JP2008076134A - Continuous nonstationary flow rate generator and continuous nonstationary flow rate generating method for compressible fluid, and flowmeter calibration device for compressible fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a nonstationary flow rate of a compressible fluid including a reciprocating flow to be generated continuously and precisely. <P>SOLUTION: A continuous nonstationary flow rate generator is equipped with: a flowmeter 12 for measuring an inflow amount of the compressible fluid; a first servo valve 13 for regulating the inflow amount; a first isothermalized pressure container 14 for holding the compressible fluid in an isothermal condition; a first pressure gage 15 for measuring a pressure in the first isothermalized pressure container 14; a second isothermalized pressure container 16 which is held in its vacuum state by a vacuum source; a second pressure gage 17 for measuring a pressure in the second isothermalized pressure container 16; a second servo valve 18 for selectively regulating the outflow from the first isothermalized pressure container 14 or the inflow to the second isothermalized pressure container 16; a third pressure gage 19 for measuring an outward pressure of the second servo valve 18; and a flow rate control means 22 for controlling the outflow amount from the second servo valve 18, based on the inflow amount and the pressure in the first isothermalized pressure container 14, and controlling the inflow amount of the compressible fluid from the second servo valve 18, based on the pressure in the second isothermalized pressure container 16 and the outward pressure of the second servo valve 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reciprocating flow-compatible compressive fluid continuous unsteady flow rate generator and continuous unsteady flow rate generating method, and a reciprocating flow-compatible compressible fluid flow meter verification device.

  In a device that continuously uses a fluid, it is required to quickly and accurately measure the flow rate of the fluid. For example, fuel cells that have been developed in recent years are required to accurately supply a predetermined amount of hydrogen into the fuel cell according to the amount of power generation required, and respond quickly to fluctuations in the amount of power generation. Therefore, it is required to supply hydrogen quickly and accurately with a short transition time from the supply amount to the next supply amount. In the semiconductor manufacturing process, in various processes such as CVD, PVD, sputtering, thermal oxidation, and dry etching, the flow rate of inert gas, oxygen, hydrogen, reactive gas, and other gases are accurately controlled and supplied. It is required to do. The gas flow rate control in the semiconductor manufacturing process is an important control factor that affects the performance of the obtained semiconductor device and, in turn, the product yield in the semiconductor manufacturing process. In addition to these applications, in pneumatic actuators such as pneumatic nailing machines, devices that control various functions and operations by air pressure such as chemical injection devices, measuring devices that use air pressure such as blood pressure measuring devices, etc. It is required to supply air, which is a compressive fluid, at a rapid and accurate flow rate as necessary.

  As described above, a device or system that is required to control the flow rate of a fluid requires a flow meter that can accurately measure the flow rate at a high response speed. However, since the density of compressible fluids such as gas changes not only with pressure but also with temperature, it is difficult to accurately measure the dynamic characteristics of the flowmeter. Therefore, the method for verifying the dynamic characteristics of the flowmeter has not yet been established. Therefore, a method for uniformly comparing responses of commercially available gas flow meters is not defined by ISO, JIS, or the like. Therefore, conventionally, the flow rate of the gas is changed stepwise with a valve or the like, and the response of the flowmeter is measured at that time to evaluate the dynamic characteristics, that is, the responsiveness.

Therefore, the present inventors previously reduced the change in the internal air temperature by accommodating the heat conductive material having a high thermal conductivity and a small volume in the container so that the contact area with the internal air is increased. Thus, a pressure vessel has been proposed that can quickly stabilize the air pressure and make the change in the state of the air in the vessel almost isothermal (Patent Document 1). According to this pressure vessel, it is possible to accurately measure the unsteady flow rate of the gas that flows out of the vessel due to the pressure change in the vessel or is filled in the vessel.
Furthermore, the present inventors have proposed a continuous unsteady flow rate generator that continuously generates an unsteady flow rate fluid flow using this pressure vessel (Patent Document 2).
JP-A-6-147320 (Claim 1, FIG. 1, etc.) Japanese Patent Laying-Open No. 2006-64418 (paragraphs 0016 to 0028, FIG. 1)

  However, the continuous unsteady flow rate generator described in Patent Document 2 has only been used to generate a fluid for a unidirectional flow. For example, a piston cylinder may be used to generate the reciprocating pulsating flow. However, it is difficult to realize a highly accurate reciprocating flow rate because it is affected by temperature changes associated with compression and expansion.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make it possible to continuously generate an unsteady flow rate fluid flow including a reciprocating flow with sufficient accuracy to be used as a measurement standard, and to test a dynamic characteristic test of a compressible fluid and a pneumatic device. It is an object of the present invention to provide a continuous unsteady flow rate generator and a continuous unsteady flow rate generation method for a compressible fluid that are useful for flow rate characteristic tests.
Another object of the present invention is to provide a flowmeter verification device that can verify the measurement accuracy of the flowmeter to be tested using the fluid flow generated by the continuous unsteady flow rate generator including the reciprocating flow as a reference. It is to provide.

The present invention has been devised to achieve the above object, and the continuous unsteady flow rate generator for compressive fluid according to claim 1 is characterized in that the inflow amount of compressive fluid supplied from a fluid supply source is controlled. A flow meter to be measured, a first servo valve that regulates an inflow amount of the compressible fluid that flows in through the flow meter, and the compressive fluid that flows in through the first servo valve are kept in an isothermal state. A first isothermal pressure vessel, a first pressure gauge for measuring the pressure of the compressible fluid in the first isothermal pressure vessel, a second isothermal pressure vessel held in a vacuum state by a vacuum source, and the first A second pressure gauge for measuring the pressure of the compressible fluid in the two isothermal pressure vessels, and the outflow of the compressible fluid from the first isothermal pressure vessel or the inflow of the compressible fluid into the second isothermal pressure vessel A second servo valve that selectively regulates any of the above, and a second servo valve A third pressure gauge for measuring the pressure of the outer compressible fluid; an inflow amount of the compressible fluid measured by the flow meter; and a first isothermal pressure vessel measured by the first pressure gauge. Based on the pressure of the compressive fluid, the flow amount of the compressive fluid from the second servo valve is controlled, and the pressure of the compressive fluid measured by the second pressure gauge and the third pressure gauge is adjusted. And a flow rate control means for controlling the inflow amount of the compressible fluid from the second servo valve.
The outside of the second servo valve is the side that outputs the flow rate of the compressible fluid including the reciprocating flow in the positive direction and the negative direction, and is the downstream side when the flow rate in the positive direction is generated. The upstream side when the flow rate is generated.

  According to such a configuration, the continuous unsteady flow rate generator for compressible fluid controls the first servo valve to supply the compressible fluid from the fluid supply source to the first isothermal pressure vessel, and by the flow meter, The flow rate flowing into the first isothermal pressure vessel is measured. The compressible fluid supplied to the first isothermal pressure vessel is maintained in an isothermal state, and the continuous unsteady flow rate generator for the compressive fluid is supplied with the compressible fluid in the first isothermal pressure vessel by the first pressure gauge. Measure the pressure. Then, the flow rate control means controls the opening of the second servo valve based on the flow rate and pressure flowing into the first isothermal pressure vessel, and causes the compressive fluid to flow out from the first isothermal pressure vessel. Generate directional flow.

