Flow calculation system, storage medium, flow calculation method and flow calculation device

Abstract

The present invention provides a flow calculation system, a storage medium, a flow calculation method and a flow calculation device. The flow calculation system comprises: a container into which a fluid flows; an inflow pipeline for allowing the fluid to flow into the container; a pressure sensor for detecting the pressure in the container, and further comprises: a pressure change data storage unit for storing pressure change data representing the time change of the pressure detected by the pressure sensor during the inflow period from the start of the fluid flowing into the container from the inflow pipeline to the stop of the fluid flowing into the container; a flow calculation unit for calculating an estimated flow rate of the fluid estimated to flow through the inflow pipeline during the inflow period based on the rate of change of pressure calculated based on the pressure change data; and a flow correction unit for correcting the estimated flow rate calculated by the flow calculation unit based on a first pressure detected by the pressure sensor after a specified time has passed since the fluid stopped flowing into the container and a second pressure higher than the first pressure contained in the pressure change data.

Description

Technical Field

[0001] The invention relates to a flow calculation system, a storage medium, a flow calculation method and a flow calculation device. Background Art

[0002] In a fluid supply system for supplying material gas (hereinafter also referred to as fluid) to a chamber of a film forming device in a semiconductor manufacturing process, etc., it is necessary to accurately manage the flow rate of the fluid supplied to the chamber, and therefore a flow control device is provided on the flow path where the fluid flows. In addition, the flow control device is a so-called mass flow controller, which is equipped with a flow sensor for detecting the flow rate of the fluid flowing through the flow path, and performs feedback control in such a way that the flow rate detected by the flow sensor approaches the set flow rate.

[0003] However, the flow control device cannot control the flow rate according to the set flow rate due to reasons such as aging, such as blockage of the flow channel, etc. Therefore, it is necessary to regularly check whether the flow control device can control the flow rate according to the set flow rate.

[0004] Therefore, in the conventional fluid supply system, a flow calculation system for checking the flow control device is sometimes assembled. For example, Patent Document 1 discloses a flow calculation system, which is provided with a fluid inspection channel for checking the flow control device independently of a fluid supply channel for supplying the fluid flowing through the flow control device to a chamber, and a container is provided in the middle of the fluid inspection channel.

[0005] In the flow calculation system, the estimated flow rate of the fluid estimated to flow through the flow control device is calculated by using a container and a dynamic constant volume method (pressure rise rate (ROR) method) to perform the inspection. Specifically, the flow calculation system causes the fluid flowing through the flow control device to flow into a container that is in a vacuum state for a specified period of time, and based on the rate of change (ΔP / Δt) of the pressure in the container generated at this time, the estimated flow rate of the fluid estimated to flow through the flow control device during the specified period is calculated. In addition, by comparing the estimated flow rate with the set flow rate, it is checked whether the flow rate of the fluid flowing through the flow control device becomes the same as the set flow rate.

[0006] Specifically, the estimated flow rate Q is calculated by the following formula 1.

[0007] [Formula 1]

[0008]

[0009] In addition, in the above formula 1, ΔP / Δt shows the rate of change of the pressure in the container per unit time, V represents the volume of the container, T represents the temperature of the container (specifically, the temperature of the internal space of the container, or the wall temperature of the container itself), and R represents the gas constant.

[0010] However, the inventors have discovered during research and development to further improve the flow calculation system that the estimated flow calculated by the formula 1 has an error relative to the actual flow of the fluid actually flowing through the flow control device due to the following phenomenon. Specifically, the inventors have discovered that in the process of causing the fluid flowing through the flow control device to flow into the container, adiabatic compression occurs in the container, causing the temperature of the fluid to rise. As a result, the rate of change of the pressure used when calculating the estimated flow by the formula 1 becomes a value affected by the temperature rise of the fluid in the container. As a result, if the estimated flow is calculated by the formula 1, an error will occur relative to the actual flow.

[0011] Prior art literature

[0012] Patent Document 1: Japanese Patent Publication No. 11-87318 Summary of the invention

[0013] Therefore, a main object of the present invention is to obtain a flow rate calculation system capable of calculating an estimated flow rate with high accuracy using a dynamic constant volume method.

[0014] That is, the flow calculation system of the present invention comprises: a container into which a fluid flows; an inflow pipeline for causing the fluid to flow into the container; and a pressure sensor for detecting the pressure in the container, and the flow calculation system is characterized in that it also comprises: a pressure change data storage unit for storing pressure change data during an inflow period, wherein the inflow period is a period from when the fluid starts to flow into the container through the inflow pipeline to when the fluid stops flowing into the container, and the pressure change data represents a time change of the pressure detected by the pressure sensor; a flow calculation unit for calculating an estimated flow rate of the fluid estimated to flow through the inflow pipeline during the inflow period based on a rate of change of pressure calculated based on the pressure change data; and a flow correction unit for correcting the estimated flow rate calculated by the flow calculation unit based on a first pressure and a second pressure, wherein the first pressure is a pressure detected by the pressure sensor after a predetermined time has passed since the fluid stopped flowing into the container, and the second pressure is a pressure higher than the first pressure included in the pressure change data.

