JPH0784649A - Flow rate control unit having both of constant flow rate function and variable flow rate function - Google Patents

Abstract

PURPOSE:To provide a device capable of executing accurate flow rate control by simple operation without being affected by a pressure difference generated before and after a flow rate control valve or pressure variation in a pipe. CONSTITUTION:A controller 5 measures a current flow rate from the output of a flow rate sensor 4 and controls a flow rate control valve 3 so that the current flow rate is approximately the same as an optionally specified set flow rate. In this case, the specified set flow rate is allowed to have some optional deviation, continuous control or inching control is automatically selected in accordance with the degree of a control error to control the valve 3, a controlled flow rate by one control is optionally set up, and the valve 3 is controlled so that the current flow rate is within the range of the deviation. A minimum control flow rate and a maximum control flow rate are optionally set up in the controller 5 as flow rate values in the specified set flow rate control and zero span is automatically controlled so that the minimum value and maximum value of analog input values are respectively set up as the minimum control flow rate and the maximum control flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate control unit having a constant flow rate function and a variable flow rate function at the same time. In particular, the flow rate of a liquid flowing through a pipe can be accurately maintained at a set and instructed value. In addition, set the liquid flow rate as necessary.
The present invention relates to a flow rate control unit that has a constant flow rate function and a variable flow rate function that can be accurately changed with an indicated value.

[0002]

2. Description of the Related Art Conventionally, in feedback control,
To control the flow rate of the liquid flowing through the pipe, a control valve, which is the main engine, and a detection sensor for temperature, pressure, concentration, pH, etc. are arranged in series in the middle of the pipe, and the output of this detection sensor is input to the regulator. It is common practice to connect the control line of the control valve to the valve control section of the controller as well as to control the opening of the control valve so that the value becomes a predetermined value.

[0003]

However, the opening control of the control valve in the conventional example as described above is actually the control of the passage area of the liquid (the opening area of the control valve). Here, the relationship among the flow rate Q of the liquid flowing through the pipe, the flow velocity V of the liquid, and the passage area S of the liquid is

[Equation 1] Can be expressed by

However, since it is impossible to directly control the liquid passage area of the control valve, it is possible to externally operate the stem of the control valve by using an actuator or the like.
The opening is controlled. Thus, even if the opening of the control valve is controlled in an integer, the passage area of the control valve does not change proportionally but changes quadratically. Furthermore, even if the control valve has the same diameter, this characteristic varies depending on the type and manufacturer of the valve.

Therefore, in the current control method in which the opening of the control valve is changed in an integer manner, the flow rate changes in a quadratic function. Therefore, each manufacturer conducts an experiment for each valve type and diameter to obtain the flow rate characteristic. ing. Also, linear characteristics are required because the valve opening and flow rate are controlled proportionally,
Since it is virtually impossible to obtain a valve having this characteristic, a valve having an equal percent characteristic has been developed.

In order to perform accurate flow rate control with the above-mentioned valve having the equal percent characteristic, a valve having the accurate equal percent characteristic is required. For this reason, the valves have to be manufactured while testing each one, so that the price is very expensive at present.

More importantly, in liquid control,
The pressure in the pipe is constantly changing, and this change in pressure appears in the change in differential pressure before and after the control valve, and the flow rate of passage changes quadratically at the same opening. This pressure difference ΔP is related to the flow velocity V of the liquid and the gravitational acceleration 2g,

[Equation 2] It is expressed by the formula. Therefore, the flow rate Q of the liquid flowing through the pipe by this equation is

[Equation 3] Therefore,

[Equation 4] Since the equation can be derived, for example, when the valve opening is 60% and ΔP changes from 1 kgf / cm ² to 3 kgf / cm ² , the flow rate increase rate is about 233.
%. Since ΔP is a variable element and 2g is constant, it is necessary to change the passage area S of the liquid in a quadratic function in order to keep the flow rate Q constant. Is impossible.

