Method and system for determining initial values ​​of parameters, and method and system for adjusting a mass flow control device.

Abstract

The present invention adjusts a parameter of a mass flow rate control device among a plurality of mass flow rate control devices under a certain control condition, and stores the adjusted parameter into a server in association with the control condition. Next, the present invention extracts pieces of data associated with a common control condition from data accumulated in the server, determines the initial value of the parameter on the basis of the extracted pieces of data, and stores the determined initial value of the parameter into the server in association with the common control condition. The present invention adjusts the mass flow rate control device by using the initial value of the parameter determined in this manner. As a result, the present invention can finish adjustment of the mass flow rate control device with fewer steps while preventing occurrence of a failure in adjustment of the mass flow rate control device.

Description

Technical Field

[0001] This invention relates to a method and system for adjusting a mass flow controller.

Background Art

[0002] A mass flow controller is a precision instrument used, for example, for quantitatively supplying a process gas to a manufacturing apparatus in a semiconductor manufacturing process. The manufacture of a mass flow controller is performed by preparing components adapted to the maximum flow rate of the fluid controlled by the mass flow controller and combining those components with each other. The assembled mass flow controller is individually adjusted before being shipped from the factory. Adjustment of the mass flow controller includes adjustment of a flow sensor (see, for example, Patent Document 1) and adjustment of a transient response (see, for example, Patent Document 2).

[0003] Adjustment of the mass flow controller is performed by rewriting one or more parameters related to flow control stored in a nonvolatile memory of a microprocessor built into the mass flow controller using an input device of a personal computer connected to the mass flow controller under certain control conditions. Rewriting of the parameters is performed until the accuracy of the control operation reaches a target value while alternately repeating the operation of actually flowing a fluid through the mass flow controller to inspect the control operation and the operation of rewriting the parameters based on the inspected control operation.

[0004] Previously, a problem arose because mass flow control devices, individually adjusted for each gas type and bottle size, were used, requiring a large inventory of backup units. Therefore, a technology called "MGMR (Multi-Gas / Multi-Range) function," which allows a single mass flow control device to be applied to multiple gas types and multiple bottle sizes, has recently been utilized, contributing to a significant reduction in the number of units to be stocked (see, for example, Patent Document 3). Adjusting a mass flow control device equipped with this MGMR function requires adjustments for multiple gas types and multiple bottle sizes, and the adjusted parameters must be stored in the mass flow control device's memory.

[0005] Furthermore, in gas supply units, the gas supply pressure to the mass flow control device may fluctuate. For example, in gas panels that supply the same type of gas to multiple lines, the gas supply path to the mass flow control device is branched in order to supply gas to multiple mass flow control devices. As a result, the gas supply pressure to the mass flow control device (gas supply inlet pressure) may fluctuate instantaneously due to phenomena such as crosstalk between mass flow control devices. Therefore, in conventional gas supply units, a regulator was installed upstream of the mass flow control device in the gas piping system. This allowed the regulator to absorb fluctuations in the gas supply inlet pressure, thereby stabilizing the actual gas flow rate controlled by the mass flow control device.

[0006] However, from the perspective of cost reduction and miniaturization of gas piping systems, the omission of regulators is required. Therefore, in this technical field, mass flow control devices equipped with a so-called "PI (Pressure Insensitive) function" are becoming widely used. The PI function is a function that corrects the difference between the measured flow rate (measured flow rate) and the actual flow rate caused by parasitic flow generated in the mass flow control device due to fluctuations in the gas supply inlet pressure. Specifically, the flow rate of the parasitic flow (parasitic flow rate) is calculated from the measured gas supply inlet pressure, the measured flow rate is accelerated so that the bandwidth of the measured flow rate is equivalent to the bandwidth of the parasitic flow rate, and the corrected flow rate (corrected flow rate) that is closer to the actual flow rate is obtained by subtracting the parasitic flow rate from the accelerated measured flow rate (see, for example, Patent Document 4). Therefore, in adjusting a mass flow control device equipped with this PI function, it is necessary to adjust for multiple types of gas and multiple bottle sizes while changing the gas supply inlet pressure, and to store the adjusted parameters in the memory of the mass flow control device. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 7-263350 [Patent Document 2] Japanese Patent Publication No. 2014-59609 [Patent Document 3] Patent No. 4957725 [Patent Document 4] International Publication No. 2021 / 039665 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In conventional mass flow control devices, adjustment starts from the default values ​​of parameters stored in non-volatile memory, and the adjustment proceeds by rewriting the parameters through trial and error, completing the adjustment according to the procedure described above. If the set default values ​​are not appropriate, it will take a lot of time to complete the adjustment, which may increase the operator's labor costs and the consumption of fluid used for adjustment. In the adjustment of a mass flow control device equipped with MGMR functionality, as mentioned above, it is necessary to store many parameters adjusted for multiple gas types and multiple bottle sizes in memory, so a particularly large amount of time, labor costs, and fluid is required. This is even more true when adjusting a mass flow control device equipped with PI functionality, which requires adjustment for multiple gas types and multiple bottle sizes while changing the gas supply inlet pressure, as mentioned above.

[0009] Furthermore, when adjustments are made using conventional methods, even if there are defects in the components of the mass flow control device and / or if the components are not properly assembled, the adjustment process itself can be completed by repeatedly rewriting the parameters. As a result, there is a risk of individual differences in performance or malfunctions occurring during use compared to a properly adjusted mass flow control device.

