JP3027802B2 - Flow controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow controller used for controlling a flow rate of a fluid, and more particularly, to a flow controller having two or more fluid transfer lines (hereinafter simply referred to as "lines"). The present invention relates to a flow controller for controlling the operation of a control valve based on signals from a plurality of flow meters in a fluid transfer facility having a flow control device.

[0002]

2. Description of the Related Art Conventionally, in a fluid transfer facility having a plurality of lines, a flow controller is installed in each line in order to adjust a flow rate of a fluid flowing through each line. For example, as shown in FIG. 5, a flow controller 100a having a flow meter 2a, a control valve 1a, and a control unit 30a for controlling the operation thereof is provided on a first line.
However, in the second line, a flow controller 100b having a flow meter 2b, a control valve 1b, and a control unit 30b for controlling the operation thereof is provided. In recent years, it has become increasingly necessary to supply a small amount of fluid with a certain amount of accuracy in a semiconductor manufacturing process or the like. Therefore, a flow controller with higher accuracy has been strongly desired, and various flow controllers have been used.

[0003] As a flow controller, a proportional solenoid type mass flow controller which is widely used in general will be described. FIG. 6 shows a proportional solenoid type mass flow controller 100a (1
00b is the same). The mass flow controller 100a includes the mass flow meter 2a in the left half and the control valve 1
a.

In the mass flow meter 2a, an input port 101 is opened on the left side of the main passage 102. The main passage 102
A columnar member 103 for keeping the flow of the fluid in a laminar state is held at a central portion of the column with a predetermined distance from the inner wall.
An inflow port 104 and an outflow port 106 are opened on inner walls on both sides of the columnar member 103, and a conduit 105 is provided.
Then, a pair of self-heating type thermometers each having a large temperature coefficient are wound around the upstream side and the downstream side of the conduit 105 through which the fluid flows, thereby forming heat-sensitive coils R1 and R2, and a bridge circuit is formed by each heat-sensitive coil. The calculation is performed from the potential difference.

[0005] In the control valve 1a, a solenoid comprising a coil 116 and a plunger 115 is disposed at an upper portion. A valve body 107 is fixed to the lower end of the plunger 115. A valve outlet port 117 is formed at a position opposing the valve element 107. The valve outlet port 117 communicates with the outlet port 112. The valve element 107 is urged by a return spring 108 in a direction in which it comes into contact with the valve outlet port 117. In the valve element 107, the positions of the plunger 115 and the valve element 107 are determined in proportion to the current supplied to the coil 116. Therefore, the flow rate is determined in proportion to the supplied current.

Next, the operation of the mass flow controller will be described. The fluid F flows inside the conduit 105 in the direction indicated by the arrow. Two heat-sensitive coils R1 and R2 are adhered to the upstream side and the downstream side of the conduit 105 with a UV curable resin or the like to form a sensor unit. Each of the heat-sensitive coils R1 and R2 is connected to a constant temperature control circuit, and controls so that the temperatures of the heat-sensitive coils R1 and R2 are always equal and constant. Therefore, the voltage output from the constant temperature control circuits is proportional to the amount of energy required to maintain the thermosensitive coils R1 and R2 at a constant temperature in each of the constant temperature control circuits.

Here, the voltage difference is proportional to the mass flow rate of the fluid F, and the mass flow rate can be measured by measuring the voltage difference. On the other hand, the mass flow controller receives a necessary flow signal from the central control device to the control means, and adjusts the current flowing through the coil 116 to match the determined flow signal. That is, when the measured flow rate is larger than the predetermined flow rate, the current flowing through the coil 116 is reduced. As a result, the force with which the coil 116 attracts the plunger 115 decreases, and the valve body 107 is urged by the return spring 108 to move downward, thereby reducing the flow rate. If the measured flow rate is smaller than the predetermined flow rate, the current flowing through the coil 116 is increased. As a result, the force by which the coil 116 attracts the plunger 115 increases, and the valve body 107 moves upward against the return spring 108 to increase the flow rate.

