Flow rate calculation system, program for flow rate calculation system, flow rate calculation method, and flow rate calculation device

Abstract

To accurately detect an estimated flow rate by a dynamic fixed volume method.SOLUTION: A flow rate calculation system comprising a container in which a fluid is caused to flow, an inflow line in which a fluid is caused to flow into the container, and a pressure sensor that detects pressure in the container, includes: a pressure change data storage unit that stores pressure change data indicating a time change of pressure detected by the pressure sensor, during an inflow period from when a fluid is caused to flow into the container from the inflow line to when the inflow of the fluid into the container is stopped; a flow rate calculation unit that, based on a change rate of pressure, calculated from the pressure change data, calculates an estimated flow rate of the fluid estimated to have been flowing in the inflow line during the inflow period; and a flow rate correction unit that, based on first pressure detected by the pressure sensor after passage of a predetermined time following the stop of inflow of the fluid into the container and second pressure higher than the first pressure included in the pressure change data, corrects the estimated flow rate calculated by the flow rate calculation unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flow rate calculation system, a program for the flow rate calculation system, a flow rate calculation method, and a flow rate calculation device. [Background technology]

[0002] In a fluid supply system that supplies a material gas (hereinafter also referred to as a fluid) to a chamber of a film forming device in a semiconductor manufacturing process or the like, the flow rate of the fluid to be supplied to the chamber must be accurately controlled, so a flow control device is provided in the flow path through which the fluid flows. Note that the flow control device is a so-called mass flow controller, which has a flow sensor that detects the flow rate of the fluid flowing through the flow path, and is configured to perform feedback control so that the flow rate detected by the flow sensor approaches a set flow rate.

[0003] However, the flow control device may become unable to control the flow rate according to the set flow rate due to aging deterioration such as clogging of the flow path, etc. For this reason, the flow control device needs to be periodically inspected to see whether it is controlling the flow rate according to the set flow rate.

[0004] Therefore, some conventional fluid supply systems incorporate a flow rate calculation system for inspecting the flow rate control device. For example, Patent Document 1 discloses a flow rate calculation system in which a fluid inspection flow path for inspecting the flow rate control device is provided in addition to a fluid supply flow path for supplying the fluid flowing through the flow rate control device to a chamber, and a container is placed midway along the fluid inspection flow path.

[0005] The flow rate calculation system is configured to use a container to calculate and inspect an estimated flow rate of a fluid estimated to have flowed through a flow control device by the dynamic constant volume method (rate of rise of pressure (ROR) method). Specifically, the flow rate calculation system causes the fluid flowing through the flow control device to flow into a vacuum container for a predetermined period of time, and calculates an estimated flow rate of the fluid estimated to have flowed through the flow control device during the predetermined period based on the rate of change (ΔP / Δt) of pressure inside the container that occurs at this time. Then, by comparing the estimated flow rate with a set flow rate, it is inspected whether the flow rate of the fluid flowing through the flow control device is in line with the set flow rate.

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

[0007]

number

[0008] In the above formula 1, ΔP / Δt represents the rate of change of pressure per unit time inside the container, 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.

[0009] Meanwhile, while the applicant was conducting research and development to further improve the flow rate calculation system, the applicant discovered that the estimated flow rate calculated by the above formula 1 has an error with respect to the actual flow rate of the fluid flowing through the flow control device due to the following phenomenon. In detail, in the process of flowing the fluid flowing through the flow control device into a container, adiabatic compression occurs in the container, causing the temperature of the fluid to rise. As a result, the rate of change of pressure used when calculating the estimated flow rate by the above formula 1 becomes a value affected by the temperature rise of the fluid in the container, and as a result, when the estimated flow rate is calculated by the above formula 1, an error occurs with respect to the actual flow rate. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 11-87318 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, a main object of the present invention is to provide a flow rate calculation system that can accurately calculate an estimated flow rate by the dynamic constant volume method. [Means for solving the problem]

[0012] That is, the flow rate calculation system of the present invention is a flow rate calculation system comprising a container into which a fluid is flowed, an inflow line through which the fluid flows into the container, and a pressure sensor that detects the pressure inside the container, and is characterized by comprising: a pressure change data memory unit that stores pressure change data indicating the time change in pressure detected by the pressure sensor during an inflow period from when the fluid starts to flow into the container from the inflow line to when the flow of the fluid into the container is stopped; a flow rate calculation unit that calculates an estimated flow rate of the fluid that is estimated to have flowed through the inflow line during the inflow period based on a rate of change of pressure calculated from the pressure change data; and a flow rate correction unit that corrects the estimated flow rate calculated by the flow rate calculation unit based on a first pressure detected by the pressure sensor a predetermined time after the flow of the fluid into the container is stopped and a second pressure higher than the first pressure included in the pressure change data.