[0015] According to the flow calculation system, since the flow calculated based on the rate of change of the pressure in the container during the inflow period is corrected based on the first pressure detected by the pressure sensor after a predetermined time has passed since the inflow of the fluid into the container was stopped and the second pressure higher than the first pressure included in the pressure change data, it is possible to suppress the error with respect to the actual flow rate generated when calculating the estimated flow rate of the fluid estimated to flow through the inflow pipe during the inflow period. Thus, the flow calculation system can calculate a more accurate estimated flow rate, in other words, a flow rate closer to the actual flow rate.

[0016] Specifically, the present inventors have found that in the process of continuously developing a flow rate calculation system using the dynamic constant volume method, a graph showing the time change of pressure with the vertical axis being the pressure P in the container and the horizontal axis being the time t (see Figure 4 ), from the point when the flow of fluid into the container stops until a certain degree of time has passed, the pressure P decreases and thereafter becomes a stable state (hereinafter, the pressure in this state is also referred to as stable pressure. In addition, to be precise, stable pressure means a state in which a sharp drop (fall) in pressure has subsided, and means a state in which the pressure is slightly reduced and continues.). It is believed that this is a phenomenon caused by the temperature rise caused by the adiabatic compression generated in the container during the inflow period. Therefore, it was found that if it is desired to calculate the estimated flow rate based on the pressure change data representing the time change of the pressure detected by the pressure sensor during the inflow period, the estimated flow rate is calculated based on the pressure affected by the temperature rise caused by the adiabatic compression generated in the container, and an error occurs between the estimated flow rate and the actual flow rate due to this reason. In addition, the inventors found that by correcting the estimated flow rate based on the first pressure and the second pressure, the influence of the temperature rise caused by the adiabatic compression on the estimated flow rate can be suppressed, thereby completing the present invention.

[0017] By the way, as shown in the present invention, the dynamic constant volume method calculates the estimated flow rate of the fluid estimated to flow through the inflow pipeline during the inflow period based on the rate of change of the pressure in the container during the inflow period. According to the flow calculation system using the dynamic constant volume method, compared with the flow calculation system using the static constant volume method, the peak formed by the maximum pressure of the pressure in the container during the inflow period and the stable pressure has a significant effect on the flow rate. Therefore, the effect of the correction based on the first pressure and the second pressure is also significantly manifested.

[0018] Furthermore, it is preferable that the second pressure is a maximum pressure or a pressure in the vicinity thereof included in the pressure change data.

[0019] According to this aspect, it is possible to significantly suppress an error caused by a temperature rise in the container included in the estimated flow rate calculated by the flow rate calculation unit.

[0020] Furthermore, specifically, the flow rate correction unit corrects the estimated flow rate based on a correction coefficient, and the correction coefficient is a ratio of the first pressure to the second pressure.

[0021] In addition, the following method may be adopted: the flow calculation system further includes a temperature sensor, the temperature sensor detects the temperature in the container or the container, and the flow calculation unit calculates the estimated flow rate based on the rate of change of the pressure and the temperature detected by the temperature sensor during the inflow period. Specifically, the following method may be adopted: the flow calculation system further includes: a temperature storage unit that stores temperature change data during the inflow period, the temperature change data indicating the time change of the temperature detected by the temperature sensor; and an average temperature calculation unit that calculates the average temperature of the container during the inflow period based on the temperature change data, and the flow calculation unit calculates the estimated flow rate based on the rate of change of the pressure and the average temperature.

[0022] As the container, for example, a container having a volume of 100 ml to 200 liters is used. In addition, the larger the volume of the container, the more temperature deviation occurs in the container, and the more the temperature sensor cannot detect the accurate temperature of the container. Therefore, when the estimated flow rate is calculated by the flow calculation unit, the estimated flow rate with a lower error can be calculated by using the average temperature of the container during the inflow period. Here, the temperature in the container or the container is, for example, the temperature of the internal space of the container or the wall temperature of the container.

[0023] Furthermore, the temperature sensor may detect the wall temperature of the container.

[0024] In addition, the following method can be adopted: the flow calculation system further includes a flow control device, the flow control device controls the flow rate of the fluid flowing through the inflow pipeline, and the flow calculation unit calculates the estimated flow rate of the fluid estimated to flow through the flow control device during the inflow period.

[0025] In addition, the following method can be adopted: the flow calculation system also includes: a branch pipeline, which branches from the inlet pipeline; and a switching mechanism, which switches between a first state and a second state, the first state is a state in which the fluid only flows to the branch pipeline, and the second state is a state in which the fluid only flows to the downstream side of the inlet pipeline and the branch point of the branch pipeline, and the flow control device is arranged on the upstream side of the inlet pipeline and the branch point of the branch pipeline.

