change rate of the valve opening signal when the signal is changed when the signal is changed is measured, and the valve opening signal PV2 at the inflection point of the change speed of the valve opening signal is stored. A valve positioner characterized in that a difference between the valve opening signals PV1 and PV2 is used as a slip width of the valve and the value of the slip width is stored. (16) In the valve positioner of (14), when measuring the slip width, it is confirmed that the valve opening signal is stationary, the valve opening PV1 at that time is stored, and then the control is performed. After the valve opening signal of the valve reacts when the signal is changed, the valve opening signal PV2 after a preset short time is stored, and the difference between the valve opening signals PV1 and PV2 is determined by the slip of the valve. A valve positioner which stores a value of the slip width as a width.

(17) An input signal for setting the valve opening of the valve, a position sensor for detecting the valve opening of the valve, and a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal by performing a control operation so that the valve opening of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner comprising: a pressure amplifier that supplies air pressure based on an air flow rate generated in a conversion mechanism to a valve, wherein the control target includes the electropneumatic conversion mechanism, a pressure amplifier, a position sensor, and a valve. The part, when receiving the automatic setting signal, measures the characteristic of the control target part, and when the measured value of the characteristic of the control target part deviates from the value of the allowable range information including the characteristic of the control target part. A valve positioner and outputs an abnormality signal via the external to the communication means.

As described above, the tuning of the valve is automatically performed, and the parameter obtained by measuring the characteristics of the control valve and the like is used as the tuning parameter. Therefore, the number of tuning steps can be reduced, and the accurate tuning parameter can be reduced. It can be set.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a valve positioner according to the present invention will be described below with reference to the drawings.

First, a valve positioner is destined to be unable to select a valve to be controlled, and it is not possible to specify what characteristic valve is to be attached. That is, there are countless combinations of the capacity of the pneumatic actuator of the valve and the spring range that determines the input / output relationship of the pneumatic actuator, and the response characteristics differ depending on the combination.

The mechanical frictional force of the valve has the effect of promoting the dead time of the response characteristic and making the response characteristic oscillatory. Also, when the valve starts to move out of the mechanical frictional force or backlash of the controlled object, a so-called slip phenomenon occurs, in which the valve opens a certain width, moves quickly and slides. This slip phenomenon causes a vibration phenomenon such as a limit cycle. Therefore, the valve positioner is required to absorb such non-linearity of the valve and make the characteristic linear, stable, and easy to control with respect to the input signal.

As described above, there is a need for a valve positioner that absorbs the non-linearity of a valve and has a characteristic that is linear, stable, and easy to control with respect to an input signal. There are two problems in development.

The first problem is the design of a control algorithm for absorbing the nonlinearity of the valve. The design of the control algorithm is considered to determine the controllability of the valve positioner.Therefore, great care must be taken in the design.However, in order to absorb the nonlinearity of the control target, the control algorithm must be complicated. I can't get it. As a result, the tuning parameters of the control algorithm have been increasing.

The second problem is a tuning method for applying the designed control algorithm to a control target. For example, taking the PID control algorithm as an example,
There are three kinds of tuning parameters, namely, a proportional gain, an integration time, and a differentiation time, and the control parameters increase as the control algorithm becomes more complicated, so that the tuning tends to be further complicated. When tuning is complicated, a great number of man-hours are required for tuning, and the usability is deteriorated.

Therefore, as a function of the valve positioner, a function of automatically determining a tuning parameter has been required. Then, in order to automatically determine the tuning parameters, it is necessary to grasp typical characteristics of the control target. Even if the characteristics of the controlled object are grasped, there are parameters that have a great influence on the control, among them, the response speed of the controlled object, the hysteresis of the controlled object, and the slip phenomenon caused by the hysteresis of the controlled object.

Assuming this, the valve positioner according to the present invention is a pneumatic valve positioner 10 having a pneumatically driven valve, which is the most common, as shown in FIG. The configuration of the pneumatic valve positioner includes a signal receiving device 11 for receiving an input signal.
And the input signal SP based on the deviation between the input signal SP and the valve opening signal PV obtained by converting the valve opening of the valve into an electrical signal.
And a control operation unit 12 that is a control operation unit that outputs a control signal MV by performing a control operation so as to match the control signal MV, and an electropneumatic conversion mechanism unit 13 that generates an air flow rate based on the control signal MV.
A pressure amplifier 14 for supplying air pressure based on the air flow rate to a valve section 15; and a valve for adjusting a valve body by changing a stem based on the air pressure, ie, a valve section 15
And the valve displacement signal P by detecting the stem displacement of the valve section 15.
And a position sensor 16 for generating V.
Among them, the electro-pneumatic conversion mechanism 13, the pressure amplifier 14, the position sensor 16, and the valve 15 constitute a control target portion 17.

As shown in FIG. 2, the valve section 15 includes an air actuator section 20 for receiving an air pressure signal Po from the pressure amplifier 14, a stem 23 connected to the air actuator section 20, and a movement of the stem 23. And a valve element 24 that opens and closes the valve in conjunction with. The actuator section 20 includes an air chamber provided therein, and a diaphragm 21 disposed so as to divide the air chamber into two.
And a spring 22 for elastically maintaining the diaphragm 21 at a predetermined position. The movement of the diaphragm 21 is linked to the stem 23.

In the valve positioner 10 having such a configuration, first, the signal receiving device 11 is connected to the valve portion 15.
When the input signal SP for setting the valve opening is received, the control arithmetic unit 12 calculates the input signal SP based on the difference between the received input signal SP and the valve opening signal PV fed back from the valve unit 15. The control signal MV is generated by performing control calculation so as to coincide with the actual valve opening of the valve section 15 that opens. This control signal MV is supplied to the electro-pneumatic conversion mechanism 13, outputs an air flow rate according to the control signal MV, and gives a signal to the pressure amplifier 14. Pressure amplifier 1
4 outputs an air flow rate corresponding to the signal obtained by the electro-pneumatic conversion mechanism section 14 and an air pressure signal Po and supplies them to the valve section 15. The valve unit 15 receives the air pressure signal Po output from the pressure amplifier 14, receives the pressure by the diaphragm 21 in the air actuator unit 20, converts the pressure into a physical force, transmits the converted force to the stem 23, and transmits the stem 23 to the stem 23. Move up and down. The stem 23 is connected to a valve element 24 in a pipe through which a process fluid flows.
Opening and closing the valve regulates the flow rate of the process fluid. Here, the position sensor 16 built in the valve positioner 10 is connected to the stem 23 through a link mechanism, and outputs a valve opening signal PV composed of an electric signal corresponding to the position where the stem 23 moves up and down. Give feedback and give. Thus, the valve positioner 10 and the valve section 15 form a closed loop, and the valve positioner 10 has a mechanism for controlling the valve opening.

