Flow diagnostic device, flow diagnostic method and program storage medium

Abstract

The present invention provides a flow diagnostic device, a flow diagnostic method and a program storage medium. Even if it is a PVTt method, the time required for flow diagnosis can be shortened compared with the past, and the container can be miniaturized and diagnosed at a large flow rate. The flow diagnostic device includes: a main line, which is provided with a container with a predetermined capacity; a branch line, which branches from the upstream side of the container in the main line; a first opening and closing valve, which is provided on the branch line; a second opening and closing valve, which is provided on the main line; a dead volume, which is a volume that specifies the diagnostic object as the upstream end and the first opening and closing valve and the second opening and closing valve as the downstream end; and a second pressure control mechanism, which controls the fluid flowing through the main line in the inflow mode in which the first opening and closing valve is closed and the second opening and closing valve is opened to allow the fluid to flow into the container after the preparation mode is implemented, so as to keep the pressure of the fluid in the dead volume at a second set pressure.

Description

Technical Field

[0001] The invention relates to a flow diagnostic device, which is used for diagnosing the flow measured by a flow sensor and controlling the flow achieved by a flow control device. Background Art

[0002] In semiconductor manufacturing processes and the like, a mass flow controller is used to control the flow rate of a fluid. The mass flow controller is a flow control device that integrates a flow sensor, a control valve, and a flow controller.

[0003] In addition, the mass flow controller may not be able to control the flow rate of the fluid according to the set flow rate due to aging, such as blockage of the flow channel. Therefore, it is necessary to regularly check whether the mass flow controller can control the flow rate according to the set flow rate.

[0004] Therefore, conventional fluid supply systems are sometimes equipped with a structure for diagnosing the flow rate of a mass flow controller, etc. For example, Patent Document 1 shows a flow rate diagnostic device that diagnoses the flow rate of a mass flow controller using a dynamic constant volume method (pressure rise rate (ROR) method).

[0005] In addition, there is a flow rate diagnosis method called the PVTt method as a static method that can perform diagnosis with higher accuracy than the dynamic constant volume method and is also adopted by NIST. Fig.13 Indicates the flow diagnostic device used to implement the PVTt method.

[0006] That is, the flow diagnostic device 100 includes: a main line ML connected between a mass flow controller as a diagnostic object DO and a container TN having a predetermined volume; and a branch line SL branching from between the diagnostic object DO and the container TN in the main line ML. A vacuum pump SP as a suction source is connected to the downstream ends of the main line ML and the branch line SL, respectively. In addition, a plurality of opening and closing valves V1, V2, and V3 are provided on the main line ML and the branch line SL. In addition, an APC as a pressure control mechanism 1 is provided on the branch line SL. By using the APC provided on the branch line SL, when the fluid flows through the branch line SL, the pressure of the dead volume DV as the space from the diagnostic object DO to each opening and closing valve V1, V2 is kept constant.

[0007] The steps of the PVTt method are as follows. First, after the pressure in the container TN becomes substantially vacuum, Fig.13 As shown in (a) of FIG. 1 , a preparation mode is implemented in which the fluid flows through the branch line SL and the fluid does not flow into the container TN. Fig.14 As shown in the graph of the temporal change of the pressure, the preparation mode continues until the pressure in the dead volume DV is stabilized within a predetermined allowable range.

[0008] After the pressure in the dead volume DV stabilizes, Fig.13 As shown in (b) of FIG. 1 , the opening and closing states of the opening and closing valves V1 and V2 are switched to implement the inflow mode in which the fluid flows into the container TN. After the inflow mode starts, the pressure in the container TN is close to vacuum, so the fluid flows into the container TN rapidly. Therefore, Fig.14 As shown in the graph of , the pressure in the dead volume DV drops sharply to near the pressure in the container. The inflow mode continues until the pressure and temperature in the dead volume DV return to the initial pressure and temperature at the start of the inflow mode, and then the on-off valve V2 before the container TN on the main line ML is closed to end. In order to calculate the reference flow rate, the elapsed time Δt from the start to the end of the inflow mode is measured.

[0009] Finally, if Fig.14 As shown, a stop mode is implemented in which a predetermined time is waited until the pressure in the container TN stabilizes after the fluid stops flowing into the container TN. The pressure difference ΔP between the final stabilized pressure in the container TN and the initial pressure at the start of the inflow mode is measured.

[0010] A reference flow rate is calculated based on the measured elapsed time Δt and the pressure difference ΔP, and the state equation of the gas, and the mass flow controller is diagnosed by comparing the reference flow rate with the flow rate measured by the mass flow controller.

[0011] Compared with the ROR method, the reference flow rate calculated by the PVTt method according to the above-mentioned steps can be calculated with high accuracy because it is less affected by pressure fluctuations, temperature fluctuations, etc., and can realize more accurate diagnosis.

[0012] However, in the previous PVTt method, Fig.14 As shown in the graph of , the inflow mode must be continued for a long time until the pressure in the dead volume DV drops significantly and returns to the original state. This is because the pressure in the container TN must be slowly increased to return the pressure and temperature in the dead volume DV to the state in the preparation mode. Therefore, the time required for the entire diagnosis becomes much longer than that of the ROR method.

[0013] In addition, since the fluid must continue to flow into the container TN until the pressure in the dead volume DV returns to its original state, the volume of the container TN needs to be larger than a certain level. As a result, the amount of fluid required to implement the PVTt method is also larger than that of the ROR method. In addition, due to the constraints of the occupied space of the equipment, etc., there is also an upper limit to the size of the container TN, so it is also difficult to make a large flow rate flow through the mass flow controller for diagnosis.

[0014] Patent Document 1: Japanese Patent Application Laid-Open No. 11-87318 Summary of the invention

[0015] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a flow rate diagnostic device that can shorten the time required for flow rate diagnosis compared with the past even if the PVTt method is used, and can also realize the miniaturization of the container and the diagnosis at a large flow rate.

[0016] That is, the flow diagnostic device of the present invention comprises: a main line, in which a diagnostic object as a flow sensor or a flow control device is arranged on the upstream side, and a container with a predetermined capacity is arranged on the downstream side; a branch line, which branches from the upstream side of the container in the main line; a first opening and closing valve, which is arranged on the branch line; a second opening and closing valve, which is arranged on the main line between the branch point of the branch line and the container; a dead volume, which is a volume that specifies the diagnostic object as the upstream end and the first opening and closing valve and the second opening and closing valve as the downstream end in the main line and the branch line; a first pressure control mechanism, which opens the first opening and closing valve and closes the second opening and closing valve to prevent the fluid from flowing. In a preparation mode for flowing into the container, the fluid flowing through the branch line is controlled so as to maintain the pressure of the fluid in the dead volume at a first set pressure; a second pressure control mechanism, after implementing the preparation mode, controls the fluid flowing through the main line in an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container, so as to maintain the pressure of the fluid in the dead volume at a second set pressure; and a reference flow calculation unit, which calculates a reference flow rate as the flow rate of the fluid flowing into the container based on a pressure change caused by the fluid flowing into the container from the start of the inflow mode to the end of the inflow mode when the second on-off valve is closed.

