JP2018096846A - Gas flow rate calculation system, and abnormality detector and method for detecting abnormality used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an abnormality in a gas flow rate calculation system 100 using a weight method.SOLUTION: The gas flow rate calculation system 100 includes: a container 10 which gas flows in or out; and an electronic scale 20 on which the container 10 is mounted. The gas flow rate calculation system calculates the flow rate of the gas flowing in or out of the container 10 on the basis of an output value output from the electronic scale 20, and detects an abnormality of the gas flow rate calculation system 100 based on the pressure in the container 10 and the output value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas flow rate calculation system using, for example, a weight method (weighing method), an abnormality detection apparatus and an abnormality detection method for detecting an abnormality of the gas flow rate calculation system.

As this type of gas flow rate calculation system, for example, as shown in Patent Document 1, there is a system in which a gas is flowed from a cylinder placed on an electronic balance to a fluid control device and the like and the gas flow rate is calculated by a gravimetric method.
Specifically, using the fact that the measured value of the electronic balance changes as the gas in the cylinder is consumed, the flow rate of gas flowing from the cylinder to the fluid control device is calculated based on the amount of change in the measured value. I have to.

  By the way, in such a gas flow rate calculation system, what detects an abnormality occurring in the system has not been known so far.

JP 2005-134138 A

  Under such circumstances, the inventors of the present application pay attention to detecting an abnormality that has occurred in the system in order to calculate the gas flow rate more accurately, so that an abnormality that could not be recognized in the past can be recognized. We studied earnestly.

  The present invention has been made based on the above-described investigation by the present inventor, and its main object is to detect an abnormality in a gas flow rate calculation system using a weight method.

  That is, the gas flow rate calculation system according to the present invention includes a container into which gas flows or gas flows out, and a weight measuring unit on which the container is placed, and based on an output value output from the weight measuring unit, A gas flow rate calculation system for calculating a flow rate of the gas flowing into or out of a container, wherein an abnormality of the gas flow rate calculation system is detected based on a pressure in the container and the output value. is there.

With such a gas flow rate calculation system, even if an abnormality occurs in the system, the abnormality can be detected based on the pressure in the container and the output value from the electronic balance, so the detected abnormality is repaired. By doing so, the system can be returned to a normal state, and the gas flow rate can be accurately calculated.
For example, based on the pressure in the container described above, a normal value that should be output from the weight measurement unit at the pressure can be obtained. Therefore, the normal value and the output value actually output from the weight measurement unit can be obtained. By comparing, it is possible to detect a malfunction of the weight measuring unit.

It is preferable to have a pressure sensor for measuring the pressure in the container.
If this is the case, an abnormality of the system can be detected while the container is placed on the weight measuring unit, and even if an abnormality occurs during the operation of the system, the abnormality can be detected quickly.

As a specific embodiment, there may be mentioned one further comprising a balance mechanism in which the container is attached to one side and a counterweight having a predetermined weight is attached to the other side.
With such a configuration, it is particularly possible to detect an abnormality in the balance mechanism.
Specifically, the abnormality of the balance mechanism is, for example, bending or cracking of the balance beam, bending of a support supporting the balance beam, displacement of a fulcrum, displacement of a hanging position of a container or a counterweight, and the like.

Moreover, according to the abnormality detection apparatus which concerns on this invention, the effect similar to the flow volume calculation system mentioned above can be acquired.
That is, the abnormality detection device according to the present invention includes a container into which gas flows or flows out, and a weight measuring unit on which the container is placed, and the container is based on an output value output from the weight measuring unit. Used in a gas flow rate calculation system for calculating the flow rate of the gas flowing into or out of the vessel, wherein an abnormality of the system is detected based on the pressure in the container and the output value. is there.

Moreover, according to the abnormality detection method which concerns on this invention, the effect similar to the flow volume calculation system mentioned above can be acquired.
That is, the abnormality detection method according to the present invention includes a container into which gas flows or flows out, and a weight measuring unit on which the container is placed, and the container is based on an output value output from the weight measuring unit. A method used in a gas flow rate calculation system for calculating the flow rate of the gas flowing into or out of the vessel, wherein the abnormality of the system is detected based on the pressure in the container and the output value. is there.

  According to the present invention configured as described above, it is possible to detect an abnormality of the system in which the gas flow rate is calculated using the gravimetric method.

The figure which shows typically the whole structure of the gas flow volume calculation system of this embodiment. The figure which shows typically the whole structure of the gas flow volume calculation system of deformation | transformation embodiment. The figure which shows typically the whole structure of the gas flow volume calculation system of deformation | transformation embodiment. The figure which shows typically the whole structure of the gas flow volume calculation system of deformation | transformation embodiment.