[0013] In this way, the 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 pressure detected by the pressure sensor a predetermined time after the inflow of the fluid into the container is stopped and the second pressure included in the pressure change data that is higher than the first pressure, so that an error with respect to the actual flow rate that occurs when calculating the estimated flow rate of the fluid estimated to have flowed through the inflow line during the inflow period can be suppressed. This makes it possible for the flow rate calculation system to calculate a more accurate estimated flow rate, in other words, an estimated flow rate that is closer to the actual flow rate.

[0014] Specifically, the applicant, while continuing research and development of a flow rate calculation system using the dynamic constant volume method, discovered that in a graph (see FIG. 4) showing the change in pressure over time, with the pressure P in the container on the vertical axis and the time t on the horizontal axis, the pressure P drops until a certain time has passed since the inflow of the fluid into the container was stopped, and then becomes stable (hereinafter, the pressure in this state is also called stable pressure. Note that, more precisely, the stable pressure indicates a state in which the sudden drop (drop) of pressure has subsided, and the pressure continues to drop slightly). This is considered to be a phenomenon caused by a temperature rise caused by adiabatic compression occurring in the container during the inflow period. For this reason, when an estimated flow rate is calculated using pressure change data showing the time change of the pressure detected by a pressure sensor during the inflow period, the estimated flow rate is calculated using pressure affected by the temperature rise caused by adiabatic compression occurring in the container, and this causes an error with the actual flow rate. The applicant then discovered that the effect of the temperature rise caused by adiabatic compression on the estimated flow rate can be suppressed by correcting the estimated flow rate based on the first pressure and the second pressure, and thus completed the present invention.

[0015] In this regard, in the flow rate calculation system using the dynamic constant volume method according to the present invention, which calculates the estimated flow rate of the fluid estimated to have flowed through the inflow line during the inflow period based on the rate of change of the pressure in the container during the inflow period, the effect on the flow rate of the peak formed by the maximum pressure in the container during the inflow period and the stable pressure is more pronounced than in the flow rate calculation system using the static constant volume method, and therefore the effect of correction based on the first pressure and the second pressure is also more pronounced.

[0016] It is preferable that the second pressure is a maximum pressure included in the pressure change data or a pressure close to the maximum pressure.

[0017] With this, it is possible to significantly reduce errors due to temperature rise inside the container that are included in the estimated flow rate calculated by the flow rate calculation section.

[0018] Specifically, the flow rate correction unit corrects the estimated flow rate based on a correction coefficient that is a ratio of the first pressure to the second pressure.

[0019] The apparatus may further include a temperature sensor for detecting a temperature inside or in the container, and the flow rate calculation unit may calculate the estimated flow rate based on a rate of change of the pressure and a temperature detected by the temperature sensor during the inflow period. Specifically, the apparatus may further include a temperature storage unit for storing temperature change data indicating a time change of the temperature detected by the temperature sensor during the inflow period, and an average temperature calculation unit for calculating an average temperature of the container during the inflow period from the temperature change data, and the flow rate calculation unit may calculate the estimated flow rate based on the rate of change of the pressure and the average temperature.

[0020] The container used has a volume of, for example, 100 ml to 200 l. The larger the volume of the container, the more the temperature inside the container becomes uneven, making it difficult for the temperature sensor to detect the exact temperature of the container. Therefore, when the flow rate calculation unit calculates the estimated flow rate, the average temperature of the container during the inflow period is used to calculate an estimated flow rate with less error. Here, the temperature inside the container or the temperature of the container refers to, for example, the temperature of the internal space of the container or the wall temperature of the container.

[0021] The temperature sensor may detect the wall temperature of the container.

[0022] The system may further include a flow control device that controls the flow rate of the fluid flowing through the inflow line, and the flow rate calculation unit may calculate an estimated flow rate of the fluid that is estimated to have flowed through the flow control device during the inflow period.

[0023] The system may further include a branch line branching off from the inlet line, and a switching mechanism for switching between a first state in which fluid is caused to flow only through the branch line and a second state in which fluid is caused to flow only downstream of a branch point of the inlet line with the branch line, and the flow control device may be provided upstream of a branch point of the inlet line with the branch line.

