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

Abstract

This method adjusts the parameters of a mass flow control device under a certain control condition, linking the adjusted parameters to the control condition in a server. Next, data sharing common control conditions is extracted from the data accumulated on the server. Initial values ​​for the parameters are determined based on this extracted data and stored on the server in association with the common control condition. The mass flow control device is then adjusted using these initial parameter values. This allows for adjustment of the mass flow control device with fewer steps and prevents misadjustment from occurring in advance.

Description

Technical Field

[0001] This invention relates to a method and system for adjusting a mass flow control device. Background Technology

[0002] Mass flow control devices are, for example, precision machines used to quantitatively supply process gases to manufacturing equipment in semiconductor manufacturing processes. Mass flow control devices are manufactured by preparing components adapted to the maximum flow rate of the fluid controlled by the device and assembling these components together. The assembled mass flow control device is individually adjusted before leaving the factory. The adjustment of the mass flow control device includes adjusting the flow sensor (e.g., see Patent Document 1) and adjusting the transient response (e.g., see Patent Document 2), etc.

[0003] The adjustment of the mass flow control device is performed as follows: Under certain control conditions, using the input device of a personal computer connected to the mass flow control device, one or more parameters related to flow control stored in the non-volatile memory of the microprocessor built into the mass flow control device are rewritten. The parameters are rewritten while repeatedly alternating between the operation of actually flowing fluid into the mass flow control device and checking the control action, and the operation of rewriting the parameters based on the checked control action, until the accuracy of the control action reaches the target value.

[0004] Furthermore, a previous problem existed that multiple spare units were required due to the use of mass flow control devices that were individually adjusted for each gas and each cell size. Therefore, recently, a technology called "MGMR (Multi-Gas / Multi-Range) function," which enables a single mass flow control device to be used for multiple gases and multiple cell sizes, has been developed, significantly reducing the number of units in stock (see, for example, Patent Document 3). Adjustments to a mass flow control device equipped with this MGMR function require adjustments for multiple gases and multiple cell sizes, and the adjusted parameters are stored in the mass flow control device's memory.

[0005] Furthermore, in gas supply units, the supply pressure of the gas supplied to the mass flow control device sometimes fluctuates. For example, in gas panels that supply the same gas to multiple lines, the supply path to the mass flow control device is branched to supply gas to multiple mass flow control devices. Therefore, due to crosstalk between mass flow control devices, the supply pressure (gas supply inlet pressure) of the gas supplied to the mass flow control device sometimes changes instantaneously. Therefore, in conventional gas supply units, by installing a regulator upstream of the mass flow control device in the gas piping system, even if the gas supply inlet pressure changes, the regulator absorbs the change, thereby stabilizing the actual flow rate of the gas controlled by the mass flow control device.

[0006] However, from the perspective of reducing the cost of gas piping systems and achieving compactness, it is desirable to omit the regulator. Therefore, mass flow control devices equipped with a so-called "PI (Pressure Insensitive) function" are becoming increasingly common in this field. The PI function refers to the function of correcting for the difference between the measured flow rate (measured flow rate) and the actual flow rate caused by parasitic flow generated within the mass flow control device due to variations in gas supply inlet pressure. Specifically, the parasitic flow rate (parasitic flow rate) is calculated based on the measured gas supply inlet pressure, and the measured flow rate is accelerated so that the bandwidth of the measured flow rate is the same as the bandwidth of the parasitic flow rate. The parasitic flow rate is then subtracted from the accelerated measured flow rate to obtain a corrected flow rate (corrected flow rate) that is closer to the actual flow rate (see, for example, Patent Document 4). Therefore, in adjusting a mass flow control device equipped with this PI function, adjustments are made simultaneously with changes in the gas supply inlet pressure for various gases and multiple surface sizes, and the adjusted parameters are stored in the mass flow control device's memory.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 7-263350

[0010] Patent Document 2: Japanese Patent Application Publication No. 2014-59609

[0011] Patent Document 3: Japanese Patent No. 4957725

[0012] Patent Document 4: International Publication No. 2021 / 039665 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] In the adjustment of existing mass flow control devices, adjustments are made starting from the default values ​​of parameters stored in non-volatile memory, and the parameters are rewritten while undergoing trial and error to complete the adjustment. When the default values ​​are inappropriate, a significant amount of time is required until the adjustment is complete, thus potentially increasing operator labor costs and fluid consumption. In the adjustment of mass flow control devices equipped with MGMR functionality, as described above, a large number of parameters adjusted for multiple gas types and multiple cell sizes need to be stored in memory, requiring particularly high time, labor costs, and fluid consumption. This is especially true in the adjustment of mass flow control devices equipped with PI functionality, which require adjustments for multiple gases and multiple cell sizes while simultaneously varying the gas supply inlet pressure.

[0015] Furthermore, when adjustments are made using conventional methods, even if components constituting the mass flow control device malfunction or are not correctly assembled, the adjustment process itself involves repeatedly rewriting the parameters. Therefore, compared to a properly adjusted mass flow control device, there is a risk of individual performance variations or malfunctions during use.

[0016] The present invention was made in view of the above-mentioned problems, and its purpose is to complete the adjustment of the mass flow control device with fewer processes and reduce the deviation (individual difference) in the performance of the mass flow control device.

[0017] Solution for solving the problem

[0018] In a first embodiment, the method of the present invention is a method for determining the initial values ​​of flow control-related parameters initially input to the mass flow control device when adjusting the mass flow control device, including the first step and the second step listed below.