[0008]

However, conventional flow controllers, including the above-described proportional solenoid type mass flow controller, have the following problems. That is, as shown in FIG. 5, two (plural) lines are provided for one fluid supply source, and a flow controller is installed in each of these lines. In order for each control means to adjust the flow rate of each line, for example, as shown in FIG.
When the flow rate Q2 of the second line is changed, the flow rate Q
There was a problem that 1 changed temporarily. By the way,
The variation of the flow rate Q1 in the first line is approximately ±
5%, and the change time is about 2 seconds. This change in the flow rate may have a great effect on the film quality in a film forming process in a semiconductor manufacturing process, and on the quality of circuit processing in an etching process, for example.

Further, since the conventional flow controller has one flow meter, one control valve, and one control means for one flow controller, it is very difficult to reduce the size of the conventional flow controller. is there. Therefore, when a large number of flow controllers are used, there is a problem that the equipment for transporting the fluid becomes large.

Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to minimize the influence of a change in flow rate generated in another line and to reduce the size of a facility for transporting fluid. It is an object of the present invention to provide a flow controller capable of performing the following.

[0011]

According to the first aspect of the present invention, there is provided a fluid transfer facility having two or more fluid transfer lines. In a flow controller used to control the flow rate, a flow meter and a control valve are installed in each fluid transfer line, and a control means for centrally controlling the operation of the control valve based on a signal from each of the flow meters is provided. It is characterized by the following.

According to a second aspect of the present invention, in order to solve the above problem, in the flow controller according to the first aspect, the control means controls the operation of the control valve by feedforward control. I do.

According to the flow controller having the above-described structure, the flow meter and the control valve installed for each of the plurality of lines are controlled by one control means. Therefore, control means for controlling the flow meter and the control valve are not required. Therefore, the flow controller can be manufactured small and inexpensively. Further, by performing centralized control by one control means, it is possible to perform automatic tuning in consideration of the balance of all lines. Further, it is possible to easily detect a change in the status or an abnormality of all the lines.

[0014] Further, the control means controls the operation of the control valve by feedforward control, so that the influence of a flow rate change, a pressure change, and the like on a certain line on other lines can be reduced. It is possible to precisely control the flow rate.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, in the flow controller according to the first or second aspect, the flow controller is provided with the flow meter installed in each fluid transfer line. A mass flora controller in which the control valve and the control means are unitized, wherein the control means detects flow rate information in all fluid transport lines, and controls the operation of the control valve based on the flow rate information in a feedforward control. Thus, the flow rate of each fluid transport line is controlled so as not to be affected by the flow rate change in other fluid transport lines.

According to the third aspect of the invention, the same effect as the first aspect of the invention can be obtained. When a conventional mass flow controller is already installed, a control means built in the mass flow controller installed in each fluid transfer line may be used. Further, by arbitrarily changing the control function for performing the calculation by the control means, it becomes possible to control the flow rate of each line with high accuracy even when the flow rate changes in various patterns. Further, control can be performed even if the control valve is not a proportional control valve. In addition, by applying feedback so as to successively correct this control function, it becomes possible to more accurately control the flow rate of each line with respect to flow rate changes of various patterns.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a flow controller according to the present invention will be described in detail with reference to the drawings, taking concrete embodiments. Therefore, the configuration of the flow controller 10 according to one embodiment of the present invention is shown in FIG. Here, in the present embodiment, a flow controller corresponding to two lines of fluid transport equipment is illustrated, but of course, the present invention is applied to a fluid transport equipment of two or more lines. It is possible. Further, the present invention can be applied even if control means is provided for each line as in the past.

The flow controller 10 includes flow meters 2a and 2b installed for the first and second lines, control valves 1a and 1b, and control valves 1a and 1b based on signals from the flow meters 2a and 2b. And control means 3 for centrally controlling the operation of the control unit. Since the flow meter 2a and the control valve 1a are the same as those exemplified as the conventional example, the description will be omitted.
Here, the flow meter and the control valve may be formed as an integrated structure or may be formed separately. Further, the control valve 1 is a solenoid valve, but the control valve is not limited to this, and may be a piezo valve, a thermal valve, a pneumatic valve, or the like. The flow meter is not limited to the mass flow meter, and may be another flow meter.