[0026] According to this method, after the container is evacuated before the inflow period, the fluid can flow to the flow control device through the branch pipe while the container is kept in a vacuum state. Thus, by switching from the first state to the second state by the switching mechanism at the same time as the fluid starts to flow into the container from the inflow pipe, a stable flow of fluid can be immediately flowed from the flow control device into the container.

[0027] In addition, a storage medium of the present invention stores a program for a flow calculation system, the flow calculation system comprising: a container into which a fluid flows; an inflow pipe for causing the fluid to flow into the container; and a pressure sensor for detecting the pressure in the container, wherein the storage medium is characterized in that the program functions as a pressure change data storage unit, a flow calculation unit, and a flow correction unit, the pressure change data storage unit storing pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container from the inflow pipe to when the fluid stops flowing into the container, the pressure change data indicating a time change of the pressure detected by the pressure sensor, the flow calculation unit calculating an estimated flow rate of the fluid estimated to flow through the inflow pipe during the inflow period based on a change rate of the pressure calculated from the pressure change data, and the flow correction unit correcting the estimated flow rate calculated by the flow calculation unit based on a first pressure and a second pressure, the first pressure being a pressure detected by the pressure sensor after a predetermined time has passed since the fluid stopped flowing into the container, and the second pressure being a pressure higher than the first pressure included in the pressure change data. The flow rate calculation program may be a program distributed electronically, or may be stored in a program storage medium such as a CD, a DVD, a BD, or a flash memory.

[0028] In addition, the flow calculation method of the present invention is used in a flow calculation system, the flow calculation system comprising: a container, into which a fluid flows; an inflow pipeline, into which the fluid flows; and a pressure sensor, which detects the pressure in the container, the flow calculation method is characterized in that it includes: a step of storing pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container through the inflow pipeline to when the fluid stops flowing into the container, the pressure change data representing the time change of the pressure detected by the pressure sensor; a step of calculating an estimated flow rate of the fluid estimated to flow through the inflow pipeline during the inflow period based on a rate of change of pressure calculated based on the pressure change data; and a step of correcting the calculated estimated flow rate based on a first pressure and a second pressure, the first pressure being a pressure detected by the pressure sensor after a specified time has passed since the fluid stopped flowing into the container, and the second pressure being a pressure higher than the first pressure contained in the pressure change data.

[0029] In addition, the flow rate calculation device of the present invention is used in a flow rate calculation system, the flow rate calculation system comprising: a container into which a fluid flows; an inflow pipe for causing the fluid to flow into the container; and a pressure sensor for detecting the pressure in the container, the flow rate calculation device being characterized in that it comprises: a pressure change data storage unit for storing pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container through the inflow pipe to when the fluid stops flowing into the container, the pressure change data representing a time change of the pressure detected by the pressure sensor; a flow rate calculation unit for calculating an estimated flow rate of the fluid estimated to flow through the inflow pipe during the inflow period based on a rate of change of pressure calculated from the pressure change data; and a flow rate correction unit for correcting the estimated flow rate calculated by the flow rate calculation unit based on a first pressure and a second pressure, the first pressure being a pressure detected by the pressure sensor after a predetermined time has passed since the fluid stopped flowing into the container, and the second pressure being a pressure higher than the first pressure included in the pressure change data.

[0030] In addition, the flow calculation system of the present invention comprises: a container into which a fluid flows; an inflow pipe for causing the fluid to flow into the container; a pressure sensor for detecting the pressure in the container; and a temperature sensor for detecting the temperature in or of the container, and is characterized in that the flow calculation system further comprises: a pressure change data storage unit for storing pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container from the inflow pipe to when the fluid stops flowing into the container, the pressure change data indicating a time change of the pressure detected by the pressure sensor; a temperature change data storage unit for storing temperature change data during the inflow period, the temperature change data indicating a time change of the temperature detected by the temperature sensor; a flow calculation unit for calculating an estimated flow rate of the fluid estimated to flow through the inflow pipe during the inflow period based on a change rate of the pressure calculated from the pressure change data; and a flow correction unit for correcting the estimated flow rate based on a first temperature and a second temperature, the first temperature being a temperature detected by the temperature sensor after a predetermined time has passed since the first on / off valve was closed, and the second temperature being a temperature higher than the first temperature in the temperature change data.

[0031] In this manner, the estimated flow rate calculated based on the rate of change of the pressure in the container during the inflow period is corrected based on the first temperature detected by the temperature sensor after a predetermined time has passed since the inflow of the fluid into the container was stopped and the second temperature higher than the first temperature included in the temperature change data, thereby suppressing the error with respect to the actual flow rate generated when calculating the estimated flow rate of the fluid estimated to flow through the inflow pipe during the inflow period. As a result, a more accurate estimated flow rate can be calculated by the flow calculation system.