[0019] The first step involves individually performing the following steps on multiple mass flow control devices: adjusting the parameters of a mass flow control device under a certain control condition, and storing the data obtained by associating the adjusted parameters with the control conditions on the server, in order to accumulate data on the server.

[0020] The second process involves executing the third, fourth, and fifth steps. In the third step, data with common control conditions is extracted from the data accumulated on the server. In the fourth step, the initial values ​​of the parameters corresponding to the common control conditions are determined based on the extracted data. In the fifth step, the determined initial values ​​of the parameters are stored on the server in association with the common control conditions.

[0021] The initial values ​​of the parameters determined by the method involved in this invention become initial values ​​that reflect the past adjustment results of the mass flow control device.

[0022] In a second embodiment, the method of the present invention is used to adjust a mass flow control device used under certain control conditions, the method including a third step, which includes the sixth to eighth steps listed below.

[0023] Step 6: Read from the server the initial values ​​of the parameters associated with the control conditions from the initial values ​​of the parameters determined by the method involved in this invention.

[0024] Step 7: Input the initial values ​​of the read parameters into the mass flow control device.

[0025] Step 8: Adjust the parameters of the mass flow control device under controlled conditions.

[0026] According to this method, the adjustment of the mass flow control device can be started from the initial value of the parameter that reflects the past adjustment results of the mass flow control device.

[0027] The effects of the invention

[0028] According to the method of the present invention, compared with conventional methods, the process required for adjusting the mass flow control device can be reduced, thereby reducing labor costs and fluid consumption during adjustment, and consequently reducing the manufacturing cost of the mass flow control device. The advantages of the above-mentioned effects achieved by the method of the present invention are significant in mass flow control devices equipped with MGMR function, where adjustment requires a large amount of time, labor costs, and fluid as described above. Moreover, this is especially true in the adjustment of mass flow control devices equipped with PI function, where adjustments are required simultaneously by varying the gas supply inlet pressure for multiple gases and multiple element sizes, as described above. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating a first embodiment of the method involved in the present invention.

[0030] Figure 2 This is a schematic diagram illustrating an example of a method for adjusting a flow sensor in the method involved in this invention.

[0031] Figure 3 This is a flowchart illustrating a second embodiment of the method involved in the present invention.

[0032] Figure 4 This is a schematic diagram illustrating an example of the structure of a mass flow control device. Detailed Implementation

[0033] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the following description is merely illustrative of specific embodiments of the invention, and the invention is not limited to the embodiments described herein.

[0034] <Structure of Mass Flow Control Device>

[0035] Figure 4 This is a schematic diagram illustrating an example of the structure of a mass flow control device. It should be noted that... Figure 4 The structure of the mass flow control device is shown conceptually, but the shape, construction, and combination of the mass flow control device and the components constituting the mass flow control device are not shown in detail.

[0036] Figure 4 The mass flow control device 1 shown includes a flow path 10 for fluid flow. Fluid flows into the mass flow control device 1 from inlet 11 and out to the outside from outlet 12. A flow sensor 20 and a flow control valve 30 are disposed between inlet 11 and outlet 12 of the flow path 10. The flow sensor 20 includes a bypass 21 disposed inside the flow path 10, a sensor tube 22 branching off from the flow path 10, and a set of heating wires 23 wound on the upstream and downstream sides of the sensor tube 22. The bypass 21 has the function of maintaining a fixed ratio between the flow rate of the fluid flowing through the flow path 10 and the flow rate of the fluid branching off to the sensor tube 22. The bypass 21 can, for example, be constructed from a laminar flow element consisting of multiple tubes bundled together. The sensor tube 22 branches off 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 energized, a set of heating wires 23 wound around the sensor tube 22 generates heat as the fluid flows inside the sensor tube 22, which moves from the upstream side to the downstream side. This temperature difference between the heating wires 23 causes a difference in resistance. By detecting this difference in resistance, the flow rate of the fluid flowing inside the sensor tube 22 can be detected, as well as the flow rate of the fluid flowing in the flow path 10. That is, Figure 4 The flow sensor 20 shown is a thermal flow sensor.

[0037] The flow rate of the fluid detected by the flow sensor 20 is used to control the flow rate of the fluid flowing through the flow path 10. Specifically, the opening degree of the flow control valve 30 is controlled by the control unit 40 provided in the mass flow control device 1, so that the flow rate of the fluid detected by the flow sensor 20 is consistent with a preset flow rate. The flow control valve 30 includes a valve body 31 and a drive mechanism 32. The opening degree of the valve body 31 is controlled by inputting a control signal output from the control unit 40 to the drive mechanism 32. When the drive mechanism 32 is composed of a piezoelectric element, a voltage signal can be used as the control signal. Figure 4The mass flow control device 1 shown has a thermal flow sensor 20, but as the flow sensor 20, a so-called pressure type flow sensor and other known flow sensors may also be provided. Regardless of the structure of the flow sensor 20, the mass flow control device 1 measures the flow rate of the fluid through the flow sensor 20 and performs automatic control to make the flow rate consistent with the set flow rate.

