JP2007255581A - Electro-pneumatic conversion system and method for controlling electro-pneumatic conversion system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize an electro-pneumatic conversion system capable of appropriately changing over amplitude according to position control or pressure control. <P>SOLUTION: This system is provided with an I/P module 15 outputting nozzle back pressure Pn according to input current signal In, a control relay 18 outputting drive output pressure according to the nozzle back pressure Pn, a change over means 16 selecting the position control or the pressure control and changing over amplitude of the I/P module 15 according to the selected control, a metal sheet 17 selecting the position control or the pressure control and changing over amplitude of the control relay 18 according to the selected control, a pressure sensor 19, a position sensor 20, and a control means 13 creating input current signal In based on drive pressure signal PV2, position signal 6V1 and control signal SV for performing position control and pressure control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electropneumatic conversion system and a control method for an electropneumatic converter system.

  Process control introduced in process plants such as petroleum / petrochemical, chemical, steel, etc. is performed mainly on feedback control. In the process control, a pneumatic control valve (hereinafter referred to as a valve) using a pneumatic actuator as a drive unit is widely used. The said valve | bulb is comprised by the valve stem etc. and performs the in / out adjustment of the gas which flows through the inside of a pipe | tube.

  Positioners and electro-pneumatic converters (electro-pneumatic converters) are used as signal converters for improving valve characteristics and controllers. The positioner controls the position of the valve stem. The electropneumatic converter controls the driving pressure for driving the valve. Positioners are classified into electro-pneumatic positioners and sky-pneumatic positioners. The electropneumatic positioner is a positioner that drives a valve with an operation signal of an electric controller as an input. The air-and-air positioner is a positioner that drives a valve with an air signal as an input. Further, the electropneumatic converter converts an operation signal (current signal) from the control device into an air signal necessary for operating the air / air positioner. The electropneumatic conversion device may be used for a purpose of directly operating a valve.

  FIG. 6 shows a block diagram of a valve positioner 80 for driving the valve. The valve positioner 80 controls the position of the valve stem 87A of the valve 87. Here, the valve stem 87 </ b> A refers to a rod portion that supports the valve 87. The opening degree of the valve 87 is controlled by the displacement of the valve stem 87A. A valve positioner 80 shown in FIG. 6 includes a MAU (Media Access Unit) 81, a fieldbus modem 82, a control means 83, a D / A (Digital / Analog) conversion means 84, and an I / P (current / pressure). The module 85 includes a control relay 86, a valve 87, a position sensor 88, and an A / D (Analog / Digital) conversion means 89. The valve 87 includes a valve stem 87A.

  The control unit 83 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Read Access Memory), and the like, and centrally controls each part of the valve positioner 80. The control unit 83 expands a program designated from the system program and various application programs stored in the ROM, and executes various processes in cooperation with the program expanded in the RAM. The ROM stores a first calculation program. Here, the first calculation program refers to a process for calculating a deviation signal Error1 between the target value signal SV1 and the position signal PV1.

  The control means 83 calculates a deviation signal Error1 between the target value signal SV1 and the position signal PV1 from the fieldbus FB by the first calculation program. Then, the nozzle back pressure Pn is controlled so that the deviation signal Error1 becomes zero. Here, the fieldbus FB refers to a communication method capable of bidirectional transmission and reception using digital signals. The target value signal SV1 is a signal indicating the target value of the position of the valve stem 87A. The position signal PV1 refers to an electrical signal corresponding to the opening degree of the valve 87. The nozzle back pressure Pn refers to the air pressure supplied to the control relay 86.

  The MAU 81 is a signal transmission / reception device. Here, the signal means the target value signal SV1 and the position signal PV1. The fieldbus modem 82 is a device that modulates and demodulates signals. The D / A converter 84 converts the deviation signal Error1 output from the controller 83 from a digital signal to an analog signal. The D / A converter 84 outputs an input current signal In. Here, the input current signal In refers to a current signal input to the I / P module 85.

  The I / P (current / pressure) module 85 includes a torque motor, and outputs a nozzle back pressure Pn corresponding to the input current signal In. Further, the supply pressure Ps is supplied to the I / P module 85, and it is converted into a nozzle back pressure Pn corresponding to the input current signal In. The control relay 86 outputs a drive output pressure Po obtained by amplifying the nozzle back pressure Pn. Here, the drive output pressure Po refers to the air pressure that drives the valve. The drive output pressure is output from the control relay 86. Further, the supply pressure Ps is supplied to the control relay 86 and is converted into a drive output pressure Po corresponding to the nozzle back pressure Pn. Based on the drive output pressure Po, the valve stem 87A is displaced, and the opening degree of the valve 87 is controlled.

  The position sensor 88 detects an operation displacement of the valve stem 87A. The A / D conversion means 89 converts the analog signal output from the position sensor 88 into a digital signal.

  Next, position control performed by the valve positioner 80 in FIG. 6 will be described. Here, the position control is to control the position of the valve stem 87A. First, the target value signal SV1 at the position of the valve stem 87A is given from the field bus FB. The target value signal SV1 is transmitted to the control means 83 via the MAU 81 and the fieldbus modem 82. In the control means 83, a deviation signal Error1 between the target value signal SV1 and the position signal PV1 is calculated. The deviation signal Error1 is input to the I / P module 85 as the input current signal In via the D / A conversion means 84 and the V / I conversion means (not shown). The nozzle back pressure Pn, which is the output of the I / P module 85, is supplied to the control relay 86.

  Then, the drive output pressure Po that is the output of the control relay 86 is supplied to the valve 87. When the drive output pressure Po is supplied to the valve 87, the valve stem 87A is displaced. The displacement of the valve stem 87A is detected by the position sensor 88 and output as an electrical signal. The output signal is fed back to the control means 83 through the A / D conversion means 89 as a position signal PV1. Then, the control means 83 calculates the deviation between the target value signal SV1 and the position signal PV1. The nozzle back pressure Pn is controlled so that this deviation becomes zero.