In such a system of the valve positioner 10 and the valve section 15, the control target portion 17 to be controlled by the control operation device 12 is controlled by the position sensor 16 based on the control signal MV output from the control operation device. All the signal conversion elements up to the valve opening signal PV value. That is, the control target portion 17 includes the electropneumatic conversion mechanism 13, the pressure amplifier 14, the valve 15, and the position sensor 16.

In the control arithmetic unit 12, the control target part 17
In order to efficiently absorb the saturation and non-linear characteristics, etc. of the
By measuring the characteristics of No. 7, accurate tuning can be performed. In the present invention, such a control target site 1
7 is automatically measured and the tuning parameters of the control arithmetic unit 12 are automatically tuned.

Hereinafter, [1] the response speed of the control target portion 17 necessary for automatic tuning, [2] hysteresis measurement of the control target portion 17, [3] measurement of slip phenomenon, and [4] electropneumatic conversion mechanism section The operation point measurement of No. 13 and the diagnosis function [5] will be described in this order.

[1] Response Speed of Controlled Part 17 The response speed of the controlled part 17 indicates the speed of the control signal MV generated by the control calculation device 12 performing control calculations. By knowing the response speed of the control target portion 17,
It is possible to calculate how much the deviation between the input signal SP and the valve opening signal PV should be amplified and output as the control signal MV. Therefore, the valve positioner 10 and the valve unit 1
5, the loop gain of the system can be determined.

In the case of the valve positioner 10 which is driven by the air actuator section 20 to control the valve, most of the response speed depends on the air processing capacity that can be processed by the pressure amplifier 14 and
It depends on the size of the air actuator section 20 of the valve section 15 and the range of the spring 22. The air actuator section 20 includes a diaphragm type as shown in FIG. 2 and a type having a piston in a cylinder (not shown).

The air pressure produced in the factory is
Normally 10kgf / cm in terms of cost ^TwoWith less pressure
is there. Also, 10kgf / cm^TwoIs the valve position
Squeezed by a pressure reducing valve instead of being supplied to
4kgf / cm^TwoFrom 4kgf / cm^TwoPressure is valve position
It is supplied to the conditioner 10. On the other hand, the air in the valve section 15
The actuator section 20 is driven by the fluid pressure flowing through the valve body 24.
Must generate enough power to win.
The area of the diaphragm 21 or the cross-sectional area of the cylinder is large.
Designed. Therefore, the air actuator unit 20 is
For driving, a large amount of air is required.

Since the amount of air that can be processed by the pressure amplifier 14 of the valve positioner 10 is limited, the response speed depends on the flow rate that can be processed by the pressure amplifier 14.
That is, the response speed of the control target of the valve positioner 10 is almost governed by the amount of air required by the air actuator unit 20 and the amount of air processed by the pressure amplifier 14. In this manner, the response speed of the valve positioner 10 tends to be determined by the size of the air actuator section 20 of the valve section 15.
Determined by the air treatment flow rate. This is because, even in the valve section 15 adopting the same size of the air actuator section 20, the response speed increases if the pressure processing capacity of the pressure amplifier 14 is high, but the response speed decreases if the air processing capacity is low. Because. The air processing capacity of the pressure amplifier 14 varies depending on the supply pressure supplied to the valve positioner 10 and the diameter and length of the air pipe to the valve section 15, and the valve positioner 10 operates under any conditions. It is not possible to choose whether it can be attached to.

In this way, the response speed of the control target portion 17 is obtained by measuring the response speed of the valve opening degree with respect to the air throughput to be processed by the pressure amplifier 14. More specifically, by providing a constant air flow rate within the range of the air flow rate that can be processed by the pressure amplifier 14 to the air actuator section 20 of the valve section 15 and measuring the rate of change of the valve opening signal PV, the response speed is reduced. Can be measured.

Next, a method for measuring the response speed of the control target portion 17 will be specifically described below.

The first measurement method for measuring the response speed of the control target portion 17 is the simplest method, and the pressure amplifier 1
4 is maximized to saturate the intake air throughput of the pressure amplifier 14. Or, conversely, the input of the pressure amplifier 14 is minimized to saturate the exhaust air throughput of the pressure amplifier 14 to determine the flow rate of air supplied to the air actuator unit 20 of the valve unit 15. In this state, the valve opening signal PV output from the position sensor 16 is output.
What is necessary is just to measure the rate of change of. However, this method has a large error in the measured value for the following reason, and cannot measure well.

Since the maximum processing flow rate of the pressure amplifier 14 is supplied to the valve section 15, the valve positioner 1
The effect of pressure loss when flowing through the air circuit inside 0 becomes large. Similarly, the pressure loss of the diameter of the air pipe connecting the valve positioner 10 and the valve portion 15 increases. In the case of the valve section 15 having the relatively small air actuator section 20, the rate of change of the valve opening is too fast, and the measurement dispersion increases. Since the pressure change is large, the air flow rate cannot be kept constant, and the measurement error increases.
Since the amount of change in the air flow rate when actually controlling the valve section 15 is not the limit value of the processing flow rate of the pressure amplifier 14,
This is because there is a difference between data measured at the limit value and characteristics at the time of actual control.

The above-mentioned problem has been solved by the measuring method in the pressure amplifier 14 according to the present invention. Less than,
A second measurement method for measuring the response speed of the control target portion 17 will be described.