[0024] In this way, after the container is evacuated before the inflow period, the fluid can be made to flow into the flow control device through the branch line while the container is maintained in a vacuum state. As a result, by starting to flow fluid into the container from the inflow line and switching from the first state to the second state by the switching mechanism, it becomes possible to instantly make the fluid flow into the container at a stable flow rate from the flow control device.

[0025] In addition, the program for a flow rate calculation system according to the present invention is a program used in a flow rate calculation system including a container into which a fluid is flowed, an inflow line through which the fluid flows into the container, and a pressure sensor for detecting the pressure within the container, and is characterized in that it functions as a pressure change data memory unit that stores pressure change data indicating the time change in pressure detected by the pressure sensor during an inflow period from when the fluid starts to flow into the container from the inflow line to when the flow of the fluid into the container is stopped, a flow rate calculation unit that calculates an estimated flow rate of the fluid that is estimated to have flowed through the inflow line during the inflow period based on a rate of change of pressure calculated from the pressure change data, and a flow rate correction unit that corrects the estimated flow rate calculated by the flow rate calculation unit based on a first pressure detected by the pressure sensor a predetermined time after the flow of the fluid into the container is stopped and a second pressure higher than the first pressure included in the pressure change data.

[0026] In addition, a flow rate calculation method according to the present invention is a method used in a flow rate calculation system including a container into which a fluid is flowed, an inflow line through which the fluid flows into the container, and a pressure sensor for detecting the pressure within the container, and is characterized by comprising the steps of: storing pressure change data indicating the time change in pressure detected by the pressure sensor during an inflow period from when the fluid starts to flow from the inflow line into the container to when the flow of the fluid into the container is stopped; calculating an estimated flow rate of the fluid that is estimated to have flowed through the inflow line during the inflow period based on a rate of change in pressure calculated from the pressure change data; and correcting the estimated flow rate calculated by the flow rate calculation unit based on a first pressure detected by the pressure sensor a predetermined time after the flow of the fluid into the container is stopped and a second pressure higher than the first pressure included in the pressure change data.

[0027] In addition, the flow rate calculation device of the present invention is used in a flow rate calculation system including a container into which a fluid is flowed, an inflow line through which the fluid flows into the container, and a pressure sensor for detecting the pressure within the container, and is characterized by comprising a pressure change data storage unit for storing pressure change data indicating the time change in pressure detected by the pressure sensor during an inflow period from when the fluid starts to flow from the inflow line into the container to when the flow of the fluid into the container is stopped, a flow rate calculation unit for calculating an estimated flow rate of the fluid estimated to flow through the inflow line 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 detected by the pressure sensor a predetermined time after the flow of the fluid into the container is stopped and a second pressure higher than the first pressure included in the pressure change data.

[0028] Furthermore, the flow rate calculation system according to the present invention is a flow rate calculation system comprising a container into which a fluid is flowed, an inflow line through which the fluid flows into the container, a pressure sensor for detecting the pressure inside the container, and a temperature sensor for detecting the temperature inside the container or the container, and is characterized in that it further comprises: a pressure change data storage unit for storing pressure change data indicating a time change in the pressure detected by the pressure sensor during an inflow period from when the fluid starts to flow into the container from the inflow line to when the fluid stops flowing into the container; a temperature change data storage unit for storing temperature change data indicating a time change in the temperature detected by the temperature sensor during the inflow period; a flow rate calculation unit for calculating an estimated flow rate of the fluid estimated to have flowed through the inflow line during the inflow period based on a rate of change in pressure calculated from the pressure change data; and a flow rate correction unit for correcting the estimated flow rate based on a first temperature detected by the temperature sensor after a predetermined time has elapsed since the first on-off valve was closed and a second temperature in the temperature change data that is higher than the first temperature.

[0029] In this way, the estimated flow rate calculated based on the rate of change of pressure in the container during the inflow period is corrected based on the first temperature detected by the temperature sensor a predetermined time after the inflow of fluid into the container is stopped and the second temperature included in the temperature change data that is higher than the first temperature, so that errors with respect to the actual flow rate that occur when calculating the estimated flow rate of the fluid estimated to have flowed through the inflow line during the inflow period can be suppressed. This makes it possible for the flow rate calculation system to calculate a more accurate estimated flow rate.

