Fluid control device, fluid control system, diagnostic method, and program recording medium

Abstract

The present invention provides a fluid control device, which can accurately determine whether there is valve seat leakage for two valves in a short time, and comprises: a fluid resistance element (R), which is arranged in a flow channel; a first valve (V1), which is arranged on the upstream side of the fluid resistance element (R); a first pressure sensor (P1), which measures the pressure in a first volume (VL1) located between the first valve (V1) and the fluid resistance element (R) in the flow channel; a second valve (V2), which is arranged on the downstream side of the fluid resistance element (R); a second pressure sensor (P2), which measures the pressure in a first volume (VL1) located in the flow channel; The pressure of the second volume (VL2) between the fluid resistance member (R) and the second valve (V2); a valve controller (4) for controlling the first valve (V1) or the second valve (V2); and a valve seat leakage judgment unit (52) for judging whether the first valve (V1) and the second valve (V2) have valve seat leakage based on the measured pressures of the first pressure sensor (P1) and the second pressure sensor (P2) when the valve controller (4) makes the first valve (V1) and the second valve (V2) completely closed.

Description

Technical Field

[0001] The present invention relates to a fluid control device in which valves are respectively provided on the upstream side and the downstream side of a fluid resistance member. Background Art

[0002] For example, in a semiconductor manufacturing process such as an ALD process in which a film is formed by one layer of atoms, supply and stop of a gas to a chamber are repeated in an extremely short cycle (see Patent Document 1).

[0003] In such applications, in order to make the flow rate of the gas follow the set flow rate in a short time, a fluid control device including two valves that independently control the pressure and flow rate of the gas may be used.

[0004] Furthermore, the fluid control device is required to reliably prevent gas from flowing to the downstream side when the valve is closed. Therefore, it is necessary to regularly diagnose valve seat leakage of both valves.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Publication No. 2012-99765 Summary of the invention

[0007] In view of the above problems, an object of the present invention is to provide a fluid control device capable of accurately determining whether or not there is valve seat leakage in two valves in a short time.

[0008] That is, the present invention provides a fluid control device, characterized in that it includes: a fluid resistance element, which is arranged in a flow channel; a first valve, which is arranged on the upstream side of the fluid resistance element; a first pressure sensor, which measures the pressure in a first volume in the flow channel between the first valve and the fluid resistance element; a second valve, which is arranged on the downstream side of the fluid resistance element; a second pressure sensor, which measures the pressure in a second volume in the flow channel between the fluid resistance element and the second valve; a valve controller, which controls the first valve or the second valve; and a valve seat leakage judgment unit, which judges whether the first valve and the second valve have valve seat leakage based on the measured pressures of the first pressure sensor and the second pressure sensor when the valve controller makes the first valve and the second valve fully closed.

[0009] According to this structure, when valve seat leakage occurs in the first valve or the second valve, the first pressure sensor or the second pressure sensor can be used to detect valve seat leakage as a pressure change caused by the inflow of fluid into the first volume or the outflow of fluid from the second volume.

[0010] Furthermore, since it is not necessary to perform a separate diagnostic operation for detecting the valve seat leakage of the first valve or the second valve, the diagnosis can be completed in a short time.

[0011] In order to determine whether the valve seat leakage occurs in the first valve or the second valve, the valve seat leakage determination unit may determine whether the first valve or the second valve has valve seat leakage based on the change trend of the measured pressure of the first pressure sensor or the second pressure sensor after the measured pressures of the first pressure sensor and the second pressure sensor become substantially the same. In addition, since the presence or absence of valve seat leakage is determined based on the change trend, even if the measured pressures indicated by the first pressure sensor and the second pressure sensor contain errors such as zero drift, the determination result can be unaffected.

[0012] As a specific structural example for detecting valve seat leakage of the first valve, when the measured pressure of the first pressure sensor or the second pressure sensor increases, the valve seat leakage determination unit determines that valve seat leakage has occurred in the first valve. According to this structure, it is possible to detect that valve seat leakage has occurred in the first valve and fluid has flowed from the upstream side into the first volume.

[0013] As a specific structural example for detecting the valve seat leakage of the second valve, it can be cited that when the measured pressure of the first pressure sensor or the second pressure sensor decreases, the valve seat leakage determination unit determines that the valve seat leakage has occurred in the second valve. According to this structure, it is possible to detect that the valve seat leakage has occurred in the second valve and the fluid has flowed out from the second volume to the downstream side.

[0014] In order to be able to diagnose whether an error occurs in, for example, measuring pressure in the second pressure sensor, the device may also include a diagnostic unit, which diagnoses the second pressure sensor based on the measured pressure of the second pressure sensor and its time change rate when the valve controller completely closes the first valve and opens the second valve.

[0015] As a specific structural example for diagnosing the second pressure sensor, when the time change rate of the measured pressure of the second pressure sensor is substantially zero and the measured pressure is maintained at a specified value, the diagnostic unit diagnoses that no zero drift occurs in the second pressure sensor.

[0016] In order to be able to diagnose whether an error occurs in, for example, measuring pressure in the first pressure sensor, the diagnostic unit may diagnose the first pressure sensor based on the measured pressures of the first pressure sensor and the second pressure sensor when the valve controller opens the first valve and completely closes the second valve.

[0017] As a specific structural example for diagnosing the first pressure sensor, when the measured pressures of the first pressure sensor and the second pressure sensor are substantially equal, the diagnosis unit diagnoses that no zero drift occurs in the first pressure sensor.

[0018] In order to improve the reliability of diagnosis by diagnosing the first pressure sensor or the second pressure sensor under the condition that no valve seat leakage occurs in the first valve or the second valve, the diagnostic trigger unit may also be included, and the diagnostic trigger unit causes the diagnostic unit to perform diagnosis of the first pressure sensor or the second pressure sensor only when the valve seat leakage judgment unit determines that no valve seat leakage occurs in the first valve and the second valve.

[0019] In order to be able to simultaneously diagnose whether zero drift has occurred in multiple pressure sensors, the supply pressure sensor may also be included to measure the pressure on the upstream side of the first valve. When the valve controller at least opens the first valve and the second valve and the front-stage valve arranged on the upstream side of the supply pressure sensor is completely closed, and when the measured pressures of the supply pressure sensor, the first pressure sensor and the second pressure sensor are approximately equal, the diagnostic unit diagnoses that zero drift has not occurred in the supply pressure sensor, the first pressure sensor and the second pressure sensor, respectively.

[0020] In order to ensure the reliability of the result of judging whether the first valve has a seat leakage, the valve seat leakage judging unit may judge that the first valve has a seat leakage when the measured pressure of the first pressure sensor or the second pressure sensor rises while the valve controller at least completely closes the first valve and the second valve and the front-stage valve is open. According to this structure, a pressure difference for judging whether there is a seat leakage can be generated before and after the first valve, and the pressure can be made roughly the same before and after the second valve. Therefore, even if there is a seat leakage in the second valve, the amount of fluid flowing out from the volume between the first valve and the second valve through the second valve can be made very small, and the influence on the judgment result of the seat leakage of the first valve can be ignored. In addition, by pre-diagnosing the zero drift of each pressure sensor, it can also be ensured that the error of each pressure sensor as the basis will not affect the judgment result of the seat leakage of the first valve.