The second measuring method for measuring the response speed of the control target portion 17 relates to the measuring method in the pressure amplifier 14 shown in FIG.
The supply pressure chamber 30 and the output pressure chamber 31 communicate with each other through an air supply valve seat 32,
The output pressure chamber 31 communicates with the atmospheric pressure chamber 33 through an exhaust valve seat 34,
A valve element for adjusting the opening area of the air supply valve seat 32 and an exhaust valve seat 34
Poppet valve 3 with integrated valve body for adjusting the opening area
5 is equipped. An output pressure diaphragm 36 and an input pressure diaphragm 37 are attached to the exhaust valve seat 34, and the output pressure diaphragm 36 and the input pressure diaphragm 37 are attached.
, An atmospheric pressure chamber 33 is provided, and the output pressure chamber 31 and the atmospheric pressure chamber 33, and the atmospheric pressure chamber 33 and the input pressure chamber 38, respectively.
The air flow is blocked. The exhaust valve seat 34 receives the difference between the force received by the input pressure diaphragm 37 by the input pressure and the force received by the output pressure diaphragm 36 by the output pressure, and is configured to move in the left-right direction with respect to FIG. I have. The movement of the exhaust valve seat 34 causes the poppet valve 3 to move.
5 and the opening area of the exhaust valve seat 34 can be changed,
The exhaust flow rate of the amount of air in the output pressure chamber 31 can be adjusted. Further, the exhaust valve seat 34 comes into contact with the poppet valve 35, and FIG.
The exhaust valve seat 34 can push the poppet valve 35 to the left to change the opening area of the air supply valve seat 32 and the poppet valve 35 by moving the poppet valve 35 to the left. The supply of the air flow rate from the pressure chamber 30 can be adjusted. In this way, the air supply and exhaust of the output pressure chamber 31 is adjusted, the exhaust valve seat 34 is balanced in a certain state, and the output pressure can be changed according to the input pressure. In the case of FIG. 3, a bleed hole 39 is provided between the supply pressure chamber 30 and the output pressure chamber 31, and the supply pressure chamber 30 and the output pressure chamber 31 communicate with a certain area. In addition, bleed hole 3
There is also a pressure amplifier having a structure in which 9 is provided in an output pressure chamber 31 and an atmospheric pressure chamber 33.

Next, the operation of the pressure amplifier 14 having such a structure will be described.

First, in the steady state, when the input pressure is constant and the exhaust valve seat 34 is balanced, the poppet valve 35 receives a force from the supply pressure and is pressed against the air supply valve seat 32. . Therefore, the air in the supply pressure chamber 30 flows into the output pressure chamber 31 from the bleed hole 39 although the air supply valve seat 32 is shut off. In the steady state, the relationship between the output pressure and the input pressure does not collapse, so the flow rate flowing into the output pressure chamber 31 through the bleed hole 39 is reduced by the exhaust valve seat 34 and the poppet valve 35.
Will be exhausted through the gap created by In other words,
The position of the exhaust valve seat 34 is determined by the balance of the forces so that the opening area for exhausting the flow rate flowing from the bleed hole 39 is maintained. Therefore, in the steady state, the exhaust valve seat 34
And the poppet valve 35 are not in contact.

When performing the exhaust operation, if the input pressure decreases or the output pressure increases due to some disturbance, the exhaust valve seat 3
4 moves to the left side with respect to FIG. 3, and the opening area with the poppet valve 35 decreases. At this time, the output pressure chamber 3
Since the flow rate of the air in the output pressure chamber 31 exhausted to the atmospheric pressure is reduced with respect to the flow rate flowing into 1, the pressure in the output pressure chamber 31 increases. Further, when the input pressure is increased, the exhaust valve seat 34 comes into contact with the poppet valve 35, and the output pressure chamber 31 and the atmospheric pressure chamber 33
Block the flow path. At this time, the air supply valve seat 32 and the poppet valve 35 are not immediately opened. Because poppet valve 35
Is received from the supply pressure in accordance with the area thereof, and the force is supported by the air supply valve seat 32. Further, when the input pressure is increased or the output pressure is increased due to some disturbance, the exhaust valve seat 34 is not connected to the poppet valve 34 until all the forces received by the poppet valve 35 from the supply pressure chamber 30 are transferred to the exhaust valve seat 34. The valve 35 is pushed open to the left with respect to FIG.
The opening area can be adjusted with respect to the air supply valve seat 32,
The flow rate flowing from the supply pressure chamber 30 to the output pressure chamber 31 can be adjusted. Therefore, the exhaust valve seat 34 is
5, the poppet valve 35 and the air supply valve seat 32 remain closed until they are pushed open from the air supply valve seat 32, so that the flow rate flowing from the supply pressure chamber 30 into the output pressure chamber 31 depends on the area of the bleed hole 39. Therefore, there is no change in the flow rate with respect to the amount of change in the input pressure during that time or the amount of increase in the output pressure due to disturbance. FIG. 4 shows the characteristics of the input air pressure and the output air flow rate. When the bleed hole 39 is located between the output pressure chamber 31 and the atmospheric pressure chamber 33, a dead zone is generated in the exhaust direction.

As described above, if the opening area of the poppet valve 35 and the air supply valve seat 32 or the opening area of the poppet valve 35 and the exhaust valve seat 34 can be kept constant by the operation principle of the pressure amplifier 14,
The flow rate of air sent to the air actuator section 20 (see FIG. 2) of the valve section 15 can be constant. This method
It is sufficient to add a certain change in the control signal MV value to the electro-pneumatic conversion mechanism section 13. However, the displacement of the exhaust valve seat 34 depends on the output pressure,
Since it changes with a slight change in input pressure,
Poppet valve 35 and air supply valve seat 32 or poppet valve 35
It is difficult to keep the opening area of the exhaust valve seat 34 constant. Therefore, paying attention to the structure and characteristics of the pressure amplifier 14, the supply pressure chamber 30 and the output pressure chamber 31, or the output pressure chamber 31 with a fixed opening area are utilized by using a dead zone peculiar to the pressure amplifier 14 of the type shown in FIG. And a method of maintaining the atmospheric pressure chamber 33.

As described in the principle of operation of the pressure amplifier 14, the pressure amplifier 14 of this type has a dead zone in the relationship between the input pressure and the output air flow rate. It is relatively easy to create a state in which both the poppet valve 35 and the air supply valve seat 32 and the exhaust valve seat 34 are closed by utilizing the dead zone. This is because the dead band width of the pressure amplifier 14 is relatively wide. That is, by setting the control signal MV value within a certain range, the output of the electropneumatic conversion mechanism 13 can be set within a certain range, and the input pressure of the pressure amplifier 14 can be set within the dead zone of the pressure amplifier 14. In that state, the flow of air is only through the bleed hole 39. The area of the bleed hole 39 is fixed, and when the bleed hole 39 is located between the supply pressure chamber 30 and the output pressure chamber 31,
The flow rate of air flowing into the air actuator section 20 of the valve section 15 is constant. When the bleed hole 39 is located between the output pressure chamber 31 and the atmospheric pressure chamber 33, the flow rate of the air flowing from the air actuator section 20 of the valve section 15 is constant.