Keeping Q constant even if ΔP changes is called a constant flow rate function and is an important matter for accurate flow rate control. Even if the liquid supply source such as a pump and the control valve are in a one-to-one relationship, the pressure loss in the pipe varies due to the increase or decrease in the flow rate. In this state, in order to perform accurate flow rate control based on the valve opening according to the flow characteristics of the control valve, control is performed so that the differential pressure across the control valve is always constant, or the opening is corrected by the differential pressure. The need arises.

The constant control and the correction control of the differential pressure are high-priced techniques, are very expensive in price, and are not practical as a general purpose. Furthermore, if there are several control valves on the same pipe of one carrier, and each performs its own flow control,
The control result of one control valve influences the differential pressure across the other control valve, and if the above-mentioned differential pressure control or correction control is performed, it becomes a very complicated control, which requires enormous equipment and cost.

Further, when the accuracy of control is required by controlling the flow rate by the opening of the control valve, it is necessary to accurately control the opening angle of the control valve, and it is necessary to increase the resolution of the positioner and the actuator. For example, in the electric actuator, the conventional resolution was about 1/300, but nowadays, products with high resolution of about 1/1000 are manufactured, but it is complicated to increase the resolution of the actuator. It requires technology and many electronic components, and the price is significantly higher than that of general-purpose actuators. But,
The flow rate control based on the opening of the control valve improves the flow rate characteristics of the control valve, and even if the resolution of the actuator that controls the opening of the control valve is increased, it is possible Since the technology does not affect, accurate flow rate control by opening instruction is impossible.

In feedback control using a sensor for temperature, pressure, etc., it is possible to obtain practical control accuracy by installing an appropriate regulator. This regulator is an electronic type that can prevent overshoot and undershoot of the valve, set deviations to eliminate the influence of minute changes, etc., and perform accurate control by PI, DI, PID control, etc. The control software of is added.

The signal from the controller is proportional to the signal amount and the valve opening. The relationship between the flow rate and the flow rate is converted into temperature, pH, pressure, etc., and the flow rate is corrected until it is fed back as a deviation from the set value. Not done. For example, at 0 to 10 VDC with a 90 ° open / close valve, the valve opening is fully closed at 0 VDC, and when 10 VDC is input, the valve is 90 °.
Although it is controlled to be fully opened, the flow rate depends on the pressure loss difference between the set location and liquid transportation equipment such as a pump, so zero span setting cannot be performed between the flow rate and the input signal.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to accurately control the flow rate by a simple operation, and at the same time, a very inexpensive flow rate control unit. To provide a general purpose.

[0014]

In order to achieve the above object, the present invention provides a flow rate sensor on the inflow side or the outflow side of a flow rate control valve installed in a pipe, and outputs the flow rate sensor. By connecting the line to the input part of the controller and connecting the control line of the flow rate control valve to the valve control part of the controller, in the facility that supplies the liquid from the liquid transportation facility to the appropriate place through the pipe, to the controller, A flow rate measuring means based on the detection output of the flow rate sensor, an instruction set flow rate setting means, a comparison calculation means for comparing the current flow rate by the flow rate measurement means and an arbitrarily set instruction flow rate, and a calculation result of the comparison calculation means. By providing valve control means for opening and closing the flow control valve, the flow control valve is controlled to open and close so that the current flow rate is almost the same as the desired set flow rate. Flow rate per unit time has a structure characterized by comprising a constant.