[0017] In addition, the flow diagnostic method of the present invention uses a flow diagnostic device, which includes: a main line, in which a diagnostic object as a flow sensor or a flow control device is provided on the upstream side, and a container with a predetermined capacity is provided on the downstream side; a branch line, which branches from the upstream side of the container in the main line; a first opening and closing valve, which is provided on the branch line; a second opening and closing valve, which is provided on the main line between the branch point of the branch line and the container; and a dead volume, which is a volume that specifies the diagnostic object as the upstream end and the first opening and closing valve and the second opening and closing valve as the downstream end in the main line and the branch line, wherein the flow diagnostic method includes: in the opening In a preparation mode in which the first on-off valve is opened and the second on-off valve is closed so that the fluid does not flow into the container, the fluid flowing through the branch line is controlled so that the pressure of the fluid in the dead volume is maintained at a first set pressure; after the preparation mode is implemented, in an inflow mode in which the first on-off valve is closed and the second on-off valve is opened so that the fluid flows into the container, the fluid flowing through the main line is controlled so that the pressure of the fluid in the dead volume is maintained at a second set pressure; and a reference flow rate as the flow rate of the fluid flowing into the container is calculated based on the pressure change caused by the fluid flowing into the container during the period from the start of the inflow mode to the end of the inflow mode when the second on-off valve is closed.

[0018] If the PVTt method is implemented in this way, the second pressure control mechanism operates in a manner to maintain the pressure in the dead volume at the second set pressure from the start of the inflow mode, so that the pressure drop of the dead volume at the start of the inflow mode can be smaller than before. Therefore, the time required for the pressure in the dead volume to return to the initial pressure at the start of the inflow mode can be greatly shortened compared to before. Therefore, the time required for flow diagnosis based on the PVTt method can be shortened compared to before.

[0019] Furthermore, since the inflow mode is implemented to return the pressure and temperature in the dead volume to the same state as in the preparation mode in a short time, the pressure rise amount in the container can be set to an arbitrary value. Therefore, the pressure rise amount in the container can be suppressed compared with the past, and the amount of fluid required can be reduced. As a result, the container can be miniaturized and flow diagnosis at a large flow rate can be achieved.

[0020] In order to calculate the reference flow rate when the pressure and temperature in the container are stable and to make the influence of changes in pressure and temperature difficult to appear on the reference flow rate, the reference flow rate calculation unit can calculate the reference flow rate based on the elapsed time Δt from the start to the end of the inflow mode and the pressure difference ΔP between the initial pressure at the start of the inflow mode and the stabilized pressure after a predetermined time from the end of the inflow mode.

[0021] As a specific structural example of the first pressure control mechanism, the first pressure control mechanism includes: a first pressure sensor, which is arranged on the branch line at a downstream side of the first opening and closing valve, or is arranged in the dead volume; a first control valve, which is arranged on the branch line; and a first pressure controller, which controls the first control valve based on the deviation between the first set pressure and the first measured pressure measured by the first pressure sensor.

[0022] As a specific structural example of the second pressure control mechanism, the second pressure control mechanism can be listed as including: a second pressure sensor, which is arranged on the main line at a downstream side of the second opening and closing valve, or is arranged in the dead volume; a second control valve, which is arranged on the branch line; and a second pressure controller, which controls the second control valve based on the deviation between the second set pressure and the second measured pressure measured by the second pressure sensor.

[0023] In order to make the pressure sensors used in the first pressure control mechanism and the second pressure control mechanism universal and reduce the number of components and achieve the required pressure control, the first pressure sensor and the second pressure sensor may be the same pressure sensor arranged in the dead volume.

[0024] In order to reproduce the pressure and temperature in the dead volume achieved in the preparation mode at the end point of the inflow mode, the second set pressure may be an initial pressure measured by the second pressure sensor at the start point of the inflow mode.

[0025] In order to correct the influence of adiabatic compression of the fluid flowing into the container and thereby obtain a high-precision reference flow rate, the reference flow rate calculation unit can correct the pre-correction flow rate calculated based on the elapsed time Δt, the pressure difference ΔP and the gas state equation based on the maximum pressure in the inflow pattern or the pressure near the maximum pressure, and the stabilized pressure to calculate the reference flow rate.

[0026] For example, when the flow value inspected in the inspection object is large, if the second pressure control mechanism continuously maintains the pressure of the dead volume at the second set pressure, the flow rate of the fluid flowing through the main line is large, so sometimes the speed at which the pressure is filled into the container becomes too large. As a result, during the period when the pressure of the dead volume changes, the pressure in the container reaches a predetermined pressure and the inflow mode may end. Therefore, in the inflow mode, the premise that the pressure of the dead volume is stable is destroyed, so the gas that should have been sealed in the container remains in the dead volume, or the gas that should be in the dead volume flows into the container. That is, if the pressure in the dead volume changes, the amount of gas sealed in the container changes, making it difficult to measure the correct flow rate. In addition, the discreteness of the elapsed time Δt also increases. Due to these circumstances, the accuracy of the reference flow calculated by the reference flow calculation unit may decrease.

[0027] In order to solve the above problem, the second pressure control mechanism may be configured not to control the pressure of the fluid in the dead volume in the inflow mode when the flow rate flowing through the main line is greater than a predetermined value. According to this structure, when the flow rate flowing through the main line is greater than a predetermined value, the same state as the conventional PVTt method can be formed. As a result, during the period from the start to the end of the inflow mode, the influence of the responsiveness of the second pressure control mechanism on the pressure in the dead volume disappears, and only the responsiveness of the first pressure control mechanism can exert an influence on the pressure in the dead volume. Therefore, even if the duration of the inflow mode is short, the operation of each device can have a margin, and the pressure in the dead volume can be easily stabilized. Furthermore, since the dispersion of the elapsed time Δt can be relatively reduced, the reference flow rate can be calculated with good accuracy even when the flow rate is greater than a predetermined value. In addition, when the flow rate flowing through the main line is large, the time required to fill the container with a predetermined pressure will not be so long, so for example, the reference flow rate can be obtained in a time substantially the same as when the flow rate is small.

[0028] As a flow diagnostic device that can calculate a reference flow rate with high accuracy even when the flow rate inspected in the inspection object is large, it can be listed that the inflow mode is ended at the point in time when the pressure in the container reaches a predetermined pressure, and when the elapsed time from the start to the end of the inflow mode is less than a prescribed time, the second pressure control mechanism is configured not to perform pressure control of the fluid in the dead volume in the inflow mode.