  Further, the continuous unsteady flow rate generator for compressive fluid uses the second pressure gauge to measure the pressure of the compressible fluid in the second isothermal pressure vessel (downstream of the second servo valve when negative flow rate is generated). At the same time, the third pressure gauge measures the pressure of the compressible fluid outside the second servo valve, that is, on the output side of the flow rate generation (upstream side of the second servo valve when the negative direction flow rate is generated). Then, the opening degree of the second servo valve is controlled by the flow rate control means based on the upstream pressure and the downstream pressure of the second servo valve, and the compressive fluid is caused to flow into the second isothermal pressure vessel. Thus, a negative flow rate is generated.

  The continuous unsteady flow rate generator for compressive fluid according to claim 2 is the continuous unsteady flow rate generator for compressive fluid according to claim 1, wherein the first isothermal pressure vessel and the second isothermal pressure pressure generator are used. The container was configured to be filled with a heat conductive material made of a fine metal wire focusing body or a porous metal body.

  According to such a configuration, the first isothermal pressure vessel and the second isothermal pressure vessel can quickly absorb the temperature change due to the inflow or outflow of the compressive fluid and maintain the isothermal state.

  A method for generating a continuous unsteady flow of a compressible fluid according to claim 3 is a method for generating a continuous unsteady flow of a compressible fluid using the continuous unsteady flow generation device for a compressible fluid according to claim 1 or 2. A first step of opening the first servo valve, supplying the compressive fluid from the fluid supply source, and increasing the pressure of the first isothermal pressure vessel to a predetermined pressure; A second step of controlling the opening of the servo valve to continuously control the flow rate of the compressive fluid flowing out of the first isothermal pressure vessel; the pressure on the output side of the second servo valve; Based on the pressure in the second isothermal pressure vessel, a third step of calculating the opening of the second servo valve, and opening the second servo valve at the calculated opening, the second isothermal pressure vessel A fourth step of flowing the compressive fluid into the first step to the fourth step When performing repeated sequentially, and to perform the first step in parallel with the third step or the fourth step.

  According to such a procedure, in the first step, the pressure of the compressive fluid in the first isothermal pressure vessel is increased to a predetermined pressure, and in the second step, the pressure is increased to the predetermined pressure in the first step. A flow rate in the positive direction is generated by causing the compressive fluid to flow out from the first isothermal pressure vessel by continuously controlling the opening of the second servo valve. Subsequently, in the third step, the opening degree of the second servo valve is calculated based on the upstream pressure and the downstream pressure of the second servo valve, and in the fourth step, the opening calculated in the third step is calculated. The second servo valve is opened at the opening of the two servo valves, and a compressive fluid is caused to flow into the second isothermal pressure vessel, thereby generating a negative flow rate. In addition, in order to generate the next positive flow rate, in parallel with the third step or the fourth step, the first isothermal pressure vessel is again pressurized to a predetermined pressure by the first step, and the positive pressure is obtained by the second step. Generate directional flow. In this way, by repeatedly performing the first to fourth steps, an unsteady flow of compressive fluid including a reciprocating flow is continuously generated.

  The method for generating a continuous unsteady flow of a compressible fluid according to claim 4 is a method for generating a continuous unsteady flow of a compressible fluid using the continuous unsteady flow rate generator for compressible fluid according to claim 1 or 2. A fifth step of calculating an opening of the first servo valve corresponding to an average flow rate of a flow waveform component in a direction in which the compressive fluid flows out of the second servo valve; and the first servo valve Based on the pressure of the compressive fluid in the first isothermal pressure vessel, and a sixth step of supplying the compressive fluid from the fluid supply source to the first isothermal pressure vessel. And controlling the opening of the second servo valve to continuously control the flow rate flowing out of the first isothermal pressure vessel, the pressure on the output side of the second servo valve, and the first 2 Based on the pressure in the isothermal pressure vessel, the opening of the second servo valve An eighth step, a ninth step of opening the second servo valve at the opening calculated in the eighth step, and flowing a compressive fluid into the second isothermal pressure vessel; and the first isothermal pressure. A tenth step of controlling the opening and closing of the first servo valve based on the pressure of the container and its differential value, and supplying the compressive fluid from the fluid supply source to the first isothermal pressure container, The tenth step is performed in parallel with the eighth step or the ninth step, and the seventh to tenth steps are sequentially repeated.

According to such a procedure, in the fifth step, the opening degree of the first servo valve corresponding to the average flow rate of the flow rate waveform component in the direction in which the compressive fluid flows out is calculated, and in the sixth step, calculated in the fifth step. The first servo valve is opened at the opening to allow the compressive fluid to flow into the first isothermal pressure vessel, and in the seventh step, the opening of the second servo valve is set based on the pressure in the first isothermal pressure vessel. By controlling the flow of the compressive fluid from the first isothermal pressure vessel, a positive flow rate is generated.
Subsequently, in the eighth step, the pressure on the output side of the second servo valve (upstream side when negative flow rate is generated) and the pressure on the second isothermal pressure vessel (downstream side when negative flow rate is generated) Based on the above, the opening degree of the second servo valve is calculated. In the ninth step, the second servo valve is opened at the opening calculated in the eighth step, and a compressive fluid is caused to flow into the second isothermal pressure vessel, thereby generating a negative flow rate. In addition, in order to generate the next positive flow rate, in the tenth step, the opening and closing of the first servo valve is controlled based on the pressure in the first isothermal pressure vessel and its differential value, and the compressibility from the fluid supply source is controlled. Fluid is supplied to the first isothermal pressure vessel. The tenth step is performed in parallel with the eighth step or the ninth step for generating a negative flow rate. Then, returning to the seventh step, the second servo valve is controlled to cause the compressive fluid to flow out from the first isothermal pressure vessel, thereby generating a positive flow rate. After that, the unsteady flow of the compressive fluid including the reciprocating flow is continuously generated by repeatedly performing the seventh to tenth steps.

  The flowmeter verification device according to claim 5 is a subject to be tested for compressible fluid flowing out through the second servo valve of the continuous unsteady flow rate generator for compressive fluid according to claim 1 or claim 2. The flow rate was measured by the flow meter, and the measurement accuracy of the flow rate by the flow meter was verified.

  According to this configuration, the non-steady flow rate of the compressible fluid including the reciprocating flow is continuously generated by the continuous non-steady flow rate generator of the compressive fluid, and the flow meter connected to the output side of the second servo valve. Supply and verify the measurement accuracy of the flow meter.