In this case, the instruction set flow rate input by the instruction set flow rate setting means is allowed to have an arbitrary amount of deviation, and either continuous control or stepwise control is automatically selected according to the magnitude of the deviation to control the control error. When the flow rate control valve is large, the flow rate control valve is continuously controlled. When the control error is small, the flow rate control valve is inching controlled. In these controls, the control flow rate for one control can be set arbitrarily, so that the current flow rate is The flow control valve is controlled so that this deviation range is accurately and speedily, and in the set flow rate setting means, the controller can set any control minimum flow rate and control maximum flow rate within the allowable flow rate control range to the controller. The minimum analog input value is set as the control minimum flow rate, and the maximum analog input value is set as the control maximum flow rate. Is span adjustment, it can be configurable relationships of signal quantity and flow reversed. In addition, the controller is provided with a display unit, and it is possible to display the current flow rate, accumulated flow rate, stopped accumulated flow rate, etc. on this display unit and various numerical information stored in the controller during setting or processing of each means. Also, the controller is provided with an abnormality occurrence notifying means, and when the value obtained by the comparison calculating means is out of the allowable value set for the value given by the instruction setting flow rate setting means, it is judged as an abnormality, Indication of insufficient or excessive flow rate of the liquid flowing through the pipe is displayed on the display unit, and at the same time, output to the outside.
When the value obtained by the comparison operation means deviates from the allowable value,
If it is outside the allowable value for a certain period of time continuously, it is judged to be abnormal, and the display indicates that the flow rate of the liquid flowing in the pipe is insufficient or excessive, and at the same time, it is output to the outside and the control is continued. The configuration is such that it can be selected to be started or stopped.

In the above construction, the controller is composed of a microcomputer system, and by providing a numerical setting switch, a display section, an input / output driver, etc., the flow rate measuring means, the instruction setting flow rate setting means, the comparison calculating means,
A valve control means, an abnormality occurrence notification means, and a timekeeping means are realized, and an LCD, an LED, or a lamp is used for the display section.
The controller is provided with remote control means so that the controller can be operated remotely. Further, the controller is provided with address setting means capable of arbitrarily changing settings, and a plurality of controllers are provided by assigning different addresses to each controller. It is preferable to be able to individually control each.

[0017]

The flow rate sensor outputs as a voltage, current, frequency, pulse or electric resistance that varies according to the instantaneous flow rate, and this detection output is sent to the controller. The detection output received by the controller measures the current flow rate (instantaneous flow rate) at the time of measurement by the flow rate measuring means of the controller. Next, the comparison operation means of the controller compares the preset instruction set flow rate value with the instantaneous flow rate obtained by the flow rate measurement means by the instruction set flow rate setting means input and set by the numerical setting switch or the analog input signal. Do. Then, the valve control means of the controller controls the opening and closing of the flow rate control valve via the output driver based on the calculation result of the comparison calculation means, and the flow rate of the liquid becomes equal to the preset set flow rate set by the preset set flow rate setting means. Adjust so that

In this case, the controller performs the opening / closing operation of the control valve so that the flow rate of the liquid flowing through the pipe is always the instructed set flow rate value. However, the deviation is caused in the instructed set flow rate value set by the instructed set flow rate setting means. Since it can be set arbitrarily, it is possible to prevent the excessive control due to the disturbance in the pipe in the liquid transportation means or the like and the result of the control of other control units, and to prevent the unstable control of the entire same flow rate control system. Further, when the control error is large, the flow control valve is quickly controlled by continuous control, while when the control error is small, the flow control valve is repeatedly controlled stepwise by the inching control (fine amount control) to set the deviation within the set deviation. To prevent hunting due to overshoot or undershoot control. At this time, in the inching control, the control amount for one time can be arbitrarily set, so that the unstable control due to the differential pressure or the type of liquid can be prevented.

Further, in the flow rate instruction control, if an arbitrary control minimum flow rate and control maximum flow rate are set in the controller,
The minimum value of the analog input signal becomes the control minimum flow rate, and the maximum value of the analog input signal is automatically zero-span adjusted to the control maximum flow rate. In this case, the relationship between the signal amount and the flow rate can be reversed by setting the control maximum flow rate and the control minimum flow rate in reverse.

The controller has a display unit such as an LCD, an LED, a lamp, etc., thereby displaying the instantaneous flow rate, the accumulated flow rate or the stopped accumulated flow rate measured by the flow rate measuring means. The controller displays various numerical information stored in the controller or stored during the processing of each means and the operating state. Further, according to the abnormality notification means provided in the controller, when the flow rate value of the liquid flowing through the pipe is out of the allowable value, it is determined to be abnormal, and at the same time, the display section displays that the flow rate is insufficient or excessive. , The abnormality information is output to the outside. Further, according to the timing means provided in the controller, when the flow rate value obtained by the comparison calculation means is out of the deviation, it is judged to be abnormal when it is continuously out of the deviation for an arbitrarily set time or longer. , When the flow rate of the liquid flowing through the pipe is insufficient or excessive, the error information is output to the outside at the same time, and when it is judged that an abnormality has occurred, the control is continued or the control is stopped. It is possible to select whether to make it.