[0010] This invention has been made in view of the above problems, and aims to complete the adjustment of a mass flow control device in fewer steps and to reduce variations (individual differences) in the performance of the mass flow control device. [Means for solving the problem]

[0011] In a first embodiment, the method according to the present invention is a method for determining initial values ​​of flow control parameters that are initially input to a mass flow control device when adjusting the mass flow control device, and includes the following first and second steps. The first step involves performing a first step of adjusting the parameters of a mass flow control device under certain control conditions, and a second step of storing data in a server that associates the adjusted parameters with the control conditions, individually for multiple mass flow control devices, thereby accumulating data in the server. The second step involves the following steps: the third step of extracting data with common control conditions from the data stored on the server; the fourth step of determining the initial values ​​of the parameters corresponding to the common control conditions based on the extracted data; and the fifth step of storing the determined initial values ​​of the parameters in the server in association with the common control conditions. The initial values ​​of the parameters determined by the method according to the present invention are initial values ​​that reflect the results of past adjustments to the mass flow control device.

[0012] In a second embodiment, the method according to the present invention is a method for adjusting a mass flow control device used under certain control conditions, and includes a third step comprising the sixth to eighth steps listed below. Step 6: Read the initial values ​​of the parameters associated with the control conditions from the initial values ​​of the parameters determined by the method according to the present invention from the server. Step 7: Input the initial values ​​of the read parameters into the mass flow control device. Step 8: Adjust the parameters of the mass flow control device under the control conditions. This method allows the adjustment of the mass flow control device to start from initial parameter values ​​that reflect the results of past adjustments of the mass flow control device. [Effects of the Invention]

[0013] According to the method of the present invention, the procedures required for adjusting the mass flow controller can be reduced compared to the conventional method, so that the labor cost and the consumption of the fluid used for adjustment can be reduced, and thus the manufacturing cost of the mass flow controller can be reduced. In the mass flow controller equipped with the MGMR function that requires a lot of time, labor cost and fluid for adjustment as described above, the merit brought by the above effect achieved by the method of the present invention is great. Moreover, it is even more so in the adjustment of the mass flow controller equipped with the PI function that requires adjustment for a plurality of types of gases and a plurality of bin sizes while changing the gas supply inlet pressure as described above.

Brief Description of the Drawings

[0014] [Figure 1] It is a flowchart showing a first embodiment of the method according to the present invention. [Figure 2] It is a schematic diagram showing an example of the adjustment method of the flow rate sensor in the method according to the present invention. [Figure 3] It is a flowchart showing a second embodiment of the method according to the present invention. [Figure 4] It is a schematic diagram showing an example of the configuration of the mass flow controller.

Embodiments for Carrying Out the Invention

[0015] The embodiments for carrying out the present invention will be described in detail below with reference to the drawings. It should be noted that the following description is only an example of specific embodiments of the present invention, and the present invention is not limited to the embodiments described below.

[0016] <Configuration of the Mass Flow Controller> FIG. 4 is a schematic diagram showing an example of the configuration of the mass flow controller. It should be noted that FIG. 4 conceptually shows the configuration of the mass flow controller, and does not specifically show the shapes, structures and combinations of these mass flow controllers and the components constituting them.

[0017] The mass flow rate control device 1 shown in Fig. 4 includes a flow path 10 through which a fluid flows. The fluid flows into the interior of the mass flow rate control device 1 from the inlet 11 and flows out to the outside from the outlet 12. Between the inlet 11 and the outlet 12 of the flow path 10, a flow rate sensor 20 and a flow rate control valve 30 are provided. The flow rate sensor 20 includes a bypass 21 provided inside the flow path 10, a sensor tube 22 branching from the flow path 10, and a set of electric heating wires 23 wound around the upstream side and the downstream side of the sensor tube 22. The bypass 21 has a function of keeping the ratio of the flow rate of the fluid flowing through the flow path 10 and the flow rate of the fluid branching into the sensor tube 22 constant. The bypass 21 can be composed of, for example, a laminar flow element formed by bundling a large number of pipes. The sensor tube 22 branches from the flow path 10 on the upstream side of the bypass 21 and rejoins the flow path 10 on the downstream side of the bypass 21. When an electric current is passed through a set of electric heating wires 23 wound around the sensor tube 22, when there is fluid flowing inside the sensor tube 22, the heat generated by the energization moves from the upstream side to the downstream side, so a difference in resistance value occurs due to the temperature difference generated between the set of electric heating wires 23. By detecting this difference in resistance value, the flow rate of the fluid flowing inside the sensor tube 22 can be detected, and further, the flow rate of the fluid flowing through the flow path 10 can be detected. That is, the flow rate sensor 20 shown in Fig. 4 is a thermal flow rate sensor.

[0018] The fluid flow rate detected by the flow sensor 20 is used to control the fluid flow rate through the flow path 10. Specifically, the control unit 40 of the mass flow control device 1 controls the opening degree of the flow control valve 30 so that the fluid flow rate detected by the flow sensor 20 matches a preset set flow rate. The flow control valve 30 comprises a valve body 31 and its drive mechanism 32. A control signal output from the control unit 40 is input to the drive mechanism 32, and the opening degree of the valve body 31 is controlled. If the drive mechanism 32 is composed of a piezoelectric element, a voltage signal can be used as the control signal. The mass flow control device 1 shown in Figure 4 is equipped with a thermal flow sensor 20, but the flow sensor 20 may be a so-called pressure type flow sensor or other known flow sensor. Regardless of the configuration of the flow sensor 20, the mass flow control device 1 measures the fluid flow rate using the flow sensor 20 and performs automatic control so that the flow rate matches the set flow rate.