  Next, FIG. 7 shows a block diagram of an electropneumatic conversion device 90 that drives a valve or an air / air positioner. 7 includes a MAU 91, a fieldbus modem 92, a control means 93, a D / A conversion means 94, an I / P module 95, a control relay 96, and a valve / air / air positioner 97. And a pressure sensor 98 and an A / D conversion means 99. The MAU 91, the field bus modem 92, the D / A conversion means 94, the I / P module 95, the control relay 96, and the A / D conversion means 99 are the MAU 81 of the valve positioner 80, the field bus modem 82, and the D / A conversion means, respectively. 84, the I / P module 85, the control relay 86, and the A / D conversion means 89. In the following, portions different from the valve positioner 80 will be mainly described.

  The control means 93 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Read Access Memory), and the like, and centrally controls each part of the electropneumatic conversion device 90. The control means 93 expands a program designated from the system program and various application programs stored in the ROM, and executes various processes in cooperation with the program expanded in the RAM. In particular, the second arithmetic program is stored in the ROM. Here, the second calculation program refers to a process of calculating a deviation signal Error2 between the target value signal SV2 and the driving pressure signal PV2.

  The control means 93 calculates a deviation signal Error2 between the target value signal SV2 from the field bus FB and the driving pressure signal PV2 by the second calculation program. Then, the nozzle back pressure Pn is controlled so that the deviation signal Error2 becomes zero. Here, the target value signal SV2 refers to a target value of the drive output pressure Po. The drive pressure signal PV2 is a signal obtained by converting the drive output pressure Po into an electrical signal.

  The valve / air / air positioner 97 is a control target of the electropneumatic converter 90. The valve / air / air positioner 97 indicates that the control target is one of the valve and the air / air positioner. The pressure sensor 98 converts the drive output pressure Po into a drive pressure signal PV2.

  Next, pressure control performed by the electropneumatic converter 90 of FIG. 7 will be described. Here, the pressure control is to control the pressure of the drive output pressure Po. First, the target value signal SV2 of the drive output pressure Po is given from the field bus. This target value signal SV2 is transmitted to the control means 93 via the MAU 91 and the fieldbus modem 92. In the control means 93, a deviation signal Error2 between the target value signal SV2 and the driving pressure signal PV2 is calculated. The deviation signal Error2 is input to the I / P module 95 as the input current signal In via the D / A conversion means 94 and the V / I conversion means (not shown). The nozzle back pressure Pn, which is an air pressure signal from the I / P module 95, is supplied to the control relay 96.

  The drive output pressure Po, which is the output of the control relay 96, is supplied to the air / vacuum positioner 97 and the pressure sensor 98. The pressure sensor 98 converts the drive output pressure Po into a drive pressure signal PV2. The drive pressure signal PV2 is fed back to the control means 93 via the A / D conversion means 99. Then, a deviation between the target value signal SV2 and the driving pressure signal PV2 is calculated by the control means 93. Then, the nozzle back pressure Pn is controlled so that the deviation becomes zero.

  A technique using the valve positioner 80 and the electropneumatic converter 90 as described above is also known (see, for example, Patent Document 1). FIG. 8 is a configuration block diagram showing an example of an electropneumatic positioner 200 (valve positioner) described in Patent Document 1. In FIG.

  FIG. 8 shows a signal conversion circuit 202, a differential amplifier 203, an electropneumatic conversion circuit 204, a pressure converter 205, a control valve 206, a stem 207, a valve 208, a valve opening detector 209, An arithmetic circuit 210, a comparison arithmetic unit 211, and a switch SW are provided.

  The signal conversion circuit 202 is a circuit that converts a current signal Io for controlling the opening of the valve into a voltage signal Vo. The differential amplifier 203 receives the voltage signal Vo and the feedback signal Vf output from the signal conversion circuit 202, and calculates their deviation (deviation signal) Vd. The electropneumatic conversion circuit 204 is a circuit that converts the deviation signal Vd into the drive output pressure Po. The pressure converter 205 converts the drive output pressure Po into a corresponding pressure signal Va. The control valve 206 displaces the stem 207 corresponding to the drive output pressure Po, and controls the valve opening degree of the valve 208. The valve opening detector 209 outputs a valve opening signal Vs corresponding to the valve opening of the valve 208. The switch SW outputs either the valve opening signal Vs or the pressure signal Va to the arithmetic circuit 210. The comparison calculator 211 compares the valve opening signal Vs with the pressure signal Va. The arithmetic circuit 210 calculates the feedback signal Vf.

  Next, the switch switching operation of the conventional example shown in FIG. 8 will be briefly described. A pressure signal Va and a valve opening signal Vs are input to the comparison calculator 211, and the switch SW is switched in accordance with the difference between them. For example, when the relationship of | pressure signal C1 · Va−valve opening signal C2 · Vs | ≦ K1 (K1 is a constant, C1 and C2 are constants or functions), the valve opening detector is determined to be normal. . Then, the switch SW is switched to the valve opening detector 209 side so that the valve opening signal Vs is output to the arithmetic circuit 210. Therefore, in this case, it operates as a valve positioner.

  When the relationship of | pressure signal C1 · Va−valve opening signal C2 · Vs |> K2 (K2 is a constant), the valve opening detector 209 is determined to be abnormal. Then, the switch SW is switched to the pressure converter 205 side so that the pressure signal Va is output to the arithmetic circuit 210. Therefore, in this case, it operates as an electropneumatic converter (electropneumatic converter).

In this way, the above-described electropneumatic positioner 201 can be used in combination with functions as a valve positioner and an electropneumatic converter. Therefore, it is possible to detect an abnormality caused by a failure or breakage of the valve opening detector 210. For example, when the valve opening detector 210 is abnormal, the valve opening detector 210 can be disconnected and control of the control valve can be continued.
Japanese Patent No. 3223433

  However, the above-described conventional technology is not used in consideration of the amplification degree (gain) characteristics when the valve positioner and the electropneumatic converter are used. Here, the gain characteristic refers to input / output characteristics of a control relay and an I / P module that are components of the valve positioner 80 and the electropneumatic converter 90. Hereinafter, a difference in gain characteristics between the valve positioner 80 and the electropneumatic converter 90 will be described with reference to FIGS.

