JP7217941B2 - Flow control device, control method for flow control device, control program for flow control device - Google Patents

Description

The present invention relates to a flow control device, its control method, and control program.

A flow control device is known that adjusts the flow rate of a fluid flowing downstream to a set value by adjusting a control valve based on the flow rate measured by a flow sensor.

Patent Document 1 describes an operation of a mass flow controller (hereinafter also referred to as "MFC") in which data such as pressure, flow rate, response time and overshoot measured by the MFC are statistically processed and stored in a long-term memory. A management method is disclosed.

Japanese translation of PCT publication No. 2014-504766

The MFC of Patent Document 1 saves data when there is a change in operational status. A change in operational state is, for example, a change in flow rate setting. However, even if the set value is not changed, the opening of the control valve may be finely controlled as a result of feedback control. For example, the pressure supplied to the MFC may change over time. Applicable. In the MFC of Patent Document 1, it is not possible to save the operation of the control valve that occurs independently of the change of the set value. Therefore, there is a need for a flow control device that can record the operation history of control valves in a simple manner for the purpose of recording mechanical component deterioration.

SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to record the operation history of a control valve by a simple method.

In order to achieve the above object, a flow control device according to one aspect of the present invention includes a control valve, a storage unit, and an operation history storage processing unit that stores an operation history of the control valve in the storage unit. , the operation history storage processing unit includes an operating time updating unit that stores the operating time of the control valve in the storage unit; an opening/closing frequency update unit that stores the opening/closing frequency of the control valve in the storage unit; and an instruction value change amount updating unit that stores the total amount of change in the opening degree instruction value in the storage unit.

In each feedback loop, a feedback control unit that calculates the opening instruction value based on the measured flow rate and controls the opening of the control valve so that the flow rate of the outflowing fluid reaches a set value; The value change amount updating unit may calculate the amount of change in the opening instruction value in the feedback loop, and add the calculated amount to the total amount of change in the opening instruction value.

The instruction value change amount updating unit may periodically update the amount of change in the opening degree instruction value while the flow rate control device is being activated.

The opening/closing frequency updating unit may update the opening/closing frequency when the set value of the flow rate set in the flow rate control device becomes zero.

The storage unit includes a volatile memory and a nonvolatile memory, the operation history storage processing unit writes the number of times of opening and closing and the amount of change in the opening instruction value to the volatile memory, and the operation history storage processing unit and a storage processing unit that writes, into the nonvolatile memory, operation history data including the number of times of opening and closing and the amount of change in the opening instruction value stored in the volatile memory.

The update process by the instruction value change amount updater and the save process by the save processor may be executed asynchronously.

The operation history storage processing unit further includes an operation time update unit that stores the operation time of the control valve in the storage unit, and the storage processing unit stores operation history data further including the operation time in the nonvolatile memory. may be written to

A wear degree calculation unit may be further provided for calculating the wear degree of the flow control device based on the operation history data.

The wear degree calculation unit may be configured by a neural network that receives the operation history data.

The control valve may include a diaphragm and a valve seat, and may adjust the flow rate of fluid by opening and closing the diaphragm with respect to the valve seat.

In order to achieve the above object, a control method for a flow rate control device according to another aspect of the present invention is a control method for a flow rate control device comprising a control valve and a storage unit, wherein the operation time of the control valve is an operating time update step of storing in the storage unit; an opening/closing count updating step of storing the number of opening/closing times of the control valve in the storage unit; and an instruction value change amount update step.

The storage unit includes a volatile memory and a nonvolatile memory, and the step of updating the number of times of opening and closing and the amount of change in the indicated value are updated in the volatile memory, respectively. further comprising a storage processing step of writing the number of times of opening and closing and the amount of change in the opening instruction value stored in the volatile memory into the nonvolatile memory; The save processing step may be performed asynchronously.

