Flow rate adjusting device and method for controlling flow rate adjusting device

Abstract

To appropriately converge a flow rate measurement value to a flow rate setting value.SOLUTION: A flow rate adjusting device 100 is provided, which comprises: an ultrasonic flow rate measuring unit 10; a flow rate adjusting unit 20; a flow rate setting unit that sets a flow rate setting value; a flow rate fluctuation state detecting unit for detecting a first flow rate state in which a flow rate measurement value is higher than the flow rate setting value by at least a first threshold, and a flow rate fluctuation state in which a second flow rate state occurs in which a flow rate measurement value is lower than the flow rate setting value by a second threshold or more; and a control device 30 that controls the flow rate adjusting unit 20 to move a valve body unit by a moving amount corresponding to a flow rate difference between the flow rate measurement value and the flow rate setting value so that the flow rate measurement value becomes the flow rate setting value. When the flow rate fluctuation state detecting unit does not detect a flow rate fluctuation state, the control device 30 controls the flow rate adjusting unit 20 to move the valve body unit 21 by a first movement amount, and when the flow rate fluctuation state detecting unit detects a flow rate fluctuation state, the control device controls the flow rate adjusting unit 20 to move the valve body unit 21 by a second movement amount smaller than the first movement amount.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flow rate control device and a control method for a flow rate control device. [Background technology]

[0002] Conventionally, there is known a flow control device that includes a flow measuring unit that measures the flow rate of a liquid, and adjusts the flow rate of liquid passing through a valve hole by moving a valve body portion toward or away from the valve hole so that the flow rate measured by the flow measuring unit becomes a preset set flow rate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-138200 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, if the pressure (back pressure) when discharging liquid downstream of the flow control device is excessively low compared to the supply pressure of the liquid upstream of the flow control device, or if the supply pressure of the liquid upstream of the flow control device is excessively high compared to the pressure (back pressure) when discharging liquid downstream of the flow control device, the flow rate of the liquid passing through the valve hole will be excessively high. In this case, a phenomenon (overshoot) may occur in which the measured value of the flow rate of the liquid passing through the flow control device becomes excessively high compared to the preset flow rate setting value.

[0005] Furthermore, if an overshoot occurs, the flow rate of the liquid passing through the valve hole may be excessively reduced in an attempt to bring the measured flow rate value closer to the set flow rate value, and the measured flow rate value may become too low relative to the set flow rate value. In this case, a phenomenon occurs in which the measured flow rate value alternates between being too high and too low relative to the set flow rate value (hunting), and the measured flow rate value does not converge to the set flow rate value.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a flow control device and a control method for a flow control device that can appropriately converge the flow measurement value to a flow set value even in a state in which the pressure (back pressure) when ejecting liquid downstream of the flow control device is excessively low compared to the supply pressure of the liquid upstream of the flow control device. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means. A flow control device according to a first aspect of the present invention includes a flow measurement unit that measures the flow rate of liquid flowing in from an inlet port and circulating through a measurement flow path, a flow adjustment unit that adjusts the flow rate of liquid flowing out from the downstream side of the measurement flow path to an outlet port by moving a valve body unit along an axis in a direction toward or away from a valve hole, a flow setting unit that sets a flow rate set value included in a flow rate range from a minimum flow rate to a maximum flow rate, and a flow rate fluctuation state that generates a first flow state in which the flow rate measurement value measured by the flow measurement unit is higher than the flow rate set value by a first threshold value or more and a second flow state in which the flow rate measurement value is lower than the flow rate set value by a second threshold value or more. and a control unit that controls the flow rate adjustment unit to move the valve body by an amount of movement corresponding to a flow rate difference between the flow rate measurement value and the flow rate set value so that the flow rate measurement value measured by the flow rate measurement unit becomes the flow rate set value, wherein the control unit controls the flow rate adjustment unit to move the valve body by a first amount of movement when the flow rate fluctuation state detection unit does not detect the flow rate fluctuation state, and controls the flow rate adjustment unit to move the valve body by the second amount of movement smaller than the first amount of movement when the flow rate fluctuation state detection unit detects the flow rate fluctuation state.

[0008] According to the flow control device according to the first aspect of the present invention, the control unit controls the flow control unit to move the valve body by a first movement amount when the flow rate fluctuation state detection unit does not detect a flow rate fluctuation state. On the other hand, the control unit controls the flow control unit to move the valve body by a second movement amount smaller than the first movement amount when the flow rate fluctuation state detection unit detects a flow rate fluctuation state. Since the second movement amount of the valve body when the flow rate fluctuation state detection unit detects a flow rate fluctuation state is smaller than the first movement amount of the valve body when the flow rate fluctuation state detection unit detects a flow rate fluctuation state, the flow rate is adjusted to reduce changes in the flow rate of the liquid flowing through the measurement flow path, so that the first flow rate state in which the measured value of the flow rate is excessively large relative to a preset flow rate set value and the second flow rate state in which the measured value of the flow rate is too small are not repeated. Therefore, even in a state in which the pressure (back pressure) when discharging the liquid downstream of the flow control device is excessively low relative to the supply pressure of the liquid upstream of the flow control device, the measured flow rate can be appropriately converged to the flow rate set value.

[0009] The flow control device according to a second aspect of the present invention is the first aspect, further configured as follows: That is, the flow rate fluctuation state is a state in which a first flow rate state and a second flow rate state are alternately repeated. According to the flow control device of the second aspect of the present invention, by detecting a state in which a first flow state and a second flow state are alternately repeated as a flow fluctuation state, it is possible to prevent the first flow state, in which the measured flow value is excessively high relative to a preset flow set value, and the second flow state, in which the measured flow value is too low, from being repeated.