[0032] According to the flow rate calculation system configured as described above, it is possible to calculate the estimated flow rate with high accuracy by the dynamic constant volume method. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram showing a flow rate calculation system according to an embodiment.

[0034] Figure 2 It is a block diagram showing the functions of the flow rate calculation system according to the embodiment.

[0035] Figure 3 This is a flowchart showing the operation of the flow rate calculation system according to the embodiment.

[0036] Figure 4 This is a diagram showing the time change of the pressure from the time when the flow rate calculation system according to the embodiment is switched to the exhaust mode to the time when a predetermined time has passed after the switching to the stop mode.

[0037] Figure 5 It is a schematic diagram showing a flow rate calculation system according to another embodiment.

[0038] Description of Reference Numerals

[0039] 100 Flow calculation system

[0040] 10 Container

[0041] 20 Pumps

[0042] L1 Inlet pipe

[0043] L2 Outflow line

[0044] L3 branch line

[0045] V1 First switch valve

[0046] V2 Second on / off valve

[0047] V3 Third switch valve

[0048] P Pressure Sensor

[0049] T Temperature sensor

[0050] C Flow Calculation Device

[0051] C1 Valve Control Unit

[0052] C2 Pressure change data storage unit

[0053] C3 Temperature change data storage unit

[0054] C4 Average temperature calculation unit

[0055] C5 Flow Calculation Unit

[0056] C6 Flow Correction Unit

[0057] C7 Display Control Unit

[0058] MFC Flow Control Device DETAILED DESCRIPTION

[0059] Hereinafter, the flow rate calculation system of the present invention will be described with reference to the drawings.

[0060] The flow rate calculation system of the present invention is used to inspect and calibrate a flow rate control device assembled in a semiconductor production line or the like.

[0061] like Figure 1As shown, the flow calculation system 100 of this embodiment includes: a container 10, into which a fluid flows; an inflow pipe L1, which allows the fluid to flow into the container 10; an outflow pipe L2, which allows the fluid to flow out of the container 10; a branch pipe L3, which branches from the inflow pipe L1; and a flow calculation device C.

[0062] The container 10 is provided with: a pressure sensor P for detecting the pressure in the container 10; and a temperature sensor T for detecting the wall temperature (specifically, the temperature of the outer wall) of the container 10. In addition, the temperature sensor T can also detect the temperature of the internal space of the container and the temperature of the inner wall of the container.

[0063] A flow control device MFC is provided on the inflow pipeline L1, and the flow control device MFC controls the flow rate of the fluid flowing through the inflow pipeline L1. The flow control device MFC is a mass flow controller, which includes: a flow sensor such as a thermal type or a pressure type; a flow control valve such as a piezoelectric valve; and a control circuit including a CPU and a memory. In addition, the flow calculation system 100 of this embodiment checks the flow control device MFC.

[0064] A pump 20 is provided on the downstream side of the outflow pipeline L2 , and the pump 20 is used to discharge the fluid from the container 10 .

[0065] The upstream end of the branch line L3 is connected to the inflow line L1 at a position downstream of the flow control device MFC, and the downstream end is connected to the outflow line L2 at a position upstream of the pump 20. That is, the branch line L3 is connected to the inflow line L1 and the outflow line L2 in a manner bypassing the container 10.

[0066] In addition, the inflow pipeline L1, the outflow pipeline L2, and the branch pipeline L3 are provided with switch valves V1 to V3, respectively. In addition, the flow calculation system 100 switches to the exhaust mode, vacuum exhausting the container 10; the preparation mode, maintaining the container 10 in a vacuum state and stabilizing the flow of the flow control device MFC; the inflow mode, allowing the fluid to flow into the container 10; and the stop mode, stopping the flow of the fluid into the container 10.

[0067] Specifically, on the inflow pipeline L1, a first switch valve V1 is provided on the downstream side of the branch point with the branch pipeline L3. In addition, on the outflow pipeline L2, a second switch valve V2 is provided on the upstream side of the confluence point with the branch pipeline L3. In addition, on the branch pipeline L3, a third switch valve V3 is provided in the middle. In addition, the first switch valve V1 and the third switch valve V3 play the role of a switching mechanism, and the switching mechanism switches between a first state and a second state, the first state is a state in which the fluid flowing in the upstream side of the branch point of the inflow pipeline L1 with the branch pipeline L3 flows only to the branch pipeline L3, and the second state is a state in which the fluid flowing in the upstream side of the branch point of the inflow pipeline L1 with the branch pipeline L3 flows only to the downstream side of the branch point of the inflow pipeline L1 with the branch pipeline L3. That is, the first switch valve V1 and the third switch valve V3 act as a switching mechanism, and the switching mechanism switches in the following manner: the fluid flowing in the ratio of the inflow pipeline L1 to the upstream side of the branch point of the branch pipeline L3 selectively flows to the branch pipeline L3 and the downstream side of the branch point of the inflow pipeline L1 to the branch pipeline L3.