The change rate of the valve opening signal PV of the valve section 15 in such a state is measured. Since the area of the bleed hole 39 is known and constant, the pressure amplifier 14 is driven by replacing the area of the bleed hole 39 with the relation between the poppet valve 35 and the supply valve seat 32 or the relation between the poppet valve 35 and the exhaust valve seat 34. The possible response speed of the valve section 15 can be obtained by calculation. Strictly speaking, even with such a contrivance, the flow rate of air supplied to the air actuator unit 20 is not constant.

Incidentally, a model when the pressure amplifier 14 enters the dead zone can be represented as shown in FIG.
In such a case, the air flow rate Q flowing through the bleed hole 39
Can be expressed by the following expression 1 from the expression of the flow rate of the throttle.

Q = Cr * A * Ps * Ψ (Po / Ps) Equation 1 where Cr: flow coefficient, A: bleed hole area, Ps:
Supply pressure, Po: output pressure, Ψ (): characteristic function.

Ψ (Po / Ps) in the above equation 1 is P1
Ψ (Po / Ps) when /Ps<0.528 can be expressed by the following equation 2.

Ψ (Po / Ps) = ｛2 gK / (RT (K + 1)) · (2 / (K + 1) ^{2 / (K−1)} ｝ ^1/2 ...

When Ψ (Po / Ps) in the above equation (1) is 0.
Ψ (Po / Ps) when 528 ≦ Po / Ps ≦ 0.9 can be expressed by the following equation 3.

Ψ (Po / Ps) = ｛2gK / (RT (K−1)｝ ^1/2 · ｛(Po / Ps) ^{2 / K} − (Po / Ps) ^{(K + 1) / K} ｝ ^{1 / 2} ... Equation 3

When Ψ (Po / Ps) in the above equation (1) is equal to 0.
Ψ (Po / Ps) when 9 <Po <Ps can be expressed by the following equation 4.

Ψ (Po / Ps) = ｛2 g / RT｝ ^1/2 ｛(Po / Ps) − (Po / Ps) ² ｝ ^1/2

Where g = 980 cm / s 2, k = specific heat ratio (air = 1.4), R = gas constant 2927 cm / ° k,
T = absolute temperature ° k, Cr = flow coefficient, A = area (c
m ² ), P1, P2 = absolute pressure kgf / cm ² .

Therefore, Ψ (Po / Ps) is Po / Ps / 0.
When measured in the state of 528, the flow rate Q is constant,
When (Po / Ps) is measured in a state where Po / Ps ≦ 0.528, the flow rate Q changes due to a change in the output pressure Po. However, also in this case, the output pressure Po is smaller than the supply pressure Ps, and the measurement is performed in a section where the pressure change is small.
The error can be reduced.

In the case of this method, the electropneumatic conversion mechanism 13
Is not considered, but the electro-pneumatic conversion mechanism 13
Is sufficiently faster than the response speed of the pressure actuator 14 and the pneumatic actuator unit 15 of the valve unit 15, and is buried in the measurement error without consideration.
In addition, the response speed of the control target portion 17 is obtained by considering the response speed of the electro-pneumatic conversion mechanism 13 with a certain constant value.

Next, a specific procedure for measuring the response speed will be described with reference to a flowchart.

The procedure of the first measuring method will be described with reference to the flowchart shown in FIG.

First, when the measurement is started in response to the setting signal, the control signal MV value is initialized (step ST1).
0). It is confirmed that the valve opening signal PV value is lower than a preset value Y1, and when the value becomes lower, the control signal MV is then set to the initial value + ΔMV, and the exhaust valve seat 34 is set in the dead zone of the dead zone of the pressure amplifier 14. (Step ST11,
ST12). In this state, the poppet valve 35 and the air supply valve seat 3
2 and the exhaust valve seat 34 are closed, and the bleed hole 3
9 is the air actuator section 20 of the valve section 15
To the air flow.

Next, it is confirmed that the valve opening signal PV value exceeds a preset value Y1 (step ST1).
3). After confirming that the value exceeds Y1, the timer is started, and it is confirmed that the valve opening signal PV value exceeds a preset value Y2 which is larger than the value of Y1. After confirming that Y2 is exceeded, the timer is stopped (steps ST14, ST15, ST16).

Then, the response speed is obtained by dividing the value of the moved Y2-Y1 by the time required therefor. Then, the loop gain, which is a tuning parameter, is obtained from the response speed, and the measurement ends (steps ST17 and S17).
T18).

Next, the procedure of the second measuring method will be described with reference to the flowchart shown in FIG.

First, when the measurement is started upon receiving the setting signal, the control signal MV value is initialized (step ST2).
0). Then, it is confirmed that the valve opening signal PV value is lower than the preset value Y1. After confirming that it becomes lower than Y1, the exhaust valve seat 34 is inserted into the dead zone of the pressure amplifier 14 as the control signal MV = initial value + ΔMV (steps ST21 and ST22). In this state, the poppet valve 35, the air supply valve seat 32, and the exhaust valve seat 34 are closed, and only the bleed hole 39 supplies the air flow rate to the air actuator section 20 of the valve section 15. Then, it is confirmed that the valve opening signal PV value exceeds Y1 (step ST23). After confirming that Y1 has been exceeded, the timer is started. After the timer is started, the unit waits for a unit time (steps ST24 and ST25).

The valve opening signal PV value after the unit time has elapsed is represented by Y
2 (step ST26). Y that moved the response speed
It is determined by dividing the value of 2-Y1 by the unit time required for the value. Then, the loop gain, which is a tuning parameter, is obtained from the response speed, and the measurement ends (step ST27).

[2] Measurement of Hysteresis of Controlled Part 17 The hysteresis of the controlled part 17 is the control arithmetic unit 1
This is a hysteresis that exists in an input / output relationship from the control signal MV output by the control signal 2 to the valve opening signal PV output by the position sensor 16. This hysteresis is a representative example of the non-linearity of the characteristic of the control target portion 17, and the characteristic has a large influence on the control. Since the valve opening signal PV does not change until the control target portion 17 passes through the hysteresis, a delay time occurs from when the control signal MV is applied to when the valve opening signal PV changes. This delay time becomes a dead time, and causes a large phase delay. Therefore, if the control arithmetic unit 12 has, for example, a PID control algorithm, it affects the differential time for performing the phase compensation and the tuning parameter for the integration time.