[0010] The flow control device according to a third aspect of the present invention is the first or second aspect, further configured as follows: That is, the first threshold value and the second threshold value are set to 5% or more and 10% or less of the flow rate range. According to the flow control device of the third aspect of the present invention, by setting the first and second threshold values ​​to be greater than or equal to 5% and less than or equal to 10% of the flow range in which the flow set value is set, it is possible to properly detect a first flow state in which the measured flow value is excessively large relative to the preset flow set value, and a second flow state in which the measured flow value is too small.

[0011] The flow control device according to a fourth aspect of the present invention is the first or second aspect, further configured as follows: the flow rate fluctuation state detection unit cancels the state of detecting the flow rate fluctuation state in response to the flow rate setting unit changing the flow rate set value. According to the flow control device of the fourth aspect of the present invention, the state of detecting the flow rate fluctuation state is canceled in response to the flow rate setting unit changing the flow rate set value, so that the flow rate fluctuation state detection unit can detect the flow rate fluctuation state again according to the changed flow rate set value.

[0012] The flow control device according to a fifth aspect of the present invention is the first or second aspect, further configured as follows: the second movement amount is 0.2 to 0.4 times the first movement amount. According to the flow control device of the fifth aspect of the present invention, by setting the second movement amount to be 0.2 or more and 0.4 or less times the first movement amount, the second movement amount of the valve body portion when the flow fluctuation state detection portion detects a flow fluctuation state can be appropriately made smaller than the first movement amount, thereby suppressing fluctuations in the flow measurement value.

[0013] In a control method for a flow control device according to a sixth aspect of the present invention, the flow control device has a flow measurement unit that measures a flow rate of liquid flowing in from an inlet port and circulating through a measurement flow path, a flow adjustment unit that adjusts a flow rate of liquid flowing out from a downstream side of the measurement flow path to an outlet port by moving a valve body unit along an axis in a direction toward or away from a valve hole, and a flow setting unit that sets a flow rate set value included in a flow rate range from a minimum flow rate to a maximum flow rate, and has a first flow state in which the flow rate measurement value measured by the flow measurement unit is higher than the flow rate set value by a first threshold value or more and a second flow state in which the flow rate measurement value is lower than the flow rate set value by a second threshold value or more. The method includes a flow rate fluctuation state detection process for detecting a flow rate fluctuation state in which two flow rate states each occur multiple times, and a control process for controlling the flow rate adjustment unit so that the flow rate measurement value measured by the flow measurement unit becomes the flow rate set value, wherein the control process controls the flow rate adjustment unit to move the valve body portion by a first movement amount corresponding to a flow rate difference between the flow rate measurement value and the flow rate set value when the flow rate fluctuation state detection process does not detect the flow rate fluctuation state, and controls the flow rate adjustment unit to move the valve body portion by a second movement amount smaller than the first movement amount when the flow rate fluctuation state detection process detects the flow rate fluctuation state.

[0014] According to the control method for the flow control device according to the sixth aspect of the present invention, the control step controls the flow control unit to move the valve body by a first movement amount when the flow rate fluctuation state detection step does not detect a flow rate fluctuation state. On the other hand, the control step controls the flow control unit to move the valve body by a second movement amount smaller than the first movement amount when the flow rate fluctuation state detection step detects a flow rate fluctuation state. Since the second movement amount of the valve body when the flow rate fluctuation state detection step detects a flow rate fluctuation state is smaller than the first movement amount of the valve body when the flow rate fluctuation state detection step detects a flow rate fluctuation state, the flow rate of the liquid flowing through the measurement flow path is reduced, and the flow rate is adjusted so that a first flow rate state in which the measured value of the flow rate is excessively large relative to a preset flow rate set value and a second flow rate state in which the measured value of the flow rate is too small are not repeated. Therefore, even in a state in which the pressure (back pressure) when discharging the liquid downstream of the flow control device is excessively low relative to the supply pressure of the liquid upstream of the flow control device, the measured flow rate value can be appropriately converged to the flow rate set value.

[0015] The control method for a flow control device according to a seventh aspect of the present invention is the sixth aspect, further configured as follows: That is, the flow rate fluctuation state is a state in which the first flow rate state and the second flow rate state are alternately repeated. According to the control method for a flow control device of the seventh aspect of the present invention, by detecting a state in which a first flow state and a second flow state are alternately repeated as a flow fluctuation state, it is possible to prevent repetition of the first flow state in which the measured flow value is excessively high relative to a preset flow set value, and the second flow state in which the measured flow value is too low.

[0016] The control method for a flow control device according to an eighth aspect of the present invention is the sixth or seventh aspect, further configured as follows: That is, the first threshold value and the second threshold value are set to 5% or more and 10% or less of the flow rate range. According to the control method for a flow control device of the eighth aspect of the present invention, by setting the first and second threshold values ​​to 5% or more and 10% or less of the flow range in which the flow set value is set, it is possible to properly detect a first flow state in which the measured flow value is excessively high relative to a preset flow set value, and a second flow state in which the measured flow value is too low.

[0017] The control method for a flow control device according to a ninth aspect of the present invention is the sixth or seventh aspect, further configured as follows: That is, the flow rate fluctuation state detection step switches a state in which the flow rate fluctuation state is detected to a state in which the flow rate fluctuation state is not detected in response to the flow rate setting unit changing the flow rate set value. According to the control method for a flow control device according to the ninth aspect of the present invention, in response to the flow setting unit changing the flow rate set value, the state of detecting the flow rate fluctuation state is switched to a state of not detecting the flow rate fluctuation state. Therefore, the flow rate fluctuation state detection step can detect the flow rate fluctuation state according to the changed flow rate set value again.