Further, according to the remote control means provided in the controller, an external host computer or the like can set and change the above-mentioned instructed flow rate and the deviation with respect to the instructed flow rate, an instantaneous flow rate display, an integrated flow rate display, a stop integrated flow rate. Each control such as display, operation state display, and various numerical information set in the controller or stored during processing of each unit can be remotely operated. Further, according to the address setting means provided in the remote control means, different addresses can be given to the respective controllers. Therefore, one host computer can be made to slave a plurality of controllers, and the above-mentioned remote operation can be individually controlled by changing conditions and the like for each controller.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the flow rate control unit of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of a unit main body 1 for controlling the flow rate of a liquid in a fixed amount or a variable amount. According to this figure, for example, a flow rate control valve 3 is installed at an appropriate position of a pipe 2 of a liquid transportation facility (not shown) such as a pump for supplying cold / hot water to an air conditioner. The flow rate sensor 4 is disposed on the inflow side, the output line 6 of the flow rate sensor 4 is connected to the controller 5, and the control line 7 of the flow rate control valve 3 is connected to the controller 5.

2 and 3 show the detailed structure of the controller 5. The structure of FIG. 2 is a block diagram of a so-called digital input type controller 5, and the numerical values are directly displayed on a control panel (not shown). The input is used to control the set flow rate. On the other hand, the configuration of FIG. 3 is a block diagram of the analog input type controller 5, in which an analog amount such as a current value, a voltage value or a resistance value is input, and the instruction set flow rate is controlled according to the magnitude of the value. Is. Which method is used depends on the implementation.

The digital input type controller 5 of this embodiment shown in FIG. 2 is constituted by a microcomputer system. In this embodiment, the MPU 500 is provided with a flow sensor input unit 501, a switch input unit 503, a display unit 504 with an LED display, a valve control unit 505, a valve abnormality output unit 506, a communication unit 507, and the like.
By installing software in the ROM 502 or the like of the PU 500, a flow rate measuring unit, an instruction setting flow rate setting unit, a comparison calculation unit, a valve control unit, an abnormality occurrence notification unit, a time counting unit, and a remote control unit are configured.

In the above, the switch input unit 503 includes a numerical value setting switch, and an instruction set flow rate value, a deviation amount added to the instruction set flow rate, a stop integrated flow rate value, a maximum value and a minimum value of the control flow rate, a multiplier, etc. It is used to set various numerical values, control start, control stop, reset, communication address setting, control delay time setting, flow rate lower limit control method, and other selections. In addition, the display unit 50
Numeral 4 indicates each of the displayed instantaneous flow rate, accumulated flow rate, stopped accumulated flow rate and set instantaneous flow rate, accumulated flow rate, stopped accumulated flow rate, and controller 5, flow control valve 3, and pipe 2 Used to display. In this embodiment, the LED display is used as the display means in the display unit 504, but an LCD display, a lamp or the like may be used instead of the LED display.

On the other hand, the analog input type controller 5 of this embodiment shown in FIG. 3 is also constituted by a microcomputer system. In this embodiment, the MPU500
Flow sensor input section 501, switch input section 503, L
A display unit 504 by a CD display, a valve control unit 505,
A valve abnormality output unit 506, a communication unit 507, an analog instruction input unit 508, an amplifier unit 509, an analog circuit power supply unit 510, and the like are provided, and the ROM 50 of the MPU 500 is further provided.
By installing software in 2 or the like, a flow rate measuring means, an instruction setting flow rate setting means, a comparison calculation means, a valve control means, an abnormality occurrence notification means, a time counting means, and a remote control means are configured.