[0021] For example, in order to improve the reliability of the judgment result on whether or not there is a valve seat leakage in the second valve by utilizing the fact that there is no valve seat leakage in the first valve, the valve seat leakage judgment unit may judge that there is a valve seat leakage in the second valve when the pressure measured by the first pressure sensor or the second pressure sensor decreases after the first valve controller opens the first valve and fully closes the second valve for a predetermined time. In addition, according to this structure, a pressure difference for judging whether or not there is a valve seat leakage can be generated before and after the second valve, and the pressure can be made roughly the same before and after the first valve. Therefore, even if there is a valve seat leakage in the first valve, or there is an outflow below a threshold value of the degree that is not judged as the occurrence of valve seat leakage in the first valve, the amount of fluid flowing from the upstream side into the volume between the first valve and the second valve can be made very small, and the influence on the judgment result of the second valve can be ignored.

[0022] For example, in order to detect the flow rate in the fluid device by utilizing the pressure in the fluid control device after diagnosing each pressure sensor and judging whether there is valve seat leakage in each valve, it can be listed that it also includes a resistance flow calculation unit, which calculates the resistance flow rate based on the measured pressures of the first pressure sensor and the second pressure sensor, and the resistance flow rate is the flow rate of the fluid flowing through the fluid resistance element. When the valve controller fully closes the first valve and opens the second valve, the resistance flow rate calculated by the resistance flow calculation unit is detected based on the change in the measured pressure of the first pressure sensor.

[0023] For example, in order to not only display whether there is an abnormality such as valve seat leakage, but also to display the degree to which the state is close to the abnormality even when no abnormality occurs, the valve seat leakage judgment unit may be composed of a valve seat leakage calculation unit and a valve seat leakage comparison unit, the valve seat leakage calculation unit calculates the valve seat leakage amount of the first valve or the second valve based on the measured pressure of the first pressure sensor or the second pressure sensor, the valve seat leakage comparison unit compares the valve seat leakage amount calculated by the valve seat leakage calculation unit with a predetermined reference value, and outputs a judgment result related to whether the first valve or the second valve has valve seat leakage, and the fluid control device also includes: an abnormal amount calculation unit, which at least includes the valve seat leakage calculation unit, and outputs an abnormal amount indicating the degree of abnormality; and an abnormal judgment unit, which at least includes the valve seat leakage comparison unit, and outputs whether there is an abnormality.

[0024] As a specific method capable of externally displaying the degree of progress of abnormalities in the various devices constituting the fluid control device, it can be listed that it also includes a resistance flow calculation unit, which calculates the resistance flow based on the measured pressures of the first pressure sensor and the second pressure sensor, and the resistance flow is the flow of the fluid flowing through the fluid resistance part, and the abnormality calculation unit also has: a sensor drift calculation unit, which calculates the zero drift of the first pressure sensor or the second pressure sensor based on the measured pressure of the first pressure sensor or the second pressure sensor; and a flow accuracy calculation unit, which calculates the flow accuracy of the resistance flow based on the resistance flow calculated by the resistance flow calculation unit and a reference flow, and the reference flow is calculated based on the measured pressure of the first pressure sensor or the second pressure sensor.

[0025] The present invention also provides a fluid control system, which includes: multiple fluid control devices of the present invention; and a status display unit, which obtains the abnormal quantity output from each abnormal quantity calculation unit of the multiple fluid control devices or the presence or absence of abnormality output from each abnormality judgment unit, and displays the abnormal quantity or the presence or absence of abnormality for each fluid control device at a glance. According to this fluid control system, in a fluid control system composed of multiple fluid control devices, the user can simply grasp not only which fluid control device has an abnormality, but also the extent to which the abnormality has progressed by referring to the output of the status display unit.

[0026] The present invention also provides a method for diagnosing a fluid control device, the fluid control device comprising: a fluid resistance element disposed in a flow channel; a first valve disposed on the upstream side of the fluid resistance element; a first pressure sensor for measuring the pressure in a first volume located between the first valve and the fluid resistance element in the flow channel; a second valve disposed on the downstream side of the fluid resistance element; and a second pressure sensor for measuring the pressure in a second volume located between the fluid resistance element and the second valve in the flow channel, the method comprising: a valve control step for completely closing the first valve and the second valve; and a valve seat leakage judgment step for judging whether the first valve and the second valve have valve seat leakage based on the respective measured pressures of the first pressure sensor and the second pressure sensor. According to this method, it is possible to accurately judge whether each valve has valve seat leakage in a short time.

[0027] In order to be able to enjoy the same effect as the fluid control device of the present invention by, for example, updating the program in an existing fluid control device, a program recording medium is provided, which records a program for a fluid control device, wherein the fluid control device includes: a fluid resistance element, which is arranged in a flow channel; a first valve, which is arranged on the upstream side of the fluid resistance element; a first pressure sensor, which measures the pressure in a first volume in the flow channel between the first valve and the fluid resistance element; a second valve, which is arranged on the downstream side of the fluid resistance element; and a second pressure sensor, which measures the pressure in a second volume in the flow channel between the fluid resistance element and the second valve, wherein the program for the fluid control device enables a computer to function as a valve controller and a valve seat leakage judgment unit, wherein the valve controller controls the first valve or the second valve, and the valve seat leakage judgment unit judges whether the first valve and the second valve have valve seat leakage based on the respective measured pressures of the first pressure sensor and the second pressure sensor when the valve controller fully closes the first valve and the second valve.

[0028] The fluid control device program may be distributed electronically or recorded in a program recording medium such as a CD, a DVD, or a flash memory.

[0029] Therefore, according to the fluid control device of the present invention, the first pressure sensor or the second pressure sensor detects the pressure change generated when the first valve and the second valve have valve seat leakage, and can determine whether the two valves have valve seat leakage in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram showing a fluid control device in a first embodiment of the present invention.

[0031] Figure 2 It is a schematic diagram showing an example of determining the valve seat leakage in the first embodiment.

[0032] Figure 3 1 is a flowchart showing a diagnostic procedure for each pressure sensor in the first embodiment.

[0033] Figure 4 This is a schematic diagram showing the state of the fluid control system during the second pressure sensor diagnosis in the first embodiment.

[0034] Figure 5 This is a schematic diagram showing the state of the fluid control system during the first pressure sensor diagnosis in the first embodiment.

[0035] Figure 6 1 is a flowchart showing the diagnosis and determination procedures in the second embodiment.

[0036] Figure 7It is a schematic diagram showing the state of the fluid control system when diagnosing each pressure sensor in the second embodiment of the present invention.

[0037] Figure 8 This is a schematic diagram showing the state of the fluid control system during the first valve diagnosis in the second embodiment of the present invention.

[0038] Fig. 9 This is a schematic diagram showing the state of the fluid control device during the second valve diagnosis in the second embodiment of the present invention.