According to the first aspect of the present invention, a continuous unsteady flow of a compressible fluid including a reciprocating flow can be generated with high accuracy.
According to the invention described in claim 2, since the temperature change of the first isothermal pressure vessel and the second isothermal pressure vessel due to the inflow or outflow of the compressive fluid can be quickly absorbed and the isothermal state can be maintained, It is possible to generate a flow rate waveform in which rising and falling rapidly change.
According to the third aspect of the present invention, when the average flow rate of the generated flow rate waveform is zero, an unsteady flow rate including a reciprocating flow can be continuously generated by simple control.
According to the fourth aspect of the present invention, when the average flow rate of the generated flow rate waveform is not zero, an unsteady flow rate including a reciprocating flow can be continuously generated with high accuracy.
According to the fifth aspect of the present invention, the measurement accuracy of the flow meter to be tested is accurately verified using the unsteady flow rate of the compressible fluid including the reciprocating flow generated by the continuous unsteady flow rate generator as a reference. can do.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
FIG. 1 is a conceptual diagram showing a configuration of a continuous unsteady flow rate generator according to an embodiment of the present invention. This embodiment shows the case where gas is used as the compressible fluid. The direction in which the gas flows from the left to the right in FIG. 1 is a positive direction, and the direction in which the gas flows from the right to the left is the negative direction.

  As shown in FIG. 1, the continuous unsteady flow generator 1 includes a gas flow meter 12, a pressure gauge 11, a pressure gauge 15, a pressure gauge 17, a pressure gauge 19, a first servo valve 13, Two servo valves 18, a first isothermal pressure vessel 14, a second isothermal pressure vessel 16, an A / D converter 20, a D / A converter 21, and a computer 22 are provided. Each device is connected by conduits 23a, 23b, 23c, 23d, 23e, 23f, and 24.

  The first servo valve 13, the first isothermal pressure vessel 14, and the second servo valve 18 are sequentially connected to the gas flow meter 12, the downstream of the gas flow meter 12, and the second isothermal pressure vessel 16. Is connected to the second servo valve 18. These devices are connected by a conduit 23b, a conduit 23c, a conduit 23d, and a conduit 23f, respectively. A gas supply source 30 is connected to the upstream side of the gas flow meter 12 via a pressure reducing valve 31, and an ejector 33, which is a vacuum source, is connected to the second isothermal pressure vessel 16 together with the pressure reducing valve 34. ing. The gas flow meter 12 is connected to the pressure reducing valve 31 and the conduit 23a, and the second isothermal pressure vessel 16 is connected to the ejector 33 and the conduit 23e. Further, the output side (the right side in FIG. 1) of the second servo valve 18 is connected to an external device by a conduit 24.

  A pressure gauge 11, a pressure gauge 15, a pressure gauge 17, and a pressure gauge 19 are connected to the conduit 23a, the first isothermal pressure vessel 14, the second isothermal pressure vessel 16, and the conduit 24, respectively. Output values (measured values) of the gas flow meter 12 and the pressure gauges 11, 15, 17, 19 are sent to the A / D converter 20 via signal lines indicated by broken lines in the figure. The A / D converter 20 converts these output values into digital values and outputs them to the computer 22. A control signal output from the computer 22 and converted into an analog value by the D / A converter 21 is input to the first servo valve 13 and the second servo valve 18 via a signal line indicated by a broken line in the figure. The

The gas flow meter (flow meter) 12 measures the flow rate of the gas supplied from the gas supply source 30 to the first isothermal pressure vessel 14 through the first servo valve 13 via the pressure reducing valve 31. A detection signal relating to the measured gas flow rate is transmitted to the computer 22 via the A / D converter 20.
As the gas flow meter 12, a laminar flow meter, an orifice flow meter, a thermal flow meter, or the like can be used. In particular, the laminar flow meter is preferable because the pressure loss is small.

As the gas supply source (fluid supply source) 30, a compressor, a cylinder filled with compressed gas, or the like can be used.
The pressure reducing valve 31 is for adjusting the pressure of the gas supplied from the gas supply source 30 to a predetermined pressure. The pressure reducing valve 31 is not particularly limited, and a commonly used one can be used. Here, the pressure of the gas supplied from the gas supply source 30 is preferably adjusted by the pressure reducing valve 31 in the range of 200 kPa to 1 MPa. This is because when the pressure is within this range, the sonic flow of gas can be secured, so that pressure control is facilitated, and there is an advantage that it can be supplied by a normal compressor or the like.

  The ejector (vacuum source) 33 is a negative pressure source for exhausting the gas in the second isothermal pressure vessel 16 to make it vacuum, and the pressure is adjusted by the pressure reducing valve 34. The pressure reducing valve 34 is not particularly limited, and a commonly used one can be used. In this embodiment, the ejector 33 is used as the negative pressure source, but a vacuum generator such as another vacuum pump may be used.

The first servo valve 13 receives a control signal transmitted from the computer 22 via the D / A converter 21, adjusts the opening and closing of the valve and the opening degree based on the control signal, and supplies a gas supply source. The flow rate of the gas supplied from 30 and flowing into the first isothermal pressure vessel 14 is adjusted, and the average flow rate of the gas flowing into the first isothermal pressure vessel 14 is managed. Here, the average flow rate indicates an average value of the flow rate when the waveform of the generated unsteady flow rate is time-averaged.
The first servo valve 13 is not particularly limited, and a conventional one can be used. However, since the inflow flow rate is variable according to the target generated flow rate, a pneumatic spool type servo valve that is a flow rate control type is used. Is preferred.

  Note that, when the flow rate is generated in the forward direction from the second servo valve 18 without using the first servo valve 13, it is based on the pressure value measured by the pressure gauge 11 and the flow rate measured by the gas flow meter 12. Thus, the flow rate in the forward direction can be controlled by adjusting the opening of the second servo valve 18. However, when generating a reciprocating flow including a negative flow rate as in the present invention, it is preferable to provide the first servo valve 13 to manage the average flow rate. As a result, the flow rate generated in the positive direction can be stabilized.

The second servo valve 18 receives a control signal transmitted from the computer 22 via the D / A converter 21 and is connected to the input side of the second servo valve 18 based on the control signal. This is a three-way valve that switches the connection between the isothermal pressure vessel 14 and the second isothermal pressure vessel 16 and the output side of the second servo valve 18. Is generated, the flow rate of the gas flowing out from the first isothermal pressure vessel 14 is continuously adjusted. When the flow rate in the negative direction is generated, the flow rate of the gas flowing into the second isothermal pressure vessel 16 is continuously adjusted. It is something to adjust to.
The second servo valve 18 is not particularly limited, and a usual three-way valve can be used, but a pneumatic spool type servo valve can be preferably used.

The first isothermal pressure vessel 14 holds the gas flowing in through the gas flow meter 12 in an isothermal state. The first isothermal pressure vessel 14 is usually made of metal.
As the shape of the first isothermal pressure vessel 14, various shapes such as a cylindrical shape, a polygonal column, a sphere, and an ellipsoid can be adopted. Gas is caused to flow in from either one of the bottom surfaces. At this time, it is preferable that the depth in the gas inflow direction is not more than twice the maximum width of the cross section. For example, in the case of a cylindrical shape, the maximum width of the cross section is preferably such that the height (depth) of the cylinder is not more than twice the diameter of the bottom surface. When the height (depth) of the cylinder is within this range, it is possible to suppress the generation of a pressure gradient when the gas flows in. In the case of a polygonal column shape, the maximum width in the cross section, and in the case of an ellipsoid, the diameter in the cross section at the center in the depth direction.