  FIG. 9A shows the input / output characteristics of the control relay. The vertical axis represents the drive output pressure Po, and the horizontal axis represents the nozzle back pressure Pn. Here, the output pressure range (hereinafter referred to as “spring range”) of the control relay necessary for driving the valve is represented by ΔPo. The nozzle back pressure when the gain of the control relay is high is ΔPn1. Further, the nozzle back pressure when the gain of the control relay is low is ΔPn2. Similarly, the vertical axis of FIG. 9B represents the drive output pressure Po, and the horizontal axis represents the nozzle back pressure Pn. Here, when the nozzle back pressure Pn is constant, the drive output pressure Po when the gain of the control relay is high is ΔPo1. Further, the drive output pressure Po when the gain of the control relay is low is ΔPo2.

  FIG. 10 is a diagram showing input / output characteristics of the I / P module. The vertical axis represents the nozzle back pressure Pn, and the horizontal axis represents the input current signal In. Here, it is assumed that the nozzle back pressure range when the gain of the control relay is high is ΔPn1 (similar to ΔPn1 in FIG. 10). Further, the nozzle back pressure range when the gain of the control relay is low is ΔPn2 (similar to ΔPn2 in FIG. 10). FIG. 11 is a diagram showing the input / output characteristics of the I / P module as in FIG. Here, the gain ΔP of the control relay is constant. In this case, the current span when the gain of the I / P module is high is ΔI3. Further, when the gain of the I / P module is low, the current span is ΔI4.

  Next, characteristics required for the control relay and the I / P module as components of the valve positioner will be described with reference to FIGS. First, the characteristics of the I / P module of the valve positioner 80 will be described. The I / P module of the valve positioner needs to control a minute pressure with sufficient resolution. In order to perform control with sufficient resolution, it is necessary to widen the current span. When the current span is wide, highly accurate current control is possible. Here, as shown in FIG. 11, ΔI4 (low gain) has a larger current span than ΔI3 (high gain). Therefore, in order to perform control with sufficient resolution, the I / P module needs to have a low gain.

  Next, the characteristics of the control relay as a component of the valve positioner 80 will be described. As described above, the I / P module of the valve positioner 80 needs to have a low gain. Further, the drive output pressure Po is used in a wide range (1.4 to 7.0 [kgf / cm 2]), and it is necessary to drive the I / P module with a small current span. Here, it is assumed that the current span of the I / P module is ΔI4 (low gain) and the nozzle back pressure is ΔPn. In this case, as shown in FIG. 9B, when the gain of the control relay is high, the drive output pressure Po is ΔPo1. Further, when the gain of the control relay is low, the drive output pressure Po is ΔPo2. That is, the higher the gain of the control relay, the wider the range in which the drive output pressure Po is used. Further, assuming that the drive output pressure Po is constant in FIG. 9A, the nozzle back pressure when the control relay is high gain is ΔPn1, and when the control relay is low gain, ΔPn2. Here, when the gain of the control relay is higher than that in FIG. 10 (ΔPn1), the current span is ΔI1. That is, if the gain of the control relay is high, the I / P module can be driven with a small current span. Therefore, a high gain is required for the control relay.

  Next, characteristics required for the control relay and the I / P module as components of the electropneumatic conversion device 90 will be described. First, the characteristics of the control relay of the electropneumatic converter will be described. The control relay of the electropneumatic converter may be used as the air pressure input to the air / air positioner. At this time, if the gain of the control relay is high, hunting may occur. Here, hunting refers to a phenomenon in which the drive output pressure Po changes periodically and does not become stable. In addition, when the gain of the control relay is high, the influence on the control system of the dead zone, which is a nonlinear element unique to the control relay, becomes strong. In order to suppress the influence of the dead zone on the control system, the nozzle back pressure range needs to be as wide as possible. Here, as shown in FIG. 10, ΔPn2 (low gain) has a wider nozzle back pressure range than ΔPn1 (high gain). Therefore, the control relay of the electropneumatic converter 90 needs to have a low gain.

  Next, characteristics of the I / P module of the electropneumatic converter will be described. Here, as described above, the control relay of the electropneumatic converter is required to have a low gain. Therefore, the current span of the I / P module becomes wider as ΔI2 shown in FIG. However, the supply current to the I / P module is limited to suppress power consumption. Therefore, the I / P module of the electropneumatic converter is required to have a high gain.

  A table summarizing the above contents is shown in FIG. As shown in FIG. 12, the control gain of the valve positioner requires a high gain (high amplification degree). On the other hand, the control gain of the electropneumatic conversion device requires a low gain (low amplification factor). In addition, the I / P module of the valve positioner requires a low gain (low amplification degree). On the other hand, the I / P module of the electropneumatic conversion device requires a high gain (high amplification degree). The valve positioner control algorithm controls the position by measuring the position of the valve stem. On the other hand, the control algorithm of the electropneumatic converter performs pressure control by measuring the pressure at a negative capacity. That is, the gain characteristics and the controlled object are different between the valve positioner and the electropneumatic converter. Therefore, it has been difficult to realize an electropneumatic conversion system that uses the functions of a valve positioner and an electropneumatic converter together. In order to realize the electropneumatic conversion system, there is a request to switch the gain (amplification degree) of the control relay and the I / P module according to the control target (position control or pressure control).

Therefore, the subject of this invention is implement | achieving the electropneumatic conversion system which can switch an amplification degree appropriately according to position control or pressure control.