[0039] Fig.10 1 is a schematic diagram showing the state of the fluid control device during resistance flow detection in the second embodiment of the present invention.

[0040] Fig.11 It is a schematic diagram showing the pressure change in the fluid control device during a series of diagnosis and detection in the second embodiment.

[0041] Fig.12 It is a schematic block diagram showing the structure of a self-diagnosis mechanism in a third embodiment of the present invention.

[0042] Fig.13 1 is a flowchart showing the diagnosis and determination procedures in the third embodiment of the present invention.

[0043] Fig.14 Schematic diagram showing a fluid control system in a fourth embodiment of the present invention.

[0044] Description of Reference Numerals

[0045] 100 Fluid Control Devices

[0046] V1 First valve

[0047] P1 First pressure sensor

[0048] R Fluid resistance

[0049] VL1 First volume

[0050] VL2 Second volume

[0051] P2 Second pressure sensor

[0052] V2 Second valve

[0053] F Flow measurement mechanism

[0054] 1 Resistance flow calculation unit

[0055] 42 Second valve control unit

[0056] 5 Self-diagnosis agency

[0057] 51 Diagnosis action command unit

[0058] 52 Valve seat leakage judgment unit

[0059] 53 Diagnosis trigger unit

[0060] 54 Diagnosis Department DETAILED DESCRIPTION

[0061] A fluid control device 100 according to a first embodiment of the present invention will be described with reference to the drawings.

[0062] The fluid control device 100 is used, for example, to supply a gas as a fluid at a set flow rate to a chamber maintaining a predetermined vacuum degree in a semiconductor manufacturing process. Here, the set flow rate is a step signal that increases or decreases from a certain flow rate value to another flow rate value in a step-like manner. The fluid control device 100 is configured to follow the step signal within a predetermined time to meet the quality of the manufactured semiconductor, for example.

[0063] That is, Figure 1 As shown, the fluid control device 100 includes a fluid device composed of a sensor and a valve disposed in a flow path, and a control calculator for controlling the fluid device.

[0064] A supply pressure sensor P0, a first valve V1, a first pressure sensor P1, a fluid resistance element R, a second pressure sensor P2, and a second valve V2 are provided in order from the upstream side relative to the flow channel. Here, the fluid resistance element R is, for example, a laminar flow element, which generates a flow rate of gas flowing into the fluid resistance element R corresponding to the pressure difference before and after it.

[0065] The supply pressure sensor P0 is used to monitor the pressure of the gas supplied from the upstream side. In addition, the supply pressure sensor P0 can be omitted when the supply pressure is guaranteed to be stable.

[0066] The first pressure sensor P1 measures the pressure of the gas filled in the first volume VL1 which is the volume between the first valve V1 and the fluid resistance member R in the flow path (hereinafter also referred to as the upstream side pressure).

[0067] The second pressure sensor P2 measures the pressure of the gas filled in the second volume VL2 which is the volume between the fluid resistance member R and the second valve V2 in the flow path (hereinafter also referred to as downstream side pressure).

[0068] Thus, the first pressure sensor P1 and the second pressure sensor P2 respectively measure the pressure of the first volume VL1 and the second volume VL2, which are two volumes formed by the first valve V1, the fluid resistance member R, and the second valve V2. In other words, the first pressure sensor P1 and the second pressure sensor P2 measure the pressure in each volume arranged before and after the fluid resistance member R.

[0069] The first valve V1 and the second valve V2 are of the same type in this embodiment, for example, a piezoelectric valve that drives the valve body relative to the valve seat by a piezoelectric element. R Control flow, the resistance flow Q R It is calculated based on the upstream pressure measured by the first pressure sensor P1 and the downstream pressure measured by the second pressure sensor P2. On the other hand, in the fluid equipment provided by the fluid control device 100, the second valve V2 provided on the most downstream side controls the opening and closing of the gas flowing out of the fluid control device 100. In addition, in the present embodiment, the second valve V2 is controlled to be only in one of the fully closed and fully opened states, but it can also be controlled not only to be fully closed or fully opened, but also to any opening degree between them, like the first valve V1.

[0070] Next, the control calculation unit COM is described in detail. The control calculation unit is a so-called computer including a CPU, a memory, an A / D, a D / A converter, an input / output device, etc., and makes various devices work together by executing a fluid control device program stored in the memory, and functions as a resistance flow calculation unit 1 mainly responsible for the flow control function, and a valve controller 4 composed of a first valve control unit 41 and a second valve control unit 42. In addition, the control calculation unit also functions as a self-diagnosis mechanism 5 composed of a diagnosis action instruction unit 51, a valve seat leakage judgment unit 52, a diagnosis trigger unit 53, and a diagnosis unit 54.

[0071] First, each part related to flow control is described in detail. The resistance flow calculation unit 1, together with the first pressure sensor P1, the fluid resistance element R, and the second pressure sensor P2, constitutes a flow measurement mechanism F as a so-called pressure flow sensor. That is, the resistance flow calculation unit 1 uses the upstream pressure measured by the first pressure sensor P1, the downstream pressure measured by the second pressure sensor P2, and the fluid or surrounding ambient temperature measured by the temperature sensor as inputs, and calculates the resistance flow Q as the flow rate of the fluid flowing through the fluid resistance element R. R Here, the calculation formula of the flow rate used in the resistance flow rate calculation unit 1 can use an existing calculation formula.

[0072] The first valve control unit 41 controls the flow rate Q calculated by the resistance flow rate calculation unit 11 based on the set flow rate set by the user and the resistance flow rate Q calculated by the resistance flow rate calculation unit 11 at least during normal operation. R That is, the first valve control unit 41 performs flow rate feedback control so that the deviation between the set flow rate and the resistance flow rate becomes small.

[0073] The second valve control unit 42 switches the second valve V2 to either a fully closed state or an open state based on the opening and closing instructions set by the user at least during normal operation. For example, the opening and closing instruction signal is a switching signal in which an opening signal and a closing signal are alternately and periodically repeated, and the opening signal indicates a supply period during which the second valve V2 is opened and gas is supplied to the chamber, and the closing signal indicates a stop period during which the second valve V2 is closed and gas supply to the chamber is stopped. The period of the opening and closing instruction signal is set in a manner that matches the length of the gas supply period and the stop period in the ALD process, etc. In addition, the set flow rate set in the first valve control unit 41 is independent of the opening and closing instruction signal, for example, it is kept fixed at a flow rate value desired to flow to the chamber during the supply period.

[0074] Next, the self-diagnosis mechanism 5 will be described. The self-diagnosis mechanism 5 performs a check of valve seat leakage of the first valve V1 and the second valve V2 and a diagnosis of the first pressure sensor P1 and the second pressure sensor P2. More specifically, the self-diagnosis mechanism 5 is configured to perform a diagnosis of the first pressure sensor P1 and the second pressure sensor P2 only when there is no valve seat leakage in the first valve V1 and the second valve V2. The details of each part of the self-diagnosis mechanism 5 will be described below.