Since the first isothermal pressure vessel 14 functions as a buffer tank, the internal volume of the first isothermal pressure vessel 14 is 5.0 × 10 5 with respect to the gas outflow amount Q _out (NL / min). ^-6 Q _{out to} 7.0 × 10 ^-5 Q _out (m ³ ) is preferable. This range corresponds to the range in which the mass velocity of the gas instrument is suitable.

  The inside of the first isothermal pressure vessel 14 is filled with a thermally conductive material having a large surface area made of a fine metal wire focusing body or a porous metal body. By filling the inside of the first isothermal pressure vessel 14 with this heat conductive material, the heat transfer area in the inside can be increased. When the gas flows into the first isothermal pressure vessel 14 and the gas flows out from the first isothermal pressure vessel 14 by this heat conductive material, the temperature change of the gas in the first isothermal pressure vessel 14 is changed. It is suppressed. And suppression of the temperature change by this heat conductive material is further effective if the first isothermal pressure vessel 14 is also made high in heat conductivity.

  As the heat conductive material having a large surface area, for example, a converging body of fine metal wires such as steel wool, a porous metal body such as copper wire, or a cotton-like body made of cotton or plastic can be employed. That is, in the case of a fiber-like form such as a bundle of fine metal wires or cotton or plastic cotton, it is preferable that the fiber diameter is in the range of 10 to 50 μm because the heat transfer area can be increased. Moreover, it is preferable that this heat conductive material is 0.05 W / mK or more in thermal conductivity. This heat conductive material is adjusted in its material and the filling amount in the first isothermal pressure vessel 14 so that the temperature change of the compressive fluid held in the first isothermal pressure vessel 14 can be suppressed to about 3K. Is done. In this way, the heat transfer area of the first isothermal pressure vessel 14 can be increased by filling the first isothermal pressure vessel 14 with a heat conductive material such as steel wool.

Moreover, it is preferable that the packing density of a heat conductive material exists in the range of 200-400 kg / m < ³ >. When the filling density is within this range, the temperature change in the first isothermal pressure vessel 14 can be sufficiently suppressed.

The second isothermal pressure vessel 16 is evacuated by the internal gas exhausted by the ejector 33, and flows the external gas through the conduit 24 via the second servo valve 18, thereby generating a negative flow rate. At this time, the gas flowing into the second isothermal pressure vessel 16 through the second servo valve 18 is kept in an isothermal state.
As the second isothermal pressure vessel 16, the same vessel as the first isothermal pressure vessel 14 described above can be used. The gas is discharged from the second isothermal pressure vessel 16 and supplied to the second isothermal pressure vessel 16. When the gas flows in, the temperature change of the gas in the second isothermal pressure vessel 16 is suppressed.

  The pressure gauge 11 measures the pressure of the gas supplied via the pressure reducing valve 31 and transmits a detection signal related to the measurement result (pressure value) to the computer 22 via the A / D converter 20. . The pressure gauge 11 is not particularly limited as long as it can output a gas pressure value as an electric signal. For example, a semiconductor pressure sensor or the like can be used. The measurable range of the pressure gauge 11 is preferably in the range of atmospheric pressure to the set pressure of the pressure reducing valve 31. The measurement accuracy of the pressure gauge 11 is preferably 0.1 kPa or less. This is because if the measurement accuracy is within this range, the measurement accuracy of the flow rate characteristic can be made sufficient.

  The pressure gauge (first pressure gauge) 15 measures the pressure of the gas held in the first isothermal pressure vessel 14 and sends a detection signal related to the measurement result (pressure value) via the A / D converter 20. It is transmitted to the computer 22. The pressure gauge 15 can be the same as the pressure gauge 11.

  The pressure gauge 17 (second pressure gauge) measures the pressure of the gas held in the second isothermal pressure vessel 16 and sends a detection signal related to the measurement result (pressure value) via the A / D converter 20. It is transmitted to the computer 22. The pressure gauge 17 can be the same as the pressure gauge 11.

  The pressure gauge (third pressure gauge) 19 measures the pressure of the gas on the output side of the second servo valve 18 and sends a detection signal related to the measurement result (pressure value) via the A / D converter 20 to the computer 22. To send to. The pressure gauge 19 can be the same as the pressure gauge 11.

  The cross-sectional areas of the conduit 23c, the conduit 23d, the conduit 23e, the conduit 23f, and the conduit 24 are preferably at least four times the effective cross-sectional area of the second servo valve 18. This is because when the cross-sectional areas of the conduit 23c, the conduit 23d, the conduit 23e, the conduit 23f, and the conduit 24 are within this range, the pressure drop caused by the conduit can be almost ignored.

  The A / D converter 20 converts analog signals from the gas flow meter 12, the pressure gauge 11, the pressure gauge 15, the pressure gauge 17, and the pressure gauge 19 into digital signals. The D / A converter 21 converts a digital signal from the computer 22 relating to opening / closing and connection switching of the first servo valve 13 and the second servo valve 18 into an analog signal.

The computer (flow rate control means) 22 includes a detection signal related to the inflow amount of gas measured by the gas flow meter 12, and gas pressures of respective parts measured by the pressure gauge 11, the pressure gauge 15, the pressure gauge 17, and the pressure gauge 19. And a detection signal regarding the amount of inflow of gas from the first servo valve 13 to the first isothermal pressure vessel 14 and the first signal based on the detection signals. 2 Control signals for controlling the outflow amounts of the positive and negative gases output from the servo valve 18 to the outside are respectively sent to the first servo valve 13 and the second servo valve 18 via the D / A converter 21. To be sent. In the computer 22, the gas inflow amount Q _in measured by the gas flow meter 12 and the gas pressures P ₁₁ and P _{15 of} each part measured by the pressure gauge 11, the pressure gauge 15, the pressure gauge 17 and the pressure gauge 19. , P ₁₇ , and P ₁₉ are appropriately used to perform an operation for controlling the opening / closing or opening of the first servo valve 13 and the opening / closing or opening of the second servo valve 18.

For example, when generating a flow rate in the positive direction, the computer 22 detects a detection signal relating to the amount of gas flowing into the first isothermal pressure vessel 14 input from the gas flow meter 12 via the A / D converter 20. Based on the detection signal relating to the pressure P ₁₅ of the gas in the first isothermal pressure vessel 14 input from the pressure gauge 15 via the A / D converter 20, the D / A converter is connected to the second servo valve 18. A control signal is output via 21 to control the second servo valve 18 so that a gas flow with an unsteady flow rate is generated from the second servo valve 18 to the conduit 24. At that time, in the computer 22, the pressure change in the first isothermal pressure vessel 14 is obtained from the pressure P ₁₅ measured by the pressure gauge 15, and the inflow amount of the gas flowing into the first isothermal pressure vessel 14 from this pressure change. And the difference ΔQ between the outflow amounts flowing out of the container. On the other hand, the gas flow meter 12 measures the inflow amount Q _{in of the} gas flowing into the first isothermal pressure vessel 14. The difference ΔQ between the inflow and outflow, and an inflow amount Q _in the gas, the flow rate (outflow) of the gas flow flowing out of the second servo valve 18 to the conduit _{24 Q out (Q in -ΔQ =} Q _out ). At this time, since the gas in the first isothermal pressure vessel 14 is kept in an isothermal state, if the pressure P ₁₅ of the gas in the first isothermal pressure vessel 14 is measured, a coefficient is added to the differential value of the pressure P _15. ΔQ can be obtained by multiplying. Therefore, by performing feedback control of the opening / closing or opening degree of the second servo valve 18 with respect to the first isothermal pressure vessel 14 so that the flow rate Q _{out of the} gas flow flowing out to the conduit 24 becomes a desired value, the reference is performed. A gas flow having a predetermined positive flow rate can be discharged from the second servo valve 18 with sufficient accuracy.