  Hereinafter, an embodiment of a gas flow rate calculation system according to the present invention will be described with reference to the drawings.

The gas flow rate calculation system 100 according to the present embodiment, for example, flows gas to a fluid control device MFC used for semiconductor manufacturing, and calculates the gas flow rate that flows to the fluid control device MFC using a so-called weight method (weighing method). In this embodiment, the fluid control device MFC is part of the calibration system 200 that calibrates the fluid control device MFC.
As shown in FIG. 1, the calibration system 200 includes a container 10 in which a gas is enclosed, an electronic balance 20 that is a weight measuring unit on which the container 10 is placed, and a gas in the container 10 that is used as a fluid control device MFC. The calibrating system 200 does not include the fluid control device MFC.

As shown in FIG. 1, the gas flow rate calculation system 100 according to the present embodiment includes a container 10 in which a gas is sealed, an electronic balance 20 that is a weight measuring unit on which the container 10 is placed, and a gas in the container 10 as a fluid. At least a part of the outflow line L1 flowing to the control device MFC and at least a part of the sealing line L2 for sealing the gas in the container 10 are provided.
The fluid control device MFC of the present embodiment is a mass flow controller having a thermal or differential pressure type flow sensor and a flow control valve.

  First, the lines L1 and L2 through which the gas flows will be described.

The outflow line L1 is for flowing the gas in the container 10 to the fluid control device MFC. Specifically, as shown in FIG. 1, one end is connected to the container 10 and the other end is connected to the suction pump P. The first pressure regulator Va, the first on-off valve V1, the second pressure regulator Vb, the pressure sensor P1, the fluid control device MFC, and the second on-off valve V2 are connected in series in this order from the container 10 side (one end side). Has been placed.
The suction pump P is not necessarily provided, and the other end of the outflow line L1 may be opened to the atmosphere.

  The enclosure line L2 is for enclosing the container 10 placed on the electronic balance 20 by flowing gas. Specifically, as shown in FIG. 1, one end is connected to a gas cylinder (not shown) and the other end Is connected to the container 10, and the filter F, the third on-off valve V3, the fourth on-off valve V4, and the check valve Vc are arranged in series in this order from the upstream side (one end side) of the calibration gas.

  With the above-described configuration, the calibration gas in the container 10 flows through the first pressure regulator Va and flows out to the fluid control device MFC, and the calibration gas in a gas cylinder (not shown) flows through the back valve Vc into the container 10. Enclosed.

In this embodiment, the outflow line L1 and the enclosed line L2 are merged and partially shared. More specifically, the sealing line L2 is configured to merge with the outflow line L1 at the confluence point X provided in the outflow line L1. In addition, the junction point X of this embodiment is between the 1st pressure regulator Va and the 1st on-off valve V1 in the outflow line L1, Comprising: Between the non-return valve Vc and the 4th on-off valve V4 in the enclosure line L2 Is provided.
With the above-described configuration, a common line L31 common to the outflow line L1 and the sealing line L2 is formed from the junction point X toward the container 10, and in this embodiment, resin or the like is allowed in the common line L31. A flexible tube 30 having flexibility is provided.

In the present embodiment, a part of the outflow line L <b> 1, a part of the sealing line L <b> 2, the container 10 and the electronic balance 20 are accommodated in the chamber 40.
Hereinafter, the configuration in the chamber 40 will be described.

  In the present embodiment, a balance mechanism 50 including a swingable balance beam 51 and a support column 52 that supports the balance beam 51 at a fulcrum C is provided in the chamber 40.

  The balance mechanism 50 according to the present embodiment includes a container 10 on one of the balance beams 51, a part of piping constituting the outflow line L1 and the sealing line L2 connected to the container 10, and a valve associated with a part of the piping. Etc. (in the present embodiment, the first pressure regulator Va and the check valve Vc) are suspended, and a counterweight 60 having a predetermined weight is suspended on the other side of the balance beam 51.

  The container 10 is a cylinder etc. which consists of carbon fiber which has heat insulation, for example, and has predetermined weight. In the present embodiment, for example, nitrogen gas or the like is sealed through the above-described sealing line L2.

  The counterweight 60 cancels out a small part of the output value (hereinafter also referred to as measured weight) output from the electronic balance 20, and in this embodiment, the weight of the container 10 and the piping connected to the container 10 It is a weight having a weight that is a combination of the weight of a part of the pipe or a part of the pipe (in this embodiment, the first pressure regulator Va and the check valve Vc).