[0018] The control method for a flow control device according to a tenth aspect of the present invention is the sixth or seventh aspect, further configured as follows: That is, the second movement amount is 0.2 to 0.4 times the first movement amount. According to the control method for a flow control device of the tenth aspect of the present invention, by setting the second movement amount to be 0.2 or more and 0.4 or less times the first movement amount, the second movement amount of the valve body portion when the flow fluctuation state detection process detects a flow fluctuation state can be appropriately made smaller than the first movement amount, thereby suppressing fluctuations in the flow measurement value. Effect of the Invention

[0019] According to the present invention, it is possible to provide a flow control device and a control method for a flow control device that can appropriately converge the flow measurement value to a flow set value even in a state in which the pressure (back pressure) when ejecting liquid downstream of the flow control device is excessively low compared to the supply pressure of the liquid upstream of the flow control device. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a partial vertical cross-sectional view showing an embodiment of a flow rate control device. [Diagram 2] 2 is a partial vertical cross-sectional view showing the ultrasonic flow rate measuring unit shown in FIG. 1. [Diagram 3] 2 is a partial vertical cross-sectional view showing a flow rate adjustment section and an outlet-side flow path section shown in FIG. 1. [Figure 4] 2 is a vertical cross-sectional view showing an inlet-side flow passage portion and a pressure sensor shown in FIG. [Diagram 5] FIG. 2 is a block diagram showing a configuration of a control device. [Figure 6] 1 is a schematic configuration diagram showing a flow control system in which a flow control device is installed. [Figure 7] 5 is a flowchart showing a control method for a flow rate adjusting unit of the flow rate adjusting device of the present embodiment. [Figure 8] 5 is a flowchart showing a method for detecting a flow rate fluctuation state by a flow rate fluctuation state detection unit. [Figure 9]5 is a graph showing an example of a change in flow rate of a liquid adjusted by the flow rate adjustment device of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, a flow control device 100 according to one embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a partial vertical cross-sectional view showing one embodiment of the flow control device 100. Fig. 2 is a partial vertical cross-sectional view showing the ultrasonic flow measurement unit shown in Fig. 1.

[0022] The flow control device 100 of this embodiment shown in Figure 1 comprises an ultrasonic flow measurement unit 10 that measures the flow rate of a fluid that flows in from an inflow port 100a and flows through a straight-tube measurement flow path 14, a flow rate adjustment unit 20 that adjusts the flow rate of the fluid, a control device 30 that controls the flow rate adjustment unit 20, a housing unit 40 that accommodates the ultrasonic flow measurement unit 10, the flow rate adjustment unit 20, and the control device 30, an inflow side flow path unit 50 that guides the fluid flowing in from the inflow port 100a to the upstream side of the measurement flow path 14, an outflow side flow path unit 60 that guides the fluid flowing out from the downstream side of the measurement flow path 14 to the outflow port 100b, and a pressure sensor (pressure measurement unit) 70.

[0023] The fluid whose flow rate is adjusted by the flow rate control device 100 of this embodiment is, for example, a liquid such as a chemical used in a semiconductor manufacturing device, pure water, etc. The temperature of the fluid is, for example, in the normal temperature range (e.g., 10°C or higher and lower than 50°C) or in the high temperature range (e.g., 50°C or higher and 80°C or lower).

[0024] The housing 40 of the flow control device 100 is fixed to an installation surface S by fastening bolts (not shown). The flow control device 100 is also connected to an external device (not shown) via a cable 200, and receives power from the external device via the cable 200 and transmits and receives various signals to and from the external device.

[0025] The signal received from the external device is, for example, a signal indicating a set value of a target flow rate adjusted by the flow control device 100. In addition, the signal transmitted to the external device is, for example, a signal indicating the flow rate of the fluid calculated by the control device 30 based on the signal measured by the ultrasonic flow measurement unit 10, or a signal indicating the pressure of the fluid measured by the pressure sensor 70.

[0026] The ultrasonic flow measurement unit 10 measures the propagation time difference of ultrasonic waves emitted by a pair of transducers, an upstream transducer 11 arranged upstream of the measurement flow path 14 and a downstream transducer 12 arranged downstream of the measurement flow path 14, in order to obtain the flow rate of a fluid flowing in from an inlet pipe (not shown) and circulating through a straight measurement flow path 14.

[0027] 2, the ultrasonic flow measurement unit 10 has an upstream transducer 11 and a downstream transducer 12 arranged on an axis X2 parallel to an installation surface S, an inflow flow path 13 connected to an inflow side flow path section 50, a straight measurement flow path 14 connected to the inflow flow path 13 and extending along the axis X2 (second axis), and an outflow flow path 15 connected to an outflow side flow path section 60. The axis X2 is parallel to an axis X1 (first axis) which is the advancing and retreating direction of a valve body section 21 described later.

[0028] The upstream transducer 11 and the downstream transducer 12 are disposed at positions facing each other across the measurement flow path 14 on the axis X2, and are capable of transmitting and receiving ultrasonic signals. The ultrasonic signal transmitted by the upstream transducer 11 propagates through the fluid flowing through the measurement flow path 14 and is received by the downstream transducer 12.

[0029] Similarly, the ultrasonic signal emitted by the downstream transducer 12 propagates through the fluid flowing through the measurement flow path 14 and is received by the upstream transducer 11. Because the fluid flows through the measurement flow path 14 from the upstream side to the downstream side, the propagation time of the ultrasonic signal emitted by the upstream transducer 11 to the downstream transducer 12 is shorter than the propagation time of the ultrasonic signal emitted by the downstream transducer 12 to the upstream transducer 11. The ultrasonic flow rate measurement unit 10 measures the flow rate of the fluid flowing through the measurement flow path 14 by utilizing this propagation time difference.

[0030] The transmission of ultrasonic signals by the upstream transducer 11 and the downstream transducer 12 is controlled by a control device 30 connected by signal lines 16 and 17 shown in Fig. 2. The reception of ultrasonic signals by the upstream transducer 11 and the downstream transducer 12 is transmitted to the control device 30 via the signal lines 16 and 17. As described below, the control device 30 calculates a propagation time difference from the transmission timing of ultrasonic signals instructed to the upstream transducer 11 and the downstream transducer 12 and the reception timing of ultrasonic signals received from the upstream transducer 11 and the downstream transducer 12 corresponding to the transmission timing, and calculates the flow rate of the fluid from the calculated propagation time difference.