In order to solve the above-described problem, an electropneumatic conversion system according to claim 1 is provided.
An electropneumatic conversion system that performs position control of a valve stem whose position changes according to drive output pressure or pressure control of a valve according to drive output pressure,
Electropneumatic conversion means for outputting air pressure in response to an input current signal;
Pressure amplifying means for outputting the drive output pressure in accordance with the air pressure;
A first amplification degree switching means for selecting the position control or the pressure control and switching the amplification degree of the electropneumatic conversion means according to the selected control;
A second amplification degree switching means for selecting the position control or the pressure control and switching the amplification degree of the pressure amplification means according to the selected control;
Pressure detection means for detecting the drive output pressure as a drive pressure signal in the case of the pressure control;
Position detecting means for detecting the position of the valve stem in the case of the position control and detecting the position as a position signal;
Control means for generating the input current signal based on the driving pressure signal or the position signal and a control signal for performing the position control or the pressure control, and inputting the input current signal to the electropneumatic conversion means; It is characterized by providing.

The invention according to claim 2 is the electropneumatic conversion system according to claim 1,
The first amplification degree switching means is
When the position control is selected, the amplification degree of the electropneumatic conversion means is switched to a low amplification degree, and when the pressure control is selected, the amplification degree of the electropneumatic conversion means is switched to a high amplification degree,
The second amplification degree switching means is
When the position control is selected, the amplification degree of the pressure amplification means is switched to a high amplification degree, and when the pressure control is selected, the amplification degree of the pressure amplification means is switched to a low amplification degree.

The invention according to claim 3 is the electropneumatic conversion system according to claim 1 or 2,
The second amplification degree switching means is
The amplification degree is switched according to an operation input signal of selection information.

The invention according to claim 4 is the electropneumatic conversion system according to claim 1 or 2,
The first amplification degree switching means is
The amplification degree is switched according to an operation input signal of selection information.

The invention according to claim 5 is the electropneumatic conversion system according to claim 1 or 2,
Further comprising a communication means for communication connection with an external device,
The first amplification degree switching means is
The amplification degree is switched based on a switching control signal received from the external device via the communication means.

The control method of the electropneumatic conversion system according to the invention of claim 6 is:
A control method of an electropneumatic conversion system that performs position control of a valve stem whose position changes according to drive output pressure or pressure control of a valve according to drive output pressure,
An electropneumatic conversion step of outputting the air pressure by the electropneumatic conversion means according to the input current signal;
A pressure amplifying step for outputting the drive output pressure by pressure amplifying means according to the air pressure;
A first amplification degree switching step of selecting the position control or the pressure control, and switching the amplification degree of the electropneumatic conversion means by the first amplification degree switching means according to the selected control;
A second amplification degree switching step of selecting the position control or the pressure control and switching the amplification degree of the pressure amplification means by a second amplification degree switching means according to the selected control;
A pressure detection step of detecting the drive output pressure as a drive pressure signal in the case of the pressure control;
A position detecting step of detecting the position of the valve stem in the case of the position control and detecting the position as a position signal;
A control step of generating the input current signal based on the driving pressure signal or the position signal and a control signal for performing the position control or the pressure control, and inputting the input current signal to the electropneumatic conversion means; , Including.

The invention according to claim 7 is the control method of the electropneumatic system according to claim 6,
The first amplification degree switching step includes:
When the position control is selected, the amplification degree of the electropneumatic conversion means is switched to a low amplification degree, and when the pressure control is selected, the amplification degree of the electropneumatic conversion means is switched to a high amplification degree,
In the second amplification degree switching step,
When the position control is selected, the amplification degree of the pressure amplification means is switched to a high amplification degree, and when the pressure control is selected, the amplification degree of the pressure amplification means is switched to a low amplification degree.

Invention of Claim 8 is the control method of the electropneumatic conversion system of Claim 6 or 7,
In the second amplification degree switching step,
The amplification degree is switched according to an operation input signal of selection information.

The invention according to claim 9 is the control method of the electropneumatic conversion system according to claim 6 or 7,
The first amplification degree switching step includes:
The amplification degree is switched according to an operation input signal of selection information.

Invention of Claim 10 is the control method of the electropneumatic conversion system of Claim 6 or 7,
The first amplification degree switching step includes:
The amplification degree is switched based on a switching control signal received from the external device via a communication connection unit that is connected to the external device.

  According to the first and sixth aspects of the invention, the amplification degree of the electropneumatic conversion means or the pressure amplification means can be switched by the first amplification degree switching means or the second amplification degree switching means. Thereby, the amplification degree of the electropneumatic conversion means or the pressure amplification means can be appropriately switched according to the position control or the pressure control.

  According to the second and seventh aspects of the present invention, the first amplification degree switching means can switch the amplification degree of the electropneumatic conversion means to a low amplification degree when the position control is selected. When pressure control is selected, the amplification degree of the electropneumatic conversion means can be switched to a high amplification degree. The second amplification degree switching means can switch the amplification degree of the pressure amplification means to a high amplification degree when position control is selected. When pressure control is selected, the amplification degree of the pressure amplification means can be switched to a low amplification degree. Therefore, the amplification degree of the electropneumatic conversion means or the pressure amplifying means can be appropriately switched according to position control or pressure control.

  According to the third and eighth aspects of the present invention, the second amplification degree switching means can switch the amplification degree according to the operation input signal of the selection information.

  According to the fourth and ninth aspects of the invention, the first amplification degree switching means can switch the amplification degree according to the operation input signal of the selection information.

  According to the fifth and tenth aspects of the present invention, the first amplification switching unit can switch the amplification based on the switching control signal received from the external device via the communication unit.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. However, the scope of the invention is not limited to the illustrated examples.