[0030] According to the flow rate calculation system configured in this manner, the estimated flow rate can be calculated with high accuracy by the dynamic constant volume method. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic diagram illustrating a flow rate calculation system according to an embodiment. [Diagram 2] 1 is a block diagram showing functions of a flow rate calculation system according to an embodiment; [Diagram 3]4 is a flowchart showing an operation of the flow rate calculation system according to the embodiment. [Figure 4] 11 is a graph showing a change in pressure over time from when the flow rate calculation system according to the embodiment is switched from an exhaust mode to a stop mode until a predetermined time has elapsed. [Diagram 5] FIG. 13 is a schematic diagram showing a flow rate calculation system according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, a flow rate calculation system according to the present invention will be described with reference to the drawings.

[0033] The flow rate calculation system according to the present invention is used to inspect and calibrate flow rate control devices incorporated in, for example, semiconductor manufacturing lines.

[0034] As shown in FIG. 1, the flow rate calculation system 100 of this embodiment includes a container 10 into which a fluid flows, an inlet line L1 through which the fluid flows into the container 10, an outlet line L2 through which the fluid flows out of the container 10, a branch line L3 branching off from the inlet line L1, and a flow rate calculation device C.

[0035] The container 10 is provided with a pressure sensor P for detecting the pressure inside the container 10, and a temperature sensor T for detecting the wall temperature (specifically, the temperature of the outer wall surface) of the container 10. The temperature sensor T may be one for detecting the temperature of the internal space of the container or the temperature of the inner wall surface of the container.

[0036] The inflow line L1 is provided with a flow control device MFC that controls the flow rate of the fluid flowing through the inflow line L1. The flow control device MFC is a mass flow controller equipped with a thermal or pressure type flow sensor, a flow rate adjustment valve such as a piezo valve, and a control circuit equipped with a CPU, memory, etc. The flow rate calculation system 100 of this embodiment is for inspecting the flow control device MFC.

[0037] A pump 20 for discharging fluid from the container 10 is provided downstream of the outflow line L2.

[0038] The branch line L3 has an upstream end connected to the inflow line L1 downstream of the flow control device MFC, and a downstream end connected to the outflow line L2 upstream of the pump 20. That is, the branch line L3 is connected to the inflow line L1 and the outflow line L2 so as to bypass the container 10.

[0039] Moreover, the inflow line L1, the outflow line L2, and the branch line L3 are provided with on-off valves V1 to V3, respectively. The flow rate calculation system 100 is configured to sequentially switch between an exhaust mode for evacuating the inside of the container 10 to a vacuum, a preparation mode for maintaining the inside of the container 10 in a vacuum state and stabilizing the flow rate of the flow control device MFC, an inflow mode for inflowing the fluid into the container 10, and a stop mode for stopping the inflow of the fluid into the container 10, by switching the opening and closing of the on-off valves V1 to V3.

[0040] Specifically, the inflow line L1 is provided with a first on-off valve V1 downstream of the branch point with the branch line L3. The outflow line L2 is provided with a second on-off valve V2 upstream of the junction with the branch line L3. The branch line L3 is provided with a third on-off valve V3 midway. The first on-off valve V1 and the third on-off valve V3 act as a switching mechanism that switches between a first state in which the fluid flowing upstream of the branch point with the inflow line L1 and the branch line L3 flows only to the branch line L3 and a second state in which the fluid flowing only downstream of the branch point with the inflow line L1 and the branch line L3. That is, the first on-off valve V1 and the third on-off valve V3 act as a switching mechanism that switches between a first state in which the fluid flowing upstream of the branch point with the inflow line L1 and the branch line L3 flows only to the downstream side of the branch point with the inflow line L1 and the branch line L3.

[0041] When the on-off valves V1 to V3 receive a switching signal to the exhaust mode, they close the first on-off valve V1, open the second on-off valve V2, and close the third on-off valve V3. As a result, the container 10 is evacuated to a vacuum by the pump 20 provided in the outflow line L2. The first on-off valve V1 and the third on-off valve V3 prevent the fluid flowing through the inflow line L1 from flowing downstream of the container 10. As a result, the pump 20 is not connected to the flow control device MFC, but is connected only to the container 10, and the inside of the container 10 is sufficiently evacuated.

[0042] Next, when the on-off valves V1 to V3 receive a switching signal to switch to the preparation mode, they close the first on-off valve V1, close the second on-off valve V2, and open the third on-off valve V3. As a result, the container 10 is sealed by the first on-off valve V1 and the second on-off valve V2 and maintained in a vacuum state. The fluid flowing through the inflow line L1 flows downstream of the container via the branch line L3. As a result, the flow control device MFC returns from a state in which the flow rate is unstable in the exhaust mode to a state in which the flow rate is stable.