In order to achieve the above object, a control program for a flow rate control device according to still another aspect of the present invention is a control program for a flow rate control device comprising a control valve and a storage unit, the operating time of the control valve an operating time update command for storing the number of times of opening and closing of the control valve in the storage unit; The computer is caused to execute an instruction to update the amount of change in the indicated value to be stored.
The computer program can be provided by downloading via a network such as the Internet, or can be provided by being recorded on various computer-readable recording media such as a CD-ROM.

ADVANTAGE OF THE INVENTION According to this invention, the operation history of a control valve can be recorded by a simple method.

1 is an overall schematic diagram showing an embodiment of a flow rate control device according to the present invention; FIG. It is a functional block diagram of the said flow control apparatus. (a) a flow chart showing a process of updating the flow rate setting value of the flow control device, (b) a flow chart showing a process of updating the opening instruction value of the flow control device, (c) the flow control device using the operation history data is a flow chart showing a process of storing in a non-volatile memory.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a flow rate control device, a control method thereof, and a control program according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1 , the flow control device 1 includes a valve body 101 , a flow sensor 102 , a conversion section 103 , a control section 104 and a control valve 105 . The flow control device 1 is a device also called a mass flow controller (also called “MFC”).

The valve body 101 is a substantially cylindrical member that defines an upstream flow path 101a and a downstream flow path 101b. The upstream side of the upstream channel 101a and the downstream side of the downstream channel 101b are connected to pipes and channel blocks through which the fluid to be controlled flows, respectively.

The upstream channel 101a is a channel into which a fluid flows from the upstream side. The upstream flow path 101 a branches halfway into a flow path passing through the flow rate sensor 102 and a bypass flow path 101 c , and then merges and flows out to the control valve 105 . The control valve 105 has a diaphragm 110 and a valve seat 112 facing the diaphragm 110 . A space between the diaphragm 110 and the valve seat 112 is a space that communicates between the upstream flow path 101a and the downstream flow path 101b. By deforming the diaphragm 110 with the actuator 111, the diaphragm 110 opens and closes with respect to the valve seat 112, thereby adjusting the flow rate of the fluid. Although the internal structure of the actuator 111 is not shown in FIG. 1, the control valve 105 is a piezo element driven control valve that opens and closes a metal diaphragm using a piezo element (piezo actuator) inside the actuator 111, for example. .

The downstream flow path 101b is configured such that the fluid whose flow rate is controlled by the control valve 105 flows in from the upstream side and flows out to the downstream side of the flow control device 1 .
The bypass flow path 101c is a flow path having a laminar flow element having a structure in which a large number of thin flow paths are arranged in parallel to the extent that the fluid becomes a laminar flow. In this embodiment, a laminar flow element is constructed by stacking a plurality of plates (bypass sheets) having grooves formed by etching.

The flow sensor 102 is a sensor that measures the flow rate of fluid flowing through the sensor tube 102a. The flow rate sensor 102 has, for example, heating resistors 102b and 102c upstream and downstream of the sensor tube 102a. Convert to Since the ratio of the flow rate flowing through the bypass flow path 101c and the flow rate flowing through the sensor tube 102a is known, the flow rate of the upstream flow path 101a can be calculated by measuring the flow rate flowing through the sensor tube 102a. Since the output value of the flow rate sensor 102 saturates as the flow rate increases, the measurable range of flow rate is limited. The range of flow rate that can be measured by the flow control device 1 can be adjusted.

The conversion unit 103 is a functional unit that converts the flow rate set value into a state that can be compared with the output value of the flow sensor 102 and then outputs the result together with the output value of the flow sensor 102 to the control unit 104 . The conversion unit 103 may rectify and amplify the output value of the flow sensor 102, or apply a low-pass filter to the output value to remove noise. The conversion unit 103 corrects the measurement error caused by the difference depending on the type of fluid and the individual difference of the flow control device 1 for the flow rate setting value, and then outputs it to the control unit 104 as the sensor output target value. .

The control unit 104 is a functional unit that compares the output value of the flow sensor 102 and the sensor output target value, and controls the control valve 105 based on the comparison result.