[0038] <Rated flow rate>

[0039] In this specification, the maximum value of the flow rate of the fluid that the mass flow control device can control is referred to as the following "rated flow rate" or "full scale flow rate" (Japanese: full scale flow rate). Regarding the rated flow rate required by the requester for the mass flow control device, after conversion using nitrogen under standard conditions, for example, it ranges widely from 10 standard cubic centimeters per minute (hereinafter referred to as "sccm") to 50,000 sccm. In Figure 4 In the exemplified mass flow control device 1, the rated flow rate largely depends on the cross-sectional area and shape of the flow path 10, bypass 21, and valve body 31 with which the fluid directly contacts. The larger the cross-sectional area of the part where the fluid flows in these components, the larger the maximum value of the flow rate of the fluid that the mass flow control device 1 can control. When using a mass flow control device designed for a large rated flow rate to control a small flow rate, the accuracy of flow control becomes low. Conversely, it is physically impossible to supply a large flow rate of fluid using a mass flow control device composed of components with a small cross-sectional area capable of controlling a small rated flow rate. Therefore, it is necessary to design components such as the flow path 10, bypass 21, and valve body 31 where the fluid flows separately to suit the magnitude of the rated flow rate.

[0040] In actual products of the mass flow control device, the producer divides the range of the rated flow rate into several partitions and produces products suitable for each partition. Such a partition of the rated flow rate is referred to as the following "bin size". In addition, the serial number added expediently to determine the bin size is referred to as the following "bin number". Examples of the bin number and bin size are shown in Table 1. In the example shown in Table 1, for example, a requester who needs a mass flow control device with a rated flow rate of 2,000 sccm can purchase and use a mass flow control device with a bin number of BIN 5 (that is, the partition of the rated flow rate is 1,001 sccm to 3,000 sccm) from the producer. In the partition of the rated flow rate shown in Table 1, regarding components such as the flow path 10, bypass 21, and valve body 31 where the fluid flows, they can be designed separately to be different for each bin size, or common components can be used for multiple bin sizes with close rated flow rates.

[0041] [Table 1]

[0042] Table 1

[0043]

[0044] <parameters>

[0045] In this specification, "parameter" refers to a variable input to determine the content of control when the mass flow control device executes the flow control algorithm. The mass flow control device may use one type of parameter or two 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 assembled and pre-shipment mass flow control device to check whether the mass flow control device meets the performance indicated by the target value. If the performance does not meet the check results, the parameters are changed 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 mass flow control device is adjusted while repeatedly alternating between checking the control action by actually flowing fluid through the mass flow control device and rewriting the parameters based on the checked control action, until the accuracy of the control action reaches the target value. The adjustment of the mass flow control device can be performed manually by the operator or automatically by operation via a computer program, as described in detail later. Each mass flow control device is adjusted individually after manufacturing and before leaving the factory. In principle, once the parameters are adjusted, they are not changed again.

[0046] <First Implementation Method>

[0047] In a first embodiment, the present invention relates to a method for determining the initial value of a parameter initially input to a mass flow control device when adjusting its parameters. In this specification, "initial value" refers to the initial value of a parameter first input to the mass flow control device when adjustment begins. In the prior art, default values ​​are used as the initial parameters input to the mass flow control device. In this specification, "default value" refers to a pre-prepared setting value intended to prevent system malfunctions (faults) that occur when no value is input during program processing that requires certain values. The default values ​​used in the prior art are fixed values ​​and do not reflect the results of parameter adjustment. In contrast, the initial value of the parameter involved in the method of the present invention is determined according to a predetermined process based on the value of the parameter, which is the result of adjustments performed individually in the past.

[0048] Figure 1This is a flowchart illustrating the method according to the first embodiment of the present invention. The method includes two steps. The first step involves individually performing a first step (S1) on multiple mass flow control devices to adjust the parameters of a certain mass flow control device under a certain control condition, and a second step (S2) to store the data obtained by associating the adjusted parameters with the control conditions in a server, thereby accumulating data in the server. In this specification, the "control conditions" of the mass flow control device refer to the conditions that affect the control of flow rate. Specific examples of the 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 values ​​of the parameters determined by the adjustment will not vary significantly depending on the individual mass flow control devices. However, due to individual differences in the components constituting the mass flow control devices, the parameter values ​​will not be exactly the same, and there will be deviations between each adjustment. In the first step, the step of storing the data obtained by associating the adjusted parameters, including the deviations, with the control conditions in a server is performed on multiple mass flow control devices to accumulate data in the server.

[0049] In this specification, "server" refers to a computer system with storage devices, preferably a computer system directly connected to the mass flow control device or connected via an operating terminal for adjustment (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 mandatory; for example, in the case of manual adjustment by an operator, data can be accumulated in the server by the operator inputting the adjusted parameters using the input device built into the server itself.

[0050] In the second step of the method according to the first embodiment, the following steps are performed: a third step (S3), extracting data with common control conditions from the data accumulated in the server; a fourth step (S4), determining the initial value of the parameter based on the extracted data; and a fifth step (S5), storing the determined initial value of the parameter in association with the common control conditions in the server. As a result of performing the first step, data that associates data with different control conditions with the control conditions is accumulated in the server. If only data with common control conditions is extracted from the data accumulated in the server, the control conditions of the extracted data are all the same, so the deviation is small. Therefore, if the initial value of the parameter is determined based on the extracted data, a highly reliable initial value of the parameter that reflects the results of past adjustments can be obtained. Regarding the determination of the initial value of the parameter, it is sufficient to use the extracted data, and there is no particular limitation on the specific method of determination. As a method for determining the initial value of the parameter based on the extracted data, statistical methods such as calculating the average value and selecting the median or most frequent value can be used. 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 read from the server at any time and used as the initial values ​​of the parameters for the next adjustment.