[0075] If the diagnostic action command unit 51 receives a diagnostic start command input by a user, for example, a full closing command or an opening command, which is a command different from the set pressure and the set flow rate, is input to the first valve control unit 41 and the second valve control unit 42. The first valve V1 and the second valve V2 operate in a manner substantially similar to the switch valves according to the full closing command or the opening command. The diagnostic action command unit 51 first inputs a full closing command to the first valve control unit 41 and the second valve control unit 42, respectively, in order to check whether there is valve seat leakage in the first valve V1 and the second valve V2. In addition, when the diagnostic action command unit 51 determines that there is no valve seat leakage in the first valve V1 and the second valve V2, the full closing command is input only to one of the first valve control unit 41 or the second valve control unit 42, and the opening command is input to the other.

[0076] When the valve controller 4 completely closes the first valve V1 and the second valve V2, the valve seat leakage determination unit 52 determines whether the first valve V1 and the second valve V2 have valve seat leakage based on the respective measured pressures of the first pressure sensor P1 and the second pressure sensor P2. Figure 2As shown, the valve seat leakage judgment unit 52 judges whether there is valve seat leakage in the first valve V1 and the second valve V2 based on the time change of each measured pressure of the first pressure sensor P1 and the second pressure sensor P2 after the first valve V1 and the second valve V2 are completely closed and the waiting time is predetermined. Here, the judgment of the start time point of starting the valve seat leakage check of the first valve V1 and the second valve V2 after the first valve V1 and the second valve V2 are completely closed can be based on, for example, the measurement pressure of the first pressure sensor P1 and the second pressure sensor P2 is roughly consistent as a reference, or it can be set only by the elapsed time since the first valve V1 and the second valve V2 are completely closed. If the start time point of the valve seat leakage judgment is judged only by the elapsed time point, for example, the following situation can be prevented: zero shift occurs in any one of the first pressure sensor P1 and the second pressure sensor P2, and the respective measured pressures are inconsistent and the valve seat leakage check is not started.

[0077] Specifically, when the measured pressures of the first pressure sensor P1 and the second pressure sensor P2 increase, the valve seat leakage determination unit 52 determines that valve seat leakage has occurred in the first valve V1. This is based on the fact that when valve seat leakage has occurred in the first valve V1, gas flows from the upstream side through the first valve V1 into the first volume VL1, thereby causing pressure increases in the first volume VL1 and the second volume VL2.

[0078] On the other hand, when the measured pressures of the first pressure sensor P1 and the second pressure sensor P2 decrease, the valve seat leakage determination unit 52 determines that valve seat leakage has occurred in the second valve V2. This is based on the fact that when valve seat leakage has occurred in the second valve V2, gas flows from the second volume VL2 to the downstream side through the second valve V2, thereby causing the pressure of the first volume VL1 and the second volume VL2 to decrease.

[0079] In addition, when the measured pressures of the first pressure sensor P1 and the second pressure sensor P2 change only within a predetermined range after being substantially consistent, the valve seat leakage determination unit 52 determines that valve seat leakage does not occur in the first valve V1 and the second valve V2. In addition, the valve seat leakage determination unit 52 sends data indicating the determination result to the diagnosis trigger unit 53.

[0080] Only when the valve seat leakage determination unit 52 determines that valve seat leakage does not occur in both the first valve V1 and the second valve V2 , the diagnosis trigger unit 53 causes the diagnosis unit 54 described later to diagnose the first pressure sensor P1 and the second pressure sensor P2 .

[0081] The diagnosis unit 54 diagnoses the first pressure sensor P1 or the second pressure sensor P2 based on each measured pressure. In the present embodiment, the diagnosis unit 54 diagnoses whether a zero point shift has occurred in the first pressure sensor P1 or the second pressure sensor P2 based on each measured pressure.

[0082] Below, refer to Figure 3 Flowchart and Figure 4 , Figure 5 The details of the diagnosis trigger unit 53 and the diagnosis unit 54 are explained with reference to the schematic diagram of FIG.

[0083] The diagnosis trigger unit 53 obtains data related to the judgment result from the valve seat leakage judgment unit 52, and only when the valve seat leakage does not occur in the first valve V1 and the second valve V2, the diagnosis trigger unit 53 outputs a diagnosis permission signal to the diagnosis unit 54 (step S1). On the other hand, when the judgment result indicates that the valve seat leakage occurs in the first valve V1 or the second valve V2, the diagnosis trigger unit 53 does not output the diagnosis permission signal. Therefore, the diagnosis unit 54 does not diagnose the first pressure sensor P1 and the second pressure sensor P2 (step S2).

[0084] When there is no valve seat leakage in the first valve V1 and the second valve V2, the diagnosis trigger unit 53 causes the diagnosis operation instruction unit 51 to output a diagnosis operation instruction to the valve controller 4. In addition, in this embodiment, after the diagnosis of the second pressure sensor P2 is performed, the diagnosis of the first pressure sensor P1 is performed. Figure 4 As shown, the valve controller 4 initially opens the second valve V2 and closes the first valve V1 (step S3 ).

[0085] In this state, the diagnosis unit 54 starts the diagnosis of the second pressure sensor P2. First, the diagnosis unit 54 determines whether the time rate of change of the measured pressure of the second pressure sensor P2 is approximately zero and stable at a certain pressure (step S4). After the pressure in the second volume VL2 is stabilized, the diagnosis unit 54 determines whether the measured pressure of the second pressure sensor P2 is approximately equal to the pressure in the chamber, that is, the vacuum pressure (step S5). Here, "approximately equal" refers to a state in which the measured pressure of the second pressure sensor P2 has only a difference within a predetermined threshold. When the measured pressure of the second pressure sensor P2 is approximately equal to the vacuum pressure, the diagnosis unit 54 diagnoses that the second pressure sensor P2 is normal (step S6). In addition, when the measured pressure of the second pressure sensor P2 is inconsistent with the vacuum pressure and, for example, is larger than a predetermined threshold, it is determined that a zero drift has occurred in the second pressure sensor P2 (step S7). In addition, the zero point calibration of the second pressure sensor P2 can also be performed based on the zero point drift amount obtained here.

[0086] If the diagnosis of the second pressure sensor P2 is completed, the diagnosis trigger unit 53 causes the diagnosis action instruction unit to output a diagnosis action instruction to the valve controller 4 to open the first valve V1 and close the second valve V2, thereby achieving Figure 5 The state shown (step S8).

[0087] Next, the diagnosis unit 54 determines whether the pressures measured by the supply pressure sensor P0, the first pressure sensor P1, and the second pressure sensor P2 are substantially equal (step S9). Here, the pressures are determined to be substantially equal even when the difference between the pressures is within a predetermined threshold.

[0088] The diagnosis unit 54 determines that the first pressure sensor P1 is normal when the measured pressures are substantially equal (step S10 ), and determines that a zero shift has occurred in the first pressure sensor P1 when the measured pressures are not equal (step S11 ).

[0089] According to the fluid control device 100 of the present embodiment configured as described above, it is possible to determine the presence or absence of valve seat leakage simultaneously with respect to the first valve V1 for pressure control and the second valve V2 for flow rate control.