The control unit 104 controls the opening degree of the control valve 105 by performing feedback control, for example, so that the flow rate discharged from the downstream flow path 101b becomes the flow rate set value. The control unit 104 incorporates a CPU, a memory M, an A/D converter, and the like. Control unit 104 may include a computer program configured to perform the operations described below, and may be implemented by a combination of hardware and software.

A configuration of the control unit 104 that stores the operation history of the control valve 105 will be described with reference to FIG. 2 . The control unit 104 includes a feedback control unit 11 , an operation history storage processing unit 12 , a wear degree calculation unit 13 and a storage unit 20 . In this embodiment, it is described that all the functional units are housed in one housing arranged adjacent to the control valve 105, but the technical scope of the present invention is not limited to this. Not limited. The flow control device 1 is a concept that includes a system in which a plurality of devices including a mechanism section and a calculation section are connected. For example, some or all of the functional units may be physically separated from the control valve 105 and may be wired or wirelessly connected.

Storage unit 20 has volatile memory 21 and nonvolatile memory 22 . The volatile memory 21 is a storage unit that can be accessed at high speed, and is composed of a DRAM such as a registered memory, for example. The nonvolatile memory 22 is a storage unit such as a flash memory that retains recorded data even when the power is turned on and off. The storage process in the nonvolatile memory 22 requires, for example, about 5 ms each time, which is longer than that in the volatile memory 21 .

The feedback control unit 11 is a functional unit that feedback-controls the opening degree of the control valve based on the measured flow rate so that the flow rate of the fluid flowing downstream reaches a set value. The feedback control unit 11 calculates the opening instruction value based on the measured flow rate in each feedback loop.

The operation history storage processing unit 12 is a functional unit that updates and stores the operation history of the control valve. The operation history storage processing unit 12 has an operating time updating unit 121 , an opening/closing number updating unit 122 , an indicated value change amount updating unit 123 and a storage processing unit 124 .

The operating time update unit 121 is a functional unit that updates the operating time of the control valve 105 and stores it in the volatile memory 21 . Run time corresponds to the life of the parts that are energized. Also, the operating time is an index of the service life of parts that are not related to mechanical operation, including electric circuits such as capacitors mounted in the control unit 104 in particular.

The opening/closing frequency update unit 122 is a functional unit that updates the opening/closing frequency of the control valve 105 and stores it in the volatile memory 21 . The open/close frequency update unit 122 counts the number of times the control valve 105 is closed when the flow controller 1 receives a command to change the flow rate set value and the command is to close the control valve 105 . The number of openings and closings, particularly the number of times closed, is an indicator of the impact when the valve is closed and the diaphragm 110 seats on the valve seat 112 .

The instruction value change amount updating unit 123 is a functional unit that updates the total amount of change in the opening degree instruction value of the control valve 105 and stores it in the volatile memory 21 . The instruction value change amount updating unit 123 calculates the amount of change in the opening degree instruction value and records the sum total. More specifically, the instruction value change amount updating unit 123 calculates the absolute value of the difference between the opening instruction value calculated by the feedback control unit 11 and the immediately preceding opening instruction value, and updates the opening instruction value. Add to total change. The transmission signal from the control unit 104 indicating the opening degree instruction value is, for example, a voltage, and may be further converted into a current to drive the actuator 111 . The amount of change in the opening degree indication value is an index of the total deformation of the diaphragm. That is, it corresponds to the life of the metal body due to continuous deformation of the metal.

The operating time, the number of times of opening and closing, and the total amount of change in the opening instruction value obtained by the operating time updating unit 121, the opening/closing number updating unit 122, and the instruction value change amount updating unit 123 are the operation history of the flow control device 1. . A data group including at least the operation time, the number of times of opening and closing, and the amount of change in the opening degree indication value is also referred to as operation history data.