[0019] <Rated flow rate> In this specification, the maximum fluid flow rate that a mass flow control device can control is referred to below as the "rated flow rate" or "full-scale flow rate." The rated flow rate that consumers require from a mass flow control device covers an extremely wide range, for example, from 10 standard cubic centimeters per minute (hereinafter referred to as "sccm") to 50,000 sccm in terms of nitrogen gas at standard conditions. In the mass flow control device 1 illustrated in Figure 4, the rated flow rate largely depends on the cross-sectional area and shape of the flow path 10, bypass 21, and valve body 31 that the fluid directly contacts. The larger the cross-sectional area of ​​the fluid-flowing portion of these components, the greater the maximum fluid flow rate that the mass flow control device 1 can control. Controlling a small flow rate using a mass flow control device designed for a large rated flow rate results in low flow rate control accuracy. Conversely, it is physically impossible to supply a large flow rate of fluid using a mass flow control device composed of components with small cross-sectional areas that can control a small rated flow rate. Therefore, components such as the flow path 10, bypass 21, and valve body 31 must be individually designed to match the magnitude of the rated flow rate.

[0020] In actual mass flow control devices, manufacturers divide the range of rated flow rates into several categories and produce products adapted to each category. These categories of rated flow rates are hereinafter referred to as "bin sizes." The numbers assigned for convenience to identify the bin size are hereinafter referred to as "bin numbers." Table 1 shows examples of bin numbers and bin sizes. In the examples shown in Table 1, for example, a customer who requires a mass flow control device with a rated flow rate of 2,000 sccm can purchase and use a mass flow control device with bin number BIN 5 (i.e., a rated flow rate category of 1,001 to 3,000 sccm) from the manufacturer. In the rated flow rate categories shown in Table 1, components such as the fluid flow path 10, bypass 21, and valve body 31 may be individually designed and different for each bin size, or common components may be used for multiple bin sizes with similar rated flow rates.

[0021] [Table 1]

[0022] <Parameters> In this specification, "parameter" refers to a variable that is input to a mass flow control device for the purpose of determining the content of the control when the mass flow control device executes a flow control algorithm. The number of parameters used in a mass flow control device may be one or more. Specific examples of parameters in this invention will be described later. In this specification, "adjusting the mass flow control device" means actually flowing fluid through the mass flow control device after assembly and before shipment to check whether the mass flow control device satisfies the performance according to the target value, and if the performance does not meet the inspection result, changing the parameters until the target value is achieved. As mentioned above, the adjustment of the mass flow control device is actually performed by rewriting the parameters. That is, the process of actually flowing fluid through the mass flow control device and checking the control operation and the process of rewriting the parameters based on the inspected control operation are repeated alternately until the accuracy of the control operation reaches the target value. The adjustment of the mass flow control device may be performed manually by an operator, or it may be performed automatically according to the operation of a computer program, as will be described in detail later. The adjustment of the mass flow control device is performed individually for each mass flow control device after manufacturing and before shipment, and the parameters, once adjusted, are not changed in principle.

[0023] <First Embodiment> In a first embodiment, the present invention relates to a method for determining the initial value of a parameter to be initially input to a mass flow control device when adjusting the parameters of the mass flow control device. In this specification, "initial value" refers to the initial value of a parameter that is initially input to the mass flow control device when starting the adjustment of the mass flow control device. In the prior art, a default value was used as the parameter to be initially input to the mass flow control device. In this specification, "default value" refers to a pre-prepared setting value for the purpose of preventing system malfunctions (faults) that occur when a value is not input in program processing that requires the input of some value. The default value used in the prior art was a fixed value and did not reflect the results of parameter adjustment. In contrast, the initial value of a parameter according to the method of the present invention is determined according to a defined procedure based on the parameter value determined as a result of adjustments performed individually in the past.

[0024] Figure 1 is a flowchart showing a method according to the first embodiment of the present invention. This method includes two steps. The first step is to individually perform the following steps for multiple mass flow control devices: a first step (S1) of adjusting the parameters of a certain mass flow control device under certain control conditions, and a second step (S2) of storing data in a server in which the adjusted parameters and control conditions are associated, thereby accumulating data in the server. In this specification, "control conditions" of a mass flow control device refer to various conditions that affect flow rate control. Specific examples of control conditions in the present invention will be described later. When the parameters of multiple mass flow control devices are individually adjusted under the same control conditions, the parameter values ​​determined by the adjustment do not differ significantly from one mass flow control device to another. However, due to individual differences in the components constituting the mass flow control device, the parameter values ​​are not completely identical, and there is variation with each adjustment. In the first step, the adjusted parameters, including the variation, are stored in a server as data associated with the control conditions, and this step is performed for multiple mass flow control devices, thereby accumulating data in the server.

[0025] In this specification, "server" means a computer system having a memory device, preferably a computer system connected directly to a mass flow control device or via an adjustment terminal (e.g., a personal computer). The connection between the mass flow control device and the server can be made via a known communication line such as a LAN cable and / or the Internet. However, a communication line connecting the mass flow control device and the server is not necessarily required. For example, if an operator makes adjustments manually, the operator can input the adjusted parameters using an input device on the server itself, thereby accumulating data on the server.

[0026] The second step included in the method according to the first embodiment is a third step (S3) of extracting data with common control conditions from data stored in the server, a fourth step (S4) of determining the initial values ​​of the parameters based on the extracted data, and a fifth step (S5) of storing the determined initial values ​​of the parameters in the server in association with the common control conditions. As a result of performing the first step, data with different control conditions is stored in the server as data associated with the control conditions. If only data with common control conditions is extracted from the data stored in the server, the extracted data will all have the same control conditions and therefore have little variation. Thus, by determining the initial values ​​of the parameters based on the extracted data, highly reliable initial values ​​of the parameters that reflect the results of past adjustments can be obtained. The determination of the initial values ​​of the parameters can be performed based on the extracted data, that is, using the extracted data, and the specific method of determination is not particularly limited. As a method for determining the initial values ​​of the parameters based on the extracted data, for example, statistical methods such as calculating the mean and selecting the median or mode can be employed. If the initial values ​​of the determined parameters are stored on the server in association with common control conditions, the initial values ​​of the parameters corresponding to the control conditions can be retrieved from the server at any time and used as the initial values ​​of the parameters for the next adjustment.