With the above-described configuration, the electronic balance 20 outputs the weight obtained by subtracting the weight of the counterweight 60 from the total weight of the container 10, piping, valves, and the like placed on the electronic balance 20.
In the present embodiment, a signal indicating the measured weight is transmitted from the electronic balance 20 to the information processing apparatus 70 described later.

  The information processing apparatus 70 calibrates the fluid control device MFC based on the measured weight output from the electronic balance 20, and physically includes a CPU, a memory, an A / D converter, a D / A converter, and the like. It is a general purpose or dedicated computer.

The information processing apparatus 70 according to the present embodiment calibrates the fluid control device MFC using a so-called dynamic weight method (weighing method).
Specifically, the information processing apparatus 70 is a unit that is output from a timer (not shown) and flows from the container 10 to the fluid control device MFC based on the time during which the gas flows from the container 10 to the fluid control device MFC and the measured weight. The actual flow rate per time is calculated, and a calibration curve between the actual flow rate and the set flow rate input to the fluid control device MFC is created to calibrate the fluid control device MFC.

  Therefore, the gas flow rate calculation system 100 of this embodiment includes an abnormality detection device that detects an abnormality that occurs in the gas flow rate calculation system 100.

  Specifically, as shown in FIG. 1, this abnormality detection device is output from a pressure sensor P <b> 2 that is a pressure measurement unit that measures the pressure in the container 10, and a measurement pressure output from the pressure sensor P <b> 2 and an electronic balance 20. And an abnormality detection unit for detecting an abnormality based on the measured weight.

The pressure sensor P2 is provided at a connection portion with the container 10 in the outflow line L1 or a connection portion with the container 10 in the sealing line L2, and more specifically, the pressure sensor P2 is connected to the container 10 in the outflow line L1. It is provided between the pressure regulator Va or between the container 10 and the check valve Vc in the sealing line L2.
In this embodiment, as shown in FIG. 1, the container 10 side (one end side) of the outflow line L1 and the downstream side (the other end side) of the sealing line L2 are shared and connected to the container 10, The pressure sensor P2 is provided in the common line L32 that is shared.

  In the present embodiment, the abnormality detection unit is provided in the information processing apparatus 70 described above, and acquires a measurement pressure that is an output from the pressure sensor P2 and a measurement weight that is an output from the electronic balance 20, and performs measurement. An abnormality of the gas flow rate calculation system 100 is detected based on the pressure and the measured weight.

More specifically, the abnormality detection unit acquires a reference weight corresponding to the measurement pressure based on correlation data indicating a correlation between the pressure in the container 10 and the reference weight that should be measured by the electronic balance 20 at the pressure. The reference weight is compared with the measured weight.
This correlation data is acquired when the gas flow rate calculation system 100 is in a normal state (for example, at the time of product shipment) and stored in a predetermined area formed in the memory. In this embodiment, for example, the container 10 It is the look-up table which summarized the pressure in the inside and the said reference | standard weight as a table | surface.
That is, the abnormality detection unit of the present embodiment is configured to compare the reference weight obtained from the measurement pressure based on the lookup table and the measurement weight obtained from the electronic balance 20.

  Then, the abnormality detection unit of the present embodiment determines that an abnormality has occurred in the gas flow rate calculation system 100 when the difference between the reference weight and the measured weight is equal to or greater than a predetermined value.

In this embodiment, when the abnormality detection unit detects an abnormality, an abnormality notification unit that notifies the abnormality is provided.
The abnormality notification unit of the present embodiment is provided in the information processing apparatus 70 described above. Specifically, the abnormality notification unit sounds an alarm when the abnormality detection unit detects an abnormality, a display (not shown), etc. In this case, characters or symbols indicating abnormality are displayed.

According to the gas flow rate calculation system 100 according to the present embodiment configured as described above, the abnormality detection unit is configured to use the gas flow rate calculation system 100 based on the measurement pressure from the pressure sensor P2 and the measurement weight from the electronic balance 20. Therefore, for example, bending or cracking of the balance beam 51, displacement of the fulcrum C, bending or cracking of the support column 52, malfunction of the electronic balance 20, gas leakage from piping constituting the outflow line L1 and the sealing line L2 In addition, it is possible to detect the presence or absence of a failure of a valve or the like (in the present embodiment, the first regulator Va or the check valve Vc) associated with the piping.
As a result, it is possible to repair an abnormality that has occurred in the gas flow rate calculation system 100 and return it to a normal state, and to accurately calculate the gas flow rate.