[0029] If the prescribed time is set based on a stabilization time required from when the inflow mode is started by pressure control using the second pressure control mechanism until the pressure of the dead volume is stabilized at the second set pressure, when the flow rate of the fluid flowing through the main line is small, the reference flow rate can be calculated at a higher speed than before, and even when the flow rate of the fluid flowing through the main line is large, the time required for diagnosis will not be so long, and the reference flow rate can be calculated with high accuracy.

[0030] In order to obtain the same effect as the flow diagnostic device of the present invention by, for example, updating the program in an existing flow diagnostic device, a flow diagnostic device program can be used, wherein the flow diagnostic device program is used for a flow diagnostic device, wherein the flow diagnostic device comprises: a main line, in which a diagnostic object as a flow sensor or a flow control device is provided on the upstream side, and a container with a predetermined capacity is provided on the downstream side; a branch line, which branches off from the upstream side of the container in the main line; a first opening and closing valve, which is provided on the branch line; a second opening and closing valve, which is provided on the main line between the branch point of the branch line and the container; and a dead volume, which is the volume in which the diagnostic object is defined as the upstream end and the first opening and closing valve and the second opening and closing valve are defined as the downstream end in the main line and the branch line, wherein the flow diagnostic device program enables a computer to function as The invention relates to a function of a first pressure controller, a second pressure controller and a reference flow calculation unit, wherein the first pressure controller controls the fluid flowing through the branch line to keep the pressure of the fluid in the dead volume at a first set pressure in a preparation mode in which the first on-off valve is opened and the second on-off valve is closed so that the fluid does not flow into the container, and the second pressure controller controls the fluid flowing through the main line to keep the pressure of the fluid in the dead volume at a second set pressure in an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container after the preparation mode is implemented, and the reference flow calculation unit calculates a reference flow rate as the flow rate of the fluid flowing into the container based on a pressure change caused by the fluid flowing into the container during a period from the start of the inflow mode to the end of the inflow mode when the second on-off valve is closed.

[0031] In addition, the flow rate diagnostic device program may be distributed electronically or stored in a program storage medium such as a CD, a DVD, or a flash memory.

[0032] In addition, as another embodiment of the flow diagnostic device of the present invention, the flow diagnostic device includes: a main line, in which a diagnostic object as a flow sensor or a flow control device is provided on the upstream side, and a container with a predetermined capacity is provided on the downstream side; a branch line, which branches from the upstream side of the container in the main line; a first opening and closing valve, which is provided on the branch line; a second opening and closing valve, which is provided on the main line between the branch point of the branch line and the container; a dead volume, which is a volume that specifies the diagnostic object as the upstream end and the first opening and closing valve and the second opening and closing valve as the downstream end in the main line and the branch line; a first pressure control mechanism, which opens the first opening and closing valve and closes the second opening and closing valve so that the fluid does not flow into the container in a preparation mode, controlling the fluid flowing through the branch line to maintain the pressure of the fluid in the dead volume at a first set pressure; and a reference flow calculation unit which, after the implementation of the preparation mode, calculates a reference flow rate as the flow rate of the fluid flowing into the container based on a pressure change caused by the fluid flowing into the container during a period from the start of an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container to the end of the inflow mode when the second on-off valve is closed, and an elapsed time from the start to the end of the inflow mode, wherein the reference flow calculation unit is configured to calculate the elapsed time based on a measured value of a physical quantity of the fluid in the dead volume or a value representing an actual action of the first on-off valve or the second on-off valve.

[0033] According to this structure, the time point when the pressure of the fluid in the dead volume actually starts to change due to the switching of the first opening and closing valve and the second opening and closing valve can be accurately determined as the start time point of the inflow mode. Therefore, as a result of setting the pressure increase range ΔP in the inflow mode to be small, even if the elapsed time Δt becomes short, the measurement accuracy of Δt can be maintained at a high level, and the reference flow rate can be calculated with high accuracy.

[0034] If the reference flow rate calculation unit calculates the elapsed time based on the measured value of the pressure of the fluid in the dead volume, the output of an existing pressure sensor can be used as a trigger for determining the elapsed time Δt, without adding a new sensor or the like.

[0035] As a specific structure for detecting the start time of the inflow mode, the reference flow calculation unit is configured to determine the start time of the inflow mode when the pressure in the dead volume changes by more than a predetermined value since the opening and closing of the first on-off valve and the second on-off valve are switched.

[0036] Thus, the flow diagnostic device of the present invention includes the second pressure control mechanism that controls to keep the pressure of the dead volume constant in the inflow mode, so that a large pressure drop in the dead volume does not occur, and the time from the start to the end of the inflow mode can be shortened. Therefore, even if the PVTt method is used, the time required for flow diagnosis can be shortened, and the amount of fluid required for flow diagnosis can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram showing the structure of the flow rate diagnostic device according to the first embodiment of the present invention.

[0038] Figure 2 It is a schematic diagram showing the details of the APC according to the first embodiment.

[0039] Figure 3 This is a schematic block diagram showing the structure of the control calculation means of the first embodiment.

[0040] Figure 4 It is a schematic diagram showing the flow of fluid in the preparation mode and the inflow mode according to the first embodiment.

[0041] Figure 5 This is a flowchart showing the flow rate diagnosis operation according to the first embodiment.

[0042] Figure 6 It is a graph showing the temporal change of pressure of the conventional flow rate diagnostic device and the temporal change of pressure of the flow rate diagnostic device according to the first embodiment.

[0043] Figure 7 It is a schematic diagram showing a flow rate diagnostic device according to a second embodiment of the present invention.

[0044] Figure 8 This is a graph showing the temporal change in pressure of the flow rate diagnosis device when the flow rate value for diagnosis is set to be large and the pressure in the dead volume is controlled by the second pressure control mechanism.

[0045] Fig. 9 This is a graph showing the operation of the flow rate diagnostic device according to the third embodiment of the present invention and the change in pressure over time.

[0046] Fig.10 This is a schematic block diagram showing the structure of a control operation unit according to a fourth embodiment of the present invention.

[0047] Fig.11 This is a scatter diagram showing a method of determining the inflow mode start time point according to the fourth embodiment.

[0048] Fig.12This is a scatter diagram showing the influence of the change in the calculated reference flow rate on the trigger method for determining the elapsed time Δt.

[0049] Fig.13 It is a schematic diagram showing the structure of a conventional flow rate diagnostic device.

[0050] Fig.14 This is a graph showing the temporal change in pressure of a conventional flow rate diagnostic device.

[0051] Description of Reference Numerals

[0052] 100 Flow Diagnostic Device

[0053] ML Main Line

[0054] SL branch line

[0055] DV Dead Volume

[0056] V1 First on-off valve

[0057] V2 Second on-off valve

[0058] V3 The third on-off valve

[0059] 1. First pressure control mechanism

[0060] 2 Second pressure control mechanism

[0061] 3. Pressure setting unit

[0062] 4 On / Off Valve Controller

[0063] 5 Measurement data storage unit

[0064] 6 Reference flow rate calculation unit

[0065] 7 Diagnosis Department DETAILED DESCRIPTION

[0066] Reference Figures 1 to 6 , a flow rate diagnostic device 100 according to a first embodiment of the present invention is described.