[0027] In a preferred embodiment, the method according to the present invention includes control conditions such as the type of mass flow control device, the type of fluid, and the bin size. As mentioned above, when the parameters of multiple mass flow control devices are individually adjusted under the same control conditions, the parameter values ​​determined by the adjustment do not differ significantly from one mass flow control device to another. In other words, if the control conditions of the mass flow control devices are different, the adjusted parameters tend to have different values ​​than the parameters when the control conditions are the same. Therefore, it is important to consider which control conditions of the mass flow control device are associated with the data stored in the server. One of the control conditions that relatively greatly affects the parameter values ​​is the type of mass flow control device. Specific examples of types of mass flow control devices include mass flow control devices equipped with thermal flow sensors and mass flow control devices equipped with pressure flow sensors. Even if common parts other than the flow sensor, such as the flow path and flow control valve, are used between different types of mass flow control devices, the parameter values ​​often differ significantly due to differences in the transient response of the flow sensor.

[0028] Furthermore, the type of fluid being controlled also significantly affects the parameter values. Different fluid types have different thermal properties, viscosity, and other dynamic properties, resulting in different fluid behavior not only in the flow sensor but also in the bypass and flow control valve. Consequently, the adjusted parameter values ​​will also differ considerably. Moreover, even if the type of mass flow control device and the type of fluid are the same, different bin sizes may result in different parameter values ​​due to differences in the Reynolds number of the fluid, etc. Thus, the parameter values ​​determined by adjustment can vary greatly depending on the various control conditions of the mass flow control device. Therefore, if adjustment is performed using initial values ​​determined without considering the control conditions, it may take a considerable amount of time to adjust the parameters.

[0029] In the method according to the present invention, parameters common to the control conditions are extracted from the data of adjusted parameters stored in the server in association with the control conditions, and initial values ​​are determined based on the extracted parameters. The initial values ​​determined in this way differ from the default values ​​of the conventional technology and reflect the results of parameter adjustments performed in the past under those control conditions. By adjusting the mass flow control device using such initial values, the time from the start of adjustment until the accuracy of the control operation reaches the target value is shortened, and adjustments can be performed quickly.

[0030] In preferred embodiments of the present invention, the control conditions, including the type of mass flow control device, the type of fluid, and the bin size, which are considered to have a significant impact on the parameters, are common, thus making the effect of reducing the time required for adjustment more pronounced. Any one of these elements, or two or all three of these elements, which are considered to have a significant impact on the parameters, may be common. The more common elements there are, the more pronounced the effect of the present invention becomes.

[0031] In a preferred embodiment, the method according to the present invention includes adjustment of a flow sensor, and parameters include parameters relating to the zero point, span, and linearity. In this specification, "adjustment of the flow sensor" means adjusting the parameters that affect the output of the flow sensor so that the difference between the flow rate corresponding to the output signal of the fluid flow rate output by the flow sensor incorporated in the mass flow control device and the actual flow rate is less than or equal to a target value. The operation of adjusting the flow sensor to bring the fluid flow rate detected by the flow sensor closer to the true value is sometimes referred to as "calibration" of the mass flow control device or the flow sensor. If the flow sensor is not properly calibrated, an error will be contained in the fluid flow rate on which the mass flow control device relies for control, and the flow rate cannot be controlled correctly. Therefore, adjusting the flow sensor is a fundamental and important operation.

[0032] Figure 2 is a schematic diagram illustrating an example of a flow sensor adjustment method. The short arrows in the figure indicate the direction in which the fluid flows through the channel. The dashed lines connecting the components represent the paths used for the exchange of signals and commands between multiple components. When adjusting a flow sensor, as illustrated in Figure 2, it is common practice to connect a reference flow meter, which serves as the basis for flow rate measurements, and a mass flow control device in series, flow fluid through them, and then adjust the flow sensor by rewriting the flow sensor parameters using a personal computer so that the output of the flow sensor matches the output of the reference flow meter. For example, a molbloc (molbloc is a registered trademark of Fluke Corporation in the United States) can be used as the reference flow meter. The adjusted parameters are stored on a server in association with the control conditions.

[0033] Specific examples of parameters that affect the output of a flow sensor include, but are not limited to, the zero point, span, and linearity. The zero point parameter is adjusted so that the output of the flow sensor is zero when no fluid is flowing. The span parameter is adjusted so that, after adjusting the zero point, both the output of the flow sensor and the reference flow meter show the full-scale flow rate when a full-scale flow rate fluid is flowed. The linearity parameter is adjusted by correcting the output of the flow sensor by software so that, when the relationship between the output of the flow sensor and the actual flow rate deviates from a proportional relationship and nonlinearity is observed, the output of the flow sensor is proportional to the actual flow rate between the zero point and the full-scale flow rate. Since all three of these parameters directly affect the output of the flow sensor, it is preferable to determine their initial values ​​as described above. However, in a preferred embodiment of the present invention, it is not prohibited to adjust other parameters that directly or indirectly affect the output of the flow sensor in addition to the zero point, span, and linearity parameters to determine their initial values. Note that the flow sensor adjustment is performed when the fluid flow rate is stable at a constant value. Adjusting parameters when the output of a flow sensor changes over time is included in the transient response adjustment described below.