  Further, the electronic balance 20 outputs the weight obtained by subtracting the weight of the counterweight 60 from the total weight of the container 10, piping, valves and the like placed on the electronic balance 20, so that the measurement of the electronic balance 20 By reducing the range, the resolution of the electronic balance 20 can be increased, and the gas weight in the container 10 can be measured with high accuracy.

  Furthermore, since the flexible tube 30 is provided in the common line L31, for example, vibration generated by the flow of gas and tension transmitted from the outflow line L1 and the sealing line L2 to the container 10 can be absorbed by the flexible tube 30. An error occurring in the output value of the balance 20 can be extremely reduced.

  The present invention is not limited to the above embodiment.

For example, in the above embodiment, the container 10 is suspended from one of the balance beams 51 and the counterweight 60 is suspended from the other. However, as illustrated in FIG. 2, the container 10 is suspended from one of the balance beams 51. On the other hand, a container 10 ′ having the same configuration as the container 10 and a pipe or valve connected to the container 10 may be suspended.
With the above-described configuration, the buoyancy applied to the containers 10 and 10 ′ suspended from one and the other of the balance beam 51 can be made substantially equal, and the weight of the gas in the container 10 can be measured with higher accuracy by the electronic balance 20. it can.

  Further, the balance mechanism 50 of the above embodiment has a configuration in which the container 10 is suspended from one of the balance beams 51. However, as shown in FIG. 3, the container 10 is placed on one of the balance beams 51 and the counterweight is placed on the other. 60 may be provided.

  Further, it is not always necessary to use the balance mechanism 50. For example, as shown in FIG. 4, an elastic member 80 such as a spring is provided in the chamber 40, one end of the elastic member 80 is attached to the container 10, and the other end is You may comprise so that the container 10 may be lifted by attaching it above the container 10 (for example, ceiling of the chamber 40).

  In addition, the container 10 may be simply placed on the electronic balance 20 without using a mechanism for lifting the container 10 such as the balance mechanism 50 so as to have a simple configuration.

  In the above embodiment, the pressure sensor P2 measures the pressure in the container 10 while the container 10 is placed on the electronic balance 20. For example, before the container 10 is placed on the electronic balance 20, the gas is preliminarily measured. , And the pressure in the container 10 is measured. Based on this measured pressure and the measured weight output from the electronic balance 20 when the container 10 is placed on the electronic balance 20, an abnormality in the gas flow rate calculation system 100 is detected. You may make it detect.

Further, the abnormality detection unit of the embodiment is configured to compare the reference weight obtained from the measurement pressure based on the lookup table and the measurement weight obtained from the electronic balance 20, but the predetermined pressure is determined from the measurement pressure. You may comprise so that the calculated weight calculated based on a calculation formula (For example, the formula containing a state equation of gas etc.) and measured weight may be compared.
Specifically, the abnormality detection unit includes a gas weight that is the weight of the gas in the container 10 obtained from the measured pressure, and a container weight that is the weight of the container 10 in an empty state measured in advance at the time of factory shipment, for example. May be calculated as the calculated weight, and the calculated weight and the measured weight may be compared. In addition, a weight obtained by subtracting the container weight from the measured weight may be calculated as a calculated weight, and the calculated weight may be compared with the gas weight.
In addition, the abnormality detection unit of the embodiment is configured to compare the reference weight and the measured weight. For example, the gas is sealed in the container 10 until the reference weight is reached, and the pressure sensor P2 is used at that time. The obtained measurement pressure is compared with the reference pressure obtained from the reference weight, and when the difference between the reference pressure and the measurement pressure is a predetermined value or more, it is determined that an abnormality has occurred in the gas flow rate calculation system 100. You may comprise as follows.

  In addition, although the pressure sensor P2 of the embodiment is provided in the common line L32, the pressure sensor P2 may be provided in the container 10 to measure the pressure in the container 10.

Moreover, in the said embodiment, although the outflow line L1 and the enclosure line L2 were comprised so that it might join, you may comprise so that the outflow line L1 and the enclosure line L2 may be connected to the container 10 without joining. good.
Furthermore, in the said embodiment, although the outflow line L1 and a part of enclosure line L2 were made common toward the container 10 from the confluence | merging point X, each line L1 until it reaches the container 10 from the confluence | merging point X, L2 may be shared. In this case, it is preferable to provide an on-off valve and a pressure regulator on the common line.
More preferably, the outflow line L1 and the sealing line L2 may be configured to be shared at a connection portion with the container 10 (more specifically, a predetermined range from a connection end portion connected to the container 10).