The storage processing unit 124 is a functional unit that writes the operation history data stored in the volatile memory 21 to the nonvolatile memory 22 . According to the configuration in which the operation history data is periodically stored in the nonvolatile memory 22, the data can be retained even if the power supply of the flow control device 1 is suddenly turned off.

The saving process to the nonvolatile memory 22 requires more time than the volatile memory 21 . The time required for the saving process is, for example, about 5 ms in the data flash characteristics of general microcomputers. Therefore, the operating time update unit 121, the opening/closing number update unit 122, and the indicated value change amount update unit 123 are temporarily stored in the volatile memory 21 in each process, and then non-volatile by periodic interrupt processing by the storage processing unit 124. The data is stored again in the property memory 22 . According to this configuration, the saving process to the non-volatile memory can be realized without affecting the response time of the process by the open/close count updating unit 122 and the instruction value change amount updating unit 123 . In addition, flash memory, which is typical as a nonvolatile memory, has a relatively small number of rewritable times. You can extend the time.

The wear degree calculator 13 is a functional unit that calculates the wear degree of the flow control device 1 based on the operation history data. The greater the operating time, the number of times of opening and closing, and the amount of change in the opening degree indication value, the greater the degree of wear. As described above, the operating time, the number of times of opening and closing, and the amount of change in the opening degree indication value are indicators corresponding to different failure modes in the control unit 104 and the diaphragm 110, respectively, and each indicator is a composite of different failures. Affects mode. For example, the life of the electric circuit depends not only on the operation time but also on the amount of power supplied to the actuator 111, which correlates with the amount of change in the opening indication value. In addition, when the amount of change in the opening instruction value is below a certain value, there is a region where the diaphragm 110 is not deformed only by increasing the closing force. It is also desirable to consider the number of opening and closing times. Therefore, by calculating the wear degree by combining a plurality of indexes, the wear degree of the flow control device 1 can be evaluated with high accuracy. In particular, the three indices employed in this embodiment can accurately calculate the degree of wear in consideration of the electrical load and physical load.

The operating time, the number of times of opening and closing, and the amount of change in the opening degree indication value are each a single value composed of an integrated value. That is, since it is not necessary to hold a plurality of histories of past values, the amount of data is small and can be stored in the volatile memory 21 and the nonvolatile memory 22 in a short period of time.

The wear degree calculator 13 is composed of a neural network that receives operation history data. Neural network parameters are calculated from statistical data and pre-stored. This teaching data is obtained by obtaining the failure rate for the flow control device 1 placed under different operation sequences, and by obtaining the amount of change from the time of manufacture of the response characteristics of the controlled system in feedback control. Created statistically. The flow control device 1 is equipped with a trained model that has been trained using these teaching data. The wear degree calculation unit 13 calculates the wear degree from the operation history data by a neural network using this learned model based on a wear degree calculation instruction.

The wear degree calculator 13 has appropriate communication means, and can output the calculated wear degree to an external device via the communication means. The external device may display an indicator of wear and tear. The wear degree calculation unit 13 also has a function of verifying whether or not the replacement frequency of each part is appropriate based on the wear degree, and determining whether the replacement time is near and notifying the user. may be Further, the wear degree calculator 13 may have a function of determining whether the wear degree satisfies a predetermined condition and outputting to an external device when the wear degree satisfies the predetermined condition.

Flowchart for Storing Operation History Data in Non-Volatile Memory As shown in FIG. 3A, the flow set value change process S10 is started by receiving a command to change the flow set value (S11). Next, it is determined whether or not the currently set flow rate set value is other than 0 and the newly set flow rate set value is 0 (S12). When the flow rate set value is changed from other than 0 to 0, 1 is added to the closing number N (S13). This is because changing the flow rate set value from other than 0 to 0 means closing the control valve 105 . Next, the flow rate set value is updated to a newly set value (S14). Step S<b>13 corresponds to an opening/closing number update process by the opening/closing number update unit 122 .