[0068] In addition, when the switch valves V1 to V3 receive a switching signal to switch to the exhaust mode, the first switch valve V1 is closed, the second switch valve V2 is opened, and the third switch valve V3 is closed. Thus, the container 10 is vacuum-exhausted by the pump 20 provided on the outflow line L2. In addition, the fluid flowing through the inflow line L1 passes through the first switch valve V1 and the third switch valve V3 without flowing to the downstream side of the container 10. Thus, the pump 20 is not connected to the flow control device MFC but is only connected to the container 10, and the container 10 is fully exhausted.

[0069] Next, when the switch valves V1 to V3 receive a switching signal to switch to the preparation mode, the first switch valve V1 is closed, the second switch valve V2 is closed, and the third switch valve V3 is opened. As a result, the container 10 is sealed by the first switch valve V1 and the second switch valve V2 and maintained in a vacuum state. In addition, the fluid flowing through the inflow pipe L1 flows to the downstream side of the container through the branch pipe L3. As a result, the flow control device MFC returns to a stable flow state from an unstable flow state in the exhaust mode.

[0070] Next, when the switch valves V1 to V3 receive a switching signal to switch to the inflow mode, the first switch valve V1 is opened, the second switch valve V2 is closed, and the third switch valve V3 is closed. As a result, the fluid flowing through the inflow line L1, in other words, the fluid flowing through the flow control device MFC, all flows into the container 10.

[0071] Next, when the switch valves V1 to V3 receive a switching signal to switch to the stop mode, the first switch valve V1 is closed, the second switch valve V2 is closed, and the third switch valve V3 is opened. Thus, the container 10 is kept sealed by the first switch valve V1 and the second switch valve V2. In addition, the fluid flowing through the inflow pipe L1 begins to flow to the downstream side of the container 10 again through the branch pipe L3.

[0072] In addition, the flow calculation device C is connected to each of the switch valves V1 to V3, the pressure sensor P, the temperature sensor T, the flow control device MFC, and a display unit (not shown). In addition, specifically, the flow calculation device C is a computer having a CPU, a memory, an AD converter, a DC converter, an input device, etc., and the CPU executes a program stored in the memory, such as Figure 2 As shown, it functions as a valve control unit C1, a pressure change data storage unit C2, a temperature change data storage unit C3, an average temperature calculation unit C4, a flow calculation unit C5, a flow correction unit C6, a display control unit C7, etc. The display unit is, for example, a display.

[0073] The valve control unit C1 controls the opening and closing of the first switch valve V1, the second switch valve V2, and the third switch valve V3. Specifically, upon receiving a flow calculation start signal, the valve control unit C1 sends a switching signal to switch to the exhaust mode, the preparation mode, the inflow mode, and the stop mode to each switch valve V1 to V3 in the following order.

[0074] The pressure change data storage unit C2 stores pressure change data indicating a temporal change in pressure detected by the pressure sensor P. Specifically, the pressure change data storage unit C2 stores at least an inflow period from the start of switching to the inflow mode to the end of switching to the stop mode (see Figure 4 ) represents the pressure change data of the time change of the pressure detected by the pressure sensor P. More specifically, the pressure change data storage unit C2 only needs to store at least the pressure change data of the period from the switching to the inflow mode to the period after the change rate (increase rate) of the pressure in the container 10 becomes stable during the inflow period. In addition, the pressure change data storage unit C2 of this embodiment stores the pressure change data of the inflow period and the standby period (refer to Figure 4 ) are added together, wherein the standby period is the period from when the mode is switched to the stop mode to when a prescribed time has passed while the mode is maintained in the stop mode.

[0075] The temperature change data storage unit C3 stores temperature change data indicating the time change of the temperature detected by the temperature sensor T. Specifically, the temperature change data storage unit C3 stores at least the temperature change data indicating the time change of the temperature detected by the temperature sensor T during the inflow period. In addition, the temperature change data storage unit C3 may store the temperature change data of a part of the inflow period, similarly to the pressure change data storage unit C2.

[0076] In addition, the pressure change data storage unit C2 can store the pressure change data during the entire operation of the flow calculation system 100, or can refer to the switching signal sent from the valve control unit C1 to each switch valve V1 to V3 to store the pressure change data during a required period. The same is true for the temperature change data storage unit C3.

[0077] The average temperature calculation unit C4 calculates the average temperature of the container 10 during the inflow period. Specifically, the average temperature calculation unit C4 calculates the average temperature based on the temperature change data during the inflow period stored in the temperature change data storage unit C3.