[0067] The flow diagnostic device 100 of the first embodiment is assembled in, for example, a semiconductor production line, and is used to diagnose the flow rate of a mass flow controller as a flow control device. In addition, the concept of flow diagnosis in this specification includes: detecting whether the flow rate output by the mass flow controller is correct relative to the reference flow rate output by the flow diagnostic device 100, or correcting the flow rate output by the mass flow controller based on the reference flow rate output by the flow diagnostic device 100. In addition, in the first embodiment, various gases flow as fluids.

[0068] like Figure 1As shown, the flow diagnostic device 100 of the first embodiment includes the following lines as flow channels: a main line ML, connected between a mass flow controller (MFC) as a diagnostic object DO and a container TN having a predetermined volume; and a branch line SL, branching from the diagnostic object DO and the container TN in the main line ML. The flow diagnostic device 100 calculates a reference flow rate based on the so-called PVTt method. That is, the flow diagnostic device 100 allows the fluid to flow through the branch line SL for a predetermined period of time to stabilize the pressure and temperature of the fluid passing through the mass flow controller, and then allows the fluid to flow into the container TN. And, based on the pressure change in the container TN, the flow rate of the fluid flowing into the container TN is calculated as the reference flow rate. In addition, the flow rate of the mass flow controller is diagnosed by comparing the measured flow rate output from the mass flow controller as the diagnostic object DO during the period when the fluid flows into the container TN with the reference flow rate.

[0069] Next, the hardware configuration of the flow rate diagnostic device 100 will be described in detail.

[0070] A pump SP as a vacuum source is connected to the downstream end of the main line ML and the branch line SL. The pump SP can be, for example, a pump that evacuates a vacuum chamber. In addition, in order to switch various flow channels or change the object of decompression, a plurality of opening and closing valves are provided in the main line ML and the branch line SL. Specifically, there are provided: a first opening and closing valve V1 provided on the branch line SL; a second opening and closing valve V2 provided in the main line ML between the branch point of the branch line SL and the container TN; and a third opening and closing valve V3 provided in the main line ML on the downstream side of the container TN.

[0071] Here, in the first embodiment, the dead volume DV is defined as a volume in which the mass flow controller as the diagnosis object DO is defined as the upstream end and the first opening and closing valve V1 and the second opening and closing valve V2 are defined as the downstream end in the main line ML and the branch line SL. In addition, in the first embodiment, a DV pressure sensor DP for measuring the internal pressure of the dead volume DV and a DV temperature sensor DT for measuring the internal temperature of the dead volume DV are provided in the dead volume DV. In addition, in order to measure the pressure and temperature of the fluid in the container TN required for calculating the reference flow rate, a container pressure sensor TP and a container temperature sensor TT are provided in the container TN.

[0072] In addition, in the branch line SL, a first APC (Auto Pressure Controller) as a first pressure control mechanism 1 is provided on the downstream side of the first opening and closing valve V1, and in the main line ML, a second APC as a second pressure control mechanism 2 is provided between the second opening and closing valve V2 and the container TN.

[0073] like Figure 2As shown, each APC as the first pressure control mechanism 1 and the second pressure control mechanism 2 includes a control valve 11, 21, a pressure sensor 12, 22 and a pressure controller 13, 23. The pressure controller 13, 23 performs feedback control on the opening of the control valve so that the deviation between the measured pressure measured by the pressure sensor 12, 22 and the set pressure is reduced. These devices are integrated in one box. In addition, in the following description, when it is necessary to distinguish the control valve 11, 21, the pressure sensor 12, 22, the pressure controller 13, 23, and the set pressure of the first APC and the second APC, the content belonging to the first APC is given "first" and the content belonging to the second APC is given "second" to distinguish. Although the first set pressure set in the first APC and the second set pressure set in the second APC can also be set to different values, they are set to the same pressure in the first embodiment. That is, each set pressure is set to the desired pressure to be maintained in the dead volume DV when used for flow diagnosis.

[0074] In addition, if Figure 1 As shown, the flow diagnostic device 100 includes a control operation mechanism COM responsible for controlling each device and performing various operations. The control operation mechanism COM receives input from the user and signals output from the mass flow controller, DV pressure sensor DP, container pressure sensor TP, and container temperature sensor TT, and outputs signals for controlling each opening and closing valve and each APC. The control operation mechanism COM is realized by a so-called computer including a CPU, a memory, an A / D converter, a D / A converter, various input and output devices, etc. Figure 3 As shown, it functions as at least a pressure setting unit 3, an on-off valve controller 4, a measurement data storage unit 5, a reference flow rate calculation unit 6, and a diagnosis unit 7.

[0075] Each part of the control calculation mechanism COM is described in detail.

[0076] The pressure setting unit 3 sets the set pressure in each APC. The pressure setting unit 3 sets the user set value input by the user as the initial value of each set pressure. In addition, the pressure setting unit 3 changes the set pressure according to the error between the pressure in the dead volume DV measured by the DV pressure sensor DP at a predetermined timing described later and the user set value. For example, when there is an error between the pressure in the dead volume DV measured at a predetermined timing and the user set value, the pressure setting unit 3 adds the error amount or the value obtained by multiplying the error by a predetermined multiplier to the user set value and sets it as the set pressure in the APC.

[0077] The on-off valve controller 4 controls the on-off state of each on-off valve V1, V2, and V3 to realize at least one of the exhaust mode, preparation mode, inflow mode, and stop mode. In the first embodiment, the on-off valve controller 4 uses the measured values ​​of the DV pressure sensor DP, the DV temperature sensor DT, the container pressure sensor TP, and the container temperature sensor TT as triggers to switch each mode in sequence. In the exhaust mode, the second on-off valve V2 is closed and the third on-off valve V3 is opened to vacuum exhaust the container TN. In addition, in the preparation mode, the inflow mode, and the stop mode, the third on-off valve V3 remains in a closed state. When the measured pressure of the container pressure sensor TP is made close to a substantially vacuum pressure by using the exhaust mode, the on-off valve controller 4 ends the exhaust mode and starts the next preparation mode.

[0078] In the preparation mode, the first on-off valve V1 is opened and the second on-off valve V2 is closed, and the fluid flows from the mass flow controller to the branch line SL. The preparation mode is maintained until the pressure and temperature of the fluid passing through the mass flow controller are stabilized. In the first embodiment, the state of the fluid is determined based on the measured pressure of the DV pressure sensor DP and the DV temperature sensor DT. Specifically, by utilizing the action of the first APC as the first pressure control mechanism 1, the pressure measured by the DV pressure sensor DP and the temperature measured by the DV temperature sensor DT are respectively stabilized for more than a predetermined time, and when it can be determined that the pressure and temperature in the dead volume DV are stable, the on-off valve controller 4 ends the preparation mode and starts the next inflow mode.

