JPH0470902A - Light/air pressure controller - Google Patents

Abstract

PURPOSE:To shorten the adjusting time of a control loop and to improve the reliability in an adverse environment by unifying a field controller, a detecting part, and an operating part together as an equipment of the field side. CONSTITUTION:A light/electricity converter 3 is provided to convert the digital light control signal A into a digital electric signal together with an air/electricity conversion part 15, the measuring circuits 14, 18 and 19 which detect various physical quantities including the pressure and the temperature, and an A/D converter 6 which converts the feedback signal S into a digital signal. Furthermore an electricity/light converter 7 is added to convert the output of a CPU 4 into an optical signal together with a D/A converter 5 which converts the operating signal outputted from the CPU 4 into an analog signal, and a control part 8 which outputs the output of the converter 5 to an electricity/air conversion part 13 as the impressed voltage. In such a constitution, a light/air pressure controller is unified with a field equipment and can withstand the application under an adverse environment. In addition, the controller, an operating part, and a detecting part are put together in a single unit and therefore the adjusting time is shortened.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is used particularly in the field of industrial measurement and control,
The present invention relates to a control device (controller) installed on the field side for controlling air pressure output in response to a setting signal from a host device.

[Conventional technology]

Conventionally, this type of control device (controller) was installed in a panel room, with a temperature transmitter and a pressure transmitter as the detection part, and an electro-pneumatic converter as the operation part, and these were installed on the field side. What is being done is boat fishing. In other words, a detector on the field side measures process variables such as temperature and pressure, a control device in the panel room performs PID calculations and outputs an operation signal, and an electro-pneumatic converter installed on the field side measures the process variables such as temperature and pressure. It is converted into the amount of air pressure operation.

[Problem to be solved by the invention]

In such systems, the detectors and operation parts installed in the field and the control equipment in the panel room are connected over long distances using electrical signal lines. Often used.

Another problem is that when the system is started up, adjustment personnel must be placed in the field and in the panel room, and furthermore, adjustment takes time.

Therefore, an object of the present invention is to provide an optical-pneumatic control device that can withstand use in adverse environments, has a control device, an operating section, and a detection section integrated into one, and can shorten adjustment time.

[Means to solve the problem]

A piezoelectric flapper that deforms according to an applied voltage, a nozzle that opens close to the piezoelectric flapper and jets out a part of the supplied air pressure to the piezoelectric flapper, and a nozzle that changes according to the distance between the nozzle and the piezoelectric flapper. an electric-to-electrical converter consisting of a viroft valve that amplifies back pressure and outputs an output air pressure; a pneumatic-to-electrical converter that has a pressure sensor that detects the output air pressure and outputs the output as a feedback signal; an optical-to-electrical converter that converts the digital optical control signal into a digital electrical signal; and a plurality of measurement circuits that detect various physical quantities including pressure and temperature that are feedback signals from the pneumatic-to-electrical converter and various processes. , an A/D converter that converts the analog feedback signals from each measurement circuit into digital signals, and the optical
a central processing unit that performs control calculations with each output of the A/D converter for setting the electrical converter; an electrical-optical converter that converts the output from the central processing unit into an optical signal; and the central processing unit. a D/A converter that converts the operation signal outputted by the D/A converter into an analog signal, and a control unit that outputs the output of the D/A converter as the applied voltage to the electro-pneumatic converter,
Each of the above parts is powered by a battery.

[Effect]

By integrating the control unit, detection unit, operation unit, etc. necessary for various process control in the field into field equipment, the adjustment time due to the control loop is shortened. In addition, by using optical fiber for data transmission with the host system and battery-powered, it is less susceptible to noise, surges, etc.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the invention. In the figure, 1 is an optical signal transmission line, 2 is an optical branching coupler, and 3 is an optical signal transmission line.
is an optical-to-electrical (0/E) converter, 4 is a central control word f (C
PU), 5 is a digital-analog (D/A) converter, 6 is an analog-digital (A/D) converter, 7 is an electro-optical (Elo) converter, 8 is a control unit, 9 is a flapper,
10 is a nozzle, 11 is a fixed throttle, 12 is a pilot valve,
13 is an electric-electrical converter, 14.18 is a pressure sensor, 15 is a pneumatic-electrical converter, 16 is a battery, and 17 is a multiplexer (M
PX), 19 is a temperature sensor. Further, A is a digital light control signal, Ei is an analog voltage, Vi is a supply air pressure, vb is a nozzle back pressure, ■0 is an output air pressure, and S is a feedback signal.

A digital optical control signal A transmitted through an optical signal transmission line 1 made of an optical fiber cable from a host device such as a central control unit (not shown) is branched by an optical branching coupler 2, and then sent to an O/E converter 3. The signal is converted into a digital electrical signal and input to the CPU 4. Note that this optical control signal A is composed of signed 16-bit data, for example.

On the other hand, the output air pressure detected by the pressure sensor 14 ■0
The feedback signal S corresponding to is converted into a digital signal by the A/D converter 6 and input to CPtJ4. As the pressure sensor 14, for example, a low power consumption type capacitance type sensor is used. As the feedback signal S, in addition to the output from this pressure sensor 14, outputs from another pressure sensor 18 and a temperature sensor 19 are sequentially taken in, for example, via the multi-breather 17. In addition,
Pressure sensor 18. A flow rate sensor may be provided in addition to the temperature sensor 19. CPU4 mainly uses RA, for example.
It consists of an 8-bit microcomputer equipped with M, ROM, input/output board, etc., and performs predetermined digital control calculations based on the difference between the input light control signal A and feedback signal S, and outputs the calculation output to D. /A converter 5.

