JPS6022404Y2 - Gas flow control device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a gas flow rate control device, and in particular, the gas flow rate can be controlled by electronic control means even in response to slight fluctuations in the gas flow rate due to disturbances such as changes in gas pressure or pulsating flow. The present invention relates to a gas flow rate control device that performs follow-up quantitative compensation using a gas flow rate controller.

Conventionally, mechanical devices such as control valves have been widely used to control the flow rate of fluid, but these are susceptible to disturbances because the differential pressure between the upstream and downstream exceeds a certain value during operation. For example, it has been impossible to follow rapid changes in the pulsating flow or flow rate of fluid.

In other words, among fluids, gases in particular are often sent as compressible gases, and are easily affected by changes in pressure and temperature. Therefore, mechanical flow control means such as conventional control valves cannot respond quickly. Furthermore, due to the processing accuracy of the valve itself, wear, and other deterioration over time, it is difficult to control the flow rate with high accuracy and its stable operation. There wasn't.

To be more specific, controllability is evaluated based on quick response such as rise and damping, and control deviation, but in conventional mechanical flow control means such as control valves, the diaphragm area and signal passage diameter are fixed in design. Therefore, it has been difficult to adapt to rapid changes.

The present invention eliminates such conventional problems, and therefore, the purpose of the present invention is to arbitrarily select the rotational speed of the blower by varying the speed of the motor that drives it. To provide a gas flow rate control device with excellent responsiveness and stability, by controlling the speed of this variable motor in response to other information, such as concentration, which is closely related to the gas flow rate. .

The present invention is to control the rotation speed of a variable speed motor based on the proportional relationship between the flow rate and the rotation speed.

In addition, the purpose of this invention is to provide a balancing zero regulator on the suction side of the blower, and when the blower is stopped, the valve is closed to suppress the inflow of gas, and the balance is adjusted according to the negative pressure on the suction side of the blower. An object of the present invention is to provide a gas flow rate control device that automatically controls the gas flow rate while eliminating fluctuations in gas pressure and pulsation by controlling the opening and closing of a valve of a balancing zero regulator.

In other words, in the past, the flow rate detection section was installed independently and the transported fluid was measured while containing disturbances, which caused the risk of accumulating errors, but with the rotation speed control of the present invention, There is a relationship between flow rate and rotation, that is, the rotation speed is synchronized to be proportional to the control signal, and a balancing regulator is used to remove disturbances, and a blower is used to obtain a desired set flow rate.

An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a basic control system diagram of a gas flow rate control device according to the present invention, in which an electric circuit system is associated with a fluid system.

First, a flow meter 2 is connected to the gas flow path 1 for checking the approximate flow rate, and following this flow meter 2, a balancing zero regulator 3 is connected to the flow path 1 to prevent the disturbance of the gas. is connected.

That is, this balancing zero regulator 3 acts to suppress pulsating flow and pressure changes when the fluid passing through the flow rate 1 is pressurized gas, and when the blower is stopped, the valve is closed to suppress the inflow of gas, and the blower - As the blower rotates, the opening of the valve corresponds to the negative pressure on the suction side of the blower, thereby promoting the inflow of gas.

A blower 4 is connected to the flow path 1 after the balancing zero regulator 3, and the blower 4 is driven by a variable motor 5 at an arbitrary speed.

Furthermore, a load 6 such as a furnace that utilizes the gas sent by the blower 4 is connected to the output side of the blower 4.

On the other hand, the load 6 is provided with a detector 7 to be controlled for obtaining information corresponding to the flow rate of gas.

For example, when analyzing CO2 gas in the furnace gas, an infrared gas analyzer or the like is used.

Note that this detector 7 converts the above information into an electrical signal and supplies it to a signal comparator 8.

Here, we compare the reference signal, which is the reference information, and the electric signal, which is the flow rate information, which is the control target (for example, level detection),
A compensation signal corresponding to the difference is output.

The detector 7 may be installed in the flow path 1 between the blower 4 and the load 6 as long as it can accurately obtain information corresponding to the gas flow rate. Since it is necessary to grip the load 6, it is preferable to provide it directly to the load 6.