As shown in FIG. 3(b), the feedback loop S20 is a loop process that is executed at fixed time intervals, for example, at intervals of 1 ms. First, a feedback process is performed in which a new opening instruction value is determined based on the measured flow rate and the flow rate set value (S21). Next, the absolute value of the difference between the new opening instruction value determined in S21 and the previous opening instruction value is calculated, and added to the total Vch of the amount of change in the opening instruction value (S22). Step S<b>22 corresponds to update processing by the instruction value change amount update unit 123 .

As shown in FIG. 3C, the saving process S30 is a loop process that is executed at intervals longer than the feedback loop S20, for example, every 10 minutes. First, the operating time t is updated (S31). Next, the total Vch of the amount of change in the opening degree indication value, the operating time t, and the number of closing times N are stored in the nonvolatile memory 22 (S32). Note that the time required for step S32 is several milliseconds. Step S<b>32 corresponds to saving processing by the saving processing unit 124 .

Note that, in the present embodiment, the operating time is recorded in the saving process S30. Since the saving process S30 has a longer execution interval than the feedback loop S20, data may be lost when saving is not done in time when the power is turned off. However, the time data lost is less than 10 minutes, which is small enough for the life of the flow controller 1 and is a negligible amount.

The operating time update unit 121 and the instruction value change amount update unit 123 periodically update the operation time and the amount of change in the opening degree instruction value, respectively, while the flow control device 1 is being activated. The operating time is updated approximately every 10 minutes, and the amount of change in the opening indication value is updated approximately every 1 ms. In this way, according to the configuration in which the operation history data is regularly updated while the flow rate control device 1 is activated, the measurement It is possible to save the operation history at an accurate frequency according to the characteristics of the object to be viewed.

The instruction value change amount updating process S22 by the instruction value change amount updating unit 123 and the saving process S32 by the saving processing unit 124 are executed asynchronously. The opening/closing count update process S13 is executed asynchronously with the instruction value change amount update process S22 and the save process S32. In other words, the change processing S10, the feedback loop S20, and the storage processing S30 including the opening/closing count update processing S13, the instruction value change amount update processing S22, and the storage processing S32, respectively, are executed by multithread processing. These three types of processing series are processed by separate interrupt processing, and the program is executed while switching between a plurality of threads.

Note that the reception processing and storage processing of the flow rate setting value may be processed by polling. Moreover, a circuit block capable of parallel processing may be configured using an FPGA or the like.

When the power is turned on, the total Vch of the amount of change in the opening instruction value, the operating time t, and the number of closing times N are read from the nonvolatile memory 22 and stored in the volatile memory 21, and then the flow rate setting value change processing S10. , processing for permitting the feedback loop S20 and the saving processing S30, and each processing is started.

Thus, according to the flow rate control device of the present invention, the operation history of the control valve can be recorded by a simple method.

Further, according to the flow rate control device of the present invention, it is possible to obtain an index that contributes to the deformation of the diaphragm by calculating the integrated value of the amount of change in the opening instruction value.

Furthermore, according to the flow control device of the present invention, according to the configuration in which the operation history data is regularly updated while the flow control device 1 is activated, the operation history is updated only when the flow rate setting value is changed, for example. Compared to the memorized configuration, it is possible to save the operation history with high frequency and accuracy.

Furthermore, according to the flow rate control device of the present invention, since the number of times of opening and closing is updated when the set value of the flow rate becomes 0, the number of times of closing can be counted efficiently and reliably.

Furthermore, according to the flow rate control device of the present invention, the process of writing the operation history data to the nonvolatile memory can be performed asynchronously with the process of updating the amount of change in the indicated value. Therefore, it is possible to avoid the time required for the storage process in the nonvolatile memory from affecting the responsiveness of the feedback loop. In addition, since the operation history data is held in the nonvolatile memory, even when the power is turned on and off, the previous operation history can be handed over and recording can be continued.

Furthermore, according to the flow rate control device of the present invention, the degree of wear of the diaphragm can be accurately calculated by calculating the degree of wear based on the operation history data. In addition, since the operation history data includes a plurality of indices, it is possible to calculate the degree of wear by considering the plurality of indices in combination.