  In addition, in the above-described embodiment, the reversely supported valve Vc is provided in the sealing line L2. However, this reversely supported valve Vc is not always necessary, for example, the first pressure regulator Va of the outflow line L1 is opened and illustrated. The calibration gas in the gas cylinder not to be used may be sealed in the container 10 from the outflow line L1.

  In addition, although the abnormality detection unit and the abnormality notification unit of the embodiment are provided in the information processing apparatus 70, they may be provided in a computer or the like different from the information processing apparatus 70.

  Further, the gas flow rate calculation system 100 of the above embodiment is configured to flow gas from the container 10 to the fluid control device MFC. However, the gas flowing into the fluid control device MFC is caused to flow into the container 10, and the electronic balance 20 You may comprise so that the flow volume of the gas which flows in into the container 10 may be calculated based on the output value output.

  Further, the counterweight 60 may be equal to or less than the total weight of the weight of the container 10 and the weight of a part of piping connected to the container 10 and the weight of a valve or the like attached to a part of the piping. It is sufficient that the weight is such that at least a part of the output value obtained by the above can be canceled.

Moreover, the flexible tube 30 of the above embodiment is made of resin, but may be made of metal such as SUS.
In this case, since the flexible tube 30 is less likely to be deformed than a resin tube, the gas can be flowed more stably to the fluid control device MFC.
However, the metal flexible tube 30 has a larger curvature than that of the resin, and the chamber 40 needs to be enlarged accordingly. Therefore, in order to reduce the size of the entire apparatus, the resin flexible tube 30 is more advantageous than the metal flexible tube 30.

In addition, a third pressure regulator may be further arranged in series continuously with the first pressure regulator Va on the upstream side or the downstream side of the first pressure regulator Va in the outflow line L1.
Accordingly, by sequentially opening the first pressure regulator Va and the third pressure regulator, the inside of the outflow line L1 can be set to a predetermined pressure, and the calibration gas can be stably flowed from the container 10 to the fluid control device MFC. .

In addition, the flow rate calculation system 100 of the above embodiment is configured to flow the calibration gas from the container 10 to the fluid control device MFC. However, the gas flowing to the fluid control device MFC is caused to flow into the container 10; Based on the output value output from the electronic balance 20, the flow rate of the gas flowing through the fluid control device MFC may be calculated.
Here, when a differential pressure mass flow controller is used as the fluid control device MFC, it is necessary to keep the pressure on the secondary side (downstream side) of the fluid control device MFC lower than the pressure on the primary side (upstream side). However, when trying to calibrate the outflow control device MFC using the flow rate calculation system 100 described above, the pressure on the secondary side increases as the gas flowing into the fluid control device MFC flows into the container 10. The fluid cannot be accurately controlled.
Therefore, when the flow rate calculation system 100 configured as described above is used for calibration of the fluid control device MFC, a thermal mass flow controller is more preferable than the differential pressure mass flow controller as the fluid control device MFC. A mass flow controller having a flow rate control unit such as a flow rate control valve on the downstream side of the sensor is suitable as an object to be calibrated using the flow rate calculation system configured as described above.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Gas flow rate calculation system 10 ... Container 20 ... Electronic balance 50 ... Balance mechanism 60 ... Counterweight 70 ... Information processing apparatus P2 ... Pressure sensor MFC ... Fluid control machine

Claims (5)

Comprising a container into which gas flows in or out and a weight measuring unit on which the container is placed, and calculates a flow rate of the gas flowing into or out of the container based on an output value output from the weight measuring unit A gas flow rate calculation system,
An abnormality in the gas flow rate calculation system is detected based on the pressure in the container and the output value.   The gas flow rate calculation system according to claim 1, further comprising a pressure sensor for measuring the pressure in the container.   The gas flow rate calculation system according to claim 1 or 2, further comprising a balance mechanism to which the container is attached on one side and a counterweight having a predetermined weight is attached to the other side. Comprising a container into which gas flows in or out and a weight measuring unit on which the container is placed, and calculates a flow rate of the gas flowing into or out of the container based on an output value output from the weight measuring unit Used for a gas flow rate calculation system,
An abnormality detection device for detecting an abnormality of the gas flow rate calculation system based on the pressure in the container and the output value. Comprising a container into which gas flows in or out and a weight measuring unit on which the container is placed, and calculates a flow rate of the gas flowing into or out of the container based on an output value output from the weight measuring unit A method used for a gas flow rate calculation system,
An abnormality detection method for detecting an abnormality in the gas flow rate calculation system based on the pressure in the container and the output value.