The control means 3, which is a feature of the present invention, will be described. The control means 3 includes an A / D converter 4, a D / A converter 5, an I / O controller 6, a CPU 7, and a memory 8, as shown in FIG. The A / D converter 4 is connected to the flow meters 2a and 2b and the D / A converter 5
Are connected to the control valves 1a and 1b. The A / D converter 4 and the D / A converter 5 are also connected to a CPU 7 via an I / O controller 6. The CPU 7 is connected to a memory 8 for storing the results of arithmetic processing and the like.

The control means 3 controls the opening of the control valves 1a and 1b as follows to regulate the flow rate of the fluid flowing through the first and second lines. That is, the flow meters 2a, 2
The signal measured at b is the A / D converter 4, I / O
Through the controller 6, a digital flow signal C
It is sent to PU7. Then, the CPU 7 sets a preset flow rate (pattern is set by a program).
To the control valve 1 via the I / O controller 6 and the D / A converter 5 as a difference signal.
a, 1b. The control valves 1a and 1b operate so that the difference signal becomes zero, and adjust the flow rate so that the set flow rate is obtained.

The control means 3 performs the following control so that the flow rate of one line is not affected by the rapid change of the flow rate of the other line. First, a case where the flow rate is changed in only one line will be described. Here, as shown in FIG. 2, the flow rate Q of the second line
2 is changed. In this case, the influence of the change of the flow rate Q2 of the second line on the flow rate Q1 of the first line can be checked in advance, so that the influence is checked and the influence is canceled out, that is, the flow rate Q1 of the first line is reduced.
Is set in advance so as to keep the constant. Then, this program is executed in accordance with the change pattern of the flow rate Q2 of the second line. This implementation period is a period T in FIG.

Next, the case where the flow rates of both lines are changed will be described with reference to FIG. First, the relationship between the flow rate Q1 of the first line and the valve opening K1 of the control valve 1a using the flow rate Q2 of the second line as a parameter (see FIG. 3A),
The relationship between the flow rate Q2 of the second line with the flow rate Q1 of the first line as a parameter and the valve opening K2 of the control valve 1b (FIG. 3)
(See (B)) is obtained by learning, or input to a memory in advance. These relations may be fixed as they are at the time of setting, but if the flow rate is controlled more precisely, it is also possible to sequentially correct these relations by feedback control.

From these relationships, the required valve opening of each control valve with respect to the flow rate change of each line is obtained, and the control valve is operated. Specifically, it is as shown below. (1) When the flow rate Q1 of the first line is maintained at Q11 (constant) and the flow rate Q2 of the second line is changed from Q21 to Q22, the valve opening K1 of the control valve 1a is changed from K11 to K12, and the control valve 1b is changed. Is changed from K21 to K23. (2) When changing the flow rate Q1 of the first line from Q11 to Q12 and keeping the flow rate Q2 of the second line at Q21 (constant), the valve opening K1 of the control valve 1a is changed from K11 to K13, and the control valve 1b is changed. Is changed from K21 to K22. (3) When the flow rate Q1 of the first line is changed from Q11 to Q12 and the flow rate Q2 of the second line is also changed from Q21 to Q22, the valve opening K1 of the control valve 1a is changed from K11 to K14, and the valve of the control valve 1b is changed. The opening K2 is changed from K21 to K24.

As described above, when the flow rate of a certain line is changed, not only the control valve of that line but also the control valves of the other lines are driven in such a direction as to eliminate the influence of the flow rate change. The effect on other lines due to the change can be minimized.

Here, the flow controller 10 was used to examine the flow rate change in a flow pattern in which the flow rate Q1 of the first line was kept constant and the flow rate Q2 of the second line was changed, as in the conventional example. FIG. 4 shows the results. FIG. 4 shows that the flow rate Q1 of the first line is hardly affected by the change of the flow rate Q2 of the second line. That is, the change of the flow rate Q1 of the first line due to the change of the flow rate Q2 of the second line to the set value of the flow rate Q1 of the conventional flow controller was about ± 5%, but within ± 1%. The time is about 1 second, which is about 2 seconds in the conventional flow controller.