In the above, the analog instruction input section 508 and the amplifier section 509 perform instruction setting such as an instruction set flow rate value, a maximum value and a minimum value of the control flow rate, which will be described later, by an analog value output from a controller (not shown). Used for. Further, the switch input unit 503 sets the deviation amount to be added to the instruction set flow rate, the stop integrated flow rate value, the multiplier, and various other numerical values, as well as control start, control stop, reset, communication address setting, control delay time setting. , The flow rate lower limit control method, and other selections. The display unit 504 displays the current instantaneous flow rate, the integrated flow rate, the stop integrated flow rate, the set instantaneous flow rate, the integrated flow rate, the stop integrated flow rate, the controller 5, the flow control valve 3, and the flow rate of the pipe 2. It is used to display anomalies. In addition to this, the display unit 504 has a power source, a sensor input,
During control, excessive flow, insufficient flow, valve fully open,
It indicates that the valve is fully closed. Further, the states of to are output as an open collector or a signal.
Although the LCD unit is used as the display means in the display unit 504 in this embodiment, an LED display, a lamp or the like may be used instead of the LCD display.

The flow control valve 3 uses a valve main body having an electric actuator mounted therein, but it does not require a high resolution one, and an inexpensive general-purpose product that operates with a general-purpose power supply voltage is used. Also, a fluid type actuator such as compressed air can be used by only slightly changing the settings and specifications of the controller 5. In this case, it is not necessary to consider the flow rate characteristics of the valve body itself on which the actuator is mounted. That is, it is not necessary to use an expensive valve body having a linear characteristic or an equal percent characteristic, and any cheapest so-called ON-OFF type can be used. The flow rate sensor 4 may be one in which the number of pulses changes according to the flow rate flowing through the pipe 2, one in which the frequency changes, one in which the current value changes, or one in which the voltage value changes. Since the controller 5 of the present embodiment can handle, for example, the one in which the number of pulses changes and the one in which the current value changes, the terminal 5 is appropriately selected according to the implementation.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. First, when the controller 5 is turned on and the control start switch of the switch input unit 503 is turned on, the power supply display and the control-in-progress display of the display unit 504 are turned on. Then, when the controller 5 receives the detection output of the flow rate sensor 4, the sensor input display of the display unit 504 is turned on. At this time, the sensor input display blinks flicker according to the flow velocity of the fluid flowing through the pipe 2. In other words, when the flow velocity is fast, it blinks at short intervals, and conversely, when the flow velocity is slow, it blinks at long intervals.

The flow rate sensor 4 outputs a pulse, for example, a voltage pulse, which changes according to the instantaneous flow rate, and the detection output is sent to the MPU 500 via the flow rate sensor input section 501. In the MPU 500, the current flow rate (instantaneous flow rate) at the time of measurement is measured by the flow rate measurement means, and the MPU
The measurement result is sent to the comparison operation means while being accumulated in the memory in 500. At this time, the display unit 504 displays the display current instantaneous flow rate, integrated flow rate, stop integrated flow rate, set instantaneous flow rate, integrated flow rate, and stop integrated flow rate. The switching of the display is performed by the switch input unit 503. Further, in the present embodiment, the pulse output type is used for the flow rate sensor 4, but when another type is used, switching is performed by the switch input unit 503.

A switch input unit 503 is provided to the instruction setting flow rate setting means of the controller 5 (MPU 500).
Numerical information on how much flow rate to control is set in the pipe 2 in advance, and the comparison calculation means sets the instruction set flow rate value instructed by the instruction set flow rate setting means and the instantaneous flow rate obtained by the flow rate measurement means. Is compared in real time. Then, the valve control unit of the controller 5 (MPU 500) is based on the calculation result of the comparison calculation unit and the valve control unit 5
The opening / closing control of the flow rate control valve 3 is performed via 05, and the opening degree of the flow rate control valve 3 is maintained when the instruction set flow rate of the liquid flow rate is within a preset deviation. It should be noted that the flow rate excess display, the flow rate insufficient display, the valve fully open display, the valve fully closed display, and the like of the display unit 504 are appropriately turned on according to the operation status.