[0031] The flow rate adjustment unit 20 adjusts the flow rate of the fluid flowing out from the downstream side of the measurement flow path 14 to the outflow port 100b connected to the outflow piping (not shown) through the outflow side flow path section 60. As shown in Fig. 1, the flow rate adjustment unit 20 is disposed between the ultrasonic flow measurement unit 10 and the control device 30 in the direction of the axis Y, which is the installation direction perpendicular to the installation surface S. As shown in Fig. 1, in the direction of the axis Y, the ultrasonic flow measurement unit 10 is disposed at a position closest to the installation surface S, the control device 30 is disposed at a position farthest from the installation surface S, and the flow rate adjustment unit 20 is disposed between them.

[0032] 3 is a partial vertical cross-sectional view showing the flow rate adjustment unit 20 and the outflow side flow path unit 60 shown in FIG. 1. As shown in FIG. 3, the flow rate adjustment unit 20 has a valve body portion 21 inserted into a valve hole 62 formed in the outflow side flow path unit 60, and an electric drive unit 22 that moves the valve body portion 21 in a direction toward or away from the valve hole 62 along an axis X1 (first axis) parallel to the installation surface S. The electric drive unit 22 moves the valve body portion 21 forward and backward along the axis X1 between a closed state position shown by a solid line in FIG. 4 and an open state position shown by a broken line. The flow rate adjustment unit 20 adjusts the amount of fluid flowing from the valve hole 62 into the valve chamber 63 by adjusting the position of the valve body portion 21 on the axis X1 by the electric drive unit 22.

[0033] Here, the configuration of the control device 30 will be described with reference to Fig. 5. Fig. 5 is a block diagram showing the configuration of the control device 30. As shown in Fig. 5, the control device 30 has a control unit 31, a flow rate setting unit 32, and a flow rate fluctuation state detection unit 33.

[0034] The control unit 31 controls the flow rate adjustment unit 20 based on the flow rate measurement value FRac of the fluid measured by the ultrasonic flow rate measurement unit 10. The control unit 31 controls the flow rate adjustment unit 20 to move the valve body unit 21 by an amount of movement according to the flow rate difference between the flow rate measurement value FRac and the flow rate set value FRset so that the flow rate of the fluid measured by the ultrasonic flow rate measurement unit 10 becomes the flow rate set value FRset set by the flow rate setting unit 32.

[0035] The control unit 31 can instruct each of the upstream transducer 11 and the downstream transducer 12 of the ultrasonic flow measurement unit 10 to emit an ultrasonic signal. The control unit 31 can also detect the timing at which an ultrasonic signal emitted from either the upstream transducer 11 or the downstream transducer 12 is received by the other one of the upstream transducer 11 and the downstream transducer 12.

[0036] The control unit 31 calculates a first propagation time from the timing of transmission of an ultrasonic signal instructed to the downstream transducer 12 and the corresponding timing of reception of the ultrasonic signal at the upstream transducer 11. The control device 30 also calculates a second propagation time from the timing of transmission of an ultrasonic signal instructed to the upstream transducer 11 and the corresponding timing of reception of the ultrasonic signal at the downstream transducer 12. The control unit 31 obtains the flow rate of the fluid flowing through the measurement flow path 14 based on a propagation time difference obtained by subtracting the second propagation time from the first propagation time and a predetermined flow rate calculation formula.

[0037] The flow rate setting unit 32 sets a flow rate set value FRset [ml / min] within a flow rate range from 0 [ml / min], which is the minimum flow rate, to a maximum flow rate FRmax [ml / min] of the flow control device 100. The flow rate setting unit 32 sets the flow rate set value FRset based on a flow rate setting signal that the control device 30 receives from an external device via the cable 200, for example.

[0038] The flow rate fluctuation state detection unit 33 detects a flow rate fluctuation state in which a first flow rate state in which the flow rate measurement value FRac [ml / min] measured by the ultrasonic flow measurement unit 10 is higher than the flow rate set value FRset by a first threshold value Th1 or more, and a second flow rate state in which the flow rate measurement value FRac is lower than the flow rate set value FRset by a second threshold value Th2 or more, each occur multiple times.

[0039] 1, the housing portion 40 is formed with an air inlet port 40a and an air outlet port 40b in this order from the side closer to the installation surface S along the axis Y. The air inlet port 40a is a port that introduces air supplied from an air supply source (not shown) into the housing portion 40. The air outlet port 40b is a port that exhausts air circulating inside the housing portion 40 to the outside of the housing portion 40.

[0040] Fig. 4 is a vertical cross-sectional view showing the inlet-side flow path section 50 and the pressure sensor 70 shown in Fig. 1. As shown in Fig. 1 and Fig. 4, the inlet-side flow path section 50 is a member having an inlet-side inclined flow path 51 formed therein, which is inclined in a direction approaching the installation surface S from the inlet port 100a toward the inlet flow path 13 on the upstream side of the measurement flow path 14. A pressure sensor 70 is attached to the inlet-side flow path section 50 to detect the pressure of the fluid flowing through the inlet-side inclined flow path 51.

[0041] As shown in Figs. 1 and 3, the outlet-side flow passage section 60 is a member having an outlet-side inclined flow passage 61 formed therein, which is inclined from the flow rate adjustment section 20 toward the outlet port 100b toward the installation surface S. The outlet-side flow passage section 60 guides the fluid from an opening 64 provided above the valve chamber 63 to the upstream side of the outlet-side inclined flow passage 61 through an outlet flow passage 65. The fluid guided to the upstream side of the outlet-side inclined flow passage 61 is guided along the outlet-side inclined flow passage 61 to the outlet port 100b. As shown in Figs. 2 and 3, the outlet-side flow passage section 60 is provided with through holes through which a plurality of fastening bolts 66 pass. The outlet-side flow passage section 60 is fixed to the electric drive section 22 by fastening the fastening bolts 66 to the electric drive section 22.