  Embodiments according to the present invention will be described with reference to FIGS. First, the apparatus configuration of the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a hybrid valve positioner 100 according to the present embodiment. The hybrid valve positioner 100 as an electropneumatic conversion system can perform position control and pressure control. Here, the position control is to control the position of the valve stem 22A. The pressure control is to control the pressure of the drive output pressure Po. The hybrid valve positioner 100 includes a MAU 11 as a communication means, a fieldbus modem 12, a control means 13, a D / A (Digital / Analog) conversion means 14, an I / P module 15 as an electropneumatic conversion means, Switching means 16 as first amplification degree switching means, metal seal 17 as second amplification degree switching means, control relay 18 as pressure amplification means, pressure sensor 19 as pressure detection means, position detection A position sensor 20 as means, an A / D conversion means 21, a valve 22, and a valve / empty positioner 23 are provided. The valve 22 includes a valve stem 22A. When used as the valve positioner 80, the hybrid valve positioner 100 controls the position of the valve stem 22A of the valve 22. Further, when used as the electropneumatic converter 90, the drive output pressure Po supplied to the valve / empty positioner 23 is controlled. The MAU 11, the field bus modem 12, the D / A conversion means 14, the I / P module 15, the control relay 18, the position sensor 20, the A / D conversion means 21, and the valve 22 are the MAU 81 and the field bus modem 82 of the valve positioner 80, respectively. , D / A conversion means 84, I / P module 85, control relay 86, position sensor 88, A / D conversion means 89, and valve 87. The pressure sensor 19 and the valve / air / air positioner 23 are the same as the pressure sensor 98 and the valve / air / air positioner 97 of the electropneumatic converter 90.

  When the hybrid valve positioner 100 is used as the valve positioner 80, the MAU 11, the fieldbus modem 12, the control means 13, the D / A conversion means 14, the I / P module 15, the switching means 16, A metal seal 17, a control relay 18, a position sensor 20, an A / D conversion means 21, and a valve 22 are provided. When the hybrid valve positioner 100 is used as an electropneumatic converter, the MAU 11, the fieldbus modem 12, the control means 13, the D / A conversion means 14, the I / P module 15, and the switching means 16 , A metal seal 17, a control relay 18, a pressure sensor 19, an A / D conversion means 21, and a valve / empty positioner 23.

  The control unit 13 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Read Access Memory), and the like, and centrally controls each part of the hybrid valve positioner 100. The control means 13 expands a program designated from among the system program and various application programs stored in the ROM, and executes various processes in cooperation with the program expanded in the RAM. In particular, the third arithmetic program is stored in the ROM. Here, the third calculation program refers to a program that executes either the above-described first calculation program of the valve positioner 80 or the second calculation program of the electropneumatic converter 90. That is, the third arithmetic program selects and executes either the first arithmetic program or the second arithmetic program.

  The control means 13 calculates a deviation signal Error between the target value signal SV and the output signal PV as a control signal from the field bus FB by the third calculation program. Then, the nozzle back pressure Pn as the air pressure is controlled so that the deviation signal Error becomes zero. Here, the nozzle back pressure Pn refers to the air pressure supplied to the control relay 17. Further, the target value signal SV uses either the target value signal SV1 of the valve positioner 80 described above or the target value signal SV2 of the electropneumatic converter 90. That is, as the SV, either the target value signal SV1 or the target value signal SV2 is selected. The output signal PV uses either the position signal PV1 of the valve positioner 80 or the driving pressure signal PV2 of the electropneumatic converter 90 described above. That is, either the position signal PV1 or the driving pressure signal PV2 is selected as the output signal PV. Further, as the deviation signal Error, either the deviation signal Error1 of the valve positioner 80 described above or the deviation signal Error2 of the electropneumatic converter 90 is used. That is, either the deviation signal Error1 or the deviation signal Error2 is selected as the deviation signal Error.

  Further, the control means 13 selects a control algorithm. Here, the control algorithm refers to selecting whether to perform position control of the valve stem position 22A or pressure control of the drive output pressure Po. The control algorithm can be selected by a switching control signal G5 received from an external device (not shown) via the MAU 11. Here, the switching control signal G5 refers to a signal for performing switching selection of the control algorithm. The selection of the control algorithm can also be manually input from the external switch 24. In this case, the control algorithm can be selected based on the operation input signal G4 of the selection information from the external switch 24. Here, the selection information refers to information for selecting position control or pressure control. The operation input signal G4 refers to a signal input by operating the external switch 24.

  Further, the control means 13 outputs a switching control signal G1 to the switching means 16. Here, the switching control signal G1 is a signal for switching the amplification degree (gain) of the I / P module 15. The switching control signal G1 is received from an external device (not shown) via the MAU 11. The gain switching of the I / P module 15 can also be manually input from the external switch 25. In this case, the gain of the I / P module 15 can be switched and selected based on the operation input signal G2 of selection information from the external switch 25. Here, the selection information refers to information for selecting a low gain in the case of position control and a high gain in the case of pressure control. The operation input signal G2 is a signal input by operating the external switch 25.

  The MAU 11 is a signal transmission / reception device. The fieldbus modem 12 is a device that modulates and demodulates signals. The D / A conversion unit 14 converts the deviation signal Error output from the control unit 13 from a digital signal to an analog signal. The D / A converter 14 outputs an input current signal In.

  The I / P module 15 includes a torque motor, and outputs a nozzle back pressure Pn corresponding to the input current signal In. Further, the supply pressure Ps is supplied to the I / P module 15 and converted into the nozzle back pressure Pn corresponding to the input current signal In.

  The switching means 16 selects at least one coil from the plurality of coils, and connects the selected coils in series. The operation of the switching unit 16 will be described later. The metal seal 17 is made of stainless steel or the like, and is a seal that utilizes the elasticity of metal. By opening and closing the metal seal 17, the pressure applied to each room of the control relay 18 is partially changed. The operation of the metal seal 17 will be described later. An operation input signal G3 of selection information for switching opening and closing of the metal seal 17 can be manually input from the external switch 26. In this case, the amplification degree (gain) of the control relay 18 can be switched based on the operation input signal G3 of the selection information from the external switch 26. Here, the selection information refers to information for selecting a high gain in the case of position control and a low gain in the case of pressure control. The operation input signal G3 refers to a signal input by operating the external switch 26.

  The control relay 18 outputs a drive output pressure Po obtained by amplifying the nozzle back pressure Pn. The supply pressure Ps is supplied to the control relay 18 and is converted into a drive output pressure Po corresponding to the nozzle back pressure Pn. When the control target is the valve 22, the valve stem 22 </ b> A is displaced based on the drive output pressure Po, and the opening degree of the valve 22 is controlled. When the control target is the air / air positioner 23, the drive output pressure Po is supplied to the air / air positioner 23 and the pressure sensor 19.