[0079] In the inflow mode, the first on-off valve V1 is closed and the second on-off valve V2 is opened, and the fluid flows from the mass flow controller into the container TN via the main line ML. This inflow mode continues until the pressure in the container TN rises to a predetermined pressure after the pressure and temperature of the fluid in the dead volume DV are roughly stabilized to the values ​​at the start time of the inflow mode. Specifically, after the pressure in the dead volume DV is maintained at the set pressure and the temperature is stabilized by the action of the second APC as the second pressure control mechanism 2, when the pressure in the container TN measured by the container pressure sensor TP rises to the pressure set by the user, the on-off valve controller 4 ends the inflow mode and starts the next stop mode.

[0080] In the stop mode, the first on-off valve V1 and the second on-off valve V2 are closed. This state lasts, even if it is short, until the pressure and temperature in the container TN stabilize.

[0081] The measurement data storage unit 5 stores the measurement values ​​measured by the tank pressure sensor TP and the tank temperature sensor TT in the flow diagnosis, for example, in the form of time series data. In this embodiment, at least the pressure and temperature in the tank TN measured in the inflow mode and the stop mode are stored in the measurement data storage unit 5.

[0082] The reference flow rate calculation unit 6 calculates the flow rate of the fluid flowing into the container TN in the inflow mode based on the data stored in the measurement data storage unit 5. The reference flow rate is calculated based on the pressure change generated in the container TN in the inflow mode. More specifically, the reference flow rate is calculated based on the elapsed time Δt from the start to the end of the inflow mode, the pressure difference ΔP between the initial pressure at the start of the inflow mode and the pressure in the container TN after stabilization in the stop mode, that is, the stabilized pressure, and the average temperature T in the container TN in the inflow mode. ave , and the state equation of the gas to calculate the reference flow rate. That is, the reference flow rate is calculated based on the following equation.

[0083] Qs=(ΔP / Δt)*22.4*V / (RT ave )

[0084] Among them, Qs is the reference flow rate, V is the volume of the container TN, and R is the gas constant. In addition, 22.4, which is multiplied as a coefficient, is the molar volume of the ideal gas L / mol. This coefficient varies by several % depending on the type of gas, so a value corrected according to the type of gas actually flowing can also be used.

[0085] The diagnosis unit 7 compares the flow rate measured by the mass flow controller in the inflow mode with the reference flow rate calculated by the reference flow rate calculation unit 6 to diagnose the flow rate of the mass flow controller.

[0086] Next, refer to Figure 4 Schematic diagram of Figure 5 The flowchart of FIG. 1 is used to explain the calculation operation of the flow diagnostic device 100 of the first embodiment thus configured to calculate the reference flow rate. Figure 5 In the flowchart, the time series data of the pressure and temperature in the container TN are continuously stored in the measurement data storage unit 5 and are not described as steps.

[0087] First, the on-off valve controller 4 closes the second on-off valve V2 and opens the third on-off valve V3 to start the exhaust mode (step S1). As a result, the pressure in the container TN starts to be reduced. Next, the on-off valve controller 4 determines whether the pressure measured by the container pressure sensor TP has become substantially vacuum (step S2).

[0088] When the pressure in the container TN becomes substantially vacuum, the on-off valve controller 4 ends the exhaust mode. Then, the on-off valve controller 4 opens the first on-off valve V1 and closes the second on-off valve V2 and the third on-off valve V3, and starts the preparation mode (step S3). Figure 4 As shown in (a) of FIG. 1 , the fluid passing through the mass flow controller flows through the branch line SL, and the fluid is not introduced into the container TN. Figure 5As shown, the on-off valve controller 4 determines whether the pressure measured by the DV pressure sensor DP is maintained near the set pressure set in the first APC for a predetermined time or more (step S4). That is, in step S4, based on the output of the DV pressure sensor DP, it is determined whether the pressure and temperature in the dead volume DV are stable.

[0089] When it is determined that the pressure and temperature in the dead volume DV are stable, the on-off valve controller 4 ends the preparation mode. Then, the on-off valve controller 4 closes the first on-off valve V1 and opens the second on-off valve V2 to start the inflow mode (step S5). Figure 4 As shown in (b), the fluid begins to flow into the container TN. Figure 5 As shown, the on-off valve controller 4 determines whether the pressure measured by the DV pressure sensor DP is stable near the pressure at the start of the inflow mode (step S6), and further determines whether the pressure measured by the container pressure sensor TP reaches the target pressure preset by the user (step S7). Here, although a slight pressure drop occurs when switching from the preparation mode to the inflow mode by the action of the second APC, it returns to the pressure near the start of the inflow mode in a short time. Therefore, in essence, according to the judgment criterion of step S7, the inflow mode will continue.

[0090] When the pressure in the container TN reaches the target pressure, the on-off valve controller 4 ends the inflow mode. And, the on-off valve controller 4 closes the second on-off valve V2 and starts the stop mode. In addition, the reference flow calculation unit 6 obtains the elapsed time Δt of the inflow mode determined at the time when the inflow mode ends (step S8). In addition, the reference flow calculation unit 6 determines whether the state in which the fluctuation range of the pressure measured by the container pressure sensor TP is within a predetermined value continues for more than a predetermined time. That is, the reference flow calculation unit 6 determines whether the pressure and temperature in the container TN are stable based on the fluctuation of the measured pressure of the container pressure sensor TP (step S9).

[0091] When the pressure and temperature in the tank TN are stable, the reference flow rate calculation unit 6 obtains the pressure measured by the tank pressure sensor TP at that time as the stabilized pressure, and calculates the pressure difference ΔP from the initial pressure at the start of the inflow mode (step S10). In addition, the reference flow rate calculation unit 6 calculates the reference flow rate based on the Δt obtained in step S8 and the ΔP obtained in step S10 (step S11).

[0092] According to the flow rate diagnostic device 100 of the first embodiment thus configured, since the second APC as the second pressure control mechanism 2 is provided in the main line ML, Figure 6As shown in the coordinate diagram, even if the preparation mode is switched to the inflow mode, the pressure in the dead volume DV can be prevented from dropping sharply as in the past, and the pressure that is stable in the preparation mode can be maintained approximately constant. Therefore, if it is the steps of the conventional PVTt method, it takes time to increase the pressure in the container TN until the pressure and temperature in the dead volume DV are sufficiently stable. In contrast, in the PVTt method of the flow diagnostic device 100 of the first embodiment, it is almost unnecessary to wait for the pressure and temperature of the dead volume DV to stabilize. Therefore, the inflow mode can be stopped at the point where the pressure reaches any target pressure set by the user. For example, Figure 6 As shown in the graph of , the target pressure is set to be smaller, and the inflow mode can be ended at a lower pressure than before, so the duration of the inflow mode can be greatly shortened compared to before. As a result, the time required for the overall flow diagnosis can also be shortened.