[0034] In a preferred embodiment, the method according to the present invention includes adjustment of the transient response, and the parameters include parameters relating to proportional gain, integral gain, and differential gain. In this specification, "adjustment of transient response" means adjusting the parameters that affect the transient response so that the index of the time change of the flow rate (transient response) when the set flow rate given to the mass flow control device changes falls within a preset range. Specific examples of the transient response index include, but are not limited to, the time from the start of control until the flow rate reaches 98% of the set flow rate, overshoot, and hunting. The operation of adjusting the transient response of a mass flow control device is sometimes called "tuning" of the mass flow control device. If the mass flow control device is not properly tuned, individual differences will occur in the time change of the flow rate when the set flow rate changes, which may cause errors in the total amount of fluid supplied. Therefore, adjusting the transient response is a fundamental and important operation, just like adjusting the flow sensor. When adjusting the transient response, it is common practice to monitor the output of the flow sensor (hereinafter sometimes referred to as the "step response") when a set flow rate change, such as 100% or 50% of the full-scale flow rate, is applied, and to adjust the parameters of the mass flow control device so that the transient response indicator (for example, the time it takes for the flow rate to reach 98% of the set flow rate) falls within a preset range.

[0035] Specific examples of parameters that affect the transient response include, but are not limited to, proportional gain, integral gain, and differential gain as parameters related to PID operation, a typical feedback control. Furthermore, the flow control algorithm in this invention is not limited to PID operation, and known automatic control methods such as feedforward control, H-infinity control, fuzzy control, and neural network control can be employed. In these automatic control methods, the term "parameter" as used herein should be interpreted in its broadest sense. In order to correctly evaluate the step response when adjusting the transient response, it is generally preferable to complete the adjustment of the flow sensor in advance. However, depending on the control conditions, adjusting the transient response may have a significant impact on the adjustment of the flow sensor, so it is preferable to decide on a case-by-case basis whether to perform the adjustment of the flow sensor or the adjustment of the transient response first. In addition, it is preferable to alternately perform the adjustment of the flow sensor and the adjustment of the transient response multiple times in order to adjust the mass flow control device more accurately.

[0036] Referring again to Table 1, Table 1 is a table showing examples of initial parameter values ​​determined as a result of tuning mass flow control devices in a preferred embodiment of the present invention, where the type of mass flow control device and the type of fluid are the same, but only the bin size differs. Table 1 lists zero point, span, and linearity parameters as parameters that affect the output of the flow sensor, and proportional gain, integral gain, and differential gain as parameters that affect the transient response. Blank spaces in Table 1 indicate that the parameters have never been tuned in the past under those control conditions, and therefore the initial parameter values ​​have not yet been determined.

[0037] Here, we will explain in detail how to adjust the parameters that affect the transient response. As illustrated in Table 1, different initial values ​​can be determined for each bin size as the initial values ​​of the parameters. However, for parameters that are not significantly affected by differences in bin size, a single initial value common to all bin sizes can be determined. Furthermore, the full scale (e.g., 2,000 sccm) at a given bin size can be divided into several divisions (e.g., 1%, 2%, 5%, 10%, 25%, 50%, 75%, 100%, 120%, 140% of the full scale), and different initial values ​​for the parameters can be determined for each division.

[0038] Of the parameters exemplified in Table 1, linearity and proportional gain are particularly effective when finely tuned as described above. This is because the flow characteristics of a flow control valve (change in flow rate with respect to valve opening) are not simply proportional but involve nonlinear elements. For the same reason, these two parameters are also susceptible to the effects of differences in bin size. On the other hand, integral gain and differential gain are parameters that are less affected by differences in full-scale divisions and bin sizes, so it is sometimes possible to use common initial values ​​regardless of division and / or bin size. As initial values ​​for parameters, for example, the average value of parameters adjusted using multiple mass flow control devices (e.g., 3 to 5 devices) can be adopted.

[0039] In parameter adjustment, the most basic adjustment is the flow sensor parameters, and this is usually the first step. In this adjustment, the flow sensor parameters are adjusted so that the flow rate measured by the mass flow control device matches the flow rate indicated by a reference flow meter (e.g., molbloc). In adjusting the transient response parameters, for example, each PID gain is adjusted so that the response time to the step input (an index of the transient response obtained from the step response) is minimized. In all of these adjustments, fine-tuning is necessary because there are individual differences in mass flow control devices. In the future, it is expected that parameter adjustments will also be possible based on the results of analyzing big data stored on a server using AI.

[0040] In a preferred embodiment, the method according to the present invention provides a temporary and general-purpose default value for the mass flow control device, which is not the optimal value for the control conditions at that time, but allows the mass flow control device to operate under a wide range of control conditions. This method is effective when adjusting the mass flow control device for the first time under certain control conditions. As mentioned above, if no adjustment has ever been made under certain control conditions, as shown in the blanks in Table 1, then the initial value referred to in the present invention does not exist. In such cases, the execution of the first step can be started by inputting a predefined default value as a parameter into the mass flow control device. The default value input at this time is not the optimal value for the control conditions, but it is a temporary and general-purpose default value that allows the mass flow control device to operate under a wide range of control conditions. Here, "temporary" means a temporary value used only until the parameter is changed by adjustment. Also, "general-purpose" means that it can be used in common for a wide range of control conditions, regardless of specific control conditions. Such default values ​​can be set based, for example, on adjusted parameters in mass flow control devices with similar configurations that have been adjusted in the past, and / or adjusted parameters when the bin sizes are similar for the same type of mass flow control device and the same type of fluid.

[0041] <Second Embodiment> In a second embodiment, the present invention relates to a method for adjusting a mass flow control device used under certain control conditions. In this method, the parameters of the mass flow control device are adjusted using initial values ​​of parameters determined by the method according to the first embodiment. As described above, the initial values ​​determined by the method according to the first embodiment differ from the default values ​​used in the prior art, and reflect the results of parameter adjustments previously performed under the control conditions for which the parameters are to be adjusted. Therefore, the time from the start of adjustment of the mass flow control device until the accuracy of the control operation reaches the target value is shortened, and the adjustment can be performed quickly.

[0042] Figure 3 is a flowchart showing a method according to a second embodiment of the present invention. This method includes a third step. The third step is to perform a sixth step (S6) of reading from a server the initial values ​​of parameters associated with control conditions, which were determined by the method according to the first embodiment; a seventh step (S7) of inputting the read initial values ​​of parameters into a mass flow control device; and an eighth step (S8) of adjusting the parameters of the mass flow control device under the control conditions.