[0042] The pressure sensor 70 measures the pressure (supply pressure) of the fluid flowing from the inflow port 100a into the inflow-side inclined flow path 51 on the upstream side of the measurement flow path 14. The pressure sensor 70 is, for example, a strain gauge type pressure sensor. The pressure sensor 70 is attached to the inflow-side flow path section 50 by a sensor holder 71. A pressure signal indicating the pressure of the fluid measured by the pressure sensor 70 is transmitted to the control device 30 and stored in a memory section (not shown) provided in the control device 30. The pressure signal is also transmitted to an external device via a cable 200.

[0043] Next, a flow control system 1 in which the flow control device 100 of this embodiment is installed will be described with reference to Fig. 6. Fig. 6 is a schematic configuration diagram showing the flow control system 1 in which the flow control device 100 is installed. As shown in Fig. 6, the flow control system 1 has a pump 2 that pressurizes a fluid, a pipe 3 that transports the fluid from an inlet end 1a to an outlet end 1b, the flow control device 100, an on-off valve 4 arranged in the pipe 3 upstream of the flow control device 100, and an on-off valve 5 arranged in the pipe 3 downstream of the flow control device 100.

[0044] In the flow rate control system 1, a fluid flowing into a pipe 3 from an inlet end 1a is pressure-fed by a pump 2 to a flow rate control device 100, and the fluid whose flow rate has been adjusted by the flow rate control device 100 is then supplied to an outlet end 1b. An on-off valve 4 switches between a state in which a fluid is supplied from the inlet end 1a to the flow rate control device 100 and a state in which a fluid is not supplied. An on-off valve 5 switches between a state in which a fluid is supplied from the flow rate control device 100 to the outlet end 1b and a state in which a fluid is not supplied.

[0045] Next, a control method for the flow control device 100 of this embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a control method for the flow control unit 20 of the flow control device 100 of this embodiment. Each process shown in Fig. 7 is performed by the control device 30 executing a control program.

[0046] In step S101, the control unit 31 sets a flow rate setting value FRset [ml / min] included in the flow rate range from 0 [ml / min], which is the minimum flow rate, to FRmax [ml / min], which is the maximum flow rate, of the flow control device 100. The flow rate setting unit 32 sets the flow rate setting value FRset based on a flow rate setting signal that the control device 30 receives from an external device via the cable 200, for example.

[0047] In step S102, the control unit 31 acquires the flow rate measurement value FRac of the fluid flowing through the measurement flow path 14 from the ultrasonic flow rate measurement unit 10.

[0048] In step S103, the control unit 31 determines whether or not a flow rate fluctuation state has been detected by the flow rate fluctuation state detection unit 33, and if YES, proceeds to step S105, and if NO, proceeds to step S104.

[0049] In step S104, since the flow rate fluctuation detection section 33 does not detect a flow rate fluctuation state, the control section 31 calculates a first movement amount MV1 of the valve body section 21 by the following formula (1). MV1 = (FRset-FRac)·α (1) Here, α is a positive coefficient.

[0050] In step S105, since the flow rate fluctuation state detection section 33 is detecting a flow rate fluctuation state, the control section 31 calculates a second movement amount MV2 of the valve body section 21 by the following formula (2). MV2 = (FRset-FRac) · β (2) Here, β is a positive coefficient.

[0051] It is preferable to set β to 0.2 to 0.4 times α. When the difference (FRset-FRac) between the flow rate set value FRset and the flow rate measurement value FRac is the same, it is preferable to set the second movement amount MV2 to 0.2 to 0.4 times the first movement amount MV1.

[0052] In step S106, the control unit 31 controls the flow rate adjustment unit 20 to start the operation of moving the valve body portion 21 along the axis X1 by the first movement amount MV1 determined in step S104 or the second movement amount MV2 determined in step S105.

[0053] When the flow rate measurement value FRac is smaller than the flow rate set value FRset, the first movement amount MV1 of the valve body 21 is a positive value. When the first movement amount MV1 is a positive value, the control unit 31 moves the valve body 21 by the first movement amount MV1 in a direction away from the valve hole 62, thereby increasing the flow rate of the fluid passing through the valve hole 62.

[0054] On the other hand, when the flow rate measurement value FRac is greater than the flow rate set value FRset, the first movement amount MV1 of the valve body 21 becomes a negative value. When the first movement amount MV1 is a negative value, the control unit 31 moves the valve body 21 by the first movement amount MV1 in a direction approaching the valve hole 62, thereby reducing the flow rate of the fluid passing through the valve hole 62.

[0055] In step S107, the control unit 31 determines whether the movement amount of the valve body portion 21 becomes the first movement amount MV1 determined in step S104 or the second movement amount MV2 determined in step S105, and whether the movement of the valve body portion 21 is completed; if YES, the process proceeds to step S108; if NO, the control unit 31 executes step S107 again.

[0056] In step S108, the control unit 31 determines whether or not to end the flow rate adjustment of the fluid by the flow rate adjustment unit 20. If YES, the process of this flowchart ends, and if NO, the process of step S101 is executed again.

[0057] Next, a method for detecting a flow rate fluctuation state by the flow rate fluctuation state detection unit 33 will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a flowchart showing a method for detecting a flow rate fluctuation state by the flow rate fluctuation state detection unit 33. Fig. 9 is a graph showing an example of a change in the flow rate of the liquid regulated by the flow control device 100 of this embodiment.