[0078] The flow calculation unit C5 calculates the estimated flow rate of the fluid estimated to flow through the inflow pipe L1 during the inflow period using a theoretical formula. Specifically, the flow calculation unit C5 calculates the estimated flow rate based on the rate of change (rate of increase) of pressure calculated based on the pressure change data during the inflow period stored in the pressure change data storage unit C2 and the average temperature calculated by the average temperature calculation unit C4. More specifically, the flow calculation unit C5 substitutes the rate of change of pressure and the average temperature into the formula 1 to calculate the estimated flow rate. In addition, the flow calculation unit C5 calculates the rate of change of pressure per unit time with reference to the pressures at multiple time points included in the pressure change data.

[0079] Here, the estimated flow rate of the fluid estimated to flow through the inflow conduit L1 is controlled by the flow control device MFC. Therefore, it can be said that the flow calculation unit C5 calculates the estimated flow rate of the fluid estimated to flow through the flow control device MFC.

[0080] The flow correction unit C6 corrects the estimated flow calculated by the flow calculation unit C5. Specifically, the flow correction unit C6 corrects the estimated flow based on a first pressure and a second pressure, wherein the first pressure is a pressure detected by the pressure sensor P after a predetermined time has passed since the inflow mode was switched to the stop mode, and the second pressure is a pressure higher than the first pressure included in the pressure change data during the inflow period. Specifically, the flow correction unit C6 corrects the estimated flow based on a correction coefficient, which is a ratio of the first pressure to the second pressure. More specifically, the flow correction unit C6 corrects the estimated flow by multiplying the correction coefficient by the estimated flow.

[0081] Here, refer to Figure 4 , the first pressure and the second pressure are described in detail. The pressure in the container 10 during the inflow period is increased not only by the increase of the fluid flowing in from the inflow line L1 but also by the temperature rise caused by the adiabatic compression in the container 10. Therefore, just after the end of the inflow period, the pressure sensor P detects the pressure affected by the temperature rise caused by the adiabatic compression in the container 10. However, if a predetermined time has passed since the end of the inflow period, the pressure sensor P detects a pressure (stable pressure) that is almost not affected by the temperature rise caused by the adiabatic compression in the container 10. In addition, this pressure becomes the first pressure.

[0082] The predetermined time is a time selected within the range of several minutes to several hours. In addition, the longer the time after the end of the inflow period, the smaller the influence of the temperature rise caused by the adiabatic compression in the container 10 on the pressure detected by the pressure sensor P. Therefore, the longer the predetermined time is, the more a correction coefficient that can correct the estimated flow rate to be close to the actual flow rate can be obtained.

[0083] In addition, the second pressure is a pressure higher than the first pressure among the pressures detected by the pressure sensor P during the inflow period. In addition, it is preferred that the second pressure is the maximum pressure of the pressures detected by the pressure sensor during the inflow period or a pressure in the vicinity thereof. In this embodiment, the maximum pressure of the pressures detected by the pressure sensor P during the inflow period is set as the second pressure.

[0084] Furthermore, the display control unit C7 displays the corrected estimated flow rate calculated by the flow rate correction unit C6 on the display unit.

[0085] Next, the operation of the flow rate calculation system 100 will be described.

[0086] First, upon receiving the flow calculation start signal, the valve control unit C1 sequentially sends switching signals to the exhaust mode, the preparation mode, the inflow mode, and the stop mode to the switch valves V1 to V3. As a result, the switch valves V1 to V3 sequentially switch to the respective modes (step S1, step S2, step S3, step S5).

[0087] Furthermore, if the inflow mode is switched to, the pressure change data storage unit C2 starts storing the pressure change data (step S4). Furthermore, if a predetermined time has passed since the inflow mode was switched to the stop mode while the stop mode was maintained, the pressure change data storage unit C2 ends storing the pressure change data (step S8). That is, the pressure change data storage unit C2 stores the pressure change data of the period of adding the inflow period and the standby period, wherein the inflow period is the period from the switching to the inflow mode to the switching to the stop mode, and the standby period is the period from the switching to the stop mode to the predetermined time having passed while the stop mode was maintained.

[0088] Furthermore, if the inflow mode is switched to the inflow mode, the temperature change data storage unit C3 starts storing the temperature change data (step 4). Furthermore, if the inflow mode is switched to the stop mode, the temperature change data storage unit C3 ends storing the temperature change data (step S6). That is, the temperature change data storage unit C3 stores the temperature change data during the inflow period.

[0089] Next, the average temperature calculation unit C4 calculates the average temperature of the container 10 during the inflow period based on the temperature change data stored in the temperature change data storage unit C3 (step S9).

[0090] Next, the flow rate calculation unit C5 calculates the change rate of the pressure during the inflow period based on the pressure change data stored in the pressure change data storage unit C2. In addition, the flow rate calculation unit C5 calculates the estimated flow rate of the fluid estimated to flow through the inflow pipe L1 during the inflow period based on the change rate of the pressure and the average temperature (step S10). Specifically, the flow rate calculation unit C5 substitutes the change rate of the pressure and the average temperature into the above formula 1 to calculate the estimated flow rate of the fluid estimated to flow through the inflow pipe L1 during the inflow period.