This hysteresis measuring method is a method of directly measuring the hysteresis of the valve section 15 if the hysteresis of the electropneumatic conversion mechanism 13 and the pressure amplifier 14 shown in FIG. 1 is known in advance.

In the measurement of the hysteresis of the valve section 15, as shown in FIG. 8, the control signal MV is increased until the valve opening signal PV obtained from the valve section 15 changes, and the valve opening signal PV changes. Later, the control signal MV is reduced until the valve opening signal PV obtained from the valve section 15 changes in the opposite direction. The hysteresis of the valve section 15 can be calculated by storing the pressure signal and the valve opening signal PV which are the drive signals of the valve section 15 in the series of operations. In this way, the hysteresis can be measured by measuring a series of data of the pressure signal and the valve opening signal PV. However, since the amount of data increases, a large amount of hardware resources such as a memory is required. Therefore, by monitoring the movement of the stem and storing only the pressure data shown in FIG. 8, the hysteresis can be calculated.

However, in this method, the valve 1
Since a sensor for measuring the pressure, which is the drive signal of No. 5, is required, it is disadvantageous in terms of cost and power consumption. In addition, this method has a disadvantage that only the hysteresis of the valve section 15 can be measured.

There is also a method of measuring hysteresis without a sensor for detecting the drive signal of the valve section 15. The method is a method of measuring the hysteresis by measuring the input / output relationship between the control signal MV and the valve opening signal PV.

That is, the control signal MV is slowly changed,
Detects a change in the valve opening signal PV and records MV1, which is a control signal MV value when a change appears in the valve opening signal PV,
The control signal MV is changed in the direction opposite to the direction in which the control signal MV has been changed so far, and the control signal MV value MV2 when the valve opening signal PV value changes is recorded, and the hysteresis is obtained by MV1-MV2.

However, this method uses the valve positioner 1
0 and the valve unit 15 are set in an open loop, and the measurement is performed.
When the gain of the 3 + pressure amplifier 14 is set to be high, it is difficult to measure. Therefore, in the present invention, the valve positioner 10 and the valve unit 15 are closed loop,
It proposes a measuring method.

The control algorithm of the control arithmetic unit 12 is as follows:
It is assumed that the control algorithm has at least proportional control. For example, proportional control or proportional or differential control is used. A certain input value is given to this control algorithm, and the valve opening signal PV
After confirming that the value has been settled, the input signal SP is slowly changed. The SP1 of the input signal SP at the time when the value of the valve opening signal PV reacts to the change of the input is recorded. Next, the input signal SP is slowly changed in a direction opposite to the direction in which the input signal SP has been changed. The input signal SP2 at the time when the value of the valve opening signal PV corresponds to the change of the input is recorded.

When this algorithm is proportional control,
The disturbance (hysteresis in this case) of the control loop becomes 1 / loop gain of the control loop, and a steady-state error remains.

Here, as shown in FIG. 9, when a unity feedback system is considered, it can be expressed by the following equation (5).

Y (S) = SP (S) * G (S) / (1 + G (S)) + D (S) / (1 + G (S)) Equation 5 where G (S): System transfer function, SP (S):
Input signal, D (S): overall system flow, Y (S):
Stem displacement.

Now, from SP1 (S) to SP2 (S), Y
If there is no change in (S), the following equations 6 and 7 can be obtained.

Y1 (S) = SP1 (S) * G (S) / (1 + G (S)) + D1 (S) / (1 + G (S)) Equation 6

Y2 (S) = SP2 (S) * G (S) / (1 + G (S)) + D2 (S) / (1 + G (S)) Equation 7

The amount of change in D (S) corresponds to the hysteresis. Here, since Y1 (S) = Y2 (S), the above equation is put together and converted into an equation for the amount of change of D (S), and the following equation 8 is obtained.

D2 (S) −D1 (S) = (SP1 (S) −SP2 (S)) * G (S) Equation 8 As described above, the hysteresis is obtained by multiplying the input change by the loop gain. become.

Since there is no sign in the hysteresis, it can be obtained by Hys = | SP1-SP2 | * loop gain.

A specific method of measuring the hysteresis will be described with reference to the flowchart shown in FIG.

First, when a measurement signal is received and measurement is started, the control algorithm of the control arithmetic unit 12 is compared and controlled (step ST30). The loop gain is replaced with the hysteresis measurement setting parameter, and the input signal S
P is set to an initial value (step ST31). It waits for the value of the valve opening signal PV to stand still (step ST32).
When the valve opening signal PV is stationary, the input signal SP =
SP + ΔSP, and the input signal SP is changed in a direction to be gradually increased (steps ST33 and ST34). When the valve opening signal PV starts to move, the value of the input signal SP at that time is stored as SP1 (steps ST33 and ST3).
5). Wait for the valve opening signal PV to stand still (step S
T36). If the valve opening signal PV is stationary, the input signal SP is set to SP-ΔSP, and the input signal SP is changed in a direction of gradually decreasing (steps ST37 and ST37).
38). When the valve opening signal PV starts to move, the value of the input signal SP at that time is stored as SP2 (step ST3).
9). Hys = | SP1−SP2 | * Hysteresis is obtained by the equation of loop gain (step ST40). Hys
Is calculated based on the value of. The derivative time = f (Hys) and the integration time = f (Hys).

[3] Measurement of slip phenomenon The movement of the stem when the slip phenomenon occurs is shown in FIG.
As shown in the figure, the pressure signal, which is the drive signal of the valve, is increased, and at the moment when the valve section 15 goes out of the hysteresis, the valve opening signal of the valve moves quickly, and thereafter, the change speed according to the pressure change is obtained. Calm down. The phenomenon in which the valve opening signal slips at the moment when the hysteresis has passed is called a slip phenomenon, and this phenomenon greatly affects controllability.