[0058] 9, the values ​​indicated by the solid line show the change in flow rate when the control method of the flow rate adjustment unit 20 shown in Fig. 7 of this embodiment is executed, and the values ​​indicated by the solid line show the change in the flow rate measurement value FRac when the control method of the comparative example is executed. The comparative example is an example in which the determination of step S103 shown in Fig. 7 is not performed, and the first movement amount MV1 of step S104 is always determined as the movement amount of the valve body portion 21.

[0059] 9, the first threshold value Th1 and the second threshold value Th2 are set to any value within a range of 5% to 10% of the flow rate range from 0 flow rate to the maximum flow rate FRmax. The first threshold value Th1 and the second threshold value Th2 are set to detect a flow rate fluctuation state in which a phenomenon occurs in which the flow rate measurement value FRac repeatedly becomes excessively large and excessively small relative to the flow rate set value FRset (hunting phenomenon).

[0060] As shown in Figure 9, in both this embodiment and the comparative example, between time 0 and time T4, a first flow state in which the flow measurement value FRac is higher than the flow set value FRset by a first threshold value Th1 or more, and a second flow state in which the flow measurement value FRac is lower than the flow set value FRset by a second threshold value Th2 or more are alternately repeated twice each.

[0061] 9, time T0 indicates the time when the flow rate adjustment operation of the flow rate adjustment unit 20 of the liquid is started. Times T1 and T3 are times when the flow rate measurement value FRac becomes a flow rate value FRa that is higher than the flow rate set value FRset by a first threshold value Th1. Times T2 and T4 are times when the flow rate measurement value FRac becomes a flow rate value FRb that is lower than the flow rate set value FRset by a second threshold value Th2.

[0062] In this embodiment, the flow rate fluctuation state is detected when the first flow rate state and the second flow rate state are alternately repeated two times, but the period from the first detection of the first flow rate state to the second detection of the second flow rate state can be any period. That is, the flow rate fluctuation state detection unit 33 of this embodiment detects the flow rate fluctuation state when the first flow rate state and the second flow rate state are alternately repeated two times, regardless of the length of the period from time T0 to time T4 shown in FIG.

[0063] This is because, for example, when the pressure (back pressure) when ejecting liquid downstream of the flow control device 100 is excessively low compared to the supply pressure of the liquid upstream of the flow control device 100 (for example, when the back pressure is 400 KPa or more lower than the supply pressure), an excessively large flow rate of fluid flows relative to the opening of the valve body portion 21 of the flow control unit 20.

[0064] In the comparative example, even after time T4, the state in which the first flow state and the second flow state each occur multiple times continues. On the other hand, when the control method of the flow rate adjustment unit 20 shown in Fig. 7 of this embodiment is executed, after time T4, neither the first flow state nor the second flow state occurs, and the flow measurement value FRac converges to a range higher than the flow rate value FRb and lower than the flow rate value FRa. Here, the flow rate value FRa is the value obtained by adding the first threshold value Th1 to the flow rate setting value FRset, and the flow rate value FRb is the value obtained by subtracting the second threshold value Th2 from the flow rate setting value FRset.

[0065] The process shown in Fig. 8 is executed in parallel with the control method of the flow control unit 20 of the flow control device 100 shown in Fig. 7. The flow rate fluctuation state detected by the detection method of the flow rate fluctuation state by the flow rate fluctuation state detection unit 33 in Fig. 8 is used for the judgment in step S103 in Fig. 7. When performing the process in Fig. 8, the ultrasonic flow measurement unit 10 sequentially acquires the flow rate measurement value FRac at a predetermined time interval, and the flow rate measurement value FRac is transmitted from the ultrasonic flow measurement unit 10 to the flow rate fluctuation state detection unit 33.

[0066] The flow rate fluctuation state detection unit 33 sets, as an initial state, a first monitoring state indicating that a flow rate fluctuation state has not been detected. Furthermore, when the flow rate fluctuation state detection unit 33 detects a flow rate fluctuation state in step S103 of Fig. 7 and judges it to be YES, and ends the flow rate adjustment in step S108 and ends the processing of the flowchart in Fig. 7, the flow rate fluctuation state detection unit 33 cancels the flow rate fluctuation state and sets the first monitoring state.

[0067] In step S201, the flow rate fluctuation state detection unit 33 determines whether or not the first monitoring state is set, and if YES, the process proceeds to step S202, and if NO, the process proceeds to step S204.

[0068] In step S202, the flow rate fluctuation state detection unit 33 determines whether the first flow rate state has been reached, where the flow rate measurement value FRac is higher than the flow rate set value FRset by at least the first threshold value Th1, and if YES, the process proceeds to step S203, and if NO, the process proceeds to step S212. The flow rate fluctuation state detection unit 33 determines that the first flow rate state has been reached in response to the flow rate gradually increasing from a flow rate of 0 [ml / min] at time 0, and the flow rate measurement value FRac becoming higher than the flow rate set value FRset by at least the first threshold value Th1 at time T1.

[0069] In step S203, since it is determined that the flow rate state has changed to the first flow rate state in the first monitoring state, the flow rate fluctuation state detection unit 33 sets the monitoring state of the flow rate measurement value FRac to the second monitoring state.

[0070] In step S204, the flow rate fluctuation state detection unit 33 determines whether or not the second monitoring state is set, and if YES, the process proceeds to step S205, and if NO, the process proceeds to step S207.

[0071] In step S205, the flow rate fluctuation state detection unit 33 determines whether the flow rate has reached a second flow rate state in which the flow rate measurement value FRac is lower than the flow rate set value FRset by at least the second threshold value Th2, and if YES, the process proceeds to step S206, and if NO, the process proceeds to step S212. The flow rate fluctuation state detection unit 33 determines that the flow rate has reached the second flow rate state in response to the flow rate measurement value FRac becoming lower than the flow rate set value FRset by at least the second threshold value Th2 at time T2 after the flow rate has increased from the flow rate value FRa to the flow rate value FR1 at time T1.