As described above, the flow controller 1
0, the flow meter 2 installed in the first and second lines
a, 2b and the control valves 1a, 1b are centrally controlled (feed forward control) by one control means 3, so that
The influence of the change in the flow rate of each of the first and second lines on the other line can be extremely reduced. Further, since it is not necessary to provide the control means for each line, the flow controller can be manufactured small and inexpensively.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various applications are possible. For example, the present invention can be applied to a case where a pressure gauge is installed in each line instead of a flow meter. In this case, the influence of a pressure change in other lines can be reduced.

[0028]

According to the present invention, in a flow controller used for controlling the flow rate of a fluid flowing through each fluid transport line in a fluid transport facility having two or more fluid transport lines, A flow meter and a control valve are respectively installed on the transfer line, and control means for centrally controlling the operation of the control valve based on a signal from each of the flow meters is provided. In addition, a control means for controlling the control valve becomes unnecessary. Therefore, the flow controller can be manufactured small and inexpensively. Further, the control means controls the operation of the control valve by feedforward control, so that the flow rate change in one line, the influence on the other lines due to the pressure change, etc. can be reduced, and the flow rate in each line can be accurately controlled. It becomes possible to control well.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a flow controller according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a control method of the flow controller according to the present invention, and is a diagram showing a flow rate change.

FIG. 3 is a diagram for explaining a control method of the flow controller according to the present invention, and is a diagram showing a relationship between a valve opening degree of a control valve and a flow rate.

FIG. 4 is a diagram showing a flow rate change when the flow rate is controlled by the flow controller according to the present invention.

FIG. 5 is a diagram showing a configuration of a conventional flow controller.

FIG. 6 is a diagram showing a configuration of a flow meter and a control valve in a conventional flow controller.

FIG. 7 is a diagram showing a flow rate change when a flow rate is controlled by a conventional flow controller.

[Explanation of symbols]

 1a, 1b Control valve 2a, 2b Flow meter 3 Control means 4 A / D converter 5 D / A converter 6 I / O controller 7 CPU 8 Memory 10 Flow controller

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05D 7/06

Claims (3)

(57) [Claims] 1. A flow controller used for controlling a flow rate of a fluid flowing through each fluid transport line in a fluid transport facility having two or more fluid transport lines, wherein a first line control valve and a second line are provided. Centralized control valve operation
The control means performs the flow rate Q1 of the first line and the first line control as data.
The relationship between the valve opening K1 and the flow rate Q2 of the second line
First line valve opening control storage unit for storing as a parameter
And the flow rate Q2 of the second line and the valve opening K2 of the second line control valve
With the flow rate Q1 of the first line as a parameter
A second line valve opening control storage unit for storing the first line valve opening control storage unit or the second line valve.
Based on the change pattern stored in the opening control memory,
A flow controller, wherein the operation of the first line control valve or the second line control valve is controlled by feedforward control. 2. The flow controller according to claim 1, wherein the first line valve opening control storage section stores the first line valve opening degree.
Keep the flow rate of the second line constant while keeping the flow rate constant
The valve opening K11 for keeping the flow rate in the first line is stored, and the flow rate in the first line is kept constant while the second opening degree K11 is kept constant.
The valve opening K12 for changing the flow rate of the second line is stored, and the second line is changed while changing the flow rate of the first line.
The valve opening degree K13 for keeping the flow rate of the second line constant is stored, and the second line is changed while changing the flow rate of the first line.
The valve opening K14 for changing the flow rate of
Ri, the second line valve opening control storage unit, of the first line
Keep the flow rate of the second line constant while keeping the flow rate constant
The valve opening K21 for maintaining the pressure in the first line is stored, and the second line is changed while changing the flow rate in the first line.
The valve opening K22 for keeping the flow rate of the first line constant is stored, and while maintaining the flow rate of the first line constant, the second opening
Storing the valve opening K23 of order by changing the flow rate of In, while changing the flow rate of the first line, the second line
A flow controller for storing a valve opening degree K24 for changing a flow rate of the valve . 3. The mass flow controller according to claim 1, wherein the flow controller, the control valve, and the control unit are unitized with each other. Wherein the control means detects flow rate information in all the fluid transport lines, and controls the operation of the control valve based on the flow rate information by feed-forward control, so that the flow rate of each fluid transport line is changed in another fluid transport line. A flow controller which controls so as not to be affected by a change in flow rate.