Specifically, the section in which the slip phenomenon is occurring is in an uncontrollable state. Thus, for example, 0.1
When trying to control a minute valve opening such as a percentage, if a slip phenomenon occurs, the valve opening cannot be stopped at a position of 0.1%, so that the valve goes too far. When an overshoot occurs, the control operation device 12 controls to the opposite side in an attempt to return the overshoot. At this time, overshoot occurs again, and a limit cycle occurs by this repetition.
In order to stop the limit cycle, the control should not be actively performed in the section where the slip phenomenon occurs. Therefore, in the section where the slip phenomenon occurs, processing such as changing the control algorithm is required. Although the slip phenomenon has been described by the hysteresis of the valve, this phenomenon is caused by the play of the link mechanism between the position sensor and the stem. Therefore, it is necessary to measure the characteristics of the entire control target.

As a measuring method, the control signal MV output from the control arithmetic unit 12 is slowly changed, and the valve opening signal P
The change in V is measured. As a phenomenon, at the moment when the control object passes through the hysteresis or the dead zone, the valve opening signal moves quickly by a certain width and then changes normally, so that the change speed of the valve opening signal may be measured. FIG. 12 shows a change speed when the valve opening signal PV starts to move from a state where the valve opening signal PV is stationary.
In FIG. 12, if the inflection point of the change speed of the valve opening signal PV is detected, the width of the slip phenomenon can be measured.

That is, in FIG. 11, the valve opening signal PV
Is the value of the valve opening signal PV signal when the valve is stationary.
3 is stored, and the valve opening signal PV at the inflection point of the changing speed of the valve opening signal PV is set to PV4, so that the slip width is obtained by the following equation: slip width = | PV4-PV3 |.

Further, the initial value at which the valve opening signal PV is stationary is simply referred to as PV3, and the value of the control signal MV is changed. By setting the valve opening signal PV to PV4, the data of the slip phenomenon may be used. However, in this case, the measurement error may increase.

A specific method of measuring the slip phenomenon will be described with reference to the flowchart of FIG.

First, the measurement is started upon receiving the measurement signal. Control signal MV is set to an initial value (step ST5)
0). Wait until the valve opening signal PV stops (step S
T51). The control signal is set to MV = MV + ΔMV, and the control signal is slowly changed until the valve opening signal PV value moves (steps ST52 and ST53). With this operation, the hysteresis of the control target is reset once. Next, it waits until the valve opening signal PV stops. Valve opening signal P
The PV value when V is stopped is stored as PV3. That is, PV3 = PV (steps ST54 and ST5).
5).

Next, assuming that the control signal MV = MV−ΔMV,
Slowly change the control signal in the opposite direction.
The change speed of the current valve opening signal PV is measured. It repeats until the inflection point of the change speed of the valve opening signal PV is detected (steps ST56, ST57, ST58, ST59).

Then, the valve opening signal at the time when the inflection point of the changing speed of the valve opening signal PV is detected is stored as PV4.
That is, PV4 = PV, slip width = | PV4-PV3
|, Control algorithm switching condition = f (slip width) (steps ST60 and ST61).

[4] Measurement of Operating Point of Electro-Pneumatic Conversion Mechanism 13 The electro-pneumatic conversion mechanism 13 performs electro-pneumatic conversion by driving the nozzle flapper mechanism with an electromagnetic actuator and changing the nozzle back pressure. . This electropneumatic conversion mechanism 13
In the case of the valve positioner 10, since electric energy supplied from the outside is limited, it is required to work with low power, and the energy that can be supplied to the electromagnetic actuator is limited. Therefore, the electropneumatic conversion mechanism 13
In order to obtain the required conversion gain, the air flow at the stage preceding the nozzle flapper mechanism is reduced, and the gain of the nozzle flapper mechanism is increased. As a result, electro-pneumatic conversion is performed with a small gap between the nozzle and the flapper, and the sensitivity to external disturbance and the range of the supply pressure supplied to the valve positioner 10 are wide. The drive signal of the electro-pneumatic conversion mechanism 13 is designed to be much wider than the operating point, so that the operating point deviation due to disturbance or supply pressure fluctuation can be absorbed.

The control arithmetic unit 12 has an integrator built therein, and changes the control signal MV in accordance with a disturbance to absorb the disturbance. Therefore, if the value of the integrator is reset after a reset such as when the power is turned on, the operating point of the electro-pneumatic conversion mechanism unit 13 is shifted, and the valve unit 15 is moved from the valve unit 15 as if the integrator was winded up. Valve opening signal PV
It takes a long time to return to the steady state value, and it cannot start up quickly.

If the output of the integrator is stored in a non-volatile memory or the like in order to solve this problem, the operating point shift of the electropneumatic conversion mechanism 13 can be reduced even at the time of reset such as when the power is turned on. However, it is substantially impossible to store the output of the integrator in a nonvolatile memory or the like. This is because the nonvolatile memory has a limit value of the number of updates, and if data is periodically updated, it will eventually deteriorate and break down.

As a solution to this problem, the operating point of the electro-pneumatic conversion mechanism 13 is measured, and the operating point is offset (Off).
By storing the data in the nonvolatile memory as fset), the operating point can be corrected by loading the data at the time of reset such as when the power is turned on.

Taking the PID control algorithm as an example, for example, if the operating point of the electropneumatic conversion mechanism 13 is the control signal MV = 5
If the initial value at the time of reset of the integrator is zero, the integrator output = 1 / Ti 弁 Edt = 50, assuming that the difference between the input signal SP and the valve opening signal PV is E, A steady deviation remains (Ti; integration time). In particular, when the integration time is long, it takes time until the steady state error disappears. Therefore, if the operating point of the electropneumatic conversion mechanism unit 13 is measured in advance and stored as an Offset value and inserted into the PID calculation unit, the operating point can be corrected, and even if the integrator is reset, Rise time can be significantly improved. That is, the control signal MV = Kp * (P + I + D) + Of
fset may be used.

In the measurement method, at least the control algorithm of the control arithmetic unit 12 is set to a control algorithm having an integrator, the input signal SP is set to 50%, and the process waits until the deviation falls within a set value, for example, ± 1%. The value of the control signal MV at this time is stored as an Offset value. By doing so, the rise time from the next reset can be shortened.

A specific method for measuring the operating point of the electro-pneumatic conversion mechanism 13 will be described with reference to the flowchart shown in FIG.