[0090] In addition, since the presence or absence of valve seat leakage is determined based on the change trend of each measured pressure after the pressure in the volume from the first valve V1 to the second valve V2 is stabilized, even if zero point drift occurs in the first pressure sensor P1 or the second pressure sensor P2, it will not be affected.

[0091] In addition, the diagnosis unit 54 performs the diagnosis of the first pressure sensor P1 and the second pressure sensor P2 only when there is no valve seat leakage in the first valve V1 and the second valve V2, thereby preventing inaccurate diagnosis results caused by valve seat leakage. Therefore, a highly reliable diagnosis can be made for both the first pressure sensor P1 and the second pressure sensor P2.

[0092] Furthermore, the determination of the presence or absence of valve seat leakage, the diagnosis of the first pressure sensor P1, and the diagnosis of the second pressure sensor P2 can be performed using only fluid devices related to pressure control or flow control. Therefore, there is no need to provide additional sensors for diagnosis.

[0093] Reference Figures 6 to 11 Next, a fluid control device 100 according to a second embodiment of the present invention will be described. Components corresponding to those in the first embodiment are given the same reference numerals.

[0094] The fluid control device 100 of the second embodiment Figure 1 The structure of the fluid control device 100 shown is substantially the same, but it is different from the first embodiment in that the diagnosis unit 54 performs diagnosis related to the zero drift of the supply pressure sensor P0 and the calculated resistance flow rate. In addition, the operation performed by the valve controller 4 for diagnosis is also different.

[0095] Specifically, if Figure 6As shown in the flowchart of , the fluid control device 100 of the second embodiment performs the following steps in the following order: (a) diagnosis of zero drift in each of the three pressure sensors, (b) determination of valve seat leakage of the first valve V1, (c) determination of valve seat leakage of the second valve V2, and (d) diagnosis of resistance flow. Each of the four steps will be described in detail below.

[0096] Before the diagnosis unit 54 performs the diagnosis of the zero drift in each of the three pressure sensors, Figure 6 and Figure 7 As shown, in a state where the fore valve AV1 disposed on the upstream side of the fluid control device 100 is completely closed, the valve controller 4 opens the first valve V1 and the second valve V2, discharges the gas in each volume in the fluid control device 100, and waits for a predetermined time until a vacuum is formed (step ST1). Here, the opening and closing of the fore valve AV1 is controlled, for example, by the user's operation of the fore valve AV1 or the instruction of the control device for various devices that control the entire process. In addition, the gas in the fluid control device 100 is sucked by a vacuum source such as a chamber connected to the downstream side of the second valve V2. When exhausting from a vacuum source such as a chamber, due to the presence of a fluid resistance member R, it sometimes takes time to completely exhaust the space on the upstream side of the fluid resistance member R. Therefore, the fluid in the volume on the upstream side of the fluid resistance member R can be discharged from an exhaust flow channel (not shown) branched between the fluid control device 100 and the fore valve AV1, thereby shortening the time.

[0097] After the volume between the front valve AV1 and the fluid control device 100, the first volume VL1 and the second volume VL2 in the fluid control device 100 are completely exhausted to form a vacuum, the diagnosis unit 54 determines whether the measured pressures of the supply pressure sensor P0, the first pressure sensor P1 and the second pressure sensor P2 are respectively substantially zero and equal within a predetermined tolerance (step ST2). Thus, the zero drift is diagnosed in the state where the first valve V1 and the second valve V2 are open, so that in the diagnosis result, even if the valve seat leakage occurs in each valve, its influence can be not reflected in the diagnosis result.

[0098] If the measured pressure of any pressure sensor is different beyond the allowable difference, the diagnostic unit 54 determines that the zero point drift has occurred in the pressure sensor that outputs the maximum measured pressure. In addition, the diagnostic trigger unit 53 does not allow the subsequent seat leakage judgment and resistance flow diagnosis and ends (step ST3).

[0099] On the other hand, when the pressures are equal, the diagnosis unit 54 diagnoses that no zero drift occurs in the supply pressure sensor P0, the first pressure sensor P1, and the second pressure sensor P2 (step ST4). In this case, the diagnosis trigger unit 53 permits the first valve V1 to start judging the valve seat leakage.

[0100] In the case where the next determination of the valve seat leakage in the first valve V1 is permitted by the diagnosis triggering section 53, as shown in FIG. Figure 6 and Figure 8 As shown in (a), the valve controller 4 completely closes the first valve V1 and the second valve V2. In addition, the fore valve AV1 is opened by the user's operation or the instruction of the control device that controls the entire process (step ST5). That is, the volume from the first valve V1 to the second valve V2 in the fluid control device 100 is kept in a substantially vacuum state, and the gas supply pressure is applied to the upstream side of the first valve V1.

[0101] In this state, the valve seat leakage determination unit 52 determines whether the first valve V1 has valve seat leakage based on whether the measured pressure of the first pressure sensor P1 or the second pressure sensor P2 increases within a predetermined time (step ST6). Here, since the vacuum state is substantially the same before and after the second valve V2, even if valve seat leakage occurs in the second valve V2, the amount of gas flowing from the first valve V1 to the second valve V2 is very small. Therefore, the influence of the presence or absence of valve seat leakage in the second valve V2 on the determination in step ST6 can be substantially ignored.

[0102] like Figure 8 As shown in (b), when the first pressure sensor P1 or the second pressure sensor P2 detects a pressure rise, the valve seat leakage determination unit 52 determines that a valve seat leakage has occurred in the first valve V1 (step ST7). This is because when a valve seat leakage has occurred in the first valve V1, gas flows into the fluid control device 100 from the upstream side of the first valve V1, causing a pressure rise.

[0103] On the other hand, when no pressure rise is detected in the first pressure sensor P1 and the second pressure sensor P2 within the prescribed time, the valve seat leakage determination unit 52 determines that no valve seat leakage occurs in the first valve V1 (step ST8). In this case, the diagnosis trigger unit 53 continues to allow the determination operation of the valve seat leakage of the second valve V2.

[0104] Then, if Figure 6 As shown, the valve controller 4 opens the first valve V1 from the fully closed state and keeps the second valve V2 in the fully closed state, and waits for a predetermined time until the volume in the fluid control device 100 is filled with gas of a predetermined pressure (step ST9). Figure 6 and Fig. 9As shown in (a) of FIG. 1 , the valve controller 4 fully closes the first valve V1 again (step ST10 ).

[0105] Furthermore, the valve seat leakage determination unit 52 determines whether the second valve V2 has valve seat leakage based on whether the measured pressure of the first pressure sensor P1 or the second pressure sensor P2 has dropped (step ST11). Here, the pressure difference required for determining valve seat leakage is formed before and after the second valve V2, and the pressure before and after the first valve V1 is maintained at a substantially equal pressure at a predetermined pressure. Therefore, even if a valve seat leakage occurs in the first valve V1 after the determination in step ST6, or a small amount of outflow occurs during the determination in step ST6 that is determined to be without valve seat leakage, the amount of gas flowing into the volume can be made very small, and the influence on the determination in step S11 can be ignored.