  The pressure sensor 19 converts the drive output pressure Po into an output signal PV. The position sensor 20 detects an operation displacement of the valve stem 22A. In the case of the electropneumatic converter 90, the A / D conversion means 21 converts the analog signal output from the pressure sensor 19 into a digital signal. In the case of the valve positioner 80, the analog signal output from the position sensor 20 is converted into a digital signal.

Next, gain switching of the I / P module 15 will be described with reference to FIGS. FIG. 2 is a diagram showing the structure of the I / P module 15 and the switching means 16. FIG. 3 is a diagram showing the types of gain. FIG. 4 is a diagram showing the switching means 16.
First, referring to FIG. 2, the structural diagram of the I / P module 15 and the switching means 16 will be described. The I / P module 15 in FIG. 2 includes an upper housing 31, a lower housing 32, a pole piece 33, a nozzle 34, a permanent magnet 35, a movable member 36, a pipe 37, and a throttle 38. , A conduit 39, an exhaust hole 40, a pole piece 41, a first coil 42, and a second coil 43. The switching means 16 is means for switching the first coil and the second coil of the I / P module 15. The switching means 16 will be described later.

  The housings 31 and 32 are both made of soft magnetic material such as pure iron, ferritic stainless steel, and permalloy. The outer portion of the housing 31 has a cylindrical shape, and a columnar pole piece 33 made of soft magnet is formed inward at the center thereof. Further, a nozzle 34 penetrating the inside and outside is formed at the center of the ball piece 33.

  A donut-shaped permanent magnet 35 is formed on the inner surface of the housing 31 so as to surround the pole piece 33. The permanent magnet 35 is magnetized in the axial direction, for example, the side fixed to the housing 31 is an N pole and the opposite side is an S pole. As this permanent magnet 35, a samarium-cobalt magnet or iron-neodymium magnet having a large energy product is suitable so that it is not necessary to make the length of the magnetization direction so long.

  On the opposite side of the permanent magnet 35 to the side fixed to the housing 31, a diaphragm-like movable member 36 is fixed to the pole piece 33 with a predetermined gap length Lg 1 and fixed by, for example, the attractive force of the permanent magnet 35. It bends up and down by external force.

  The movable member 36 is a magnetic spring material having both characteristics of spring characteristics such as precipitation hardened stainless steel, iron-nickel alloy, iron-chromium-cobalt alloy, and particularly magnetic characteristics with a high saturation magnetic flux density. Composed. The movable member 36 is magnetized by the permanent magnet 35 to a single pole having only an S pole or an N pole.

  The nozzle 34 is connected to a throttle 38 via a pipe 37, and supply pressure Ps is supplied to the throttle 38 from the outside, and the nozzle back pressure Pn generated at the throttle 38 is taken out via a conduit 39. Further, an exhaust hole 40 communicating with the outside is formed in the housing 31.

  The lower housing 32 has an outer diameter portion that is cylindrical, and is fixed integrally with the outer diameter portion of the housing 31. A cylindrical pole piece 41 made of a soft magnetic material is fixed to the center portion of the movable member 36 while holding a predetermined gap length Lg2. Around the pole piece 41, first and second coils 42 and 43 for passing a current signal I are wound. The first coil and the second coils 42 and 43 are independent of each other and are not connected to each other. In this case, the number of turns is the same.

  That is, as shown in FIG. 3, two types of gains, gain 1 and gain 2, are obtained by the combination of the first and second coils 42 and 43.

  The gain of the I / P module 15 depends on the number of turns of the coil. That is, in the case of a low gain, only one of the first coil 42 or the second coil 43 is used, and in the case of a high gain, the first coil 42 and the second coil 43 are used in series. The switching unit 16 selects at least one of the plurality of coils 42 and 43 and connects the selected coils in series.

  Next, the operation of the switching means 16 will be described with reference to FIG. When selecting the gain 1, the switching means 16 connects the movable contact 1a of the switch SW1 to the fixed contact 1c, and connects the movable contact 2a of the switch SW2 to the fixed contact 2c. When gain 2 is selected, the movable contact 1a of the switch SW1 is connected to the fixed contact 1b, and the movable contact 2a of the switch SW2 is connected to the fixed contact 2b.

  In the above configuration, by changing the current to the first coil 42 and the second coil 43, the magnetic flux of the air gap on both sides of the movable member 36 is changed, thereby the gap between the movable member 36 and the nozzle 34. Control. When the gap changes, the nozzle back pressure Pn changes due to the change in the amount of air leakage.

  Next, gain switching of the control relay 18 will be described with reference to FIG. 5A includes an exhaust valve 61, an input diaphragm 62, a movable portion 63, a feedback diaphragm 64, an air supply valve 65, a poppet 66, a spring 67, and a bleed hole 68. It is prepared for.

  In FIG. 5A, when the pressure of the nozzle back pressure Pn as indicated by CP61 increases, the input diaphragm 62 is deformed so as to be convex on the right side of the drawing and pushes the movable portion 63. Then, the poppet 66 in contact with the exhaust valve 61 is pushed.

  When a certain pressure or more is applied to the poppet 66 held by the spring 67, the poppet 66 is deformed so as to be convex on the right side of the drawing and pushes the movable portion 63. Then, the poppet 66 in contact with the exhaust valve 61 is pushed.

  On the other hand, when the pressure of the nozzle back pressure Pn as shown by CP61 in FIG. 5A increases, the input diaphragm 62 is deformed so as to protrude to the right side of the drawing and pushes the movable portion 63. Then, the poppet 66 in contact with the exhaust valve 61 is pushed.

  When a certain pressure or more is applied to the poppet 66 held by the spring 67, the poppet 66 moves to the right side of the drawing. Then, a gap is created between the air supply valve 65 and the poppet 66, and the supply pressure supplied to SP61 in FIG. 6 flows into the output pressure side indicated by OP61 in FIG. .