[0043] In this method, the control conditions for the mass flow control device to be used after adjusting the parameters are assumed to be predetermined. In step 6, S6, the initial values ​​of the parameters stored in the server as a result of performing the second step of the method according to the first embodiment are searched for, and initial values ​​of the parameters adjusted under the same control conditions as those for which the parameters are to be adjusted are found. If such initial values ​​are found, they are read from the server. The read-out initial values ​​are input to the mass flow control device (step 7, S7), and the parameters of the mass flow control device are adjusted again under the same control conditions as the read-out initial values ​​(step 8, S8). If the desired initial values ​​are not stored in the server, the third step cannot be performed. In such cases, before performing the third step, the initial values ​​of the parameters under the control conditions can be determined by performing the first and second steps of the first embodiment under the necessary control conditions, and then the third step can be performed.

[0044] In a preferred embodiment, the method according to the second embodiment includes a fourth step. The fourth step is to store additional data in a server, which is associated with the parameters and control conditions of the mass flow control device adjusted in step 8 (S8); a tenth step (S10) to extract data and additional data that have common control conditions from the data and additional data stored in the server; and an eleventh step (S11) to re-determine the initial values ​​of the parameters based on the extracted data and additional data, and update the initial values ​​stored in the server to the re-determined initial values.

[0045] The fourth step not only utilizes the parameters adjusted in the third step for controlling the mass flow control device, but also the parameters adjusted in the first step. 2nd This step is performed with the aim of using the adjusted parameters stored in the server in step S2 as data to determine the initial values ​​of parameters used in subsequent adjustments. By performing the fourth step, new additional data is accumulated in the server each time the mass flow control device is adjusted, so the re-determined and updated initial values ​​will reflect the results of the latest adjustment. This ensures that even if the initial values ​​to be determined change over time for any reason, the initial values ​​input to the mass flow control device can be adjusted to reflect that change. 11th Step S11 In the initial values ​​of the parameters Re Decide Therefore, it is extracted in the 10th step S10. Data and additional data: All data and additional data stored on the server extraction Alternatively, you can select only a certain number of data points and additional data points by going back in time from the present moment. extraction This may also be done. The former method is preferred when the initial value of the parameter to be determined increases or decreases repeatedly over time, while the latter method is preferred when the initial value increases or decreases only over time.

[0046] In a preferred embodiment, the method according to the second embodiment further includes a 12th step (S12) in which an alarm is issued when the difference between the initial value of a parameter read from the server and input to the mass flow control device and the parameter adjusted under the control conditions and the input initial value exceeds a threshold. In other words, the 12th step (S12) is a step in which an alarm is issued when the difference between the initial value input to the mass flow control device in step 7 and the parameter adjusted in step 8 exceeds a predetermined threshold. The alarm issued in step 12 is not particularly limited as long as it can notify the operator of the occurrence of an abnormality. Specific examples of such alarms include, for example, auditory alarms such as buzzers and synthesized voices, and visual alarms such as warning lights and display indicators.

[0047] As mentioned above, when the parameters of multiple mass flow control devices are individually adjusted under the same control conditions, the parameter values ​​determined by the adjustment generally do not differ significantly from one mass flow control device to another. However, due to individual differences in the components that make up the mass flow control device, the parameter values ​​are not perfectly identical, and there is variation with each adjustment. While this is not a problem if the variation remains within a certain range, if the degree of variation is larger than ever before, it is highly likely that some problem has occurred during the adjustment process. Causes of such large variations include, for example, inappropriate combinations of components that make up the mass flow control device, component defects, improper adjustment, and changes over time, as mentioned above. However, with this method, when the difference between the initial parameter value input to the mass flow control device before adjustment and the parameter value after adjustment exceeds a threshold, an alarm is issued to notify the operator of the occurrence of an abnormality, thereby preventing the supply of incorrectly adjusted mass flow control devices to customers.

[0048] <Third Embodiment> As stated at the beginning of this specification, the present invention relates not only to a method for determining initial values ​​of parameters and a method for adjusting a mass flow control device, but also to a system for determining initial values ​​of parameters and a system for adjusting a mass flow control device.

[0049] In a third embodiment, the present invention is a system used to determine initial values ​​of flow control parameters that are initially input to a mass flow control device when adjusting the mass flow control device. The system according to the present invention comprises at least one operating terminal configured to be connected to the mass flow control device and to be able to adjust parameters, at least one server, and communication means enabling the exchange of data between the mass flow control device, the operating terminal, and the server.

[0050] The operating terminal is not particularly limited as long as it is connected to the mass flow control device and capable of adjusting parameters, and as mentioned above, it may be a computer system such as a personal computer. The server is also a computer system having storage devices such as hard disk drives (HDDs) and solid-state drives (SSDs), as mentioned above. The communication means is not particularly limited as long as it enables the exchange of data between the mass flow control device, the operating terminal, and the server, and as mentioned above, it consists of a series of devices (such as a communication circuit board) that exchange data via known communication lines such as LAN cables and / or the internet.

[0051] Furthermore, the system according to the present invention is configured such that, according to a program stored in a storage device provided in the operating terminal and / or server, the processing device provided in the operating terminal and / or server executes a predetermined instruction, thereby executing at least the second step included in the method according to the first embodiment of the present invention described above. That is, in the system according to the present invention, at least the following steps are executed by an application installed in the operating terminal and / or server: a third step (S3) of extracting data with common control conditions from data stored in the server; a fourth step (S4) of determining initial values ​​of parameters based on the extracted data; and a fifth step (S5) of storing the determined initial values ​​of parameters in the server in association with the common control conditions.