[0093] Furthermore, since the pressure in the container TN does not need to be increased to such a high pressure, the amount of fluid required for flow diagnosis can be greatly reduced compared to the past. Furthermore, since the pressure and temperature in the dead volume DV can be stabilized in a short time, the flow rate of the fluid flowing into the container TN in the inflow mode can be increased, and flow diagnosis at a large flow rate can be realized.

[0094] Next, refer to Figure 7 A flow rate diagnostic device 100 according to a second embodiment will be described. Components corresponding to those described in the first embodiment are denoted by the same reference numerals.

[0095] The flow rate diagnostic device 100 of the second embodiment is different from the first embodiment in the configuration of the first pressure control mechanism 1 and the second pressure control mechanism 2. That is, the pressure control mechanisms are not integrated like the APC, but are provided separately.

[0096] Specifically, the first pressure control mechanism 1 includes: a DV pressure sensor DP, which is arranged in the dead volume DV, equivalent to the first pressure sensor 12; a first control valve 11, which is arranged in the branch line SL; and a first pressure controller 13, which performs feedback control on the opening of the first control valve 11 based on the deviation between the measured pressure of the DV pressure sensor DP and the first set pressure.

[0097] In addition, the second pressure control mechanism 2 includes: a DV pressure sensor DP, which is equivalent to the second pressure sensor 22 and is shared by the second pressure control mechanism 2 and the first pressure control mechanism 1; a second control valve 21, which is arranged between the second on-off valve V2 and the container TN in the main line ML; and a second controller 23, which performs feedback control on the opening of the second control valve 22 based on the deviation between the measured pressure of the DV pressure sensor DP and the second set pressure.

[0098] Even in the flow diagnostic device 100 of the second embodiment, when switching from the preparation mode in which the fluid flows through the branch line SL to the inflow mode in which the fluid flows into the container TN, the second pressure control mechanism 2 can be used to prevent a large pressure drop in the dead volume DV. Therefore, the time required until the pressure and temperature in the dead volume DV, which are conditions for ending the inflow mode, become stable can be shortened. As a result, the amount of fluid required for flow diagnosis can be reduced, and the time required for the entire flow diagnosis can be shortened.

[0099] Next, refer to Figure 8 , Fig. 9 Next, a flow rate diagnostic device 100 according to a third embodiment will be described. In addition, components corresponding to those described in the first embodiment are given the same reference numerals.

[0100] The flow diagnostic device 100 of the third embodiment includes Figure 1 The flow diagnostic device 100 of the first embodiment shown in the figure has a substantially similar structure, but is different from the flow diagnostic device 100 of the first embodiment in that the operation is changed according to the flow diagnosed in the diagnostic object. Specifically, when the corrected flow rate is greater than a predetermined value, that is, when the flow rate of the fluid flowing through the main line ML is greater than a predetermined value, the pressure control of the fluid in the dead volume DV is not performed by the second pressure control mechanism 2 in the inflow mode. In addition, when the flow rate of the fluid flowing through the main line ML is less than the predetermined value, the pressure control of the dead volume DV is performed by the second pressure control mechanism 2 in the inflow mode as in the first embodiment.

[0101] When the corrected flow rate value is greater than the predetermined value, if the pressure in the dead volume DV in the inflow mode is maintained at the second set pressure by the second pressure control mechanism 2, then Figure 8 As shown in FIG. 1 , when the elapsed time Δt, which is the time from the start to the end of the inflow mode, is short, the pressure in the dead volume DV may remain unstable. This is because if both the first pressure control mechanism 1 and the second pressure control mechanism 2 perform pressure control and opening and closing control in a short period of time, the responsiveness of the second pressure control mechanism 2 cannot stabilize the pressure in the dead volume DV and maintain it at a constant value.

[0102] Therefore, the flow diagnostic device 100 of the third embodiment maintains the accuracy of the calculated reference flow rate substantially constant regardless of the magnitude of the corrected flow rate. Specifically, when the corrected flow rate of the diagnostic object is less than a predetermined value, such as Fig. 9As shown in (a) of the embodiment, pressure control is performed in the inflow mode so that the pressure in the dead volume DV is maintained at the second set pressure by the second APC as the second pressure control mechanism 2. That is, the opening of the control valve 21 in the second APC is controlled by the same control action as in the first embodiment. On the other hand, when the flow rate corrected in the diagnosis object is greater than the predetermined value, as shown in FIG. Fig. 9 As shown in (b), in the inflow mode, the second APC as the second pressure control mechanism 2 does not perform pressure control, and a natural increase in pressure is generated due to the inflow of the fluid into the container TN. That is, the second APC operates in a manner that maintains the control valve 21 fully open and does not become a flow path resistance.

[0103] Such switching of control in the second APC as the second pressure control mechanism 2 is realized, for example, by using the pressure setting unit 3 that sets the second set pressure for the second APC. Specifically, information related to the flow rate flowing through the main line ML, that is, the flow rate value of the correction object, is input to the pressure setting unit 3, and by comparing the value with a preset threshold value, it is determined whether to set the second set pressure for the second APC to perform pressure control or to set a full-open instruction for maintaining the control valve 21 in full open.

[0104] According to the flow diagnostic device 100 of the third embodiment thus constructed, when the flow value diagnosed in the diagnostic object is greater than the predetermined value, the reference flow rate can be calculated using the conventional PVTt method, and when the flow value diagnosed in the diagnostic object is less than the predetermined value, the reference flow rate can be calculated using the improved PVTt method similar to the flow diagnostic device 100 of the first embodiment. As a result, when the flow rate flowing through the main line ML is large and the elapsed time Δt, which is the length of the period during which the inflow mode is implemented, is short, the control action of the second pressure control mechanism 2 is not performed, and the responsiveness of the second pressure control mechanism 2 can be prevented from affecting the pressure in the dead volume DV and becoming an unstable state. Therefore, even when a large flow rate is corrected, the reproducibility of the flow rate of the gas flowing from the dead volume DV into the container TN can be improved, and the reference flow rate can be calculated with good accuracy.

[0105] Furthermore, regarding the time required to calculate the reference flow rate, when the flow rate is large, even if the same PVTt method as in the past is used, the time required to increase the pressure of the container TN is short, so that, for example, the time length can be substantially the same as when the flow rate of the fluid flowing through the main line is small.

[0106] In addition, in the third embodiment, the flow value that becomes the threshold value for determining whether the second pressure control mechanism 2 performs pressure control in the inflow mode may be set based on the length of the elapsed time Δt achieved when the second pressure control mechanism 2 performs pressure control, or may be set by other methods. For example, when the pressure of the dead volume DV is controlled by the second pressure control mechanism 2, an overshoot or undershoot occurs relative to the second pressure setting value, and the threshold value of the flow value may be set in such a way that the elapsed time Δt is longer than the period during which the second pressure setting value is not stable within the allowable value.