[0051] In a preferred embodiment, the control conditions in the method of the present invention include the type of mass flow control device, the type of fluid, and the size of the flow element. As mentioned above, if the parameters of multiple mass flow control devices are individually adjusted under the same control conditions, the values ​​of the parameters determined by the adjustment will not vary significantly depending on the individual mass flow control device. In other words, when the control conditions of the mass flow control devices are different, the adjusted parameters tend to have values ​​different from those under the same control conditions. Therefore, it is important to consider which conditions among the control conditions of the mass flow control devices are associated with when accumulating data on the server. One of the control conditions that has a significant impact on the value of the parameters 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 components other than the flow sensor, such as the flow path and flow control valve, are used in common between different types of mass flow control devices, the values ​​of the parameters can vary significantly due to differences in the transient response of the flow sensor.

[0052] Furthermore, the type of fluid being controlled also significantly affects the parameter values. Different fluid types exhibit varying thermal properties, viscosity, and other dynamic properties, thus affecting not only flow sensors but also the behavior of fluids in bypass and flow control valves. Consequently, the adjusted parameter values ​​vary considerably. Moreover, even with the same type of mass flow control device and fluid, differences in element size can sometimes lead to variations in parameter values ​​due to differences in the fluid's Reynolds number. Thus, the parameter values ​​determined through adjustment can vary drastically depending on the various control conditions of the mass flow control device. Consequently, when adjustments are made using initial values ​​determined without considering control conditions, parameter adjustments can be extremely time-consuming.

[0053] In the method of this invention, parameters sharing common control conditions are extracted from data of adjusted parameters stored on a server in association with control conditions, and initial values ​​are determined based on the extracted parameters. These initial values ​​differ from the default values ​​of the prior art, becoming values ​​that reflect the results of parameter adjustments performed in the past under these control conditions. Using such initial values ​​to adjust the mass flow control device can shorten the time from the start of adjustment to the point where the accuracy of the control action reaches the target value, thereby enabling rapid adjustment.

[0054] In a preferred embodiment of the invention, since the control conditions, including the type of mass flow control device, the type of fluid, and the size of the surface area, which are considered to have a significant impact on the parameters, are common, the time required for adjustment is significantly reduced. These factors considered to have a significant impact on the parameters can be any one factor, two factors, or all three factors. The more common the factors, the more significant the effect of the invention.

[0055] In a preferred embodiment, the adjustment in the method of the present invention includes adjusting the flow sensor, with parameters including those related to zero point, range, and linearity. In this specification, "adjusting the flow sensor" refers to adjusting the parameters that affect the output of the flow sensor so that the difference between the flow rate corresponding to the output signal related to the fluid flow rate from the flow sensor assembled in the mass flow control device and the actual flow rate is below a target value. Sometimes, the operation of adjusting the flow sensor to bring the fluid flow rate detected by the flow sensor closer to the true value is called "calibration" of the mass flow control device or the flow sensor. When the flow sensor is not properly calibrated, the fluid flow rate, which is the basis for the control of the mass flow control device, includes errors, and therefore the flow rate cannot be properly controlled. Therefore, adjusting the flow sensor is a fundamental and important operation.

[0056] Figure 2 This is a schematic diagram illustrating an example of a flow sensor adjustment method. The short arrows in the diagram indicate the direction of fluid flow within the flow path. Additionally, the dashed lines connecting the constituent components represent the paths for exchanging signals, commands, etc., between the multiple constituent components. When adjusting the flow sensor, as... Figure 2 As illustrated, generally, a reference flow meter, serving as the baseline for measuring flow rate, is connected in series with a mass flow control device, and fluid is flowed through it. The parameters of the flow sensor are rewritten by a personal computer so that the flow sensor's output matches the output of the reference flow meter, thereby adjusting the flow sensor. For example, a molbloc (a registered trademark of Fluke Corporation) can be used as the reference flow meter. The adjusted parameters are stored on a server in association with the control conditions.

[0057] Specific examples of parameters affecting the output of a flow sensor include, but are not limited to, zero point, range, and linearity. Zero-point related parameters are adjusted so that the flow sensor output is zero when no fluid is flowing. Range related parameters are adjusted so that the outputs of both the flow sensor and the reference flow meter represent full-scale flow when fluid at full scale flows after zero-point adjustment. When the relationship between the flow sensor output and the actual flow rate deviates from a proportional relationship and non-linearity is confirmed, the flow sensor output is corrected using software, and linearity related parameters are adjusted so that the flow sensor output is proportional to the actual flow rate between zero point and full-scale flow. All three parameters directly affect the flow sensor output, so it is preferable to determine the initial values ​​as described above. However, in a preferred embodiment of the invention, it is also permissible to determine the initial values ​​by adjusting other parameters that directly or indirectly affect the flow sensor output, in addition to zero-point, range, and linearity related parameters. Furthermore, the flow sensor is adjusted when the fluid flow rate is stable at a fixed value. Adjustments to the parameters of the flow sensor when its output changes over time are included in the adjustment of the transient response, which will be described below.