[0106] like Fig. 9 As shown in (b), when a drop in the measured pressure is detected within a specified time, the valve seat leakage determination unit 52 determines that a valve seat leakage has occurred in the second valve V2 (step ST12). When a drop in the measured pressure is not detected within a specified time, the valve seat leakage determination unit 52 determines that a valve seat leakage has not occurred in the second valve V2 (step ST13).

[0107] Only when there is no valve seat leakage in the second valve V2, the diagnosis trigger 53 permits the following resistance flow-related diagnosis. Figure 6 and Fig.10 As shown, the valve controller 4 keeps the first valve V1 in a fully closed state and opens the second valve V2, so that the pressure of the gas filled in the volume of the fluid control device 100 decreases (step ST14). Based on the pressure drop generated at this time, the diagnosis unit 54 diagnoses the resistance flow calculated based on the first pressure and the second pressure in the resistance flow calculation unit 1 (step ST15). As a diagnosis method using pressure drop, various known methods such as the ROF method can be used. For example, in the pressure drop interval within a specified time generated in the first volume VL1, by comparing the integrated value of the resistance flow with the outflow volume of the gas flowing out of the first volume VL1 calculated based on the state equation of the gas, it is possible to determine whether the resistance flow is normal.

[0108] Thus, in the fluid control device 100 of the second embodiment, it is also possible to diagnose the zero drift of each pressure sensor or to determine whether each valve has valve seat leakage. In addition, in the second embodiment, it is also possible to diagnose whether the resistance flow calculated as the output of the flow sensor is abnormal. And, these multiple diagnoses and judgments are performed by Figure 6 The steps shown in the flowchart are implemented, thereby enabling efficient filling or opening of the gas in the volume of the fluid control device 100. Fig.11 As shown, the valves on the upstream side are opened in sequence to fill the gas into the downstream side of the fluid control device 100, and finally the gas filled in the fluid control device 100 is discharged, thereby enabling the resistance flow to be diagnosed, thereby enabling the gas to be used without waste.

[0109] A modified example of the second embodiment will be described. In determining whether the first valve V1 and the second valve V2 have valve seat leakage, it is possible to determine whether valve seat leakage has occurred based on, for example, the difference between the supply pressure measured by the supply pressure sensor P0 and the first pressure or the second pressure, or the change in the difference, rather than the change in the change in the first pressure or the second pressure. That is, Figure 8 (b) Fig. 9 As shown in (b) , even when a seat leak occurs in the valve, the supply pressure measured by the supply pressure sensor P0 is kept substantially constant and can therefore be used as a reference for comparison with the first pressure or the second pressure.

[0110] Reference Fig.12 and Fig.13 , a fluid control device 100 according to a third embodiment of the present invention will be described. In addition, components corresponding to those in the second embodiment are given the same reference numerals. Fig.12 The main hardware parts are the same as those in the first embodiment and are therefore omitted.

[0111] like Fig.12 As shown, the fluid control device 100 of the third embodiment has a different structure of the self-diagnosis mechanism 5 compared to the first embodiment. That is, the self-diagnosis mechanism 5 receives the outputs of the supply pressure sensor P0, the first pressure sensor P1, the second pressure sensor P2, and the resistance flow calculation unit 1, and calculates the abnormal amount indicating the degree of progress of the abnormality in each part of the fluid control device 100 based on these measured values ​​or calculated values. In addition, the self-diagnosis mechanism 5 also determines whether there is an abnormality in each part of the fluid control device 100 based on the calculated abnormal amount. Here, the abnormality refers to a state in which, for example, valve seat leakage or measurement error occurs to a degree that cannot guarantee the desired control accuracy. In addition, the non-abnormality refers to a state in which, for example, the calculated abnormal amount is a value within the allowable value and the desired control accuracy is guaranteed.

[0112] More specifically, the self-diagnostic mechanism 5 is composed of an abnormality amount calculation unit 5A, an abnormality determination unit 5B, a diagnostic state management unit 5C, and a diagnostic action instruction unit 51. The diagnostic state management unit 5C is equivalent to the diagnostic trigger unit 53 of the first embodiment, and controls the operation of the abnormality amount calculation unit 5A and the diagnostic action instruction unit 51 according to the output of the abnormality determination unit 5B.

[0113] The abnormal amount calculation unit 5A calculates the abnormal amount indicating the states of each pressure sensor, the first valve V1, and the second valve V2 based on the supply pressure output from the supply pressure sensor P0, the upstream pressure output from the first pressure sensor P1, and the downstream pressure output from the second pressure sensor P2. Specifically, the abnormal amount calculation unit 5A is composed of a valve seat leakage calculation unit 521, a sensor drift calculation unit 541, and a flow rate accuracy calculation unit 543.

[0114] In addition, the abnormality determination unit 5B compares the abnormality calculated by the abnormality calculation unit 5A with a predetermined reference value to determine whether each pressure sensor, each valve or flow sensor has an abnormality. Specifically, the abnormality determination unit 5B is composed of a valve seat leakage comparison unit 522, a sensor drift comparison unit 542 and a flow accuracy comparison unit 544.

[0115] The abnormality amount calculation unit 5A and the abnormality determination unit 5B will be described in detail.

[0116] When the valve controller 4 completely closes the first valve V1 and the second valve V2, the valve seat leakage calculation unit 521 calculates the valve seat leakage of the first valve V1 and the second valve V2 based on the respective measured pressures of the first pressure sensor P1 and the second pressure sensor P2. The valve seat leakage calculation unit 521 calculates the flow rate of the gas flowing into or out of the first volume VL1 and the second volume VL2 as the valve seat leakage (sccm) based on, for example, the amount of pressure increase or decrease from the time when each valve is completely closed and the state equation of the gas. That is, the valve seat leakage calculation unit 521 calculates the valve seat leakage of the first valve V1 in the case of a pressure increase, and calculates the valve seat leakage of the second valve V2 in the case of a pressure drop.

[0117] In addition, the valve seat leakage comparison unit 522 compares the valve seat leakage amount calculated by the valve seat leakage calculation unit 521 with the reference value, and when the valve seat leakage amount exceeds the reference value, it is determined that valve seat leakage has occurred in the first valve V1 or the second valve V2. In addition, the valve seat leakage calculation unit 521 and the valve seat leakage comparison unit 522 correspond to the valve seat leakage determination unit 52 in the second embodiment.

[0118] The sensor drift calculation unit 541 calculates the zero drift amount of each pressure sensor based on the respective measured pressures of the first pressure sensor P1 and the second pressure sensor P2 in a state where the first valve V1 and the second valve V2 are fully opened by the valve controller 4, for example. The sensor drift comparison unit 542 compares the zero drift amount calculated by the sensor drift calculation unit 541 with a reference value, and outputs that an abnormality has occurred in the first pressure sensor P1 or the second pressure sensor P2 when the zero drift amount exceeds the reference value.