Here, the detection signal relating to the inflow amount Q _in of the gas into the first isothermal pressure vessel 14 and the detection signal relating to the gas pressure P ₁₅ in the first isothermal pressure vessel 14 are measured for 10 to 15 seconds, respectively. The measurement is preferably performed with a sampling time of 10 milliseconds or less, and the measurement result is preferably input to the computer 22. When the sampling time is within this range, the flow rate detection accuracy can be sufficiently increased.

Note that when the gas (working fluid) flows into the first isothermal pressure vessel 14, the pressure gauge 11 and the pressure gauge 15 measure so that the gas flowing through the first servo valve 13 passes in a choked state. The pressures P ₁₁ and P ₁₅ before and after the first servo valve 13 are confirmed, and the pressure reducing valve 31 is adjusted as necessary.

Further, in the negative flow, a vacuum source using the ejector 33 is connected to the downstream side of the second servo valve 18 (left side in FIG. 1) via the second isothermal pressure vessel 16, and the second servo valve 18. Is controlled to control the flow rate of the gas flowing into the second isothermal pressure vessel 16 to generate a negative unsteady flow. At this time, absolute pressures P ₁₉ and P ₁₇ before and after the second servo valve 18 are measured by the pressure gauge 19 and the pressure gauge 17 so that the gas (working fluid) passes through the second servo valve 18 in a choked state. The ejector 33 and the pressure reducing valve 34 are adjusted as necessary, and the second isothermal pressure vessel is adjusted based on the pressure P ₁₉ and the pressure P ₁₇ and the effective sectional area of the second servo valve 18. The flow rate ΔQ flowing into the flow rate 16 is calculated and set as a negative direction flow rate Q _out . Further, the pressure change of the second isothermal pressure vessel 16 is measured by the pressure gauge 17 to calculate the flow rate ΔQ flowing into the second isothermal pressure vessel 16 to compensate the accuracy of the negative flow rate Q _out .

Next, a method for continuously generating a reciprocating flow of a gas having a predetermined flow rate from the second servo valve 18 by the continuous unsteady flow rate generating device 1 shown in FIG. 1 will be described.
In the continuous unsteady flow rate generator 1 of the present embodiment, the flow in the positive direction is controlled by controlling the amount of inflow from the gas supply source 30 by operating the first servo valve 13 to continuously generate the flow rate. Do. On the other hand, by operating the second servo valve 18, the pressure change in the first isothermal pressure vessel 14 is controlled to generate an arbitrary unsteady flow in the positive direction.

  Further, in the negative flow, a vacuum source using the ejector 33 is connected to the downstream side of the second servo valve 18 (left side in FIG. 1) via the second isothermal pressure vessel 16, and the second servo valve 18. Is controlled to control the flow rate of the gas flowing into the second isothermal pressure vessel 16 to generate a negative unsteady flow.

Next, the generation of the forward flow will be described in detail.
In the forward flow, first, the pressure reducing valve 31 is opened, and the gas flow source 12 flows from the gas supply source 30 through the conduit 32 and the conduit 23a. At this time, the pressure reducing valve 31 is operated to set the supply pressure of the gas flowing into the continuous unsteady flow rate generator 1 from the gas supply source 30 through the gas flow meter 12 to a predetermined pressure. The supply pressure is preferably set in the range of 400 to 600 kPa. When the supply pressure is within this range, it becomes a pressure range when using a device such as a normal flow meter, which is desirable for measuring dynamic characteristics and flow characteristics with high accuracy.
Further, the pressure gauge 11 measures the pressure P _{11 of} the gas flowing in through the pressure reducing valve 31. A detection signal related to the gas pressure P ₁₁ measured by the pressure gauge 11 is converted from an analog signal to a digital signal via the A / D converter 20 and input to the computer 22.

  The gas flowing into the gas flow meter 12 flows into the first isothermal pressure vessel 14 through the conduit 23b and the conduit 23c when the first servo valve 13 is opened. At this time, the gas flow meter 12 measures the inflow amount of the gas flowing into the first isothermal pressure vessel 14 through the conduit 23b, the first servo valve 13 and the conduit 23c. A detection signal related to the amount of gas inflow measured by the gas flow meter 12 is converted from an analog signal to a digital signal via the A / D converter 20 and input to the computer 22.

  The first servo valve 13 is operated to open and close the valve according to a control signal output from the computer 22 and converted from a digital signal to an analog signal via the D / A converter 21.

  And the gas which flowed into the 1st isothermal pressure vessel 14 is hold | maintained in an isothermal state. At this time, the thermally conductive material filled in the first isothermal pressure vessel 14 is the first in the flow of gas into the first isothermal pressure vessel 14 and outflow of gas from the first isothermal pressure vessel 14. It has a function of suppressing the temperature change of the gas in the isothermal pressure vessel 14. For example, when the gas is rapidly flowed into the first isothermal pressure vessel 14 before the first servo valve 13 is opened, the pressure in the first isothermal pressure vessel 14 rapidly increases. Temperature rises. However, the thermal energy of the gas is transmitted to the inner wall of the first isothermal pressure vessel 14 through the heat conductive material, and further radiated from the first isothermal pressure vessel 14 to the outside. At this time, since the heat conductive material has good heat conductivity and a high heat transfer rate, the temperature rise of the gas in the first isothermal pressure vessel 14 is suppressed to a low level. As described above, when the gas is introduced, the temperature of the internal gas tends to increase with an increase in pressure, but the heat is radiated from the first isothermal pressure vessel 14 through the heat conductive material. The increase in temperature is small.

  Next, when the second servo valve 18 is opened, the gas held in the first isothermal pressure vessel 14 flows out from the second servo valve 18 to the conduit 24 through the conduit 23d. At this time, since a large amount of gas flows out of the first isothermal pressure vessel 14 instantaneously, the gas in the first isothermal pressure vessel 14 rapidly expands, and the temperature decreases with this expansion. . In this case, heat is quickly supplied from the heat conductive material, and further, the first isothermal pressure vessel 14 absorbs heat from the outside, and heat is supplied to the heat conductive material. A decrease in temperature is suppressed.

Here, the pressure of the gas in the first isothermal pressure vessel 14 is measured by the pressure gauge 15, and the measured pressure value is converted from an analog signal to a digital signal via the A / D converter 20. 22 is input.
The second servo valve 18 is operated from the connection direction (opening / closing) of the three-way valve according to a control signal output from the computer 22 and converted from a digital signal to an analog signal via the D / A converter 21. The opening degree is adjusted.