[0107] Next, refer to Fig.10 , Fig.11 , Fig.12 Next, a flow rate diagnostic device 100 according to a fourth embodiment will be described. In addition, components corresponding to those described in the first embodiment are given the same reference numerals.

[0108] The structure of the flow diagnostic device 100 of the fourth embodiment for obtaining the elapsed time Δt from the start to the end of the inflow mode is different from that of the first embodiment. Specifically, in the control operation mechanism COM, in the first embodiment, it is configured to detect the start point of the inflow mode based on the switching instructions of the on-off valves V1 and V2 of the on-off valve controller 4. In contrast, in the fourth embodiment, the start point of the inflow mode is determined based on the change in the physical quantity of the fluid in the dead volume DV. That is, Fig.10 As shown in the control calculation mechanism COM of the fourth embodiment, the reference flow rate calculation unit 6 is configured to set the start time point of the elapsed time Δt based on the pressure measured by the DV pressure sensor DP.

[0109] More specifically, if Fig.11 As shown, during a short period from the time when the signal for switching the opening and closing of the on-off valves V1 and V2 is outputted at zero, the pressure in the dead volume DV measured by the DV pressure sensor DP hardly changes. This is due to the fact that there is a slight time delay between the actual action of the on-off valves V1 and V2 and the output of the on-off command signal. Therefore, if the on-off command signal of the on-off valves V1 and V2 is used as a trigger to determine the start time of the inflow mode, it is actually determined that the fluid starts to flow into the container TN from the time when the on-off valves V1 and V2 do not operate. Although the offset of the start time is an extremely short time, for example, when the pressure rise ΔP is reduced to shorten the time required for flow diagnosis, or when the value of the corrected flow is large and the elapsed time Δt becomes short, the proportion of the error contained in the elapsed time Δt becomes a non-negligible amount.

[0110] In a fourth embodiment, if Fig.10As shown in the figure, the reference flow rate calculation unit 6 determines the start time of the elapsed time Δt when the pressure measured by the DV pressure sensor DP changes by a predetermined amount or more after the opening and closing command signals of the opening and closing valves V1 and V2 are output, that is, when the pressure jumps from a stable state as a trigger. In addition, for the end time of the elapsed time Δt, the reference flow rate calculation unit 6 determines the pressure in the container TN reaching a predetermined value as a trigger in the same manner as in the first embodiment.

[0111] According to the flow diagnostic device 100 of the fourth embodiment configured as above, Fig.11 The experimental results comparing the dispersion of the reference flow rate calculated when the elapsed time Δt is determined based on the pressure change of the dead volume DV and when the elapsed time Δt is determined based on the opening and closing command signals of the opening and closing valves V1 and V2 are shown. Fig.11 It can be seen that by determining the elapsed time Δt based on the pressure change, the dispersion of the finally calculated reference flow rate can be reduced. Therefore, according to the flow rate diagnostic device 100 of the fourth embodiment, it is possible to perform calibration, detection, etc. with higher reliability.

[0112] Here, a modified example of the fourth embodiment is described. The starting time of the elapsed time Δt is not limited to the pressure measured by the DV pressure sensor DP, but may also be a physical quantity of the fluid measured by other sensors. That is, the change of physical quantities such as temperature representing the actual operation of each on-off valve V1 and V2 may be used as a trigger to determine the starting time of the elapsed time Δt. In addition, an opening sensor may be pre-assembled in the second on-off valve V2, and the opening sensor may detect that the valve body leaves the valve seat as a trigger to determine the starting time of the elapsed time Δt.

[0113] In addition, the method for determining the starting point of the elapsed time Δt described in the fourth embodiment can be applied to the previous PVTt method that does not control the pressure in the dead volume DV in the inflow mode, or can also be applied to the PVTt method that is improved in a manner that controls the pressure in the dead volume DV in the inflow mode as in the present invention.

[0114] Other embodiments will be described.

[0115] The object of diagnosis is not limited to the flow control device, and may be, for example, a flow sensor alone.

[0116] The branch line may also be configured to branch from the main line and merge at the downstream side of the container. That is, the branch line may also be configured as a bypass flow channel that bypasses the container. According to this structure, the required pumps can be concentrated into one.

[0117] In each embodiment, whether the pressure and temperature of the fluid in the dead volume are stable is determined only based on the measurement values ​​of the DV pressure sensor, but a DP temperature sensor may also be provided in the dead volume, and the stability of the outputs of both the DV pressure sensor and the DP temperature sensor may be used as a determination condition for switching between the modes.

[0118] The method by which the reference flow rate calculation unit calculates the reference flow rate is not limited to the above method. For example, the reference flow rate calculation unit may also calculate the reference flow rate by correcting the pre-correction flow rate calculated based on the elapsed time Δt, the pressure difference ΔP, and the state equation of the gas based on the maximum pressure in the inflow mode or the pressure near it, and the pressure after stabilization. More specifically, the pre-correction flow rate may be multiplied by the value of the ratio of the maximum pressure to the pressure after stabilization to be corrected as the reference flow rate. Here, the maximum pressure, for example, Figure 6 As shown in FIG. 1 , the pressure measured by the container pressure sensor at the time when the inflow mode ends, and the stabilized pressure is the pressure measured by the container pressure sensor after a predetermined time has passed since the stop mode started. In addition, the pressure near the maximum pressure refers to the pressure measured before and after the maximum pressure in the inflow mode or the stop mode, and its concept includes pressures higher than the stabilized pressure.

[0119] Furthermore, various embodiments may be modified or parts of the embodiments may be combined with each other as long as they do not depart from the spirit of the present invention.

Claims

1. A flow diagnostic device, It is characterized in that include: A main line having a diagnostic object as a flow sensor or a flow control device disposed on an upstream side and a container having a predetermined capacity disposed on a downstream side; a branch line branching from an upstream side of the container in the main line; A first on-off valve is arranged on the branch line; a second on-off valve, arranged on the main line between a branch point of the branch line and the container; The dead volume is a volume in which the diagnosis object is defined as an upstream end and the first opening and closing valve and the second opening and closing valve are defined as downstream ends in the main line and the branch line; a first pressure control mechanism that controls the fluid flowing through the branch line to maintain the pressure of the fluid in the dead volume at a first set pressure in a preparation mode in which the first on-off valve is opened and the second on-off valve is closed so that the fluid does not flow into the container; a second pressure control mechanism that controls the fluid flowing through the main line to maintain the pressure of the fluid in the dead volume at a second set pressure in an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container after the preparation mode is implemented; as well as The reference flow rate calculation unit calculates a reference flow rate as a flow rate of the fluid flowing into the container based on a pressure change caused by the fluid flowing into the container from the start of the inflow mode to the end of the inflow mode when the second on-off valve is closed.