[0091] Next, the flow correction unit C6 corrects the estimated flow calculated by the flow calculation unit (step S11). Specifically, the flow correction unit C6 refers to the pressure change data during the standby period, and obtains the pressure at a predetermined time after the inflow mode is switched to the stop mode as the first pressure. In addition, the flow correction unit C6 refers to the pressure change data during the inflow period, and obtains a pressure higher than the first pressure as the second pressure. Specifically, the flow correction unit C6 refers to the pressure change data during the inflow period, and obtains the maximum pressure during the inflow period or the pressure in the vicinity thereof as the second pressure. That is, the flow correction unit C6 obtains the pressure at the time point when the inflow mode is switched to the stop mode, or just before or immediately after the time point, as the second pressure.

[0092] In addition, the flow correction unit C6 calculates a correction coefficient based on the first pressure and the second pressure obtained, and corrects the estimated flow calculated by the flow calculation unit C5 according to the correction coefficient. Specifically, the flow correction unit C6 uses the ratio of the first pressure P1 to the second pressure P2, that is, P1 / P2, as the correction coefficient, and multiplies the estimated flow by the correction coefficient for correction.

[0093] Thereafter, the display control unit C7 displays the estimated flow rate after correction obtained by the flow rate correction unit C6 on the display unit (step S12).

[0094] <Other Implementation Methods>

[0095] In the flow rate calculation system 100 of the embodiment, the branch line L3 branched from the inflow line L1 is connected to the outflow line L2 in a manner bypassing the container 10. Figure 5 As shown, the downstream side of the branch line L3 may be connected to the chamber CH to which the fluid is supplied, thereby forming a fluid supply system incorporating the flow rate calculation system 100. With the fluid supply line thus constructed, the fluid flowing through the inflow line L1 can be continuously supplied to the chamber CH except during the inflow period. Thus, when calculating the estimated flow rate, the supply stop time to the chamber CH can be shortened.

[0096] In addition, in the flow calculation system 100 of the embodiment, the flow calculation device C can also be used as a flow inspection device, and the flow inspection device not only plays the various functions of the flow calculation device C but also plays the function of a flow comparison unit. In this case, the flow comparison unit only needs to compare the set flow set for the flow control device MFC during the inflow period with the corrected estimated flow calculated by the flow correction unit C6. In addition, the flow calculation device C can be used as a flow calibration device, and the flow calibration device not only plays the various functions of the flow calculation device but also plays the functions of a flow comparison unit and a calibration unit. In this case, the calibration unit only needs to calibrate the flow control device MFC according to the comparison result of the flow comparison unit. In addition, like the flow calculation device, the flow inspection device and the flow calibration device are computers having a CPU, a memory, an AD converter, a DC converter, an input device, etc., and the functions of each mechanism are played by the CPU executing the program stored in the memory.

[0097] In addition, in the above-described embodiment, the pressure change data during the inflow period and the standby period are stored in the pressure change data storage unit C2, but the present invention is not limited thereto. For example, only the pressure change data during the inflow period may be stored in the pressure change data storage unit C2. In this case, the flow correction unit C6 may obtain the pressure detected by the pressure sensor P when a predetermined time has passed since the inflow mode was switched to the stop mode, and set the pressure as the first pressure. In addition, the pressure change data during the period other than the inflow period and the standby period may be stored in the pressure change data storage unit C2.

[0098] In addition, in the above embodiment, the flow correction unit C6 corrects the estimated flow calculated by the flow calculation unit C5 based on the first pressure and the second pressure, but the present invention is not limited thereto. For example, the flow correction unit C6 may correct the estimated flow based on the first temperature and the second temperature, wherein the first temperature is the temperature detected by the temperature sensor T after a predetermined time has passed since the first switch valve V1 was closed, and the second temperature is a temperature higher than the first temperature in the temperature change data.

[0099] Furthermore, the present invention is of course not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

Claims

1. A flow rate calculation system comprising: a container into which a fluid flows; an inflow pipe through which the fluid flows into the container; and a pressure sensor for detecting the pressure in the container. The flow calculation system is characterized in that it further comprises: A pressure change data storage unit storing pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container through the inflow pipe to when the fluid stops flowing into the container, the pressure change data indicating a time change of the pressure detected by the pressure sensor; a flow rate calculation unit that calculates a pressure change rate using pressures at a plurality of time points within the inflow period included in the pressure change data, and calculates an estimated flow rate of a fluid estimated to flow through the inflow pipe during the inflow period using the calculated pressure change rate; as well as The flow correction unit corrects the estimated flow calculated by the flow calculation unit based on the ratio of a first pressure and a second pressure as a correction coefficient, wherein the first pressure is a pressure detected by the pressure sensor after a specified time has passed since the flow of fluid into the container was stopped, and the second pressure is a pressure higher than the first pressure included in the pressure change data.