  When the second servo valve 18 is opened, the gas held in the first isothermal pressure vessel 14 flows out from the second servo valve 18 to the conduit 24 through the conduit 23d, and a positive flow rate is generated. To do.

Next, the negative flow will be described.
The second isothermal pressure vessel 16 is held in a vacuum state by the ejector 33 through the conduit 23e. Further, the vacuum pressure by the ejector 33 is adjusted by a pressure reducing valve 34 connected through a conduit 35.
At this time, the pressure in the second isothermal pressure vessel 16 decreases and the temperature of the internal gas decreases, but the heat in the second isothermal pressure vessel 16 is the same as the first isothermal pressure vessel 14 described above. Heat is quickly supplied through the conductive material, and the gas inside is kept isothermal.

Next, when the second servo valve 18 is operated and the second isothermal pressure vessel 16 is opened to the outside of the second servo valve 18, the outside air (gas) passes through the conduit 24 and passes through the second servo valve 18. Then, it flows into the conduit 23f and further flows into the second isothermal pressure vessel 16.
At this time, the pressure in the second isothermal pressure vessel 16 is rapidly increased by the gas that has flowed in, so that the internal temperature rises. However, the thermal energy of this gas is quickly radiated to the outside of the second isothermal pressure vessel 16 through the heat conducting material, and the gas that flows in is kept in an isothermal state. The gas flowing into the second isothermal pressure vessel 16 is exhausted by the ejector 33 through the conduit 23e.
At this time, since the pressure in the second isothermal pressure vessel 16 decreases again, the internal temperature decreases, but heat is quickly supplied through the heat conducting material, and the internal gas is held in an isothermal state.

Here, the pressure of the gas in the second isothermal pressure vessel 16 and the pressure of the gas flowing out from the second servo valve 18 are measured by the pressure gauge 17 and the pressure gauge 19, respectively. The analog signal is converted into a digital signal via the / D converter 20 and input to the computer 22.
The second servo valve 18 is operated from the connection direction (opening / closing) of the three-way valve according to a control signal output from the computer 22 and converted from a digital signal to an analog signal via the D / A converter 21. The opening degree is adjusted.

  When the second servo valve 18 is opened, gas flows from the outside through the conduit 24 to the conduit 23 f from the second servo valve 18 and then into the second isothermal pressure vessel 16. As a result, a negative flow rate is generated.

In the present embodiment, when generating a reciprocating flow including flow rates in the positive direction and the negative direction, there are two types depending on whether the average flow rate of the flow waveform of the generated reciprocating flow is zero or the average flow rate is not zero. Use different control methods.
Hereinafter, each control method will be described.

(When the average flow rate is zero)
First, referring to FIG. 3 (refer to FIG. 1 as appropriate), the control of the continuous unsteady flow rate generator 1 when the average flow rate of the generated reciprocating flow rate waveform is zero will be described. Here, FIG. 3 is a flowchart showing the flow of processing when the average flow rate is zero in the continuous unsteady flow rate generator according to the embodiment of the present invention.

When the average flow rate of the generated flow rate waveform is zero, the operation of the first servo valve 13 and the second servo valve 18 differs depending on whether a positive flow is generated or a negative flow is generated. .
First, when generating a flow in the positive direction, the first servo valve 13 is opened, gas is flowed from the gas supply source 30 into the first isothermal pressure vessel 14, and a predetermined flow waveform required for the generated flow rate waveform is generated. The first isothermal pressure vessel 14 is pressurized to a pressure (step S11 (first step)).

Next, an operation signal for realizing the flow waveform of the forward flow is output from the computer 22 to the second servo valve 18 via the D / A converter 21 to generate a forward flow (step S12 ( Second step)). In step S11, after raising the first isothermal pressure vessel 14 to a predetermined pressure, the first servo valve 13 is fully closed. That is, the flow in the positive direction is basically only the process of releasing the gas from the first isothermal pressure vessel 14.
This generates a positive flow rate.

  Next, when generating a negative flow, the pressure gauge 17 and the pressure gauge 19 measure the absolute pressure on the downstream side of the second servo valve 18 and the atmospheric pressure on the upstream side (pressure on the outside side), respectively. The computer 22 calculates an appropriate opening degree of the second servo valve 18 based on these measured values (step S13 (third step)). The second servo valve 18 is controlled in accordance with the calculated opening, and a gas is caused to flow into the second isothermal pressure vessel 16 from the conduit 24, thereby generating a negative flow rate (step S14 (fourth process)). . At this time, the ejector 33 and the pressure reducing valve 34 are adjusted so as to maintain an absolute pressure that is in a choked state when the working fluid (gas) passes through the second servo valve 18.

  On the other hand, the first isothermal pressure vessel 14 is depressurized because a positive flow is generated. Therefore, while the negative flow rate is being generated (from step S13 to step S14), the first servo valve 13 is opened in parallel, and the gas supply source 30 supplies the first isothermal pressure vessel 14 to the next time. The generated working fluid is filled and the pressure is increased to a predetermined pressure (step S15 (first step)). Further, after the pressure increase, the first servo valve 13 is fully closed.

  When the average flow rate of the generated flow rate waveform is zero, the flow rate waveform in the positive and negative directions is symmetrical with respect to zero, so the pressure change due to the flow rate discharged in the positive direction and the pressure change in the negative direction Is to increase the pressure of the first isothermal pressure vessel 14 by operating the first servo valve 13 in step S15, targeting a waveform in which the positive and negative signs are opposite pressure changes.

  After the negative flow rate is generated in step S14, the process returns to step S12 again, and the first isothermal pressure vessel 14 and the second servo valve 18 that have been pressurized in step S15 are connected to each other, and the second servo Operate the valve to generate positive flow.

  Thereafter, by repeating Step S12 to Step S15, the reciprocating flow when the average flow rate is zero can be continuously generated with high accuracy.

(When the average flow rate is not zero)
Next, the control of the continuous unsteady flow rate generator 1 when the average flow rate of the flow waveform of the reciprocating flow generated is not zero will be described with reference to FIG. Here, FIG. 4 is a flowchart showing the flow of processing when the average flow rate is not zero in the continuous unsteady flow rate generator according to the embodiment of the present invention.

  The case where the average flow rate of the generated flow rate waveform is not zero will be described separately in the case of generating a positive flow and the case of generating a negative flow.

  First, when generating a flow in the positive direction, an average flow value of only the flow rate waveform component in the positive direction of the generated flow (that is, the portion where the flow rate is zero or more) is calculated (step S21 (fifth step)). The first servo valve 13 is opened at the opening degree of the first servo valve 13 corresponding to the calculated value, and the flow rate of the gas flowing from the gas supply source 30 into the first isothermal pressure vessel 14 is controlled (step S22 ( Sixth step)). Further, at this time, the pressure reducing valve 31 is adjusted so that the pressure at which the working fluid (gas) enters the choke state when passing through the first servo valve 13 is maintained.