In this case, the controller 5 opens and closes the flow rate control valve 3 so that the flow rate of the liquid flowing through the pipe 2 is always at the instructed set flow rate value. In this embodiment, it is set by the instructed set flow rate setting means. Since an arbitrary amount of deviation is given to the indicated set flow rate value, the valve control means does not control the opening / closing of the flow rate control valve 3 if the measured instantaneous flow rate is within this deviation as a result of the calculation. That is, the controller 5 controls the opening and closing of the flow rate control valve 3 only when the deviation is out of this range, and adjusts the flow rates of the liquids of all system systems so as to be within the deviation. The deviation around the indicated flow rate value is set by the switch input unit 503 of the controller 5, and the deviation amount can be arbitrarily changed. Further, by arbitrarily setting the control amount for performing the control at one time, it is possible to prevent unstable control due to overshoot or undershoot of control in the control valve having a low control resolution.

In the present embodiment, even if a differential pressure across the flow control valve 3 occurs, the command set flow rate value instructed by the command set flow rate setting means is reached in about 7 to 20 seconds. Further, since such a constant flow rate function minimizes mutual interference of other control systems, hunting does not occur in the entire system.
Therefore, when the unit main body 1 of the present embodiment is applied to, for example, a liquid transportation facility (not shown) that supplies cold / hot water to an air conditioner, the flow rate of the cold / hot water can be kept constant, so that it is accurate. Room temperature control and proper flow rate control can be performed, and heat energy, pump power, and indoor environment can be improved.

The controller 5 of this embodiment has a flow rate of 30.
With cc or more, the maximum flow rate can be controlled with one type up to infinite flow rate.
The flow rate sensor 4 detects the flow velocity of the fluid flowing in the pipe 2 by the change in the number of pulses or the analog current value.
By setting the flow rate per pulse or the flow rate per analog unit in the controller 5 according to the diameter of
With one type of controller 5, the unit body 1 with a flow rate of 30 cc or more and an infinite maximum flow rate can be configured.

When the controller 5 is the analog input type shown in FIG. 3, if the controller 5 is set with an arbitrary control minimum flow rate and maximum flow rate within the allowable flow control range for each series, the analog for flow rate control is set. The minimum value of the signal becomes the control minimum flow rate, and the maximum value of the analog signal is automatically set to the control maximum flow rate. In this case, the signal amount, the control minimum flow rate, and the control minimum flow rate can be set in reverse. For example, in the unit main body 1 having an allowable control flow rate of 3 l / min to 80 l / min, when 0 to 10 VDC is used for the control input signal and it is desired to control the minimum flow rate to 3 l / min and the maximum flow rate to 50 l / min, MIN = 3l / mi for controller 5
If you set n and MAX = 50l / min, it will automatically be 0V.
If DC is input, the instantaneous flow rate per unit is automatically set to 3 l / min, and if 10 VDC is input, the instantaneous flow rate per unit is automatically set to 50 l / min. Therefore, a zero-span flow rate is automatically set in which the input signal amount and the instantaneous flow rate setting per unit are perfectly proportional. Accordingly, when the configuration of the unit main body 1 of the present embodiment is applied to a liquid transportation facility (not shown) that supplies cold / hot water to an air conditioner, even if a plurality of air conditioners start operating at the same time, pressure loss There is no air conditioning rise time difference due to the difference (number of floors where the air conditioner is installed).

Further, the controller 5 (MPU500)
According to the abnormality occurrence notification means, the abnormality is judged when the flow rate value of the liquid flowing through the pipe 2 is out of the allowable value, and if the flow rate is excessive, the excess flow rate display of the display unit 504 is turned on, and if the flow rate is insufficient. The insufficient flow rate display on the display unit 504 is turned on. In addition, this abnormality occurrence notifying means also monitors the abnormality of the control valve 3, and the valve control means is operated by the valve control unit 50.
If the flow control valve 3 does not operate even after an arbitrary fixed time although the control command for the flow control valve 3 is issued via 5, the display unit 504 displays that an abnormality has occurred. The abnormality occurrence information is output to the outside through the abnormality output unit 506 or the communication unit 507. The above-mentioned allowable value and time can be arbitrarily changed by the switch input unit 503.