[0119] The flow accuracy calculation unit 543 calculates the difference between the flow rate calculated from the measurement value of the first pressure sensor P1 or the second pressure sensor P2 by, for example, the ROR method and the resistance flow rate calculated by the resistance flow calculation unit 1 during the ROR method as the flow accuracy. The flow accuracy comparison unit 544 compares the flow accuracy calculated by the flow accuracy calculation unit 543 with the reference value, and outputs that an abnormality has occurred in the flow sensor when the flow accuracy exceeds the reference value. In addition, the sensor drift calculation unit 541, the sensor drift comparison unit 542, the flow accuracy calculation unit 543, and the flow accuracy comparison unit 544 are equivalent to the diagnosis unit 54 in the second embodiment.

[0120] Fig.13 The flowchart shows the diagnostic operation of the third embodiment configured as described above. Fig.13 A flowchart showing the diagnostic operation of the second embodiment Figure 6 The actions in step ST2, step ST6, and step ST11 in the flowchart are different. Specifically, Fig.13 Specifically, after step ST1 is completed, the abnormality calculation unit 5A calculates the zero drift of each pressure sensor based on the measurement values ​​of the first pressure sensor P1 and the second pressure sensor P2 (step ST2A). Next, the abnormality determination unit 5B determines whether there is a zero drift based on whether the calculated zero drift is a value that does not exceed the reference value and is approximately close to zero (step ST2B).

[0121] Furthermore, after step ST5 and step ST10 are completed, the abnormal amount calculation unit 5A calculates the valve seat leakage of the first valve V1 or the second valve V2 respectively (step ST6A, step ST11A). Next, the abnormality determination unit 5B determines whether there is valve seat leakage based on whether the calculated valve seat leakage is a value that does not exceed the reference value and is approximately close to zero (step ST6B, step ST11B).

[0122] According to the fluid control device 100 of the third embodiment configured as described above, the abnormality amount calculation unit 5A calculates the abnormality amount indicating the progress of the abnormality of each pressure sensor or each valve, and the presence or absence of zero point shift and valve seat leakage can be determined based on the value of the abnormality amount.

[0123] Next, a fluid control system 200 according to a fourth embodiment will be described. Fig.14 As shown, a fluid control system 200 according to the fourth embodiment includes a plurality of fluid control devices 100 according to the third embodiment, and includes an integrated control device 6 that performs control related to at least diagnosis of each fluid control device 100 .

[0124] If a diagnosis request is received from the user, the integrated control device 6 inputs a diagnosis input to the diagnosis operation instruction unit 51 of each fluid control device 100. Each fluid control device 100 causes the self-diagnosis mechanism 5 to perform self-diagnosis of valves and various sensors through the operation described in the above embodiment. Data related to the abnormal amount output from the abnormal amount calculation unit 5A of each fluid control device 100 and the presence or absence of abnormality output from the abnormality judgment unit 5B are sent to the integrated control device 6. The integrated control device 6 also functions as a status display unit that displays the abnormal amount and the presence or absence of abnormality received from each fluid control device 100 to the user at a glance.

[0125] According to the fluid control system 200 of the fourth embodiment, even if the fluid control system 200 is composed of a plurality of fluid control devices 100, the user can immediately understand which fluid control device 100 has an abnormality and in which part of the abnormal fluid control device 100. In addition, since the abnormal amount, which is the basis for abnormality judgment, is displayed simultaneously for devices that have not experienced an abnormality, the user can predict the degree of progress of the abnormality.

[0126] Other embodiments will be described.

[0127] The valve seat leakage judgment unit can judge whether there is a valve seat leakage based on the change tendency of the measured pressure of either the first pressure sensor or the second pressure sensor. For example, the judgment start time point can be set after the pressure in the first volume and the second volume stabilizes after the first valve and the second valve are closed. After that, only the measured pressure of the first pressure sensor or the measured pressure of the second pressure sensor is monitored. In addition, the change tendency of the measured pressure can be calculated by various calculation methods such as calculating the time change rate and calculating the differential value. In addition, it is also possible to judge whether there is a valve seat leakage in the first valve or the second valve based on the absolute value or positive or negative difference between the measured pressure at the judgment start time point and the measured pressure after the specified time from the judgment start. For example, when the measured pressure of the first pressure sensor at the judgment start time point is greater than the measured pressure of the first pressure sensor after the specified time from the judgment start time point, the valve seat leakage judgment unit judges that the valve seat leakage has occurred in the first valve. On the contrary, when the measured pressure of the second pressure sensor at the judgment start time point is less than the measured pressure of the second pressure sensor after the specified time from the judgment start time point, the valve seat leakage judgment unit judges that the valve seat leakage has occurred in the second valve.

[0128] The diagnosis unit may be configured to initially diagnose the first pressure sensor and thereafter diagnose the second pressure sensor. In addition, the diagnosis of the first pressure sensor may, for example, not use the measured pressure supplied to the pressure sensor, but only use the measured pressures of the first pressure sensor and the second pressure sensor. In addition, the diagnosis of the pressure sensor is not limited to zero drift, and other errors and the like may also be diagnosed. In addition, in the embodiment described above, a valve seat leakage check is performed, and the first pressure sensor and the second pressure sensor are diagnosed when no valve seat leakage occurs in the first valve and the second valve, but the diagnosis of the first pressure sensor and the second pressure sensor may also be performed regardless of the result of the valve seat leakage check. In addition, the first pressure sensor and the second pressure sensor may be diagnosed independently without performing a valve seat leakage check.

[0129] The fluid resistance element is not limited to a laminar flow element, and may be, for example, a flow divider element used in a thermal flow sensor.

[0130] The valve seat leakage judgment unit, diagnosis unit or self-diagnosis mechanism is not limited to realizing its functions through a computing device such as a computer or control board built into the fluid control device, and its functions can be realized by, for example, a general computer set separately from the fluid control device.

[0131] The opening controller described in the second embodiment controls the opening and closing of the first valve and the second valve, but may be configured to also control the opening and closing of a preceding valve or the like provided outside the fluid control device.

[0132] Furthermore, the embodiments may be modified and parts or all of the embodiments may be combined as long as the spirit of the present invention is not violated.

Claims

1. A fluid control device, characterized in that include: A fluid resistance member is arranged in the flow channel; a first valve, disposed on the upstream side of the fluid resistance element; a first pressure sensor for measuring the pressure in a first volume in the flow channel between the first valve and the fluid resistance element; a second valve, disposed on the downstream side of the fluid resistance element; a second pressure sensor for measuring the pressure of a second volume in the flow channel between the fluid resistance element and the second valve; a valve controller, controlling the first valve or the second valve; as well as a valve seat leakage judging unit, which judges whether the first valve and the second valve have valve seat leakage based on the respective measured pressures of the first pressure sensor and the second pressure sensor when the valve controller completely closes the first valve and the second valve; After the measured pressures of the first pressure sensor and the second pressure sensor are roughly consistent, the valve seat leakage judgment unit judges whether the first valve and the second valve have valve seat leakage based on the change trend of the measured pressure of the first pressure sensor or the second pressure sensor, and the change trend is the trend of the measured pressure of the first pressure sensor or the second pressure sensor changing over time.