[0072] In step S206, since it is determined that the flow rate state has changed to the second flow rate state in the second monitoring state, the flow rate fluctuation state detection unit 33 sets the monitoring state of the flow rate measurement value FRac to the third monitoring state.

[0073] In step S207, the flow rate fluctuation state detection unit 33 determines whether or not the third monitoring state is set, and if YES, the process proceeds to step S208, and if NO, the process proceeds to step S210.

[0074] In step S208, the flow rate fluctuation state detection unit 33 determines whether the first flow rate state has been reached, where the flow rate measurement value FRac is higher than the flow rate set value FRset by at least the first threshold value Th1, and if YES, the process proceeds to step S209, and if NO, the process proceeds to step S212. The flow rate fluctuation state detection unit 33 determines that the first flow rate state has been reached in response to the flow rate measurement value FRac becoming higher than the flow rate set value FRset by at least the first threshold value Th1 at time T3 after the flow rate has decreased from the flow rate value FRb to the flow rate value FR2 at time T2.

[0075] In step S209, since it is determined that the flow rate state has changed from the third monitoring state to the first flow rate state, the flow rate fluctuation state detection unit 33 sets the monitoring state of the flow rate measurement value FRac to the fourth monitoring state.

[0076] In step S210, the flow rate fluctuation state detection unit 33 determines whether the flow rate has reached a second flow rate state in which the flow rate measurement value FRac is lower than the flow rate set value FRset by at least the second threshold value Th2, and if YES, proceeds to step S211, and if NO, proceeds to step S212. The flow rate fluctuation state detection unit 33 determines that the flow rate has reached the second flow rate state in response to the flow rate increasing from the flow rate value FRa at time T3 to the flow rate value FR3, and then the flow rate measurement value FRac becoming a flow rate value FRb lower than the flow rate set value FRset by at least the second threshold value Th2 at time T4. After time T4 has passed, the flow rate measurement value FRac further decreases from the flow rate value FRb to a flow rate value FR4, and then increases.

[0077] In step S211, since the first flow state and the second flow state are alternately repeated twice each, the flow rate fluctuation state detection unit 33 sets a flow rate fluctuation state. The flow rate fluctuation state detection unit 33 of this embodiment detects the flow rate fluctuation state in response to occurrence of fluctuations in the flow rate measurement value FRac in the order of the first flow state, the second flow state, the first flow state, and the second flow state.

[0078] In step S212, the flow rate fluctuation state detection unit 33 determines whether to return the monitoring state to the first monitoring state, which is the initial state, and if YES, proceeds to step S213, and if NO, ends the processing of this flowchart and repeats the processing from step S201 again. The flow rate fluctuation state detection unit 33 determines YES in step S212 when the flow rate adjustment is ended in step S108 in Fig. 7, or when the flow rate setting unit 32 changes the flow rate set value FRset in step S101 in Fig. 7.

[0079] In step S213, if the second monitoring state, the third monitoring state, the fourth monitoring state or the flow rate fluctuation state is set, the flow rate fluctuation state detection unit 33 cancels the set state and sets the first monitoring state.

[0080] In the process shown in Fig. 8, the flow rate fluctuation state detection unit 33 detects the flow rate fluctuation state when the first flow rate state and the second flow rate state are alternately repeated twice, but other aspects are also possible. For example, the flow rate fluctuation state detection unit 33 may detect the flow rate fluctuation state when the first flow rate state and the second flow rate state alternate only once. Also, the flow rate fluctuation state detection unit 33 may detect the flow rate fluctuation state when the first flow rate state and the second flow rate state alternately occur an arbitrary number of times set to be three or more times.

[0081] The actions and effects of the flow control device 100 of the present embodiment described above will be described. According to the flow control device 100 of this embodiment, the control unit 31 controls the flow control unit 20 to move the valve body 21 by the first movement amount MV1 when the flow rate fluctuation state detection unit 33 does not detect a flow rate fluctuation state. On the other hand, the control unit 31 controls the flow control unit 20 to move the valve body 21 by the second movement amount MV2 that is smaller than the first movement amount MV1 when the flow rate fluctuation state detection unit 33 detects a flow rate fluctuation state. Since the second movement amount MV2 of the valve body 21 when the flow rate fluctuation state detection unit 33 detects a flow rate fluctuation state is smaller than the first movement amount MV1 of the valve body 21 when the flow rate fluctuation state detection unit 33 detects a flow rate fluctuation state, the change in the flow rate of the liquid flowing through the measurement flow path 14 is reduced, and the flow rate is adjusted so that the first flow rate state in which the flow rate measurement value FRac is excessive relative to the preset flow rate set value FRset and the second flow rate state in which the flow rate measurement value FRac is too small are not repeated. Therefore, even if the pressure (back pressure) when ejecting liquid downstream of the flow control device 100 is excessively low compared to the supply pressure of the liquid upstream of the flow control device 100, the flow measurement value FRac can be appropriately converged to the flow set value FRset.

[0082] In the flow control device 100 of this embodiment, the flow rate fluctuation state is a state in which a first flow rate state and a second flow rate state are alternately repeated. According to the flow control device 100 of this embodiment, by detecting a state in which a first flow state and a second flow state are alternately repeated as a flow fluctuation state, it is possible to prevent the first flow state in which the flow measurement value FRac is excessively large relative to a preset flow set value FRset, and the second flow state in which the flow measurement value FRac is too small from being repeated.

[0083] In the flow control device 100 of this embodiment, the first threshold value Th1 and the second threshold value Th2 are set to be equal to or greater than 5% and equal to or less than 10% of the flow rate range. According to the flow control device 100 of this embodiment, by setting the first threshold value Th1 and the second threshold value Th2 to be greater than 5% and less than 10% of the flow range in which the flow set value FRset is set, it is possible to properly detect a first flow state in which the flow measurement value FRac is excessively large relative to the preset flow set value FRset, and a second flow state in which the flow measurement value FRac is too small.