[0043] Next, when the on-off valves V1 to V3 receive a switching signal to the inflow mode, the first on-off valve V1 is opened, the second on-off valve V2 is closed, and the third on-off valve V3 is closed. As a result, the fluid flowing through the inflow line L1, in other words, the fluid flowing through the flow rate control device MFC, all flows into the container 10.

[0044] Next, when the on-off valves V1 to V3 receive a switching signal to the stop mode, the first on-off valve V1 is closed, the second on-off valve V2 is closed, and the third on-off valve V3 is opened. As a result, the container 10 is kept sealed by the first on-off valve V1 and the second on-off valve V2. The fluid flowing through the inlet line L1 starts to flow again downstream of the container 10 via the branch line L3.

[0045] The flow rate calculation device C is connected to the on-off valves V1 to V3, the pressure sensor P, the temperature sensor T, the flow rate control device MFC, and a display unit (not shown). Specifically, the flow rate calculation device C is a computer having a CPU, a memory, an AD converter, a DC converter, an input means, and the like, and is configured to perform 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 rate calculation unit C5, a flow rate correction unit C6, a display control unit C7, and the like, by executing a program stored in the memory with the CPU, as shown in Fig. 2. The display unit is, for example, a display.

[0046] The valve control unit C1 controls the opening and closing of the first on-off valve V1, the second on-off valve V2, and the third on-off valve V3. Specifically, upon receiving a flow rate calculation start signal, the valve control unit C1 transmits switching signals to switch the on-off valves V1 to V3 to an exhaust mode, a preparation mode, an inflow mode, and a stop mode in this order.

[0047] The pressure change data storage unit C2 stores pressure change data indicating a time change in pressure detected by the pressure sensor P. Specifically, the pressure change data storage unit C2 stores pressure change data indicating a time change in pressure detected by the pressure sensor P at least during an inflow period (see FIG. 4) from when the inflow mode is switched to and when the stop mode is switched to. More specifically, the pressure change data storage unit C2 may store pressure change data relating to at least a period after the inflow mode is switched to and when the rate of change (rate of increase) of the pressure in the container 10 becomes stable during the inflow period. The pressure change data storage unit C2 of this embodiment stores pressure change data relating to a period including the inflow period and a standby period (see FIG. 4) from when the mode is switched to the stop mode until a predetermined time has elapsed in the stop mode.

[0048] The temperature change data storage unit C3 stores temperature change data indicating a change over time in temperature detected by the temperature sensor T. Specifically, the temperature change data storage unit T stores temperature change data indicating a change over time in temperature detected by the temperature sensor T at least during the inflow period. Note that the temperature change data storage unit C3 may store temperature change data for a part of the inflow period, similar to the pressure change data storage unit C2.

[0049] The pressure change data storage unit C2 may store pressure change data relating to the entire period during which the flow rate calculation system 100 is in operation, or may store pressure change data relating to a required period by referring to the switching signals transmitted from the valve switching unit C1 to each of the on-off valves V1 to V3. The same applies to the temperature change data storage unit C3.

[0050] 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 related to the inflow period stored in the temperature change data storage unit C3.

[0051] The flow rate calculation unit C5 uses a theoretical formula to calculate an estimated flow rate of a fluid estimated to have flowed through the inflow line L1 during the inflow period. Specifically, the flow rate calculation unit C5 calculates the estimated flow rate based on a pressure change rate (rate of increase) calculated from pressure change data related to the inflow period stored in the pressure change data storage unit C2 and an average temperature calculated by the average temperature calculation unit C4. More specifically, the flow rate calculation unit C5 calculates the estimated flow rate by substituting the pressure change rate and the average temperature into the formula 1. The flow rate calculation unit C5 calculates the pressure change rate per unit time by referring to pressures at multiple time points included in the pressure change data.

[0052] Here, the estimated flow rate of the fluid estimated to have flowed through the inflow line L1 is controlled by the flow rate control device MFC. Therefore, it can be said that the flow rate calculation unit C5 calculates the estimated flow rate of the fluid estimated to have flowed through the flow rate control device MFC.

[0053] The flow rate correction unit C6 corrects the estimated flow rate calculated by the flow rate calculation unit C5. Specifically, the flow rate correction unit C6 corrects the estimated flow rate based on a first pressure detected by the pressure sensor P after a predetermined time has elapsed since the inflow mode was switched to the stop mode, and a second pressure higher than the first pressure included in the pressure change data during the inflow period. Specifically, the flow rate correction unit C6 corrects the estimated flow rate based on a correction coefficient that is the ratio of the first pressure to the second pressure. More specifically, the flow rate correction unit C6 corrects the estimated flow rate by multiplying the estimated flow rate by the correction coefficient.