  On the other hand, when the pressure of the nozzle back pressure Pn as shown by CP61 in FIG. 5A decreases, the input diaphragm 62 is deformed so as to protrude to the right side of the drawing and pulls the movable portion 63 to the left side of the drawing.

  For this reason, a gap is generated between the exhaust valve 61 and the poppet 66 held by the spring 67. 5A, the pressure on the output pressure side indicated by OP61 flows into the exhaust side indicated by VE61 in FIG. 5A from the hole provided in the movable portion 63 indicated by HL61 in FIG. 5A. The output pressure decreases.

  As a result, the output pressure (control pressure) can be controlled by adjusting the nozzle back pressure Pn supplied to the control relay 55. FIG. 5B is a diagram showing FIG. 5A in detail. The flow path connected to each room of the control relay 18 shown in FIG. 5B can be changed by the metal seal 17. Thereby, the pressure of the room of the control relay 18 can be partially switched, and the combination of diaphragms that function by force balance can be changed. That is, the gain of the control relay 18 can be switched by the metal seal 17.

  Next, an operation for switching the gains of the I / P module 15 and the control relay 18 in the hybrid valve positioner 100 will be described with reference to FIG. First, an operation for switching the gain of the I / P module 15 will be described.

  First, a signal for switching the gain of the I / P module 15 is transmitted by the field bus. Then, a switching control signal G 1 is sent from the control means 13 to the switching means 16 via the MAU 11 and the fieldbus modem 12. The combination of the coils 42 and 43 of the I / P module 15 is changed by switching the switches SW1 and SW2 of the switching unit 16.

  Next, an operation for switching the gain of the control relay 18 will be described. First, an operation input signal G 3 is input from the external switch 26 to the metal seal 17. The flow path connected to each room of the control relay 18 is changed by the metal seal 17. Thereby, the gain of the control relay 18 is switched.

  For example, the operation when the hybrid valve positioner 100 is used as the electropneumatic converter 90 will be described. From FIG. 12, the I / P module 15 is required to have a high gain, and the control relay 18 is required to have a low gain. Therefore, a signal for switching the I / P module 15 to a high gain is transmitted by the field bus. Then, a switching control signal G 1 is sent from the control means 13 to the switching means 16 via the MAU 11 and the fieldbus modem 12. In the switching means 16, the movable contact 1a of the switch SW1 is connected to the fixed contact 1b so that the gain 2 (high gain) in FIG. 4 is selected. Further, the movable contact 2a of the switch SW2 is connected to the fixed contact 2b. Therefore, the I / P module 15 has a high gain. The nozzle back pressure Pn is output from the I / P module 15. The nozzle back pressure Pn is input to the control relay 18. The control relay 18 needs to have a lower gain than in FIG. Therefore, the operation input signal G3 is manually input by the external switch 26 so that the control relay 18 has a low gain. In this case, the flow path connected to each room of the control relay 18 of FIG. And the control relay 18 becomes a low gain, and the drive output pressure Po is output. The drive output pressure Po is supplied to the air / air positioner 23 and the pressure sensor 19. Then, an output signal PV is output from the pressure sensor 19 and fed back to the control means 13 via the A / D conversion means 21.

  When the hybrid valve positioner 100 is used as the valve positioner 80, control is performed so that the I / P module 15 has a low gain and the control relay 18 has a high gain.

  As described above, according to the present embodiment, the gain of the I / P module 15 or the control relay 18 can be switched by the switching means 16 or the metal seal 17. Thereby, the gain of the I / P module 15 or the control relay 18 can be appropriately switched according to the position control of the valve stem 22A or the pressure control of the drive output pressure Po.

  Moreover, the switching means 16 can switch the gain of the I / P module 15 to a low gain when the position control of the valve stem 22A is selected. Further, when the pressure control of the drive output pressure Po is selected, the gain of the I / P module 15 can be switched to a high gain. Further, the metal seal 17 can switch the gain of the control relay 18 to a high gain when the position control of the valve stem 22A is selected. Further, when the pressure control of the drive output pressure Po is selected, the gain of the control relay 18 can be switched to a low gain. Therefore, the gain of the I / P module 15 or the control relay 18 can be appropriately switched according to the position control of the valve stem 22A or the pressure control of the drive output pressure Po.

  The metal seal 17 can switch the gain according to the operation input signal G3 of the selection information.

  Further, the switching unit 16 can switch the gain according to the operation input signal G2 of the selection information.

  The switching unit 16 can switch the gain based on the switching control signal G1 received from the external device via the MAU 11.

  Further, when the position control of the valve stem 22A does not require accuracy, the valve 23 can be directly controlled as the electropneumatic converter 90. In addition, instrumentation costs can be reduced because only one type of maintenance product is required. In addition, since it can be operated as a valve positioner after first operating as the electropneumatic conversion device 90, the controllability is improved and the valve diagnosis function and the like can be effectively utilized.

  In addition, the detailed structure and detailed operation of the hybrid valve positioner 100 in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram of hybrid valve positioner 100 in an embodiment of the invention. It is principal part structure explanatory drawing of this invention. It is the figure which showed the kind of gain. FIG. 4 is a diagram showing a switching unit 16. 2 is a structural diagram of a control relay 18. FIG. 3 is a block diagram of a valve positioner 80. FIG. 2 is a block diagram of an electropneumatic conversion device 90. FIG. It is a block diagram which shows an example of the electropneumatic positioner 200 of a prior art example. It is the figure which showed the input / output characteristic of the control relay. It is the figure which showed the input / output characteristic of the I / P module. It is the figure which showed the input / output characteristic of the I / P module. It is the figure which compared the characteristic of the valve positioner and the electropneumatic converter.