  On the other hand, the second servo valve 18 on the downstream side of the first isothermal pressure vessel 14 controls the pressure of the first isothermal pressure vessel 14 corresponding to the generated flow rate, and generates a positive flow rate (step S23 ( 7th process)).

  Next, when generating a negative flow, the pressure gauge 17 and the pressure gauge 19 measure the absolute pressure on the downstream side of the second servo valve 18 and the atmospheric pressure on the upstream side (pressure on the outside side), respectively. The computer 22 calculates an appropriate opening degree of the second servo valve 18 based on these measured values (step S24 (eighth step)). Then, the second servo valve 18 is controlled according to the opening calculated in step S24, and gas is caused to flow from the conduit 24 into the second isothermal pressure vessel 16, thereby generating a negative flow rate (step S25 ( Ninth step)). At this time, the ejector 33 and the pressure reducing valve 34 are adjusted so as to maintain an absolute pressure that is in a choked state when the working fluid (gas) passes through the second servo valve 18.

  Here, the first servo valve 13 needs to maintain the pressure of the first isothermal pressure vessel 14 in order to generate the next forward flow. However, if the flow rate waveform to be generated is a periodic waveform such as a sine wave, for example, the pressure value in the first isothermal pressure vessel 14 is the same as when the previous positive flow was generated. The differential value (time derivative) of the pressure is not necessarily the same, and if this differential value is not the same, a smooth flow rate waveform cannot be obtained. That is, if the differential values are different, it is difficult to accurately generate the flow rate waveform near the flow rate of zero.

  Therefore, while the negative flow rate is being generated (step S24 to step S25), in parallel, the differential of the pressure in the first isothermal pressure vessel 14 at the first time point when the next positive flow is generated. The pressure control of the first isothermal pressure vessel 14 is performed by operating the first servo valve 13 so that the value becomes the same as the differential value of the pressure at the first time point when the previous positive flow is generated. The differential value between the pressure and the pressure is adjusted (step S26 (tenth process)). Further, at this time, the pressure reducing valve 31 is adjusted so that the pressure at which the working fluid (gas) enters the choke state when passing through the first servo valve 13 is maintained.

  After the negative flow rate is generated in step S25, the process returns to step S23 again, and the first isothermal pressure vessel 14 and the second servo valve 18 that have adjusted the pressure value and the differential value of the pressure in step S26. And the second servo valve 18 is operated to generate a positive flow rate.

  Thereafter, by repeating Step S23 to Step S26, the reciprocating flow when the average flow rate is not zero can be continuously generated with high accuracy.

  As described above, the flow rate of the gas reciprocating flow generated in the conduit 24 provided on the output side of the second servo valve 18 is controlled with high accuracy. Therefore, the conduit 24 is connected to a device for performing a dynamic characteristic test or a flow characteristic test of the flow rate, and the unsteady flow rate that is a measurement reference continuously generated from the continuous unsteady flow rate generator 1 and the connected device. By comparing the response results, the devices can be verified. For example, like the flow meter verification device 2 of the embodiment shown in FIG. 2, the gas flowing out and flowing in through the second servo valve 18 of the continuous unsteady flow rate generator 1 is guided to the flow meter 40 to be tested. The flow rate measurement accuracy by the flow meter 40 can be verified. In the flow meter verification device 2, the measurement result of the gas flow rate by the flow meter 40 is converted into a digital value by the A / D converter 20 and input to the computer 22. In the computer 22, the flow rate measurement result by the flow meter 40 is compared with the flow rate (reference value) of the gas reciprocating flow output from the second servo valve 18 to the conduit 24. The measurement accuracy of the flow rate can be verified. Then, the first servo valve 13 is operated, and the opening / closing and opening of the second servo valve 18 are adjusted by the computer 22, and the flow rate (reference value) of the gas reciprocating flow output from the second servo valve 18 is adjusted. The flow meter 40 is continuously measured, and the measurement result of the flow meter 40 is continuously measured with respect to the gas flow whose flow rate is changed. Can do.

  According to the present invention, not only can a dynamic characteristic test for a reciprocating flow of a gas flow meter for which there has been no effective method so far be performed, but also the flow characteristic test of a pneumatic device can be performed.

  As mentioned above, although the case where gas was used as compressive fluid was shown as an embodiment, the present invention is not limited to this embodiment, and is applicable also when using other compressible fluid.

The continuous unsteady flow rate generator 1 having the configuration shown in FIG. 2 was used to control the flow rate of air output from the second servo valve 18 to the conduit 24. The specifications and experimental conditions of each component of the continuous unsteady flow rate generator used are as follows. In addition, each device was connected by a nylon conduit having an inner diameter of 6 mm.
Gas supply source: manufactured by Anest Iwata Co., Ltd., compressor Ejector: manufactured by Myotoku Co., Ltd., ejector (CV Convum)
Pressure reducing valve: manufactured by SMC, precision pressure reducing valve Gas flow meter: manufactured by Tokyo Meter Co., Ltd., laminar flow type flow meter Pressure gauge (11, 15, 17, 19): manufactured by Toyota Koki Co., Ltd., semiconductor pressure sensor First isothermal Pressure vessel, second isothermal pressure vessel:
Internal volume: 0.1L (liter)
Material: Aluminum Shape: Cylindrical Thermally conductive material Material: Copper wire (Tokyo Meter, wire diameter: 50 μm)
Packing density: 300 kg / m ³
1st servo valve: Fest, spool type servo valve 2nd servo valve: Fest, spool type servo valve Computer: Sampling cycle 0.2ms

(When the average flow rate in the flow waveform is zero)
In FIG. 5, a laminar flow meter (QFS) is connected as the flow meter 40 to be tested using the flow meter verification device 2 shown in FIG. The result of having generated and measuring the flow rate with this laminar flow meter is shown.
In FIG. 5, the broken line indicates the target value of the flow waveform applied to the continuous unsteady flow generator 1, the solid line indicates the flow waveform actually generated by the continuous unsteady flow generator 1, and the two-dot chain line indicates the subject to be tested. The measurement result by the flow meter 40 (laminar flow type flow meter (QFS)) is shown.

  As shown in FIG. 2, a flow meter verification device 2 in which a flow meter 40 to be tested is connected to the continuous unsteady flow rate generator 1 is configured. In the flow meter verification device 2, a first servo valve is operated by a computer 22. 13, by controlling the second servo valve 18 and the like, as indicated by a broken line in FIG. 5, the vibration flow having an average flow rate of 0 (NL / min), a flow rate fluctuation amplitude of 10 (NL / min), and a fluctuation frequency of 1 Hz is generated. It was generated as a target value. At this time, the flow rate calculated based on the flow rate and the pressure value measured by the gas flow meter 12, the pressure gauge 15, the pressure gauge 17, and the pressure gauge 19 are shown by a solid line in FIG. 5 and measured by the flow meter 40. The flow rate is shown by a two-dot chain line in FIG.

As a result, as shown in FIG. 5, the actual generated flow rate (solid line), the target value (broken line), and the laminar flow meter to be tested (two-dot chain line) are in good agreement, and the average flow rate is zero. It can be seen that the reciprocating flow can be generated accurately.
Since the measurement accuracy of the gas flow meter 12 is within 2%, it can be seen that this apparatus can guarantee an accurate flow rate with an accuracy of within 5%.