9 is a drive control circuit for the variable motor 5, and switch 1
3 to the output side of the signal comparator 8, and receives a signal corresponding to the comparison signal output to slow down the rotational speed of the information motor 5.

Further, the drive control circuit 9 can arbitrarily select the drive control current by manual operation. In this case, the switch 13 is opened to disconnect the signal comparator 8,
The flow rate can be arbitrarily set with a resolution of 0.5% or more with respect to the maximum flow rate of the flowmeter 2.

Next, the operation of the control system diagram according to the above configuration will be explained.

First, before the gas is supplied to the load 6, it enters the flow meter 2 and is sent to the load 6, and the approximate flow rate can be confirmed by this.

The gas is then supplied to the balancing zero regulator 3, where disturbances such as pulsating flow and pressure changes are removed to create an equalized gas flow, which is then supplied to the blower 4.

This blower 4 is driven by the variable speed motor 5 as described above, and blows a predetermined flow rate of gas into the load 6 side.

Here, the gas flow rate and the rotation speed of the blower 4 are almost proportional to each other, and in order to precisely adjust that relative relationship,
The closed loop circuit described above is used to feed back output information to input information.

That is, the flow rate of gas is generally controlled as the volume through which it flows per unit time, but not only the flow meter 2 but also the electric signal from the detector 7 to be controlled is supplied to the signal comparator 8 to control the variable speed motor. The speed is controlled and the flow rate is precisely regulated.

The concentration of the controlled object, for example, gas, in the load 6 to which gas is supplied as described above is detected moment by moment by a detector such as a gas analyzer, and this detection information is converted into an electrical signal at a predetermined level. and is applied to the signal comparator 8.

This signal comparator 8 compares the level of the electric signal with a reference signal corresponding to a predetermined value of the controlled object in the load 6, and when the controlled object exceeds the predetermined value, the level of the electrical signal is compared. Supplying the difference signal information to the drive control circuit 9 to slow down the drive rotation of the variable speed motor 5,
The amount of gas blown by the blower 4 relative to the load is adjusted.

In this way, the gas flow rate for the load is constantly monitored and corrected to maintain a constant value.

In the above, the detector 7 detects the controlled object in an analog manner and processes this detection signal in an analog manner using the signal comparator 8. In addition, a voltage controlled frequency oscillator (Vco ) is used to convert the voltage level into a frequency, and by comparing this with a reference signal frequency or performing phase comparison, the rotational speed of the motor can be automatically controlled.

FIG. 2 shows the application of the principle of the present invention to flow rate control of enriched gas in gas carburizing.

Note that the same constituent parts as in FIG.

In this system, a balancing zero regulator 3 is connected to a flow meter 2, and a gas carburizing furnace 10 is connected to this via a blower 4.

Further, the gas carburizing furnace 10 is equipped with an infrared gas analyzer 7 that detects the components of the furnace atmosphere, for example, CO2, and a program controller 11 is connected to the output side of the gas analyzer 7 via a signal comparator 8. A drive control circuit 9 for the variable speed motor 5 is connected.

In the figure, 12 is a carrier gas supply passage.

According to this method, a small amount of enrichment gas is added to the gas carburizing furnace 10 in order to create a carburizing atmosphere during gas carburizing, but if this addition amount is unstable, the carburizing atmosphere It also becomes unstable, which adversely affects the quality of the products to be treated in the gas carburizing furnace 10.

Therefore, in gas carburizing, it is important to stabilize the carburizing atmosphere in the furnace to the required components, and these effects can be fully obtained by using the flow rate control device having the above configuration.

That is, the enriched gas flowing through the flow path 1 is always supplied to the balancing zero regulator 3 via the flow meter 2, where pulsating flow, pressure fluctuations, etc. are removed, and the enriched gas is supplied to the blower 4 connected to the variable speed motor 5. Therefore, gas carburizing furnace 10
sent inside.

In this gas carburizing furnace 10, a gas analyzer such as an infrared gas analyzer 7 analyzes a gas component such as CO2 necessary for controlling the carburizing atmosphere, converts it into an electric signal, and sends it to a signal comparator 8. Here, the desired reference signal and the analysis signal are compared and calculated, and the electric signal as the error correction signal is sent to the program controller 1 which sets the carburizing conditions.
1.