The D/A converter 5 converts this calculation output into an analog signal Ei, and outputs it to the electrical-electrical converter 13 as an operation signal.

One end of the flapper 9 is fixed, and when a voltage is applied, the maximum displacement occurs at the other end in response to the applied voltage. A nozzle 10 that opens toward the flapper 9 is arranged near the free end of the flapper 9 . The distance between the flapper 9 and the nozzle 10 is determined by the piezoelectric flapper 9.
It is determined by the analog voltage Ei applied to. A portion of the constant pressure supply air Vi is supplied to the pilot valve 12, and the other portion is supplied to the nozzle 10 via the fixed throttle 11, and is ejected from the nozzle 10 toward the flapper 9.

At this time, the nozzle back pressure vb is determined depending on the distance between the flapper 9 and the nozzle 10, and this nozzle back pressure vb is amplified by the pilot valve 12 to obtain an output air pressure of 0. The output air pressure ■0 is transmitted to an operating device such as a valve (not shown) and drives the operating device.

On the other hand, the pressure sensor 14, which is the process feedbank amount,
The controller 8 performs digital control calculations such as PID control on the measured values from the temperature sensor 18 or the temperature sensor 19. It is possible to send the data to the transmission path 1 and transmit it to higher-level equipment as control result data.

FIG. 2 shows the configuration of the PID calculation section provided in CPUd.

This is based on the deviation between the setting value given from the host device as a digital light control signal and the feedback amount such as pressure, temperature, flow rate, etc. given via the coefficient element 24. A computing unit 21 that performs II control calculations and a computing unit 22 that performs PID control calculations using the output as a target value and a feedback amount given via the coefficient element 23 of the pneumatic manipulated variable are provided. This controls the electrical conversion section 13. By doing so, it is also possible to control other process variables (pressure, temperature, flow rate, etc.) that are controlled based on the output air pressure from the electrical-electrical conversion section 13. Therefore, the entire plant can be optimally controlled.Note that other pressures excluding the feedback signal from the pneumatic-electric converter 15.

Signals such as temperature and flow rate may be fed back individually, or all of them may be fed back to perform comprehensive control.

Note that a battery 16 is connected to the control section 8 and the pneumatic-to-electric conversion section 15 as a driving power source, and a lithium battery is suitable as this battery. It is also conceivable to use a pneumatically driven generator instead of batteries. In addition, by adopting a microcomputer in the control unit 8, the power supply voltage can be reduced by 1
Various self-diagnosis functions such as manual abnormality, output abnormality, etc. can be easily added.

〔Effect of the invention〕

According to this invention, since the control device, detection unit, and operation unit used for field control are integrated as field-side equipment, it is possible to shorten the adjustment time of the control loop, and it is possible to reduce the adjustment time with the host system. By using optical fiber for data transmission and using battery power, it is possible to construct a system with high reliability even under adverse environments such as noise and surge.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a configuration diagram showing the configuration of a PID calculation section provided in the CPU of FIG. 1. 1... Optical signal transmission line, 2... Optical branching coupler, 3...
・Optical-electrical (0/E) converter, 4... Central control unit (
CPU), 5... Digital-analog (D/A) converter, 6... Analog-digital (A/D) converter, 7... Electrical-optical (B10) converter, 8... Control unit, 9...Flapper, 10...Nozzle, 11...Fixed throttle, 12...Pilot valve, 13...Electrical-electric conversion unit, 1418...Pressure sensor, 15... Air-to-electrical converter, 16...Battery, 17...Multiplexer (M
PX), 19... Temperature sensor, 21.22... Arithmetic unit, 23.24... Coefficient element, A... Digital light control signal, Ei... Analog voltage, Vi... Supply air pressure , vb... Nozzle back pressure, Vo... Output air pressure, S... Feedback signal.

Claims (1)

[Scope of Claims] 1) A piezoelectric flapper that deforms according to an applied voltage, a nozzle that opens close to the piezoelectric flapper and jets out a part of the supplied air pressure to the piezoelectric flapper, and a combination of the nozzle and the piezoelectric flapper. A pilot valve that amplifies the nozzle back pressure that changes depending on the interval between the two and outputs an output air pressure.
a pneumatic converter; a pneumatic-electrical converter having a pressure sensor that detects the output air pressure and outputs the output as a feedback signal; and a photo-electrical converter that converts an input digital optical control signal into a digital electrical signal. , a plurality of measurement circuits that detect various physical quantities including pressure and temperature, which are feedback signals from the pneumatic-electrical converter and various processes, and A that converts analog feedback signals from each measurement circuit into digital signals. /D converter, a central processing unit that performs control calculations on each output of the A/D converter and the settings of the optical-electrical converter, and an electrical-to-digital converter that converts the output from the central processing unit into an optical signal. an optical converter and a D/A that converts the operation signal output from the central processing unit into an analog signal;
a converter; and a control unit that outputs the output of the D/A converter as the applied voltage to the electro-pneumatic conversion unit, and each of the units is driven by a battery. Control device.