JPS58203522A - Controlling device of flow rate - Google Patents

Abstract

PURPOSE:To control a flow rate smoothly without being overshot, by detecting the deviation of the flow rate in each unit operation of an interruptor and adjusting the working and stopping time in accordance with the deviation of the flow rate. CONSTITUTION:An operation part 5 compares a set flow rate Rs with a measured flow rate Ra detected by a flow rate detector 3, and if Rs>Ra, outputs a value opening/closing command 6 and a comparator 7 inputs the deviation (e) of the flow rate to a time setting part 8. The setting part 8 compares a border flow rate deviation ec larger than the flow rate given from the flow rate Rs at the maximum operation time corresponding to one operation at least with the flow rate deviation (e), and if e>ec, decides that the real flow rate is included in a fixed interruptor area and sets up the operation time Ta and stop time Tb in the maximum operation time tam and the maximum stop time Tbm, respectively. In accordance with the time setting, an interruptor part 10 opens a motor value 2 by the time Tam and then stops the valve 2 under the opened status by the time Tbm to complete one unit operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow control device that controls the operation of an electric valve using a microcomputer.

Conventionally, incretors that control the opening of a motor-operated valve in flow control by dividing the opening into multiple steps are called slow starters or cushion starters, and are known as slow starters or cushion starters. The purpose is to prevent changes in status.

Even if PID control is performed after the set flow rate is reached, the interrupter operation time and stop time are fixed to a predetermined fixed time, and these times cannot be changed. It was just an adjustment to the operating time. In other words, in order to reach the set flow rate quickly, as shown in Fig. 1, the operating time Ta of the interrupter should be made relatively long and the stop time Tb should be set small. If the next operation command is issued before the change in flow rate due to opening of the valve is stabilized, there is a risk that the flow rate will become excessive and exceed the set flow rate, resulting in an overshoot as shown by A. Note that the nine-dot line B shows the flow rate change characteristic when there is no next opening command.

If you set the operating time Ta short and the stop time Tb long as shown in Figure 2, the effect of overshoot will be reduced, but it will take longer to reach the set flow rate Rs. However, the disadvantage is that the electric motor that operates the valve has to be turned on and off more frequently, resulting in increased mechanical wear and tear.

In view of the above-mentioned points, the present invention adjusts the interrupter operation to the optimum time for every 7 unit operations including the opening operation of the valve and the stop operation to stabilize the flow rate, so that the flow rate reaches the set value smoothly. This will be explained with reference to a first embodiment shown in FIGS. 3 to 5.

It is possible to use some of the computers installed in the water and sewage facilities. 2 is an electric valve, 3 is a flow rate detector, Rs is a set flow rate, Ra is an actual measured flow rate of the flow rate detector 3, t is a set flow rate Rs, J is a set flow rate Rs and an actual measured flow rate Ra, and input the set flow rate Rs. 7 is a comparator that detects the flow rate deviation e between the set flow rate and the actual measured flow rate; a time setting section for calculation; 9 a storage section for storing elements necessary for the calculation of the time setting section;
IO is an interrupter section that operates the electric valve 2 based on the valve opening command 6 from the calculation section j and the output from the time setting section Z.

First, considering safety and maintenance,
The maximum operating time Tam permissible as a unit operation is determined by actual measurement or estimation, and the electric valve 2 is operated for the maximum operating time T.
The time from the completion of the operation when the valve is opened at am until the actual flow rate stabilizes is actually measured as the maximum stop time Tbm. In this case, it is desirable to take the average value of several measurements with different initial values of the measured flow rate.

Next, the flow rate range is such that even if the interrupter operation is repeated for the maximum operation time, there is no risk of overshooting with respect to the set flow rate, for example, the flow rate Rm is larger than the flow rate Rm given by at least one maximum operation time from the set flow rate Rs. A boundary flow rate deviation eC of the value is set, and a range equal to or less than the flow rate value Rc, which is obtained by excluding the range of this boundary flow rate deviation eC from the set flow rate Rs, is set as a fixed incretor range C.

The storage unit 9 stores the maximum operation time Tam, the maximum stop time Tbm, and the boundary flow rate deviation ec, and also uses the value obtained by multiplying the maximum operation time Tam by the reciprocal of the boundary flow rate deviation eC as a flow rate-operation time conversion coefficient. Furthermore, a value obtained by multiplying the maximum stop time Tbm by the reciprocal of the maximum operation time Tam is stored as the optimum time ratio P.