However, the flow rate changes in the pipe 2 due to various causes, and if this flow rate change is large, it takes time to control to the value (within the deviation) defined by the instruction setting flow rate setting means. . The fluctuation of the flow rate is often transient, and in this case, if the abnormality is judged in real time, the control cannot be established. For this reason, in this embodiment, when the calculation value obtained by the comparison calculation means is outside the deviation, the time measuring means provided in the controller 5 judges that the deviation is abnormal when the deviation is continuously outside the deviation for an arbitrary time or more. If the flow rate is excessive, the flow rate excess display on the display unit 504 is turned on, and if the flow rate is insufficient, the flow rate insufficient display on the display unit 504 is turned on. The set time of the time measuring means can be arbitrarily changed by the switch input unit 503, for example, in the range of 0 to 999 seconds, depending on the use situation.

When the flow velocity of the liquid flowing through the pipe 2 drops below a certain level, the accuracy of flow rate measurement and the flow control valve 3
The control accuracy of is deteriorated. Then, the abnormality occurrence notification means of the controller 5 lights up the insufficient flow rate display on the display unit 504 or notifies the outside that an abnormality has occurred via the communication unit 507. In such a case, even if there is a proportional control input of 0 to 100%, when the constant flow velocity is reached, the flow rate control valve 3 is fully closed to make the flow rate 0 l / min, or the control accuracy is ignored and the flow rate is kept as it is. The switch input unit 503 can select whether to continue the control. Also, piping 2
Even when the flow velocity of the liquid flowing through the liquid is increased to a certain level or more, the control method can be selected in the same manner as described above.

According to the remote control means by the communication section 507 provided in the controller 5 of this embodiment, an external host computer or the like (not shown) can be used via the communication line 8.
All the above-mentioned displays and setting changes can be operated remotely. This remote control means is, for example, RS-2.
It uses a 32C standard communication interface,
Besides this, communication interfaces of various standards can be used. Further, the remote control means of this embodiment is provided with address setting means. According to this, when the unit main body 1 is installed for each of a plurality of different pipes 2, a different address can be given to each controller 5.
Therefore, a plurality of controllers 5 can be slaved to one host computer, and the remote operation described above can be individually controlled by changing the conditions and the like for each controller 5.

[0040]

As is apparent from the above description, according to the present invention, the instruction set flow rate and the instantaneous flow rate are compared and calculated in real time, and even if a differential pressure occurs before and after the flow rate control valve, the flow rate control is performed immediately. Since it is possible to control the flow rate by adjusting the opening degree of the valve, it is possible to easily and accurately control the constant flow rate. In particular, when multiple flow control valves are installed in the same piping system and each performs arbitrary flow control, even if pressure changes occur in the piping, correction control can be performed to the set flow rate in a short time. Is. Further, the flow rate itself set and instructed can be accurately controlled.

Moreover, it is not necessary to use an expensive valve having a linear characteristic or an equal percent characteristic or a high-resolution actuator for the flow control valve, and the controller can be manufactured at low cost with general-purpose parts, so that it is very cost effective. It is possible to provide an improved system.
Also, unlike conventional systems, hunting does not occur, the movement of the flow control valve is small, the life of the valve is greatly extended, system maintenance is easy, and only the required flow rate is passed, so liquid The energy saving effect of transportation means and heat energy is great. Further, by checking the flow rate excess and deficiency by the LED or the like of the display unit of the flow rate control unit of the present invention, lighting of the valve fully opened / closed, and the abnormality occurrence information and valve fully opened / closed information output to the outside, this unit It has an excellent effect that it is possible to easily discriminate whether the failure is due to the failure or the failure due to the pump or the piping which is the fluid transportation facility.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a unit body.

FIG. 2 is a block diagram showing a configuration of a digital input type controller.

FIG. 3 is a block diagram showing a configuration of an analog input type controller.

FIG. 4 is a flowchart for constant flow rate control.