Furthermore, according to the flow rate control device of the present invention, by calculating the degree of wear using a neural network, the degree of wear of the diaphragm can be calculated more accurately.

1 flow control device 104 control unit 11 control unit (feedback control unit)
12 Operation history storage processing unit 121 Operating time update unit 122 Switching times update unit 123 Indicated value change amount update unit 124 Storage processing unit 20 Storage unit 21 Volatile memory 22 Non-volatile memory

Claims (13)

a control valve;
a storage unit;
an operation history storage processing unit that stores an operation history of the control valve in the storage unit;
with
The operation history storage processing unit
an opening/closing frequency updating unit that stores the opening/closing frequency of the control valve in the storage unit;
an instruction value change amount updating unit that integrates a total amount of change in the opening degree instruction value of the control valve and stores the amount in the storage unit;
having
Flow controller. In each feedback loop, further comprising a feedback control unit that calculates the opening degree indication value based on the measured flow rate and controls the opening degree of the control valve so that the flow rate of the outflowing fluid becomes a set value;
The instruction value change amount updating unit calculates the amount of change in the opening instruction value in the feedback loop and adds it to the total amount of change in the opening instruction value.
The flow control device according to claim 1. The instruction value change amount updating unit periodically updates the amount of change in the opening degree instruction value while the flow rate control device is running.
The flow control device according to claim 1 or 2. The opening/closing frequency update unit updates the opening/closing frequency when the set value of the flow rate set in the flow rate control device becomes 0.
The flow control device according to any one of claims 1 to 3. The storage unit includes a volatile memory and a nonvolatile memory,
The opening/closing number update unit and the instruction value change amount update unit write the opening/closing number of times and the amount of change in the opening instruction value to the volatile memory, respectively;
The operation history storage processing unit further includes a storage processing unit that writes, into the nonvolatile memory, the opening/closing count and the amount of change in the opening instruction value stored in the volatile memory.
The flow control device according to any one of claims 1 to 4. The updating process by the instruction value change amount updating unit and the saving process by the saving processing unit are performed asynchronously.
The flow control device according to claim 5. The operation history storage processing unit
further comprising an operating time update unit that stores the operating time of the control valve in the storage unit;
wherein the storage processing unit writes an operation history further including the operating time to the nonvolatile memory;
The flow control device according to claim 5 or 6. Further comprising a wear degree calculation unit that calculates the wear degree of the flow control device based on the operation history,
The flow control device according to any one of claims 1 to 7. The wear degree calculation unit is configured by a neural network that receives the operation history as input,
The flow control device according to claim 8. The control valve comprises a diaphragm and a valve seat, and the diaphragm adjusts the flow rate of the fluid by opening and closing with respect to the valve seat.
The flow control device according to any one of claims 1 to 9. a control valve;
a storage unit;
A control method for a flow control device comprising
an opening/closing count update step of storing the opening/closing count of the control valve in the storage unit;
an instruction value change amount update step of accumulating a total amount of change in the opening degree instruction value of the control valve and storing the amount in the storage unit;
including,
A control method for a flow control device. The storage unit includes a volatile memory and a nonvolatile memory,
The step of updating the number of times of opening and closing and the step of updating the amount of change in the indicated value are steps of writing the number of times of opening and closing and the amount of change in the indicated value of opening to the volatile memory, respectively;
further comprising a storage processing step of writing the number of times of opening and closing and the amount of change in the opening instruction value stored in the volatile memory into the nonvolatile memory;
The instruction value change amount update step and the storage processing step are performed asynchronously,
The control method of the flow control device according to claim 11. a control valve;
a storage unit;
A control program for a flow control device comprising
an open/close count update command for storing the open/close count of the control valve in the storage unit;
an instruction value change amount update command for accumulating a total amount of change in the opening degree instruction value of the control valve and storing the amount in the storage unit;
cause the computer to run
Control program for flow controller.

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