[0054] Here, the first pressure and the second pressure will be described in detail with reference to Fig. 4. The pressure inside the container 10 during the inflow period increases due to the influence of not only the increase in the fluid flowing in from the inflow line L1 but also the temperature rise caused by the adiabatic compression inside the container 10. Therefore, immediately after the end of the inflow period, the pressure sensor P detects a pressure that is influenced by the temperature rise caused by the adiabatic compression inside the container 10. However, after a predetermined time has elapsed since the end of the inflow period, the pressure sensor P detects a pressure (stable pressure) that is hardly influenced by the temperature rise caused by the adiabatic compression inside the container 10. This pressure becomes the first pressure.

[0055] The predetermined time is selected in the range of several minutes to several hours. Note that the longer the time after the end of the inflow period, the smaller the effect of the temperature rise due to adiabatic compression inside the container 10 on the pressure detected by the pressure sensor P. Therefore, the longer the predetermined time, the more a correction coefficient can be obtained that can correct the estimated flow rate to a value closer to the actual flow rate.

[0056] The second pressure is a pressure higher than the first pressure among the pressures detected by the pressure sensor P during the inflow period. The second pressure is preferably a maximum pressure of the pressures detected by the pressure sensor during the inflow period or a pressure close to the maximum pressure. In this embodiment, the maximum pressure of the pressures detected by the pressure sensor P during the inflow period is defined as the second pressure.

[0057] The display control unit C7 displays the estimated flow rate after correction calculated by the flow rate correction unit C6 on the display unit.

[0058] Next, the operation of the flow rate calculation system 100 will be described.

[0059] First, when the valve control unit C1 receives a flow rate calculation start signal, it sequentially transmits switching signals to switch the on-off valves V1 to V3 to the exhaust mode, preparation mode, inflow mode, and stop mode, so that the on-off valves V1 to V3 are sequentially switched to each mode (steps S1, S2, S3, S5).

[0060] When the flow-in mode is switched to, the pressure change data storage unit C2 starts storing the pressure change data (step S4). Then, when a predetermined time has elapsed while maintaining the stop mode after switching from the flow-in mode to the stop mode, 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 pressure change data related to a period including the flow-in period from switching to the flow-in mode motor until switching to the stop mode, and the standby period from switching to the stop mode until the predetermined time has elapsed while maintaining the stop mode.

[0061] Furthermore, when the flow-in mode is switched to, the temperature change data storage unit C3 starts storing the temperature change data (step 4). Then, when the flow-in mode is switched to the stop mode, the temperature change data storage unit C3 stops storing the temperature change data (step S6). That is, the temperature change data storage unit C3 stores the temperature change data related to the flow-in period.

[0062] 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).

[0063] Next, the flow rate calculation unit C5 calculates the rate of change of pressure during the inflow period based on the pressure change data stored in the pressure change data storage unit C2. Then, the flow rate calculation unit C5 calculates the estimated flow rate of the fluid estimated to have flowed through the inflow line L1 during the inflow period based on the rate of change of pressure and the average temperature (step S10). Specifically, the flow rate calculation unit C5 substitutes the rate of change of pressure and the average temperature into the above formula 1 to calculate the estimated flow rate of the fluid estimated to have flowed through the inflow line L1 during the inflow period.

[0064] Next, the flow rate correction unit C6 corrects the estimated flow rate calculated by the flow rate calculation unit (step S11). Specifically, the flow rate correction unit C6 refers to the pressure change data related to the standby period and acquires the pressure at a predetermined time after switching from the inflow mode to the stop mode as the first pressure. Also, the flow rate correction unit C6 refers to the pressure change data related to the inflow period and acquires a pressure higher than the first pressure as the second pressure. Specifically, the flow rate correction unit C6 refers to the pressure change data related to the inflow period and acquires the maximum pressure or a pressure close to the maximum pressure during the inflow period as the second pressure. That is, the flow rate correction unit C6 acquires the pressure at the time of switching from the inflow mode to the stop mode, or immediately before or after that, as the second pressure.

[0065] Then, the flow rate correction unit C6 calculates a correction coefficient based on the acquired first pressure and second pressure, and corrects the estimated flow rate calculated by the flow rate calculation unit C5 using the correction coefficient. Specifically, the flow rate correction unit C6 uses the ratio of the first pressure P1 to the second pressure P2, i.e., P1 / P2, as a correction coefficient, and corrects the estimated flow rate by multiplying the correction coefficient by the estimated flow rate.