[0052] Specific examples of storage devices provided by the operating terminal and / or server include, for example, hard disk drives (HDDs), solid-state drives (SSDs), and memory (RAM or ROM). Specific examples of processing devices provided by the operating terminal and / or server include, for example, a so-called central processing unit (CPU). The program for causing the processing device to execute the second step may be stored in a storage device provided by either the operating terminal or the server, or it may be distributed and stored in storage devices provided by both the operating terminal and the server. Furthermore, each of the above steps may be executed by a processing device provided by either the operating terminal or the server, or it may be executed by distributed processing by processing devices provided by both the operating terminal and the server.

[0053] As mentioned above, for example, if an operator manually adjusts the parameters of the mass flow control device in the first step of the first process included in the method according to the present invention, the adjusted parameters can be entered by the operator using an input device on the server itself in the next second step, thereby accumulating the data on the server. Alternatively, the adjusted parameters can be entered by the operator using an input device on the operation terminal and transmitted to the server via a communication means, thereby accumulating the data on the server. However, from the viewpoint of efficiency, it is desirable that the adjusted parameters be automatically accumulated on the server by the application (i.e., by the processing device executing a predetermined command according to the program).

[0054] Therefore, in a preferred embodiment, the system according to the present invention is configured such that, once the accuracy of flow control by the mass flow control device reaches a predetermined target value after the execution of the first step, the processing device executes a predetermined command according to the program to execute the second step. That is, in this system, the process of accumulating data in the server by individually executing the second step for each of the multiple mass flow control devices, in which data relating adjusted parameters and control conditions is stored in the server, is performed by an application installed on the operating terminal and / or the server.

[0055] Furthermore, the operator may determine whether the accuracy of flow control by the mass flow control device has reached a predetermined target value, and when it is determined that the accuracy of flow control has reached the predetermined target value, the operator may perform some operation (for example, inputting a predetermined command or clicking an object such as a button on the user interface) to start the execution of the second step in the application. Alternatively, it is desirable that the determination of whether the accuracy of flow control by the mass flow control device has reached a predetermined target value is also performed automatically by the application (i.e., by the processing device executing a predetermined instruction according to the program).

[0056] In the latter case, specifically, the application needs to determine whether the difference between the flow rate corresponding to the output signal related to the fluid flow rate output by the flow sensor incorporated in the mass flow control device and the actual flow rate is below a target value, and whether the index of the time change (transient response) of the flow rate when the set flow rate given to the mass flow control device changes is within a preset range. Therefore, in this case, the system according to the present invention is equipped with means for receiving signals from the mass flow control device that are necessary to detect the difference between the flow rate corresponding to the output signal from the flow sensor incorporated in the mass flow control device and the actual flow rate (i.e., the flow rate corresponding to the output signal from the reference flow meter), and the index of the time change (transient response) of the flow rate when the set flow rate given to the mass flow control device changes, and the program is equipped with instructions for executing the algorithm necessary to make the above determinations.

[0057] Furthermore, from the viewpoint of further efficiency, it is desirable that the first step included in the method according to the present invention is also performed automatically by the application (i.e., by the processing unit executing a predetermined instruction according to the program).

[0058] Therefore, in a preferred embodiment, the system according to the present invention is configured such that in the first step, the processing unit increases or decreases a parameter by a predetermined amount by executing a predetermined command according to a program. That is, with this system, in the first step, under certain control conditions, the parameter of the mass flow control device is automatically adjusted by the application (i.e., by the processing unit executing a predetermined command according to a program).

[0059] Furthermore, the extent to which the parameters are increased or decreased in the first step by this system (i.e., the magnitude of the increase or decrease) may be a fixed value predetermined for each parameter, or it may be a value that increases or decreases according to the degree of deviation from the target value of flow control accuracy. In the latter case, the program may be configured such that the greater the degree of deviation from the target value of flow control accuracy, the greater the increase or decrease in the parameter.

[0060] <Fourth Embodiment> In a fourth embodiment, the present invention relates to a system for adjusting a mass flow control device used under certain control conditions. In this system, the parameters of the mass flow control device are adjusted using initial values ​​of parameters determined by the method according to the first embodiment. As described above, the initial values ​​determined by the method according to the first embodiment differ from the default values ​​used in the prior art, and reflect the results of parameter adjustments previously performed under the control conditions for which the parameters are to be adjusted. Therefore, the time from the start of adjustment of the mass flow control device until the accuracy of the control operation reaches the target value is shortened, and the parameter adjustment can be completed quickly.

[0061] In other words, the system according to the fourth embodiment is configured such that the processing unit executes at least the sixth and seventh steps included in the method according to the second embodiment of the present invention by executing predetermined instructions according to a program. Specifically, in this system, in the third step described above, the sixth step of reading from the server the initial values ​​of various parameters that are associated with the control conditions at that time, among the initial values ​​of various parameters determined by the execution of the first and second steps described above and stored in the server, and the seventh step of inputting the initial values ​​of the parameters thus read out to the mass flow control device are automatically executed by the application (i.e., by the processing unit executing predetermined instructions according to a program).

[0062] Furthermore, from the standpoint of efficiency, it is desirable that the eighth step included in the method according to the present invention is also automatically executed by the application (i.e., by the processing unit executing a predetermined instruction according to the program). Therefore, in a preferred embodiment, the system according to the present invention is configured such that in the eighth step, the processing unit increases or decreases a parameter by a predetermined amount by executing a predetermined instruction according to the program.

[0063] Furthermore, the extent to which the parameters are increased or decreased in the eighth step by this system (i.e., the magnitude of the increase or decrease) may be a predetermined fixed value for each parameter, or it may be a value that increases or decreases according to the degree of deviation from the target value of flow control accuracy. In the latter case, the program may be configured such that the greater the degree of deviation from the target value of flow control accuracy, the greater the increase or decrease in the parameter.