First, the measurement is started upon receiving the setting signal.
The control algorithm of the control arithmetic unit is set to proportional integral (PI) control (step ST70). Control for giving an initial value to the input signal SP starts, and the valve opening signal PV is changed to the input signal SP.
(Step ST71). The control is continued until the deviation between the input signal SP and the valve opening signal PV falls below a certain set value. The control signal M when the deviation falls below a certain set value
The V value is stored as Offset. Then, the measurement ends (steps ST72 and ST73).

[5] Diagnosis Function When the characteristics of the control target portion 17 are measured and the automatic tuning is performed, the characteristics of the measured control target portion 17 greatly deviate from those of a general control target portion. If so, it can be considered an installation error of the valve positioner 10, so that an error message or a warning message can be issued.
For example, if the response speed measurement result of the control target portion 17 is orders of magnitude slower than a normal value, the valve unit 15
Leakage of the air actuator section 20 (see FIG. 2)
The setting of the supply air pressure may be wrong. Further, when the measurement result of the hysteresis of the control target portion 17 is larger than a normal value, it is considered that galling of the valve portion 15 or an abnormality of a link of the displacement sensor to the stem is caused. Further, when the measurement result of the slip width of the control target portion 17 is larger than a normal value, a failure of the position sensor 16 or a failure of the valve portion 15 is considered. Further, when the measurement result of the operating point of the electropneumatic conversion mechanism unit 13 is greatly deviated from a normal value,
A mistake in setting the supply air pressure, a failure in the electropneumatic conversion mechanism 13, and the like are considered. In such a case, after the automatic tuning is completed, a message for notifying the operator is output.

[0105]

As described above, the valve positioner according to the present invention has the following effects.

(1) Since the valve positioner is provided with the automatic tuning function, there is an effect that anyone can easily tune the valve positioner regardless of the operator.

(2) Further, by providing the valve positioner with an automatic tuning function, there is an effect that the number of steps for starting the valve positioner can be reduced.

(3) Further, by obtaining a tuning parameter by calculation from the characteristics of the control target part, there is an effect that accurate tuning can be performed.

(4) By measuring the response speed of the control target portion, there is an effect that not only the characteristics of the valve but also more accurate tuning information can be obtained.

(5) More accurate tuning information can be obtained by measuring the hysteresis of the control target portion.

(6) By measuring the slip width of the control target portion, more accurate tuning information can be obtained.

(7) By measuring the operating point of the electro-pneumatic conversion mechanism, there is an effect that the rise time from the reset of the valve positioner can be shortened.

(8) There is an effect that the installation error of the positioner can be prevented beforehand by measuring the control target part and issuing an error message or a warning message depending on the measurement result.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an overall configuration of a valve positioner according to the present invention.

FIG. 2 is an explanatory view schematically showing a valve section in FIG. 1;

FIG. 3 is a plan view showing the structure of the pressure amplifier in FIG.

FIG. 4 is a graph showing a dead zone based on nozzle back pressure and air flow characteristics in the pressure amplifier in FIG. 3;

FIG. 5 is an explanatory diagram showing a configuration of a bleed hole of the pressure amplifier in FIG.

FIG. 6 is a flowchart showing a method of measuring a response speed at the control target part.

FIG. 7 is a flowchart showing a method of measuring a response speed at the control target part.

FIG. 8 is an explanatory diagram showing a method for calculating hysteresis of the valve section.

FIG. 9 is a conceptual diagram showing a unity feedback system.

FIG. 10 is a flowchart for obtaining the hysteresis.

FIG. 11 is an explanatory diagram showing a movement of a stem when the slip phenomenon occurs.

FIG. 12 is a graph showing an inflection point of the stem speed.

FIG. 13 is a flowchart showing a specific measurement method for measuring the slip width.

FIG. 14 is a flowchart showing a method of measuring a control signal in a control operation device equipped with the integrator.

[Explanation of symbols]

10; valve positioner, 11; signal receiving device, 12;
Control arithmetic unit, 13; electro-pneumatic conversion mechanism, 14; pressure amplifier, 15; valve, 16; position sensor, 17; controlled object, 20; pneumatic actuator, 21; diaphragm, 22; spring, 23; , 24; valve body, 30; supply pressure chamber, 31; output pressure chamber, 32; air supply valve seat, 33; atmospheric pressure chamber, 34; exhaust valve seat, 35; poppet valve, 36; output pressure diaphragm, 37; Input pressure diaphragm, 38; Input pressure chamber, 39; Bleed hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // F16K 17/32 F16K 17/32 9A001 31/126 31/126 Z F-term (Reference) 3H001 AA01 AB10 AC03 AD04 AE12 3H056 AA01 BB24 CA07 CB01 CC02 CC05 CC20 CD04 DD10 EE01 EE06 GG12 3H060 AA03 BB03 CC32 DC05 DC14 DD04 EE08 HH06 3H065 AA01 BA01 BA07 BB12 BB26 BC13 5H004 GA11 GA28 GA30 HA07 HB07KB07 KB07 KB07 KB07 KB MA05 MA41 9A001 KK32 LL05

Claims (17)