[0066] Thereafter, the display control unit C7 displays the estimated flow rate corrected by the flow rate correcting unit C6 on the display unit (step S12).

[0067] <Other embodiments> In the flow rate calculation system 100 according to the above embodiment, the branch line L3 branching off from the inflow line L1 is connected to the outflow line L2 so as to bypass the container 10. However, as shown in Fig. 5, the downstream side of the branch line L3 may be connected to the chamber CH to which the fluid is to be supplied, forming a fluid supply system incorporating the flow rate calculation system 100. With a fluid supply line configured in this way, the fluid flowing through the inflow line L1 can be continuously supplied to the chamber CH except during the inflow period. This makes it possible to shorten the time during which the supply to the chamber CH is stopped when calculating an estimated flow rate.

[0068] In addition, in the flow rate calculation system 100 according to the embodiment, the flow rate calculation device C may be a flow rate inspection device that performs the function of a flow rate comparison unit in addition to the functions of the flow rate calculation device C. In this case, the flow rate comparison unit may be configured to compare the set flow rate set in the flow rate control device MFC during the inflow period with the estimated flow rate after correction calculated by the flow rate correction unit C6. Furthermore, the flow rate calculation device C may be a flow rate calibration device that performs the functions of a flow rate comparison unit and a calibration unit in addition to the functions of the flow rate calculation device. In this case, the calibration unit may be configured to calibrate the flow rate control device MFC based on the comparison result of the flow rate comparison unit. Note that the flow rate inspection device and the flow rate calibration device are computers having a CPU, memory, AD converter, DC converter, input means, etc., similar to the flow rate calculation device, and each mechanism is performed by executing a program stored in the memory by the CPU.

[0069] In the above embodiment, the pressure change data storage unit C2 stores pressure change data related to the inflow period and the standby period, but the present invention is not limited to this. For example, only pressure change data related to the inflow period may be stored in the pressure change data storage unit C2. In this case, the flow rate correction unit C6 may be configured to obtain the pressure detected by the pressure sensor P at a predetermined time after switching from the inflow mode to the stop mode, and set this as the first pressure. Furthermore, pressure change data related to periods other than the inflow period and the standby period may also be stored in the pressure change data storage unit C2.

[0070] In the above embodiment, the flow rate correction unit C6 corrects the estimated flow rate calculated by the flow rate calculation unit C5 based on the first pressure and the second pressure, but is not limited to this. For example, the flow rate correction unit C6 may correct the estimated flow rate based on the first temperature detected by the temperature sensor T after a predetermined time has elapsed since the first on-off valve V1 was closed and the second temperature in the temperature change data that is higher than the first temperature.

[0071] Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0072] 100 Flow Calculation System 10 containers 20 Pump L1 Inlet line L2 Outflow line L3 Branch Line V1 First opening and closing valve V2 Second shutoff valve V3 Third opening and closing valve P Pressure Sensor T Temperature Sensor C Flow rate calculation device C1 Valve control section C2 Pressure change data storage section C3 Temperature change data storage section C4 Average temperature calculation section C5 Flow rate calculation section C6 Flow Correction Unit C7 stands for Control Unit MFC Flow Control Machine

Claims

1. A flow rate calculation system including a container into which a fluid flows, an inlet line through which the fluid flows into the container, and a pressure sensor for detecting a pressure in the container, a pressure change data storage unit configured to store pressure change data indicating a time change in pressure detected by the pressure sensor during an inflow period from when the inflow of fluid from the inflow line into the container starts to when the inflow of fluid into the container stops; a flow rate calculation unit that calculates a rate of change in pressure using pressures at multiple points in time during the inflow period included in the pressure change data, and calculates an estimated flow rate of a fluid that is estimated to have flowed through the inflow line during the inflow period using the calculated rate of change in pressure; a flow rate correction unit that corrects the estimated flow rate calculated by the flow rate calculation unit based on a first pressure detected by the pressure sensor after a predetermined time has elapsed since the inflow of fluid into the container was stopped and a second pressure that is higher than the first pressure and is included in the pressure change data; the second pressure is a maximum pressure included in the pressure change data or a pressure close to the maximum pressure, A flow rate calculation system, wherein the flow rate correction unit corrects the estimated flow rate based on a correction coefficient that is a ratio of the first pressure to the second pressure.

2. Further comprising a temperature sensor for detecting a temperature in or on the container; 2. The flow rate calculation system according to claim 1, wherein the flow rate calculation unit calculates the estimated flow rate based on a rate of change of the pressure and a temperature detected by the temperature sensor during the inflow period.

