JPS6190217A - Flow rate control method - Google Patents

Abstract

PURPOSE:To make it possible to control a flow rate with high responsiveness and with less loss of energy by controlling the rotation speed of a flow delivery means according to the necessary volume. CONSTITUTION:When a setting signal Sf is step by step reduced at time point t1, a flow rate adjuster 5 makes control calculation to meet with the signal Sf and temporarily reduce the opening angle of a flow control valve 4 diminishing operational output SM. A valve opening adjuster 10 issues a setting signal for reducing the rotation speed of a blower 1 to a rotation adjuster 11. The adjuster 11 makes an output to rotation adjusting circuit 9 so that the rotation of a motor 7 may coincide with the setting signal. As a result, a flow volume signal Vf tends to become small due to the reduction of the blower 1 and opening of the valve 4, but the adjuster operates so that the signal Vf may coincide with the signal Sf, the opening of the valve 4 eventually opens until the angle which coincide with the initial setting signal Sv.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a flow rate control system, and particularly to a flow rate control system in which flow rate is controlled by changing the rotational speed of a compressor or a turbo compressor. .

<Prior Art> Conventionally, there are various flow rate control methods for controlling the flow rate flowing through piping. These typical flow control methods are
This is shown in FIGS. 3 to 3 and will be described below.

The flow rate control system shown in FIG. 1 controls the flow rate by controlling a flow rate control valve provided on the outlet side of the proa. ■ is proa. A piping 2 is connected to the outlet side of the flow meter 2, a flow meter 3 is inserted into a portion of the piping 2, and a flow control valve 4 is further inserted downstream of the flow meter 3. The flow rate signal of the flow meter 3 is the setting signal S preset by the flow rate controller 5.
, and the flow rate control valve 4 is controlled so that this deviation becomes zero. A discharge valve 6 for surge prevention is installed in the piping 2 on the outlet side of the pro-arl. The proar 1 is rotated at a constant speed by a motor 7, takes in an air flow rate Q from a pipe 8 on the inlet side of the proar 1, and sends it out to the pipe 2 side.

In the above flow control method, the flow rate control valve 4 is immediately controlled in response to a change in the setting signal S, so the response is good, but since the proar 1 rotates at a constant speed, the required energy is the cube of the rotation speed. Considering that it is proportional to , the disadvantage is that the energy loss becomes large.

The flow rate control method shown in FIG. 2 controls the flow rate by controlling a flow rate control valve provided on the inlet side of the proa. The deviation between the flow rate signal of the flow meter 3 and the setting signal S is taken, and the flow control valve 4 is adjusted by the flow controller 5 so that this deviation becomes zero.
control. Therefore, since the pro-arl is installed between piping 2 and 8, the response is inferior to the flow rate control method shown in Fig. 1, but since the air flow rate Q to the pro-arl changes, the flow rate control method shown in Fig. 1 is The energy loss is small compared to the conventional method.

The flow rate control system shown in FIG. 3 controls the flow rate by controlling the rotation speed of the prower. The deviation between the flow rate signal of the flow meter 3 and the setting signal S is detected by the flow rate controller 5, and its output is given to the rotation control circuit 9 to control the motor 7 so that the deviation becomes zero. be. Since this method controls changes in the air flow rate by changing the rotational speed of the motor 7, energy loss is small, but it has the drawback of lacking responsiveness.

Various typical flow rate control methods are shown in Figures 1 to 3. The method shown in Figure 1 has the best responsiveness but the worst energy loss, and the method shown in Figure 3 has the lowest responsiveness. It is the worst, but the energy loss is the least.

The method shown in FIG. 2 is an intermediate method between these methods.

Therefore, no matter which method is adopted, there is a problem that a method with good responsiveness and low energy loss cannot be obtained.

<Objective of the Invention> In view of the above-mentioned prior art, an object of the present invention is to provide a flow control method that has good responsiveness and low energy loss.

<Configuration of the Invention> The configuration of the present invention to achieve this object relates to a flow rate control system, and includes a flow rate sending means for sending a flow rate to a pipe, a detection end for detecting the flow rate in the pipe, and a flow rate signal from the detection end and a flow rate signal from the detection end. A flow control means that calculates the deviation from the set flow rate setting signal and controls the deviation to zero; a flow control valve inserted into the piping that is controlled by the output of the flow control means; A valve opening control means for controlling the deviation between the output and a preset valve opening setting signal to be zero; and a rotation speed control means for controlling the rotation speed of the flow rate sending means based on the output of the valve opening control means. , the flow rate is controlled by controlling the flow rate sending means by the output of the rotation speed control means.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Note that parts having the same functions as those in the prior art are denoted by the same reference numerals, and redundant explanations will be omitted.

FIG. 4 is a block diagram of a flow rate control system showing one embodiment of the present invention.

A flow meter 3 is inserted into a pipe 2 on the outlet side of the proar 1, and a flow control valve 4 is connected downstream thereof.

The flow rate controller 5 has a setting signal S that determines the flow rate in advance;
is given, and further a flow rate signal V is given from the flow meter 3.

is entered. The output end of the flow rate controller 5 outputs an operation output for operating the flow rate control valve 4, and the flow rate is adjusted by the flow rate controller 5 so that the deviation between the setting signal S and the flow rate signal V becomes zero. The opening degree of the control valve 40 is controlled. This first flow rate control loop corresponds to the flow rate control method shown in FIG. 1, and can control the flow rate with good responsiveness.