2. The flow calculation system according to claim 1, characterized in that: The second pressure is a maximum pressure or a pressure in the vicinity of a maximum pressure included in the pressure change data.

3. The flow calculation system according to claim 1, characterized in that: The flow rate calculation system further includes a temperature sensor, which detects the temperature in the container or the container. The flow rate calculation unit calculates the estimated flow rate based on the rate of change of the pressure and the temperature detected by the temperature sensor during the inflow period.

4. The flow calculation system according to claim 3, characterized in that: The flow calculation system also has: a temperature storage unit that stores temperature change data during the inflow period, the temperature change data indicating a time change in temperature detected by the temperature sensor; and an average temperature calculation unit that calculates an average temperature of the inside of the container or the container during the inflow period based on the temperature change data, The flow rate calculation unit calculates the estimated flow rate based on the rate of change of the pressure and the average temperature.

5. The flow calculation system according to claim 3, characterized in that: The temperature sensor detects a wall temperature of the container.

6. The flow calculation system according to claim 1, characterized in that: The flow calculation system further comprises a flow control device, which controls the flow rate of the fluid flowing through the inflow pipeline. The flow rate calculation unit calculates an estimated flow rate of a fluid estimated to flow through the flow rate control device during the inflow period.

7. The flow calculation system according to claim 6, characterized in that: The flow calculation system also has: A branch line branching from the inflow line; and The switching mechanism switches between a first state and a second state, wherein the first state is a state in which the fluid flows only to the branch pipeline, and the second state is a state in which the fluid flows only to the downstream side of the inlet pipeline relative to the branch point of the branch pipeline, The flow control device is disposed on the upstream side of the inflow pipeline relative to a branching point with the branch pipeline.

8. A storage medium storing a program for a flow calculation system, the flow calculation system comprising: a container into which a fluid flows; an inflow pipe for causing the fluid to flow into the container; and a pressure sensor for detecting a pressure in the container. The storage medium is characterized in that The program functions as a pressure change data storage unit, a flow rate calculation unit, and a flow rate correction unit. The pressure change data storage unit stores pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container through the inflow pipe to when the fluid stops flowing into the container, the pressure change data indicating a temporal change in pressure detected by the pressure sensor, The flow rate calculation unit calculates a pressure change rate using pressures at a plurality of time points within the inflow period included in the pressure change data, and calculates an estimated flow rate of the fluid estimated to flow through the inflow pipe during the inflow period using the calculated pressure change rate. The flow correction unit corrects the estimated flow calculated by the flow calculation unit based on the ratio of a first pressure and a second pressure as correction coefficients, wherein the first pressure is a pressure detected by the pressure sensor after a specified time has passed since the flow of fluid into the container was stopped, and the second pressure is a pressure higher than the first pressure and included in the pressure change data.

9. A flow calculation method, which is used in a flow calculation system, the flow calculation system comprising: a container, into which a fluid flows; an inflow pipeline, which allows the fluid to flow into the container; and a pressure sensor for detecting the pressure in the container, The flow calculation method is characterized by comprising: a step of storing pressure variation data during an inflow period, wherein the inflow period is a period from when the fluid starts to flow into the container through the inflow pipe to when the fluid stops flowing into the container, the pressure variation data indicating a temporal variation of the pressure detected by the pressure sensor; a step of calculating a pressure change rate using pressures at a plurality of time points within the inflow period included in the pressure change data, and calculating an estimated flow rate of a fluid estimated to flow through the inflow pipe during the inflow period using the calculated pressure change rate; as well as A step of correcting the calculated estimated flow rate based on a ratio of a first pressure and a second pressure as correction coefficients, wherein the first pressure is a pressure detected by the pressure sensor after a specified time has passed since the flow of fluid into the container was stopped, and the second pressure is a pressure higher than the first pressure included in the pressure change data.

10. A flow calculation device, the flow calculation device being used in a flow calculation system, the flow calculation system comprising: a container into which a fluid flows; an inflow pipe into which the fluid flows; and a pressure sensor for detecting the pressure in the container. The flow rate calculation device is characterized by comprising: A pressure change data storage unit storing pressure change data during an inflow period, the inflow period being a period from when the fluid starts to flow into the container through the inflow pipe to when the fluid stops flowing into the container, the pressure change data indicating a time change of the pressure detected by the pressure sensor; a flow rate calculation unit that calculates a pressure change rate using pressures at a plurality of time points within the inflow period included in the pressure change data, and calculates an estimated flow rate of a fluid estimated to flow through the inflow pipe during the inflow period using the calculated pressure change rate; as well as The flow correction unit corrects the estimated flow calculated by the flow calculation unit based on the ratio of a first pressure and a second pressure as a correction coefficient, wherein the first pressure is a pressure detected by the pressure sensor after a specified time has passed since the flow of fluid into the container was stopped, and the second pressure is a pressure higher than the first pressure included in the pressure change data.

Images