[0058] In a preferred embodiment, the adjustment in the method of the present invention includes adjustment of the transient response, with parameters including those related to proportional gain, integral gain, and derivative gain. In this specification, "adjustment of the transient response" refers to adjusting the parameters that affect the transient response so that the indicator of the change in flow rate over time (transient response) when the set flow rate provided by the mass flow control device changes is within a predetermined range. Specific examples of transient response indicators 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 fluctuations. Sometimes, the operation of adjusting the transient response of the mass flow control device is referred to as "tuning" the mass flow control device. When the mass flow control device is not properly tuned, the change in flow rate over time when the set flow rate changes results in individual differences, and therefore the total fluid supply may be inaccurate. Therefore, adjusting the transient response is as fundamental and important as adjusting the flow sensor. When adjusting the transient response, generally, the output of the flow sensor (hereinafter sometimes referred to as the "step response") is monitored when a change in the set flow rate relative to 100%, 50%, etc., of the full-scale flow rate occurs. The parameters of the mass flow control device are then adjusted so that the transient response index (e.g., the time it takes for the flow rate to reach 98% of the set flow rate) falls within a preset range.

[0059] Specific examples of parameters affecting the transient response include, but are not limited to, proportional gain, integral gain, and derivative gain, which are parameters related to feedback control, i.e., PID action. Furthermore, the flow control algorithm in this invention is not limited to PID action; it can employ known automatic control methods such as feedback control, H-infinity control, fuzzy control, and neural network control. In these automatic control methods, the term "parameter" in this specification should be interpreted in its broadest sense. When adjusting the transient response, it is generally preferable to adjust the flow sensor beforehand to accurately evaluate the step response. However, depending on the control conditions, the adjustment of the transient response can sometimes significantly influence the adjustment of the flow sensor; therefore, it is preferable to determine, based on the specific circumstances, whether to perform the adjustment of the flow sensor or the transient response first. Additionally, to more accurately adjust the mass flow control device, it is preferable to repeatedly and alternately perform the adjustment of the flow sensor and the transient response.

[0060] Referring again to Table 1, Table 1 shows examples of initial parameter values ​​determined as a result of adjusting a mass flow control device of the same type and fluid type, differing only in the size of its surface cells, in a preferred embodiment of the present invention. In Table 1, parameters affecting the output of the flow sensor include zero point, range, and linearity parameters; parameters affecting the transient response include proportional gain, integral gain, and derivative gain. In Table 1, blank columns indicate that no parameter adjustments have been made under this control condition in the past, and therefore the initial parameter values ​​have not yet been determined.

[0061] Here, the adjustment of parameters that affect the transient response is explained in detail below. As illustrated in Table 1, different initial values ​​for the parameters can be determined for each cell size. However, it is also possible to determine a common single initial value for parameters that are almost unaffected by differences in cell size for all cell sizes. Furthermore, it is also possible to divide the full scale (e.g., 2,000 sccm) at a certain cell size into several partitions (e.g., 1%, 2%, 5%, 10%, 25%, 50%, 75%, 100%, 120%, 140% of the full scale) and determine different initial values ​​for the parameters for each partition.

[0062] Among the parameters listed in Table 1, the linear and proportional gains are particularly effective for setting extremely fine parameters as described above. This is because the flow characteristics of a flow control valve (the change in flow rate relative to the valve opening) are not a simple proportional relationship, but include nonlinear elements. For this reason, these two parameters are easily affected by differences in the size of the flow cells. On the other hand, the integral and derivative gains are parameters less affected by differences in the size of the full-scale division and the size of the flow cells, and therefore, it is sometimes possible to use common initial values ​​without considering the division and / or the size of the flow cells. As initial values ​​for the parameters, for example, the average value of the parameters adjusted using multiple (e.g., 3 to 5) mass flow control devices can be used.

[0063] Furthermore, among the parameter adjustments, the adjustment of the flow sensor parameters is the most fundamental and is usually performed first. 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 shown by a reference flow meter (e.g., a Molbloc). In the adjustment of the transient response parameters, the gains of the PID controller are adjusted to minimize, for example, the response time to a step input (an indicator of the transient response derived from the step response). Adjustments to either side are fine-tuning necessary due to individual differences in the mass flow control device. It is conceivable that in the future, parameter adjustments could also be based on the results of AI analyzing large amounts of data accumulated on servers.

[0064] In a preferred embodiment, in the method of the present invention, the parameters initially input to the mass flow control device when adjusting the parameters are not optimal values ​​for the current control conditions, but rather provisional and general default values ​​that enable 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 a certain control condition. As mentioned above, in cases where no adjustment has been performed under a certain control condition (as shown in the blank column of Table 1), the initial value described in the present invention does not exist. Therefore, in such cases, 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 aforementioned control conditions, but rather a provisional and general default value that enables the mass flow control device to operate under a wide range of control conditions. Here, "provisional" means a temporary value used only until the parameters are changed through adjustment. Furthermore, "general" means a value that can be used under a wide range of control conditions regardless of specific control conditions. Such default values ​​can be set, for example, based on adjusted parameters in a mass flow control device with a similar structure that has been adjusted in the past, and / or adjusted parameters for the same mass flow control device and the same type of fluid with similar cell sizes.

[0065] <Second Implementation Method>

[0066] In a second embodiment, the present invention is an invention 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 mentioned above, the initial values ​​determined by the method according to the first embodiment differ from the default values ​​used in the prior art; they are values ​​reflecting the results of parameter adjustments performed in the past under the control conditions under which the parameters are to be adjusted. Therefore, the time from the start of adjusting the mass flow control device to the point where the accuracy of the control action reaches the target value can be shortened, thereby enabling rapid adjustment.