[Explanation of symbols]

 2 Piping 3 Flow control valve 4 Flow sensor 5 Controller

Front page continuation (72) Inventor Hiroyuki Kajiyama 1-10-1 Nakase, Mihama-ku, Chiba Chiba Prefecture

Claims (10)

[Claims] 1. A flow rate sensor is disposed on an inflow side or an outflow side of a flow rate control valve inserted in a pipe, an output line of the flow rate sensor is connected to an input part of a controller, and a control line of the flow rate control valve. By connecting to the valve control unit of the controller, in the equipment that supplies the liquid from the liquid transportation equipment to the appropriate place through the pipe, the controller is provided with the flow rate measuring means by the detection output of the flow rate sensor and the instruction setting flow rate setting means. By providing the comparison calculation means for comparing the current flow rate by the flow rate measurement means with the arbitrarily set instruction set flow rate, and the valve control means for opening and closing the flow control valve based on the calculation result of this comparison calculation means, The flow rate control valve is controlled to be opened and closed so that the flow rate is substantially the same as an arbitrary instruction set flow rate, and the flow rate per unit time is constant. A flow rate control unit that has both a flow rate function and a variable flow rate function. 2. An instruction set flow rate input by the instruction set flow rate setting means is allowed to have an arbitrary amount of deviation, and either continuous control or stepwise control is automatically selected according to the magnitude of the deviation, and a large control error occurs. The flow rate control valve is continuously controlled when the control error is small, and the flow rate control valve is inching-controlled when the control error is small. The flow rate control unit having the constant flow rate function and the variable flow rate function at the same time, which controls the flow rate control valve so that the deviation falls within the range of speed. 3. The instruction set flow rate setting means sets arbitrary control minimum flow rate and control maximum flow rate within the allowable flow rate control range as flow rate numerical values in the controller, and sets the minimum analog input value as the control minimum flow rate, and analog input The zero span of the flow rate is automatically adjusted by setting the maximum value to the control maximum flow rate, and the relationship between the signal amount and the flow rate can be set reversely.
Alternatively, a flow rate control unit having the constant flow rate function and the variable flow rate function described in 2 at the same time. 4. A controller is provided with a display unit, and the display unit displays a current flow rate, an integrated flow rate, a stop integrated flow rate, and the like.
4. A flow rate control unit having a constant flow rate function and a variable flow rate function at the same time, which is capable of displaying various numerical information stored in the controller during setting or processing of each means. 5. The controller is provided with an abnormality occurrence notifying means, and when the value obtained by the comparison calculating means is out of an allowable value set for the value given by the instruction setting flow rate setting means, it is judged as an abnormality. 5. A flow rate control unit having a constant flow rate function and a variable flow rate function according to claim 1, wherein the liquid flow through the pipe is output to the outside at the same time when the display shows that the flow rate is insufficient or excessive. 6. The controller is provided with timing means, and when the value obtained by the comparison operation means deviates from the allowable value, it is judged to be abnormal if continuously out of the allowable value for an arbitrary fixed time,
6. The constant flow rate function according to claim 1, wherein it is possible to display on the display unit that the flow rate of the liquid flowing through the pipe is insufficient or excessive and output it to the outside at the same time, and at the same time, to select whether to continue or stop the control. And a flow rate control unit that simultaneously has a variable flow rate function. 7. The controller comprises a microcomputer system, and by providing a numerical setting switch, a display unit, an input / output driver, etc., to the flow rate measuring means, instruction setting flow rate setting means, comparison calculation means, valve control means, Claim 1 which realized the abnormality occurrence notification means and the timekeeping means.
6. A flow rate control unit having the constant flow rate function and the variable flow rate function described in 6 at the same time. 8. A flow rate control unit having a constant flow rate function and a variable flow rate function at the same time, wherein an LCD, an LED or a lamp is used for the display section. 9. A flow rate control unit having a constant flow rate function and a variable flow rate function at the same time according to claim 1, wherein the controller is provided with remote control means, and the controller can be operated remotely. 10. The constant controller according to claim 1, wherein the controller is provided with an address setting unit whose setting can be arbitrarily changed, and a plurality of controllers can be individually controlled remotely by assigning different addresses to each controller. A flow rate control unit that has both a flow rate function and a variable flow rate function.