2. The fluid control device according to claim 1, characterized in that: The valve seat leakage determination unit determines that valve seat leakage has occurred in the first valve when the measured pressure of the first pressure sensor or the second pressure sensor increases.

3. The fluid control device according to claim 1, characterized in that: The valve seat leakage determination unit determines that valve seat leakage has occurred in the second valve when the measured pressure of the first pressure sensor or the second pressure sensor decreases.

4. The fluid control device according to claim 1, characterized in that: The system further includes a diagnostic unit that diagnoses the second pressure sensor based on the measured pressure of the second pressure sensor and its time change rate when the valve controller completely closes the first valve and opens the second valve. The diagnosis unit diagnoses that no zero shift has occurred in the second pressure sensor when the time change rate of the measured pressure of the second pressure sensor is substantially zero and the measured pressure is maintained at a predetermined value.

5. The fluid control device according to claim 4, characterized in that: The diagnosis unit diagnoses the first pressure sensor based on respective measured pressures of the first pressure sensor and the second pressure sensor in a state in which the valve controller opens the first valve and fully closes the second valve.

6. The fluid control device according to claim 5, characterized in that: When the measured pressures of the first pressure sensor and the second pressure sensor are substantially equal, the diagnosis unit diagnoses that no zero shift occurs in the first pressure sensor.

7. The fluid control device according to claim 4, characterized in that: A diagnosis trigger unit is further included, which causes the diagnosis unit to perform a diagnosis of the first pressure sensor or the second pressure sensor only when the valve seat leakage determination unit determines that valve seat leakage does not occur in the first valve and the second valve.

8. The fluid control device according to claim 4, characterized in that: further comprising a supply pressure sensor for measuring pressure on an upstream side of the first valve, In a state where the valve controller opens at least the first valve and the second valve and the front-stage valve provided on the upstream side of the supply pressure sensor is completely closed, When the measured pressures of the supply pressure sensor, the first pressure sensor, and the second pressure sensor are substantially equal, the diagnosis unit diagnoses that the supply pressure sensor, the first pressure sensor, and the second pressure sensor do not have zero point drift.

9. The fluid control device according to claim 8, characterized in that: In a state where the valve controller at least completely closes the first valve and the second valve and opens the front-stage valve, The valve seat leakage determination unit determines that the valve seat leakage has occurred in the first valve when the measured pressure of the first pressure sensor or the second pressure sensor increases.

10. The fluid control device according to claim 9, characterized in that: After a predetermined time has passed since the valve controller opened the first valve and completely closed the second valve, the first valve and the second valve are completely closed. The valve seat leakage determination unit determines that the second valve has valve seat leakage when the measured pressure of the first pressure sensor or the second pressure sensor decreases.

11. The fluid control device according to claim 10, characterized in that: The system further includes a resistance flow calculation unit, which calculates a resistance flow based on the pressures measured by the first pressure sensor and the second pressure sensor, wherein the resistance flow is a flow rate of the fluid flowing through the fluid resistance element. The diagnosis unit detects the resistance flow rate calculated by the resistance flow rate calculation unit based on a change in the measured pressure of the first pressure sensor in a state in which the valve controller fully closes the first valve and opens the second valve.

12. The fluid control device according to claim 1, characterized in that: The valve seat leakage judgment unit is composed of a valve seat leakage calculation unit and a valve seat leakage comparison unit. The valve seat leakage calculation unit calculates a valve seat leakage amount of the first valve or the second valve based on a measured pressure of the first pressure sensor or the second pressure sensor. The valve seat leakage comparison unit compares the valve seat leakage amount calculated by the valve seat leakage calculation unit with a predetermined reference value, and outputs a determination result regarding whether the first valve or the second valve has valve seat leakage. The fluid control device further comprises: an abnormality amount calculation unit, including at least the valve seat leakage calculation unit, and outputting an abnormality amount indicating a degree of abnormality; and The abnormality determination unit includes at least the valve seat leakage comparison unit and outputs whether or not an abnormality exists.

13. The fluid control device according to claim 12, characterized in that: The system further includes a resistance flow calculation unit, which calculates a resistance flow based on the pressures measured by the first pressure sensor and the second pressure sensor, wherein the resistance flow is a flow rate of the fluid flowing through the fluid resistance element. The abnormal amount calculation unit further comprises: a sensor drift calculation unit, which calculates a zero drift amount of the first pressure sensor or the second pressure sensor based on a measured pressure of the first pressure sensor or the second pressure sensor; as well as The flow rate accuracy calculation unit calculates the flow rate accuracy of the resistance flow rate based on the resistance flow rate calculated by the resistance flow rate calculation unit and a reference flow rate calculated based on the measured pressure of the first pressure sensor or the second pressure sensor.

14. A fluid control system, characterized in that include: A plurality of fluid control devices as claimed in claim 12; as well as The state display unit obtains the abnormal amount output from each abnormal amount calculation unit of the plurality of fluid control devices or the presence or absence of abnormality output from each abnormality determination unit, and displays the abnormal amount or the presence or absence of abnormality for each fluid control device at a glance.

15. A method for diagnosing a fluid control device, the fluid control device comprising: A fluid resistance member is arranged in the flow channel; a first valve, disposed on the upstream side of the fluid resistance element; a first pressure sensor for measuring the pressure in a first volume in the flow channel between the first valve and the fluid resistance element; a second valve disposed on a downstream side of the fluid resistance element; and a second pressure sensor for measuring the pressure of a second volume in the flow channel between the fluid resistance element and the second valve, The diagnostic method is characterized by comprising: a valve control step to completely close the first valve and the second valve; as well as a valve seat leakage judging step, judging whether the first valve and the second valve have valve seat leakage based on the respective measured pressures of the first pressure sensor and the second pressure sensor, The valve seat leakage judgment step judges whether the first valve and the second valve have valve seat leakage based on the change tendency of the measured pressure of the first pressure sensor or the measured pressure of the second pressure sensor as a tendency to change over time after the measured pressures of the first pressure sensor and the second pressure sensor are roughly consistent.

16. A program recording medium recording a program for a fluid control device, the fluid control device comprising: A fluid resistance member is arranged in the flow channel; a first valve, disposed on the upstream side of the fluid resistance element; a first pressure sensor for measuring the pressure in a first volume in the flow channel between the first valve and the fluid resistance element; a second valve disposed on a downstream side of the fluid resistance element; and a second pressure sensor for measuring the pressure of a second volume in the flow channel between the fluid resistance element and the second valve, The program recording medium is characterized in that the recorded program for the fluid control device causes the computer to function as a valve controller and a valve seat leakage determination unit. The valve controller controls the first valve or the second valve, The valve seat leakage judging unit judges whether the first valve and the second valve have valve seat leakage based on the respective measured pressures of the first pressure sensor and the second pressure sensor when the valve controller completely closes the first valve and the second valve. The valve seat leakage judgment unit judges whether the first valve and the second valve have valve seat leakage based on the change tendency of the measured pressure of the first pressure sensor or the measured pressure of the second pressure sensor as a tendency to change over time after the measured pressures of the first pressure sensor and the second pressure sensor are roughly consistent.

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