3. a temperature storage unit that stores temperature change data indicating a time change of the temperature detected by the temperature sensor during the inflow period; an average temperature calculation unit that calculates an average temperature in the container or in the container during the inflow period from the temperature change data; 3. The flow rate calculation system according to claim 2, wherein the flow rate calculation unit calculates the estimated flow rate based on the rate of change of the pressure and the average temperature.

4. 4. The flow rate calculation system according to claim 2, wherein the temperature sensor detects a wall temperature of the container.

5. Further comprising a flow control device for controlling the flow rate of the fluid flowing through the inlet line, 5. The flow rate calculation system according to claim 1, wherein the flow rate calculation unit calculates an estimated flow rate of a fluid that is estimated to have flowed through the flow rate control device during the inflow period.

6. a branch line branching off from the inlet line; a switching mechanism for switching between a first state in which the fluid is caused to flow only to the branch line and a second state in which the fluid is caused to flow only to a downstream side of a branch point of the inflow line with the branch line, 6. The flow rate calculation system according to claim 5, wherein the flow rate control device is provided upstream of a branch point of the inflow line with the branch line.

7. A program for use in a flow rate calculation system including a container into which a fluid flows, an inlet line through which the fluid flows into the container, and a pressure sensor for detecting a pressure inside the container, a pressure change data storage unit configured to store pressure change data indicating a time change in pressure detected by the pressure sensor during an inflow period from when the inflow of fluid from the inflow line into the container starts to when the inflow of fluid into the container stops; a flow rate calculation unit that calculates a rate of change in pressure using pressures at multiple points in time during the inflow period included in the pressure change data, and calculates an estimated flow rate of a fluid that is estimated to have flowed through the inflow line during the inflow period using the calculated rate of change in pressure; a flow rate correction unit that corrects an estimated flow rate calculated by the flow rate calculation unit based on a first pressure detected by the pressure sensor after a predetermined time has elapsed since the inflow of fluid into the container was stopped and a second pressure that is higher than the first pressure and is included in the pressure change data; the second pressure is a maximum pressure included in the pressure change data or a pressure close to the maximum pressure, A program for a flow rate calculation system, in which the flow rate correction unit corrects the estimated flow rate based on a correction coefficient that is a ratio of the first pressure to the second pressure.

8. A method for use in a flow rate calculation system including a container into which a fluid is flowed, an inlet line through which the fluid flows into the container, and a pressure sensor for detecting a pressure in the container, comprising: storing pressure change data indicating a time change in pressure detected by the pressure sensor during an inflow period from when the inflow of fluid from the inflow line into the container starts to when the inflow of fluid into the container stops; calculating a rate of change in pressure using pressures at multiple time points during the inflow period included in the pressure change data, and calculating an estimated flow rate of the fluid estimated to have flowed through the inflow line during the inflow period using the calculated rate of change in pressure; and correcting the calculated estimated flow rate based on a first pressure detected by the pressure sensor after a predetermined time has elapsed since the inflow of fluid into the container was stopped and a second pressure higher than the first pressure included in the pressure change data. the second pressure is a maximum pressure included in the pressure change data or a pressure close to the maximum pressure, A flow rate calculation method, comprising: correcting the estimated flow rate based on a correction coefficient that is a ratio of the first pressure to the second pressure, in the step of correcting the estimated flow rate.

9. The present invention is used in a flow rate calculation system including a container into which a fluid flows, an inlet line through which the fluid flows into the container, and a pressure sensor for detecting a pressure inside the container, a pressure change data storage unit configured to store pressure change data indicating a time change in pressure detected by the pressure sensor during an inflow period from when the inflow of fluid from the inflow line into the container starts to when the inflow of fluid into the container stops; a flow rate calculation unit that calculates a rate of change in pressure using pressures at multiple points in time during the inflow period included in the pressure change data, and calculates an estimated flow rate of a fluid that is estimated to have flowed through the inflow line during the inflow period using the calculated rate of change in pressure; a flow rate correction unit that corrects the estimated flow rate calculated by the flow rate calculation unit based on a first pressure detected by the pressure sensor after a predetermined time has elapsed since the inflow of fluid into the container was stopped and a second pressure that is higher than the first pressure and is included in the pressure change data; the second pressure is a maximum pressure included in the pressure change data or a pressure close to the maximum pressure, The flow rate calculation device, wherein the flow rate correction unit corrects the estimated flow rate based on a correction coefficient that is a ratio of the first pressure to the second pressure.

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