The program controller 11 supplies a drive control signal to the drive control circuit 9 to create the most preferable gas flow rate according to the carburizing program, thereby correcting the rotational speed of the variable motor 5.

The enriched gas is thus sent to the gas carburizing furnace 10 at a flow rate commensurate with the rotation speed of the blower 4.

In this way, the carburizing atmosphere within the gas carburizing furnace 10 is precisely and automatically controlled.

The program controller 11 is equipped with a manual control mechanism, and can perform constant speed control of the blower rotation and constant component control of the furnace atmosphere according to the carburizing conditions.
Control can be performed using relay sequence circuits, program setting devices, etc.

Figure 3 shows an example of a time chart of the carburizing process in the batch type gas carburizing furnace during the operation process of each part of the process shown in Figure 2.To briefly explain this, first, at the start of the carburizing process, the gas The temperature of the carburizing furnace 10 is raised, and during this temperature raising process, the blower 4 is not rotated at the end, and therefore the enriched gas is not supplied.

Simultaneously with the start of carburizing, the blower 4 is rotated, and the enriched gas and carburizing gas are fed into the gas carburizing furnace 10.

The blower 4 is initially rotated at a constant speed, enriched gas is also supplied in a fixed amount, and when the CO2 gas in the carburizing gas furnace 10 decreases to the target value as time passes, a signal from the program controller 10 is sent to the blower 4. , the error correction signal from the signal comparator 8 is sent to the drive control circuit 9 so that the amount of CO2 in the gas carburizing furnace 10 is maintained at the target value.
The amount of CO2 is fed into the system, and quantitative control of the amount of CO2 is carried out precisely.

At this time, that is, from the time when the CO2 gas decreases to the target value until the end of carburization, the rotational speed of the blower 4 and the flow rate of the enriched gas are reduced to some extent.

As described above, according to the present invention, when the gas flow rate to be controlled in the load connected to the gas flow path deviates from the target value, the signal between the detector and the reference signal is By controlling the drive control means for driving the motor using the comparator, the rotational speed of the blower can be adjusted to compensate for the above-mentioned error, so that the gas flow rate can always be maintained automatically and constant.

Therefore, the present invention can be applied to any device that is used to precisely send a minute flow rate of gas that requires quick response.

In addition, according to the present invention, by providing a balancing zero regulator on the suction side of the blower, the valve is closed when the blower is stopped, and as the blower rotates, it responds to the negative pressure on the suction side of the blower. In particular, it is possible to effectively eliminate disturbances such as fluctuations in gas pressure on the blower suction side and pulsating flow, thereby ensuring accurate compensation of the gas flow rate.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; Fig. 1 is a block diagram of a gas flow rate control device according to the invention, Fig. 2 is a block diagram showing an example of its application, and Fig. 3 is a block diagram of its application. It is a time chart of the gas flow path carburizing process in an example. 1...Gas flow path, 3...Balancing zero regulator, 4...Blower 15...
...Variable speed motor, 6...Load (furnace),
7...Detector, 8...Signal comparator, 9
...Program controller.

Claims (3)

[Scope of utility model registration request] (1) By a blower driven by a variable speed motor,
In a gas supply device that supplies gas to a load through a gas flow path, a valve on the suction side of the blower is closed when the blower is stopped, and as the blower rotates, the valve opens according to the negative pressure on the suction side. A balancing zero regulator is connected to remove disturbances in the gas flow, and a detector that detects information corresponding to the gas flow rate and a comparator that compares this detected information with reference information that is a control target are connected in sequence to the load. When the gas inflow amount at the load deviates from the control target, the drive control circuit of the variable speed motor is controlled based on the output of the comparator to operate the blower in a manner that compensates for the error. A gas flow rate control device that is driven by speed. (2) The signal comparator compares the electrical signal output from the detector to be controlled with a target reference signal, and inputs an output signal corresponding to the difference to the drive control circuit. A gas flow rate control device according to claim 1 of the utility model registration claim. (3) A program controller is connected to the drive control circuit, whereby the rotational speed of the blower can be arbitrarily set and the gas flow rate can be controlled. 2. The gas flow rate control device according to item 1.