2. The flow diagnostic device according to claim 1, It is characterized in that The reference flow rate calculation unit calculates the reference flow rate based on the elapsed time from the start to the end of the inflow mode and the pressure difference between the initial pressure at the start of the inflow mode and the stabilized pressure after a predetermined time has passed since the end of the inflow mode.

3. The flow diagnostic device according to claim 1, It is characterized in that The first pressure control mechanism comprises: a first pressure sensor disposed on the branch line at a downstream side of the first on-off valve or disposed in the dead volume; A first control valve is disposed on the branch line; and The first pressure controller controls the first control valve based on a deviation between the first set pressure and a first measured pressure measured by the first pressure sensor.

4. The flow diagnostic device according to claim 3, It is characterized in that The second pressure control mechanism comprises: a second pressure sensor disposed on the main line at a downstream side of the second on-off valve or at the dead volume; a second control valve, disposed on the branch line; and The second pressure controller controls the second control valve based on a deviation between the second set pressure and a second measured pressure measured by the second pressure sensor.

5. The flow diagnostic device according to claim 4, It is characterized in that The first pressure sensor and the second pressure sensor are the same pressure sensor disposed in the dead volume.

6. The flow diagnostic device according to claim 4, It is characterized in that The second set pressure is an initial pressure measured by the second pressure sensor at the start point of the inflow mode.

7. The flow diagnostic device according to claim 2, It is characterized in that The reference flow rate calculation unit calculates a reference flow rate by correcting a pre-correction flow rate calculated based on the elapsed time, the pressure difference, and a gas state equation based on a maximum pressure or a pressure near the maximum pressure in the inflow pattern and the stabilized pressure.

8. The flow diagnostic device according to claim 1, It is characterized in that The second pressure control mechanism is configured not to perform pressure control of the fluid in the dead volume in the inflow mode when the flow rate through the main line is equal to or greater than a predetermined value.

9. The flow diagnostic device according to claim 1, It is characterized in that The inflow mode is set to end when the pressure in the container reaches a predetermined pressure, The second pressure control mechanism is configured not to perform pressure control of the fluid in the dead volume in the inflow mode when an elapsed time from the start to the end of the inflow mode is equal to or shorter than a predetermined time.

10. The flow diagnostic device according to claim 9, It is characterized in that The predetermined time is set based on a stabilization time required from when the inflow mode is started by the pressure control of the second pressure control mechanism until the pressure of the dead volume is stabilized at the second set pressure.

11. A flow diagnostic method, using a flow diagnostic device, wherein the flow diagnostic device include: A main line having a diagnostic object as a flow sensor or a flow control device disposed on an upstream side and a container having a predetermined capacity disposed on a downstream side; a branch line branching from an upstream side of the container in the main line; A first on-off valve is arranged on the branch line; a second on-off valve, arranged on the main line between a branch point of the branch line and the container; and a dead volume, which is a volume in which the diagnosis object is defined as an upstream end and the first opening and closing valve and the second opening and closing valve are defined as downstream ends in the main line and the branch line, The flow diagnosis method is characterized by comprising: In a preparation mode in which the first on-off valve is opened and the second on-off valve is closed so that the fluid does not flow into the container, controlling the fluid flowing through the branch line so that the pressure of the fluid in the dead volume is maintained at a first set pressure; After the preparation mode is implemented, in an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container, controlling the fluid flowing through the main line so that the pressure of the fluid in the dead volume is maintained at a second set pressure; and A reference flow rate as a flow rate of the fluid flowing into the container is calculated based on a pressure change caused by the fluid flowing into the container during a period from when the inflow mode starts to when the second on-off valve closes and the inflow mode ends.

12. A program storage medium storing a flow diagnostic device program, wherein the flow diagnostic device program is used in a flow diagnostic device, wherein the flow diagnostic device include: A main line having a diagnostic object as a flow sensor or a flow control device disposed on an upstream side and a container having a predetermined capacity disposed on a downstream side; a branch line branching from an upstream side of the container in the main line; A first on-off valve is arranged on the branch line; a second on-off valve, arranged on the main line between a branch point of the branch line and the container; and a dead volume, which is a volume in which the diagnosis object is defined as an upstream end and the first opening and closing valve and the second opening and closing valve are defined as downstream ends in the main line and the branch line, The program storage medium is characterized in that The flow diagnostic device program causes the computer to function as a first pressure controller, a second pressure controller, and a reference flow calculation unit. The first pressure controller controls the fluid flowing through the branch line to maintain the pressure of the fluid in the dead volume at a first set pressure in a preparation mode in which the first on-off valve is opened and the second on-off valve is closed so that the fluid does not flow into the container. After the preparation mode is implemented, the second pressure controller controls the fluid flowing through the main line in an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container so that the pressure of the fluid in the dead volume is maintained at a second set pressure. The reference flow rate calculation unit calculates a reference flow rate as a flow rate of the fluid flowing into the container based on a pressure change caused by the fluid flowing into the container from the start of the inflow mode to the end of the inflow mode when the second on-off valve is closed.

13. A flow diagnostic device, It is characterized in that include: A main line having a diagnostic object as a flow sensor or a flow control device disposed on an upstream side and a container having a predetermined capacity disposed on a downstream side; a branch line branching from an upstream side of the container in the main line; A first on-off valve is arranged on the branch line; a second on-off valve, arranged on the main line between a branch point of the branch line and the container; The dead volume is a volume in which the diagnosis object is defined as an upstream end and the first opening and closing valve and the second opening and closing valve are defined as downstream ends in the main line and the branch line; a first pressure control mechanism that controls the fluid flowing through the branch line to maintain the pressure of the fluid in the dead volume at a first set pressure in a preparation mode in which the first on-off valve is opened and the second on-off valve is closed so that the fluid does not flow into the container; as well as a reference flow rate calculation unit that calculates, after the preparation mode is implemented, a reference flow rate as a flow rate of the fluid flowing into the container based on a pressure change caused by the fluid flowing into the container from the start of an inflow mode in which the first on-off valve is closed and the second on-off valve is opened to allow the fluid to flow into the container until the second on-off valve is closed and the inflow mode ends, and an elapsed time from the start to the end of the inflow mode, The reference flow rate calculation unit is configured to calculate the elapsed time based on a measured value of a physical quantity of the fluid in the dead volume or a value indicating an actual operation of the first opening and closing valve or the second opening and closing valve.

14. The flow diagnostic device according to claim 13, It is characterized in that The reference flow rate calculation unit calculates the elapsed time based on a measured value of the pressure of the fluid in the dead volume.

15. The flow diagnostic device according to claim 13, It is characterized in that The reference flow rate calculation unit is configured to determine a time point when the pressure in the dead volume changes by a predetermined value or more after the first on-off valve and the second on-off valve are switched to open or close as a start time point of the inflow mode.

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