1O is a valve opening controller, which calculates the deviation between a predetermined setting signal Sv that determines the valve opening and the operation output SM, performs calculations on this, and uses the output signal as the setting value of the rotation speed controller 11. give as.

The rotation speed signal SR from the rotation speed detector 12 attached to the motor 7 is input to the rotation speed controller 11, and a predetermined calculation is performed on the deviation from the output signal of the valve opening controller 10. and outputs it to a rotation speed control circuit 9 that controls the rotation speed of the motor 7. This controls the rotation speed of the blower 1 and controls the air flow rate Q.

The above valve opening controller 10, rotation speed controller 11. The rotational speed control circuit 9, motor 7, proar 1, etc. constitute a second flow rate control loop, which corresponds to the flow rate control method shown in FIG. Therefore, flow rate control can be performed with less energy loss.

In this embodiment, five of the above first and second flow rate control loops are combined to create a flow rate control system with good responsiveness and low energy loss. Regarding the above points, the waveform diagram shown in Fig. 5 is used. Explain using.

FIG. 5(a) shows the flow rate setting signal S2 of the flow rate controller 5, (
(b) is the operating output SM% of the flow rate controller 5 (c) is the rotational speed signal SR1 indicating the rotational speed of the motor, (e) is the flow rate signal v7 which is the output of the flowmeter 3, and (e) is the valve of the flow control valve 4. Each shows the opening degree. The horizontal axis is time.

First, as shown in Fig. 5 (0), when the setting signal Sf is lowered in a stepwise manner at time t1, the flow rate controller 5 performs control calculations so as to match this setting signal S, as shown in Fig. 5 (b). As shown in FIG. 5, the operating output SM is temporarily decreased, and the opening degree of the flow rate control valve 4 is decreased as shown in FIG. Since this control calculation has a fast response, the flow rate rapidly decreases in response to the setting signal S, as shown in FIG. 5), and reaches the set flow rate value.

On the other hand, since the manipulated output SM is also input to the valve opening controller 10, the valve opening controller 10 outputs a setting signal that reduces the rotation speed of the proar 1 in response to the decrease in the manipulated output. Output to the number controller 11. The rotation speed controller 11 is the motor 7
is outputted to the rotation speed control circuit 9 so that the rotation speed matches the setting signal from the valve opening controller 10. As a result, the flow rate signal V becomes smaller because the rotational speed of the pro-arl becomes smaller (Fig. 5 (c)) and the opening degree of the flow control valve 40 becomes smaller (Fig. 5 (e)). However, the flow rate controller 5
operates so that the flow rate signal V matches the setting signal Sf, so conclude! The operating output SM is gradually increased in response to the decrease in the flow rate signal V due to the decrease in the circumferential rotational speed (Fig. 5 (b)), and finally the valve opening degree of the flow rate control valve 4 is adjusted to the initial setting signal ~. Open the valve to the matching opening degree (Fig. 5 (e)). The reason for the above operation is that there is a large difference in the operating speeds of the flow rate control valve 4 and the motor 7.

In the final state where the above series of operations are completed, the rotation speed of the proar 1 is lower than in the initial state, and the flow rate control valve 4 is in the initial valve open state, so energy loss is reduced. It is in a low state. Moreover, the flow rate signal V, is set as the setting signal 8.K as shown in FIG. (Fig. 5, 0)))).

In the embodiment shown in FIG. 4, the flow rate controller 5, valve opening controller 10, rotation speed controller 11, etc. are configured in a discrete manner. It may also be carried out in a form @ <Effects of the Invention> As specifically explained above with the embodiments, according to the present invention, the number of revolutions of the flow rate sending means is controlled according to the required flow rate, which saves money. Since the energy effect is large and flow control is also performed using a flow control valve, it is possible to ensure responsiveness to disturbances.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing the conventional first flow rate control method, #E
2 is a block diagram showing the conventional second flow control method, FIG. 3 is a block diagram showing the conventional fJ3 flow control method, and FIG. 4 is a block diagram showing the structure of an embodiment of the present invention. FIG. 5 #'i is a waveform diagram illustrating the operation of the embodiment shown in FIG. 4. 1... Proa, 2, 8... Piping, 3... Flowmeter,
4... Flow rate control valve, 5... Flow rate controller, 7... Motor, 10... Valve opening controller, 11... Rotation speed controller, Sf... Setting signal, SM.・・Operation output, SR・
...Rotation speed signal, ■,...Flow rate signal. Agent Patent Attorney Shinsuke Ozawa□1.12.
ㅅ7A1 figure tail 2 figure 3 figure tail 4 figure

Claims (1)

[Claims] A flow rate sending means for sending the flow rate to the piping, a detection end for detecting the flow rate in the piping, a deviation between the flow rate signal from the detection end and a preset flow rate setting signal is calculated, and control is performed so that this deviation becomes zero. and a flow rate control valve inserted into the piping that is controlled by the output of the flow rate control means, so that the deviation between the output of the flow rate control means and a preset valve opening setting signal becomes zero. a valve opening control means for controlling, a rotation speed control means for controlling the rotation speed of the flow rate sending means by the output of the valve opening degree control means, and a rotation speed control means for controlling the rotation speed of the flow rate sending means by the output of the rotation speed control means; A flow rate control method characterized by controlling the flow rate.