[Claims] An input signal for setting a valve opening of a valve, a position sensor for detecting the valve opening of the valve, and a difference between the input signal and the valve opening signal obtained by the position sensor. A control operation unit that generates a control signal by performing a control operation so that a valve opening degree of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner including a pressure amplifier that supplies air pressure based on an air flow rate generated in a mechanism unit to the valve, and a control target including the electropneumatic conversion mechanism unit, a pressure amplifier, a position sensor, and a valve. When the part receives the automatic setting signal, the tuning parameter for generating the control signal of the control calculation part is obtained by calculation by automatically measuring each characteristic of the control target part. A valve positioner characterized by replacing both with the current tuning parameters. 2. An input signal for setting a valve opening of a valve, a position sensor for detecting the valve opening of the valve, and a difference between the input signal and the valve opening signal obtained by the position sensor. A control operation unit that generates a control signal by performing a control operation so that a valve opening degree of the valve matches the input signal; an electro-pneumatic conversion mechanism unit that generates an air flow rate based on the control signal; A valve positioner including a pressure amplifier that supplies air pressure based on an air flow rate generated in a mechanism unit to the valve, and a control target including the electropneumatic conversion mechanism unit, a pressure amplifier, a position sensor, and a valve. The part, when receiving the automatic setting signal, automatically measures the response speed of the control target part,
A valve positioner that calculates a tuning parameter for generating a control signal of the control calculation unit based on the automatically measured response speed parameter. 3. The valve positioner according to claim 2, wherein the automatic measurement of the response speed of the control target portion is to saturate the output of the electropneumatic conversion mechanism and measure the response speed of the valve at that time. A valve positioner characterized in that: 4. The valve positioner according to claim 2, wherein the automatic measurement of the response speed of the control target portion is performed by keeping a change speed of an output of the electro-pneumatic conversion mechanism unit constant. Measuring the response speed of a valve. 5. The valve positioner according to claim 3, wherein the response speed of the valve is measured by measuring a time when the valve changes from a first valve opening to a second valve opening. A valve positioner characterized in that: 6. The valve positioner according to claim 3 or 4, wherein the response speed of the valve is measured by detecting a first valve opening of the valve by the position sensor. A valve positioner characterized by measuring a valve opening signal after a certain unit time after passing. 7. The valve positioner according to claim 4, wherein the changing speed of the output of the electro-pneumatic conversion mechanism is kept constant by utilizing a dead zone caused by the structure of the electro-pneumatic conversion mechanism. A valve positioner characterized in that: 8. An input signal for setting a valve opening of a valve, a position sensor for detecting the valve opening of the valve, and a difference between the input signal and the valve opening signal obtained by the position sensor. A control operation unit that generates a control signal by performing control operation so that the valve opening signal of the valve matches the input signal;
An electro-pneumatic conversion mechanism that generates an air flow rate based on the control signal, and a valve positioner that includes a pressure amplifier that supplies an air pressure based on the air flow rate generated in the electro-pneumatic conversion mechanism to a valve, The control calculation unit uses at least one integrator in the control calculation to detect that the deviation between the valve opening signal and the input signal falls within a preset range, and performs the control calculation at that time. A valve positioner, wherein a control signal output from the unit is used as an operation start reference signal and stored in a predetermined storage unit. 9. The valve positioner according to claim 8, wherein the operation start reference signal stored in said storage section is used as a reference point of a control signal output from said control operation section. 10. An input signal for setting a valve opening of a valve,
A position sensor for detecting the valve opening of the valve, and a control operation is performed so that the valve opening of the valve matches the input signal based on a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal, an electro-pneumatic conversion mechanism that generates an air flow rate based on the control signal, and a pressure that supplies air pressure based on the air flow rate generated in the electro-pneumatic conversion mechanism to a valve. A valve positioner comprising an amplifier, the control target portion configured by the electro-pneumatic conversion mechanism, the pressure amplifier, the position sensor and the valve, when receiving the automatic setting signal, the hysteresis of the control target portion. A valve position calculating means for automatically measuring and calculating a tuning parameter of a control signal generated by the control calculating unit based on the automatically measured hysteresis parameter. Yona. 11. The valve positioner according to claim 10, wherein the automatic measurement of the hysteresis of the controlled part is performed by:
A valve positioner comprising: a sensor for detecting a drive signal supplied to the valve; and measuring input / output characteristics of the valve based on the detection of the sensor to calculate and measure hysteresis of the valve by calculation. . 12. The valve positioner according to claim 10, wherein the automatic measurement of the hysteresis of the control target portion is performed by:
In the control operation of the control operation unit, at least a control algorithm using a comparator is performed, the input signal is changed to monitor the valve opening signal of the valve, and the input signal when the valve opening signal reacts SP1 is stored, and then the direction of change of the input signal is reversed, the input signal SP2 when the valve opening degree signal of the valve responds in the opposite direction is stored, and the stored input signals SP1, SP2 are then stored. A valve positioner for calculating and measuring the hysteresis of the control target part from the difference between the two. 13. The valve positioner according to claim 12, wherein the calculation of the hysteresis of the controlled part uses a value obtained by multiplying a difference between the input signals SP1 and SP2 by a loop gain of a stem of the valve. Characterized valve positioner. 14. An input signal for setting a valve opening of a valve,
A position sensor for detecting the valve opening of the valve, and a control operation is performed so that the valve opening of the valve matches the input signal based on a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal, an electro-pneumatic conversion mechanism that generates an air flow rate based on the control signal, and a pressure that supplies air pressure based on the air flow rate generated in the electro-pneumatic conversion mechanism to a valve. A valve positioner comprising an amplifier, the control target portion configured by the electro-pneumatic conversion mechanism, the pressure amplifier, the position sensor and the valve, when receiving the automatic setting signal, the valve opening degree of the valve Measure the slip width of the slip phenomenon that occurs when starting to move from a stationary state,
A valve positioner, wherein a tuning parameter of a control signal generated by the control calculation unit is calculated based on a parameter including the measured slip width. 15. The valve positioner according to claim 14, wherein when measuring the slip width, it is confirmed that the valve opening signal of the valve is stationary, and the valve opening PV1 at that time is stored. The change rate of the valve opening signal when the valve opening signal reacts when the control signal is changed is measured, and the valve opening signal P at the inflection point of the change rate of the valve opening signal is measured.
V2, and stores the difference between the valve opening signals PV1 and PV2,
A valve positioner, wherein the value is set as a slip width of the valve. 16. The valve positioner according to claim 14, wherein when measuring the slip width, it is confirmed that the valve opening signal is stationary, and the valve opening PV1 at that time is stored. After the valve opening signal of the valve reacts when the control signal is changed, a valve opening signal PV2 after a preset short time is stored, and the valve opening signals PV1 and PV2 are stored.
A valve positioner, wherein a difference between V2 and the slip width of the valve is stored as a value of the slip width of the valve. 17. An input signal for setting a valve opening of a valve,
A position sensor for detecting the valve opening of the valve, and a control operation is performed so that the valve opening of the valve matches the input signal based on a deviation between the valve opening signal obtained by the position sensor and the input signal. A control operation unit that generates a control signal, an electro-pneumatic conversion mechanism that generates an air flow rate based on the control signal, and a pressure that supplies air pressure based on the air flow rate generated in the electro-pneumatic conversion mechanism to a valve. A valve positioner comprising an amplifier, the control target portion comprising the electro-pneumatic conversion mechanism, the pressure amplifier, the position sensor and the valve, when receiving the automatic setting signal, the characteristics of the control target portion, Measuring, and when the measured value of the characteristic of the control target portion deviates from the value of the allowable range information composed of the characteristic of the control target portion, outputting an abnormal signal through an external communication means. And a valve positioner.