[0084] In the flow control device 100 of this embodiment, the flow rate fluctuation state detection unit 33 cancels the state of detecting the flow rate fluctuation state in response to the flow rate setting unit 32 changing the flow rate set value FRset. According to the flow control device 100 of this embodiment, the state of detecting the flow rate fluctuation state is canceled in response to the flow rate setting value FRset being changed by the flow rate setting unit 32. Therefore, the flow rate fluctuation state detection unit 33 can detect the flow rate fluctuation state according to the changed flow rate setting value FRset again.

[0085] In the flow control device 100 of the present embodiment, the second movement amount MV2 is not less than 0.2 times and not more than 0.4 times the first movement amount MV1. According to the flow control device 100 of this embodiment, by setting the second movement amount MV2 to be 0.2 or more and 0.4 or less times the first movement amount MV1, the second movement amount MV2 of the valve body portion 21 when the flow fluctuation state detection unit 33 detects the flow fluctuation state can be appropriately made smaller than the first movement amount MV1, thereby suppressing fluctuations in the flow measurement value FRac. [Explanation of symbols]

[0086] 1a Inlet end 1b Outflow end 10 Ultrasonic flow measurement section 14 Measurement flow path 20 Flow rate adjustment section 21 Valve body 30 Control device 31 Control Unit 32 Flow rate setting section 33 Flow rate fluctuation state detection unit 62 Valve hole 100 Flow rate adjustment device 100a inlet port 100b Outlet port FRac flow measurement value FRmax Maximum flow rate FRset Flow rate setting value MV1 First travel distance MV2 Second movement amount Th1 First threshold Th2 Second threshold

Claims

1. a flow rate measuring unit that measures a flow rate of a liquid that flows in through the inflow port and circulates through the measurement flow path; a flow rate adjusting section that adjusts a flow rate of liquid flowing out from the downstream side of the measurement flow path to the outlet port by moving a valve body section along an axis in a direction toward or away from the valve hole; a flow rate setting unit that sets a flow rate setting value within a flow rate range from a minimum flow rate to a maximum flow rate; a flow rate fluctuation state detection unit that detects a flow rate fluctuation state in which a first flow rate state occurs in which a flow rate measurement value measured by the flow rate measurement unit is higher than the flow rate set value by a first threshold value or more, and a second flow rate state occurs in which the flow rate measurement value is lower than the flow rate set value by a second threshold value or more; a control unit that controls the flow rate adjustment unit to move the valve body unit by an amount of movement corresponding to a flow rate difference between the flow rate measurement value measured by the flow rate measurement unit and the flow rate set value so that the flow rate measurement value measured by the flow rate measurement unit becomes the flow rate set value, The control unit controls the flow rate adjustment unit to move the valve body portion by a first amount of movement when the flow rate fluctuation state detection unit does not detect the flow rate fluctuation state, and controls the flow rate adjustment unit to move the valve body portion by a second amount of movement that is smaller than the first amount of movement when the flow rate fluctuation state detection unit detects the flow rate fluctuation state.

2. The flow control device according to claim 1 , wherein the flow rate fluctuation state is a state in which the first flow rate state and the second flow rate state are alternately repeated.

3. 3 . The flow rate control device according to claim 1 , wherein the first threshold value and the second threshold value are set to be equal to or greater than 5% and equal to or less than 10% of the flow rate range.

4. 3. The flow rate adjusting device according to claim 1, wherein the flow rate fluctuation state detecting section cancels the state of detecting the flow rate fluctuation state in response to the flow rate setting section changing the flow rate set value.

5. 3. The flow rate control device according to claim 1, wherein the second movement amount is 0.2 to 0.4 times the first movement amount.

6. A method for controlling a flow rate control device, comprising: The flow rate control device is a flow rate measuring unit that measures a flow rate of a liquid that flows in through the inflow port and circulates through the measurement flow path; a flow rate adjusting section that adjusts a flow rate of liquid flowing out from the downstream side of the measurement flow path to the outlet port by moving a valve body section along an axis in a direction toward or away from the valve hole; a flow rate setting unit that sets a flow rate setting value included in a flow rate range from a minimum flow rate to a maximum flow rate, a flow rate fluctuation state detection process for detecting a flow rate fluctuation state in which a first flow rate state in which a flow rate measurement value measured by the flow rate measurement unit is higher than the flow rate set value by a first threshold value or more and a second flow rate state in which the flow rate measurement value is lower than the flow rate set value by a second threshold value or more occur multiple times; A control step of controlling the flow rate adjusting unit so that the flow rate measurement value measured by the flow rate measuring unit becomes the flow rate setting value, The control step controls the flow rate adjustment unit to move the valve body portion by a first movement amount corresponding to a flow rate difference between the flow rate measurement value and the flow rate set value when the flow rate fluctuation state detection step does not detect the flow rate fluctuation state, and controls the flow rate adjustment unit to move the valve body portion by a second movement amount smaller than the first movement amount when the flow rate fluctuation state detection step detects the flow rate fluctuation state.

7. The method for controlling a flow control device according to claim 6 , wherein the flow rate fluctuation state is a state in which the first flow rate state and the second flow rate state are alternately repeated.

8. 8. The method for controlling a flow rate control device according to claim 6, wherein the first threshold value and the second threshold value are set to be equal to or greater than 5% and equal to or less than 10% of the flow rate range.

9. 8. The control method for a flow control device according to claim 6 or claim 7, wherein the flow rate fluctuation state detection process switches a state in which the flow rate fluctuation state is detected to a state in which the flow rate fluctuation state is not detected in response to the flow rate setting unit changing the flow rate set value.

10. 8. The method for controlling a flow rate control device according to claim 6, wherein the second movement amount is equal to or greater than 0.2 times and equal to or less than 0.4 times the first movement amount.

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