[0067] Figure 3 This is a flowchart illustrating a method according to a second embodiment of the present invention. The method includes a third step. The third step performs the following steps: a sixth step (S6), reading from a server the initial value of a parameter associated with control conditions from the initial values ​​of parameters determined by the method according to the first embodiment; a seventh step (S7), inputting the read initial value of the parameter into a mass flow control device; and an eighth step (S8), adjusting the parameters of the mass flow control device under control conditions.

[0068] In this method, the control conditions for the mass flow control device whose parameters are to be adjusted are predetermined. In the sixth step S6, an initial value for the parameter after adjustment under the same control conditions as the desired adjustment is searched from the initial values ​​of the parameters stored on the server as a result of executing the second step of the method according to the first embodiment. If such an initial value exists, it is read from the server. The read initial value is input to the mass flow control device (seventh step S7), and the parameters of the mass flow control device are readjusted under the same control conditions as the read initial value (eighth step S8). If the required initial value has not been accumulated in the server, the third step cannot be executed. In such cases, before executing the third step, the initial value of the parameter under the required control conditions is determined by executing the first and second steps of the first embodiment, and then the third step can be executed.

[0069] In a preferred embodiment, the method of the second embodiment includes a fourth step. The fourth step performs the following steps: a ninth step (S9), storing additional data (formed by associating the parameters of the mass flow control device adjusted in the eighth step (S8) with control conditions) in a server; a tenth step (S10), extracting data and additional data with common control conditions from the data stored in the server and the additional data; and an eleventh step (S11), 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.

[0070] The purpose of performing the fourth step is to ensure that the parameters adjusted in the third step are not only used in the control of the mass flow control device, but also effectively used as data for determining the initial values ​​of parameters to be used in subsequent adjustments, just like the adjusted parameters stored on the server in the second step S2 of the first step. By performing the fourth step, new additional data is accumulated in the server whenever the mass flow control device is adjusted, so the re-determined updated initial values ​​reflect the latest adjustment results. Thus, even if the determined initial values ​​change over time for some reason, the initial values ​​input to the mass flow control device can be set to the initial values ​​corresponding to that change. Regarding the data and additional data extracted in the tenth step S10 for re-determining the initial values ​​of the parameters in the eleventh step S11, all data and additional data stored in the server can be extracted, or only a fixed number of data and additional data can be selected and extracted by tracing back from the current point in time. The former method is preferred when the initial values ​​of the determined parameters repeatedly increase or decrease over time, and the latter method is preferred when the initial values ​​only increase or decrease over time.

[0071] In a preferred embodiment, the method of the second embodiment further includes a twelfth step (S12), in which an alarm is issued when the difference between the initial value of the 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, in the twelfth step (S12), an alarm is issued when the difference between the initial value input to the mass flow control device in the seventh step and the parameter adjusted in the eighth step exceeds a predetermined threshold. Furthermore, there are no particular limitations on the alarm issued in the twelfth step, as long as it can notify the operator of the occurrence of an anomaly. Specific examples of such alarms include auditory alarms such as buzzers and synthesized sounds, and visual alarms such as warning lights and display screens.

[0072] As mentioned above, if the parameters of multiple mass flow control devices are adjusted individually under the same control conditions, the resulting parameter values ​​generally do not vary 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 ​​will not be exactly the same, resulting in deviations for each adjustment. This is not a problem when the deviation converges within a fixed range, but when the degree of deviation is unprecedentedly large, certain problems may arise during the adjustment process. Reasons for such increased deviations include, for example, improper combinations of components constituting the mass flow control device, component malfunctions, improper adjustment, and changes over time, as mentioned above. However, according to this method, when the difference between the initial value of the parameters input to the mass flow control device before adjustment and the adjusted parameters exceeds a threshold, an alarm can be issued to notify the operator of the abnormality, thereby preventing the delivery of an incorrectly adjusted mass flow control device to the user.

[0073] <Third Implementation Method>

[0074] As stated at the beginning of this specification, the present invention relates not only to methods for determining initial values ​​of parameters and methods for adjusting mass flow control devices, but also to systems for determining initial values ​​of parameters and systems for adjusting mass flow control devices.

[0075] In a third embodiment, the present invention is a system used to determine the initial values ​​of flow control-related parameters initially input to the mass flow control device when adjusting the mass flow control device. The system according to the present invention includes: at least one operating terminal configured to be connected to the mass flow control device and capable of adjusting parameters; at least one server; and a communication unit capable of transmitting and receiving data between the mass flow control device, the operating terminal, and the server.

[0076] The operating terminal is not particularly limited as long as it can connect to the mass flow control device and adjust parameters; for example, it can be a computer system such as a personal computer. Similarly, the server is also as mentioned above, for example, a computer system with storage devices such as hard disk drives (HDDs) and solid-state drives (SSDs). The communication unit is not particularly limited as long as it can transmit and receive data between the mass flow control device, the operating terminal, and the server; for example, it can consist of a series of devices (such as communication circuit boards) that transmit and receive data via known communication lines such as LAN cables and / or the Internet.

[0077] Furthermore, the system according to the present invention is configured such that: by executing a predetermined command according to a program stored in a storage device of the operating terminal and / or server using a processing device, at least the second step included in the method according to the first embodiment of the present invention is performed. That is, in the system according to the present invention, at least the following steps are performed by an application installed on the operating terminal and / or server: third step (S3), extracting data with common control conditions from data accumulated in the server; fourth step (S4), determining the initial value of the parameter based on the extracted data; and fifth step (S5), storing the determined initial value of the parameter in association with the common control conditions in the server.