When the set flow rate is set, as shown in the flowchart in Figure 1, the calculation unit j compares the set flow rate Rs with the measured flow rate Ra from the flow rate detector 3, and if it is Rs) Ra, a valve opening command is issued. The comparator 7 outputs the flow rate deviation e to the time setting section.

The time setting section compares this flow rate deviation e with the boundary flow rate deviation ec, and if e>e-C, determines that the actual flow rate is within the fixed interrupter area C, and sets the operating time Ta to the maximum operating time. Tam, the stop time Tb is set to the maximum stop time Tbm, and with this time setting, the interrupter unit IO opens the electric valve 2 for a time Tam, and then continues to open the motorized valve 2 for a time Tbm. One unit operation is completed by stopping. In Fig. 5, time to, tl
This corresponds to the case where the flow rate deviation eO1e-1 at .

The time setting section is set every time the 7 unit operations are completed.

The flow rate deviation e and the boundary flow rate deviation ec are compared.

When it is detected that the flow rate deviation e2 has become smaller than the boundary flow rate deviation ec at time t2, it is determined that the actual flow rate has escaped the fixed interrupter region C, and the absolute value of this flow rate deviation e2 is set as the flow rate-operation time conversion coefficient K. The operating time Ta is the value multiplied by
2, and further multiplied by the optimal time ratio Pi, the stop time T
It is output to the interrupter section /θ as b2. At time t3, similar arithmetic processing is performed with a new flow rate deviation e6, and such arithmetic processing is performed in a dead zone where the measured flow rate Ra matches the set flow rate Rs and the flow rate difference becomes 0 or is considered to match. Repeat until it's in.

In the above embodiment, a fixed interrupter region C is set, the operation time within this region is constant, and the interrupter is activated only within the range of a flow rate difference larger than the flow rate given by the maximum operation time of seven times from the set flow rate Rs. Although the operation time is adjusted, if there is a margin in the operation time, control may be performed by using the set flow rate Rs as the boundary flow rate deviation ec and substantially eliminating the fixed interrupter region C. Furthermore, it is clear that the present invention can be implemented in the same manner when controlling the electric valve to close.

In this way, the present invention includes a calculation unit that inputs the set flow rate Rs and the measured flow rate Ra to command the opening, exit IL, and closing operations of the electric valve, the maximum operating time Tam of the 10 incretors that was actually measured or estimated in advance, and The maximum stop time Tbm is memorized, and the flow rate deviation e is calculated every 7 unit operations.
This is because the flow rate deviation is detected and the operating time and stop time are adjusted accordingly.

The flow rate is set reliably in each unit operation, the flow rate deviation is detected accurately, and as this flow rate deviation becomes smaller and approaches the set flow rate, the operation time is shortened, the flow rate change becomes smaller, and the flow rate is smoothed. It can be controlled without causing overshoot, has the effect of shortening the time required for operation, and provides highly reliable control without failure of the operating end or undue influence on the pipe system. be able to.

[Brief explanation of drawings]

FIGS. 1 and 2 are control characteristic diagrams showing conventional embodiments,
FIG. 3 is a block diagram showing an embodiment of the present invention, FIG. 3 is a flowchart thereof, and FIG. 5 is a control characteristic diagram. 1 is a microcomputer, 2 is a motorized valve, 3 is a flow rate detector, ≠ is a set flow rate, 3 is a calculation section, 7 is a comparator, za is a time setting section, ? □ is the memory section, /θ is the interrupter section, Ta is the operating time, and Tb is the stopping time. Tam is the maximum operating time and Tbm is the maximum stopping time. Rs is the set flow rate, Ra is the measured flow rate, and e is the flow rate deviation. ec is the boundary flow deviation and C is the fixed incluctor area. Figure 1 A Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] 1. Opening the electric valve by inputting the set flow rate and the measured flow rate. It has a calculation unit that commands stop and close operations, stores the measured or estimated maximum operation time and maximum stop time of the interrupter, detects the flow rate deviation for each unit operation of the interrupter, and calculates the operation time and A flow rate control device characterized in that it is equipped with a microcomputer that adjusts the stop + h time to the flow rate deviation according to the flow rate deviation. Flow control device according to claim 7, characterized in that the adjustment is carried out within a range of boundary flow deviations greater than the flow rate given by time. 3. The maximum operating time prestored in the absolute value of the flow deviation. is multiplied by the flow rate-operating time conversion coefficient multiplied by the reciprocal of the flow rate value in the adjustment range to obtain the operating time, and this is multiplied by the optimal time ratio obtained by multiplying the pre-stored maximum stop time by the reciprocal of the maximum operating time to determine the stop time. A flow rate control device according to claims 1 and 2.