[0064] In a preferred embodiment, the system according to the fourth embodiment is configured such that the processing unit executes a predetermined command in accordance with a program to perform the fourth step included in the method according to the preferred second embodiment described above. That is, in this system, in the fourth step described above, the following steps are automatically performed by the application (i.e., by the processing unit executing a predetermined command in accordance with a program): a ninth step of storing additional data in a server, which is associated with the parameters and control conditions of the mass flow control device adjusted in the eighth step; a tenth step of extracting data and additional data with common control conditions from the data and additional data stored in the server; and an eleventh step of re-determining the initial values ​​of the parameters based on the extracted data and additional data, and updating the initial values ​​stored in the server to the re-determined initial values. Therefore, with this system, the initial values ​​of the parameters can be updated more efficiently by automatically performing the fourth step.

[0065] In a preferred embodiment, the system according to the fourth embodiment is configured such that the processing unit executes a predetermined instruction in accordance with a program, thereby performing the twelfth step included in the method according to the preferred second embodiment described above. That is, the system is configured to issue an alarm when the difference between the initial value of a parameter read from the server and input to the mass flow control device and the parameter adjusted under the control conditions and the input initial value exceeds a threshold.

[0066] According to this system, when the difference between the initial value of the parameter entered into the mass flow control device before adjustment and the parameter after adjustment exceeds a threshold, an alarm is issued to notify the operator of the occurrence of an abnormality, thereby preventing the supply of incorrectly adjusted mass flow control devices to customers. [Explanation of symbols]

[0067] 1 Mass flow controller 10 channels 11 Entrance 12 Exit 20 Flow Sensor 21 Bypass 22 Sensor tubes 23 Electric heating wire 30 Flow control valve 31 Valve body 32 Drive mechanism 40 Control Unit

Claims

1. A method for determining the initial values ​​of flow control parameters that are initially input to a mass flow control device when adjusting the mass flow control device, A first step of adjusting the parameters of a certain mass flow control device under certain control conditions, A second step is to store data in a server, relating the adjusted parameters and the control conditions; A first step is to perform the following individually for each of the multiple mass flow control devices and store the data in the server, A third step involves extracting data from the data stored in the server that share the same control conditions, A fourth step is to determine the initial values ​​of the parameters corresponding to the common control conditions based on the extracted data, A fifth step involves storing the initial values ​​of the determined parameters in the server in association with the common control conditions, The second step is to carry out the following, A method that includes this.

2. The control conditions include the type of mass flow control device, the type of fluid, and the bin size. The method according to claim 1.

3. The adjustment of the mass flow control device includes the adjustment of the flow sensor. The initial values ​​of the determined parameters include the initial values ​​of the zero point, span, and linearity parameters. The method according to claim 1 or 2.

4. The adjustment of the mass flow control device includes adjustment of the transient response. The initial values ​​of the determined parameters include the initial values ​​of the parameters relating to proportional gain, integral gain, and differential gain. The method according to any one of claims 1 to 3.

5. In the first step, the parameter initially input to the mass flow control device when adjusting the parameter is not the optimal value for the control conditions, but is a provisional and general-purpose default value that allows the mass flow control device to operate under a wide range of control conditions. The method according to any one of claims 1 to 4.

6. A method for adjusting a mass flow control device used under certain control conditions, A sixth step of reading from the server the initial values ​​of the parameters associated with the control conditions, among the initial values ​​of the parameters determined by the method according to any one of claims 1 to 5, A seventh step involves inputting the initial values ​​of the read-out parameters to the mass flow control device, An eighth step of adjusting the parameters of the mass flow control device under the aforementioned control conditions, The third step is to carry out the following: A method that includes this.

7. A ninth step involves storing additional data in the server, which is a combination of the parameters and control conditions of the mass flow control device adjusted in the eighth step, A tenth step of extracting data and additional data from the data and additional data stored in the server that have common control conditions, An eleventh step involves re-determining the initial values ​​of the parameters based on the extracted data and the additional data, and updating the initial values ​​stored in the server with the re-determined initial values. The fourth step is to carry out the following: The method according to claim 6, further comprising:

8. Step 12: An alarm is issued when the difference between the initial value input to the mass flow control device in step 7 and the parameter adjusted in step 8 exceeds a predetermined threshold. The method according to any one of claims 6 or 7, further comprising:

9. A system used to determine the initial values ​​of flow control parameters that are initially input to a mass flow control device when adjusting the mass flow control device, The system comprises at least one operating terminal connected to the mass flow control device and configured to adjust the parameters, at least one server, and communication means enabling the exchange of data between the mass flow control device, the operating terminal, and the server. A system configured to perform at least the second step included in any one of claims 1 to 5 by having a processing unit provided in the operating terminal and / or server execute a predetermined command in accordance with a program stored in a storage device provided in the operating terminal and / or the server.

10. The system is configured to execute the second step when, after the execution of the first step, the accuracy of flow rate control by the mass flow rate control device reaches a predetermined target value, the processing device executes a predetermined command according to the program. The system according to claim 9.

11. In the first step, the processing device is configured to increase or decrease the parameter by a predetermined amount by executing a predetermined instruction in accordance with the program. The system according to claim 9 or 10.

12. The processing device is configured to execute at least the sixth and seventh steps included in the method of claim 6 by executing a predetermined command in accordance with the program, The system according to any one of claims 9 to 11.

13. In the eighth step, the processing device is configured to increase or decrease the parameter by a predetermined amount by executing a predetermined instruction in accordance with the program. The system according to claim 12.

14. The processing device is configured to execute the fourth step included in the method of claim 7 by executing a predetermined command in accordance with the program, The system according to claim 12 or 13.

15. The processing device is configured to execute the 12th step included in the method of claim 8 by executing a predetermined command in accordance with the program, The system according to any one of claims 11 to 14.

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