[0078] Specific examples of storage devices provided by the operating terminal and / or server include 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 central processing units (CPUs). The program for causing the processing device to perform the second step can be stored in the storage device provided by either the operating terminal or the server, or it can be stored separately in the storage devices provided by both the operating terminal and the server. Furthermore, the above steps can be performed by the processing device provided by either the operating terminal or the server, or they can be performed through distributed processing by the processing devices provided by both the operating terminal and the server.

[0079] Furthermore, as mentioned above, for example, if the 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, in the subsequent second step, the adjusted parameters can be input by the operator using the input device of the server itself, and data can be accumulated in the server. Alternatively, the adjusted parameters can be input by the operator using the input device of the operating terminal and sent to the server via the communication unit, and data can be accumulated in the server. However, from the viewpoint of efficiency, it is desirable to automatically accumulate the adjusted parameters in the server through an application program (i.e., by having a processing device execute prescribed commands according to a program).

[0080] Therefore, in a preferred embodiment, the system of the present invention is configured such that, after the accuracy of flow control using a mass flow control device reaches a predetermined target value by performing a first step, a second step is performed by the processing device executing predetermined commands according to a program. That is, in this system, the following steps are performed by an application installed on the operating terminal and / or server: a second step is performed individually on each of the multiple mass flow control devices to store data that correlates the adjusted parameters with control conditions on the server, thereby accumulating data on the server.

[0081] Furthermore, the operator determines whether the accuracy of the flow control performed by the mass flow control device has reached the specified target value. If the operator determines that the accuracy has reached the target value, they perform certain operations (e.g., inputting a specified command or clicking an object such as a button on the user interface), thereby causing the application program to begin executing the second step. Alternatively, it is also desirable to automatically perform the determination of whether the accuracy of the flow control performed by the mass flow control device has reached the specified target value through the application program (i.e., by executing specified commands according to the program through the processing device).

[0082] 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 from the flow sensor assembled in the mass flow control device and the actual flow rate is below a target value, and whether the indicator of the flow rate change over time (transition response) when the set flow rate provided by the mass flow control device changes falls within a predetermined range. Therefore, in this case, the system according to the present invention includes the following unit: receiving from the mass flow control device the signal required for detecting the difference between the flow rate corresponding to the output signal from the flow sensor assembled 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 indicator of the flow rate change over time (transition response) when the set flow rate provided by the mass flow control device changes, and the program needs to have commands for executing the algorithm required to make the above determinations.

[0083] Furthermore, from the viewpoint of further efficiency, the first step included in the method of the present invention is also expected to be executed automatically by an application (i.e., by a processing device executing a prescribed command according to a program).

[0084] Therefore, in a preferred embodiment, the system according to the present invention is configured such that, in a first step, a parameter is increased or decreased by a predetermined amount by a processing device executing a predetermined command according to a program. That is, according to the system, in the first step, under certain control conditions, the parameters of the mass flow control device are automatically adjusted by an application program (i.e., by a processing device executing a predetermined command according to a program).

[0085] Furthermore, the degree to which the parameters are increased or decreased in the first step by this system (i.e., the magnitude of the increase or decrease) can be a fixed value predetermined for each parameter, or it can be a value that is increased or decreased based on the degree to which the accuracy of the flow control deviates from the target value. In the latter case, the program can be configured such that the greater the degree to which the accuracy of the flow control deviates from the target value, the greater the magnitude of the increase or decrease in the parameter.

[0086] <Fourth Implementation Method>

[0087] In the fourth embodiment, the present invention is an invention 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 involved in the first embodiment. As mentioned above, the initial values ​​determined by the method involved in the first embodiment differ from the default values ​​used in the prior art; they are values ​​reflecting the results of parameter adjustments performed in the past under the control conditions under which the parameters were to be adjusted. Therefore, the time from the start of adjusting the mass flow control device to the point where the accuracy of the control action reaches the target value can be shortened, thereby rapidly completing the parameter adjustment.

[0088] That is, the system configuration of the fourth embodiment is such that at least the sixth and seventh steps included in the method of the second embodiment of the present invention are executed by the processing device executing predetermined commands according to the program. That is, in this system, in the aforementioned third step, the following steps are automatically executed by the application program (i.e., by the processing device executing predetermined commands according to the program): the sixth step, reading from the server the initial value of the parameter associated with the current control conditions from the initial values ​​of various parameters determined and accumulated in the server by executing the aforementioned first and second steps; and the seventh step, inputting the initial value of the parameter read in this way into the mass flow control device.

[0089] Furthermore, from the viewpoint of efficiency, the eighth step included in the method of the present invention is also expected to be configured to be executed automatically by an application program (i.e., by a processing device executing a predetermined command according to a program). Therefore, in a preferred embodiment, the system of the present invention is configured such that, in the eighth step, the parameter is increased or decreased by a predetermined amount by the processing device executing a predetermined command according to a program.

[0090] Furthermore, the degree to which the parameters are increased or decreased in the eighth step by this system (i.e., the magnitude of the increase or decrease) can be a fixed value predetermined for each parameter, or it can be a value that is increased or decreased based on the degree to which the accuracy of the flow control deviates from the target value. In the latter case, the program can be configured such that the greater the degree to which the accuracy of the flow control deviates from the target value, the greater the magnitude of the increase or decrease in the parameter.