Explanation of symbols

Error, Error1, Error2 Error signal FB Fieldbus G1, G5 Switching control signals G2, G3, G4 Operation input signal In Input current signal Io Current signal Lg1, Lg2 Gap length Pe Exhaust fluid pressure Pn Nozzle back pressure Po Drive output pressure P Valve Plug Ps Supply pressure PV Output signal PV1 Position signal PV2 Drive pressure signal SV, SV1, SV2 Target value signal SW, SW1, SW2 Switch Va Pressure signal Vd Deviation signal Vf Feedback signal Vo Voltage signal Vs Valve opening signal 1a Movable contact 1b, 1c fixed contact 2a movable contact 2b, 2c fixed contact 11 MAU
12 Fieldbus modem 13 Control means 14 D / A conversion means 15 I / P module 16 Switching means 17 Metal seal 18 Control relay 19 Pressure sensor 20 Position sensor 21 Conversion means 22 Valve 22A Valve stem 23 Valve / empty positioners 24, 25 26 External switch 31, 32 Housing 33 Pole piece 34 Nozzle 35 Permanent magnet 36 Movable member 37 Piping 39 Conduit 40 Exhaust hole 41 Ball piece 42 Coil 43 Coil 43 Pole piece 43, 44 Coil 61 Exhaust valve 62 Input diaphragm 63 Movable part 64 Feedback Diaphragm 65 Air supply valve 66 Poppet 67 Spring 68 Bleed hole 80 Valve positioner 82 Fieldbus modem 83 Control means 84 D / A conversion means 85 I / P module 86 Control relay 87 Valve 87A Valve stem 88 Position sensor 89 A / D conversion means 90 Electropneumatic conversion device 92 Fieldbus modem 93 Control means 94 Conversion means 95 Module 96 Control relay 97 Air empty positioner 98 Pressure sensor 99 Conversion means 100 Hybrid valve positioner 201 Electro air Positioner 202 Signal conversion circuit 203 Differential amplifier 204 Electropneumatic conversion circuit 205 Pressure converter 206 Control valve 207 Stem 208 Valve 209 Valve opening detector 210 Calculation circuit 210 Valve opening detector 211 Comparison calculator

Claims (10)

An electropneumatic conversion system that performs position control of a valve stem whose position changes according to drive output pressure or pressure control of a valve according to drive output pressure,
Electropneumatic conversion means for outputting air pressure in response to an input current signal;
Pressure amplifying means for outputting the drive output pressure in accordance with the air pressure;
A first amplification degree switching means for selecting the position control or the pressure control and switching the amplification degree of the electropneumatic conversion means according to the selected control;
A second amplification degree switching means for selecting the position control or the pressure control and switching the amplification degree of the pressure amplification means according to the selected control;
Pressure detection means for detecting the drive output pressure as a drive pressure signal in the case of the pressure control;
Position detecting means for detecting the position of the valve stem in the case of the position control and detecting the position as a position signal;
Control means for generating the input current signal based on the driving pressure signal or the position signal and a control signal for performing the position control or the pressure control, and inputting the input current signal to the electropneumatic conversion means; ,
An electropneumatic conversion system comprising: The first amplification degree switching means is
When the position control is selected, the amplification degree of the electropneumatic conversion means is switched to a low amplification degree, and when the pressure control is selected, the amplification degree of the electropneumatic conversion means is switched to a high amplification degree,
The second amplification degree switching means is
The amplification degree of the pressure amplification means is switched to a high amplification degree when the position control is selected, and the amplification degree of the pressure amplification means is switched to a low amplification degree when the pressure control is selected. 1. The electropneumatic conversion system according to 1. The second amplification degree switching means is
The electropneumatic conversion system according to claim 1 or 2, wherein the amplification degree is switched in accordance with an operation input signal of selection information. The first amplification degree switching means is
The electropneumatic conversion system according to claim 1 or 2, wherein the amplification degree is switched in accordance with an operation input signal of selection information. Further comprising a communication means for communication connection with an external device,
The first amplification degree switching means is
The electropneumatic conversion system according to claim 1 or 2, wherein the amplification degree is switched based on a switching control signal received from the external device via the communication means. A control method of an electropneumatic conversion system that performs position control of a valve stem whose position changes according to drive output pressure or pressure control of a valve according to drive output pressure,
An electropneumatic conversion step of outputting the air pressure by the electropneumatic conversion means according to the input current signal;
A pressure amplifying step for outputting the drive output pressure by pressure amplifying means according to the air pressure;
A first amplification degree switching step of selecting the position control or the pressure control, and switching the amplification degree of the electropneumatic conversion means by the first amplification degree switching means according to the selected control;
A second amplification degree switching step of selecting the position control or the pressure control and switching the amplification degree of the pressure amplification means by a second amplification degree switching means according to the selected control;
A pressure detection step of detecting the drive output pressure as a drive pressure signal in the case of the pressure control;
A position detecting step of detecting the position of the valve stem in the case of the position control and detecting the position as a position signal;
A control step of generating the input current signal based on the driving pressure signal or the position signal and a control signal for performing the position control or the pressure control, and inputting the input current signal to the electropneumatic conversion means; ,
A control method for an electropneumatic conversion system, comprising: The first amplification degree switching step includes:
When the position control is selected, the amplification degree of the electropneumatic conversion means is switched to a low amplification degree, and when the pressure control is selected, the amplification degree of the electropneumatic conversion means is switched to a high amplification degree,
In the second amplification degree switching step,
The amplification degree of the pressure amplification means is switched to a high amplification degree when the position control is selected, and the amplification degree of the pressure amplification means is switched to a low amplification degree when the pressure control is selected. The control method of the electropneumatic conversion system of Claim 6. In the second amplification degree switching step,
The method of controlling an electropneumatic conversion system according to claim 6 or 7, wherein the amplification degree is switched in accordance with an operation input signal of selection information. The first amplification degree switching step includes:
The method of controlling an electropneumatic conversion system according to claim 6 or 7, wherein the amplification degree is switched in accordance with an operation input signal of selection information. The first amplification degree switching step includes:
8. The method of controlling an electropneumatic conversion system according to claim 6 or 7, wherein the amplification degree is switched based on a switching control signal received from the external device via a communication connection means that is connected to the external device.

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