[0091] In a preferred embodiment, the system configuration of the fourth embodiment is such that a processing device executes a predetermined command according to a program to perform the fourth step included in the method of the aforementioned preferred second embodiment. That is, in this system, in the aforementioned fourth step, the following steps are automatically performed by an application program (i.e., by the processing device executing a predetermined command according to a program): a ninth step, storing additional data obtained by associating the parameters of the mass flow control device adjusted in the eighth step with control conditions in a server; a tenth step, extracting data and additional data with common control conditions from the data and additional data stored in the server; and an eleventh step, 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, according to this system, by automatically executing the fourth step, the initial values ​​of the parameters can be updated more efficiently.

[0092] In a preferred embodiment, the system configuration of the fourth embodiment is such that the twelfth step included in the method of the aforementioned preferred second embodiment is executed by a processing device executing a predetermined command according to a program. That is, the system configuration is such that an alarm is issued when the difference between the initial value of the parameter read from the server and input to the mass flow control device and the parameter adjusted under control conditions and the input initial value exceeds a threshold.

[0093] According to this system, when the difference between the initial value of the parameter input to the mass flow control device before adjustment and the adjusted parameter exceeds a threshold, an alarm can be issued to notify the operator of the abnormality, thereby preventing the incorrectly adjusted mass flow control device from being provided to the user in advance.

[0094] Explanation of reference numerals in the attached figures

[0095] 1: Mass flow control device; 10: Flow path; 11: Inlet; 12: Outlet; 20: Flow sensor; 21: Bypass; 22: Sensor tube; 23: Heating wire; 30: Flow control valve; 31: Valve body; 32: Drive mechanism; 40: Control unit.

Claims

1. A method for determining initial values ​​of flow control-related parameters initially input to the mass flow control device during adjustment, the method comprising the steps of: In a first step, the plurality of mass flow controllers are individually adjusted under predetermined control conditions, and in a second step, data associating the adjusted parameters with the control conditions are stored in a server, so that the data are accumulated in the server. as well as The second step involves the following steps: The third step is to extract data that share the common control conditions from the data accumulated in the server. The fourth step is to determine the initial value of the parameter corresponding to the common control conditions based on the extracted data; as well as The fifth step is to store the initial values ​​of the determined parameters in association with the common control conditions on the server.

2. The determination method according to claim 1, characterized in that, The control conditions include the type of mass flow control device, the type of fluid, and the size of the surface area.

3. The determination method according to claim 1, characterized in that, The adjustment of the mass flow control device includes the adjustment of the flow sensor. The initial values ​​of the determined parameters include initial values ​​of parameters related to zero, range, and linearity.

4. The determination method according to claim 1, characterized in that, The adjustment of the mass flow control device includes the adjustment of the transient response. The initial values ​​of the determined parameters include initial values ​​of parameters related to proportional gain, integral gain, and derivative gain.

5. The determination method according to claim 1, characterized in that, In the first step, the parameters initially input to the mass flow control device when adjusting the parameters are not the optimal values ​​for the control conditions, but rather provisional and general default values ​​that enable the mass flow control device to operate under a wide range of control conditions.

6. An adjustment method for adjusting a mass flow control device used under controlled conditions. The adjustment method includes a third step, in which the following steps are performed: The sixth step is to read from the server the initial value of the parameter associated with the control condition from the initial values ​​of the parameter determined by the determination method according to any one of claims 1 to 5; The seventh step is to input the initial value of the read parameter into the mass flow control device; as well as The eighth step is to adjust the parameters of the mass flow control device under the control conditions.

7. The adjustment method according to claim 6, characterized in that, It also includes a fourth step, in which the following steps are performed: The ninth step is to store the additional data obtained by associating the parameters of the mass flow control device adjusted in the eighth step with the control conditions in the server. The tenth step is to extract the data and the appended data that share the same control conditions from the data and the appended data stored in the server. as well as The 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 to the re-determined initial values.

8. The adjustment method according to claim 6 or 7, characterized in that, It also includes a twelfth step, in which an alarm is issued when the difference between the initial value input to the mass flow control device in the seventh step and the parameter adjusted in the eighth step exceeds a predetermined threshold.

9. A decision system for determining initial values ​​of flow control-related parameters initially input to the mass flow control device during adjustment. The decision-making system comprises: at least one operating terminal configured to be connected to the mass flow control device and capable of adjusting the parameters; at least one server; and a communication unit capable of sending and receiving data between the mass flow control device, the operating terminal, and the server. The decision system is configured to execute at least the second step included in the decision method according to any one of claims 1 to 5 by executing a predetermined command according to a program stored in a storage device provided by the operating terminal and / or the server through a processing device.

10. The decision system according to claim 9, characterized in that, The decision system is configured such that, after the accuracy of flow control using the mass flow control device reaches a predetermined target value by executing the first step, the second step is executed by the processing device executing predetermined commands according to the program.

11. The decision system according to claim 9 or 10, characterized in that, The decision system is configured such that, in the first step, the parameter is increased or decreased by a predetermined amount by the processing device executing a predetermined command according to the program.

12. The decision system according to claim 9, characterized in that, The decision system is configured to execute at least the sixth and seventh steps included in the adjustment method according to claim 6 by the processing device executing a predetermined command according to the program.

13. The decision system according to claim 12, characterized in that, The decision system is configured such that, in the eighth step, the parameter is increased or decreased by a predetermined amount by the processing device executing a predetermined command according to the program.

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

15. The decision system according to claim 11, characterized in that, The decision system is configured to execute the twelfth step included in the adjustment method according to claim 8 by the processing device executing a predetermined command according to the program.

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