(If the average flow rate in the flow waveform is not zero)
In FIG. 6, a laminar flow meter (QFS) is connected as the flow meter 40 to be tested using the flow meter verification device 2 shown in FIG. The result of having generated and measuring the flow rate with this laminar flow meter is shown.
In FIG. 6, the broken line indicates the target value of the flow waveform applied to the continuous unsteady flow generator 1, the solid line indicates the flow waveform actually generated by the continuous unsteady flow generator 1, and the two-dot chain line indicates the subject to be tested The measurement result by the flow meter 40 (laminar flow type flow meter (QFS)) is shown.

  As shown in FIG. 2, a flow meter verification device 2 in which a flow meter 40 to be tested is connected to the continuous unsteady flow rate generator 1 is configured. In the flow meter verification device 2, a first servo valve is operated by a computer 22. 13, by controlling the second servo valve 18 and the like, as indicated by a broken line in FIG. 6, an oscillation flow having an average flow rate 5 (NL / min), a flow fluctuation amplitude 10 (NL / min), and a fluctuation frequency 1 Hz is generated. Generated as a target value. At this time, the flow rate calculated based on the flow rate and the pressure value measured by the gas flow meter 12, the pressure gauge 15, the pressure gauge 17, and the pressure gauge 19 is shown by a solid line in FIG. 6 and measured by the flow meter 40. The flow rate is shown by a two-dot chain line in FIG.

As a result, as shown in FIG. 6, the actual generated flow rate (solid line), the target value (broken line), and the laminar flow meter to be tested (two-dot chain line) are in good agreement, and the average flow rate is not zero. It can be seen that the reciprocating flow can be generated accurately.
Since the measurement accuracy of the gas flow meter 12 is within 2%, it can be seen that this apparatus can guarantee an accurate flow rate with an accuracy of within 5%.

It is a conceptual diagram which shows the structure of the continuous unsteady flow volume generator which concerns on embodiment of this invention. It is a conceptual diagram which shows the structure of the flowmeter verification apparatus which concerns on embodiment of this invention. It is a flowchart which shows the flow of a process in case the average flow volume is zero of the continuous unsteady flow volume generator which concerns on embodiment of this invention. It is a flowchart which shows the flow of a process in case the average flow volume is not zero of the continuous unsteady flow volume generator which concerns on embodiment of this invention. It is a graph which shows the generation | occurrence | production result of the reciprocating flow in case the average flow volume is zero by the continuous unsteady flow volume generator of this invention. It is a graph which shows the generation | occurrence | production result of the reciprocating flow in case the average flow volume is not zero by the continuous unsteady flow volume generator of this invention.

Explanation of symbols

1 Continuous unsteady flow generator 2 Flow meter verification device 11 Pressure gauge 12 Gas flow meter (flow meter)
13 First servo valve 14 First isothermal pressure vessel 15 Pressure gauge (first pressure gauge)
16 Second isothermal pressure vessel 17 Pressure gauge (second pressure gauge)
18 Second servo valve 19 Pressure gauge (3rd pressure gauge)
20 A / D converter 21 D / A converter 22 Computer (flow rate control means)
30 Gas supply source (fluid supply source)
31 Pressure reducing valve 33 Ejector (vacuum source)
34 Pressure reducing valve 40 Flow meter to be tested

Claims (5)

A flow meter for measuring the inflow of a compressible fluid supplied from a fluid supply source;
A first servo valve that regulates an inflow amount of the compressible fluid flowing through the flow meter;
A first isothermal pressure vessel for maintaining the compressible fluid flowing through the first servo valve in an isothermal state;
A first pressure gauge for measuring the pressure of the compressible fluid in the first isothermal pressure vessel;
A second isothermal pressure vessel maintained in a vacuum state by a vacuum source;
A second pressure gauge for measuring the pressure of the compressible fluid in the second isothermal pressure vessel;
A second servo valve that selectively regulates either the outflow of the compressive fluid from the first isothermal pressure vessel or the inflow of the compressive fluid into the second isothermal pressure vessel;
A third pressure gauge for measuring the pressure of the compressible fluid outside the second servo valve;
Based on the inflow of the compressible fluid measured by the flow meter and the pressure of the compressible fluid in the first isothermal pressure vessel measured by the first pressure gauge, While controlling the outflow amount of the compressive fluid, the inflow amount of the compressive fluid from the second servo valve is controlled based on the pressure of the compressive fluid measured by the second pressure gauge and the third pressure gauge. And a flow rate control means for controlling the continuous unsteady flow rate generator for compressible fluid.   The said 1st isothermal pressure vessel and the said 2nd isothermal pressure vessel are filled with the heat conductive material which consists of a focusing body of a metal fine wire, or a porous metal body inside. A continuous unsteady flow rate generator for compressible fluids. A method for generating a continuous unsteady flow rate of a compressible fluid using the continuous unsteady flow rate generation device for a compressible fluid according to claim 1 or 2,
A first step of opening the first servo valve, supplying the compressive fluid from the fluid supply source, and increasing the pressure of the first isothermal pressure vessel to a predetermined pressure;
A second step of controlling an opening amount of the second servo valve to continuously control an outflow amount of the compressive fluid flowing out of the first isothermal pressure vessel;
A third step of calculating an opening degree of the second servo valve based on an outer pressure of the second servo valve and a pressure of the second isothermal pressure vessel;
Opening the second servo valve at the calculated opening, and flowing a compressive fluid into the second isothermal pressure vessel,
Continuously unsteady flow generation of a compressible fluid, wherein the first step is performed in parallel with the third step or the fourth step when the first step to the fourth step are sequentially repeated. Method. A method for generating a continuous unsteady flow rate of a compressible fluid using the continuous unsteady flow rate generation device for a compressible fluid according to claim 1 or 2,
A fifth step of calculating an opening degree of the first servo valve corresponding to an average flow rate of a flow waveform component in a direction in which the compressive fluid flows out from the second servo valve;
A sixth step of opening the first servo valve at the calculated opening and supplying the compressive fluid from the fluid supply source to the first isothermal pressure vessel;
Based on the pressure of the compressible fluid in the first isothermal pressure vessel, the opening of the second servo valve is controlled to continuously control the flow rate flowing out of the first isothermal pressure vessel. Process,
An eighth step of calculating the opening of the second servo valve based on the pressure outside the second servo valve and the pressure in the second isothermal pressure vessel;
A ninth step of opening the second servo valve at the opening calculated in the eighth step and flowing a compressive fluid into the second isothermal pressure vessel;
Based on the pressure of the first isothermal pressure vessel and its differential value, the opening and closing of the first servo valve is controlled, and the compressive fluid is supplied from the fluid supply source to the first isothermal pressure vessel. Including a process,
The tenth step is performed in parallel with the eighth step or the ninth step, and the seventh step to the tenth step are sequentially repeated.   The compressive fluid flowing out through the second servo valve of the continuous unsteady flow rate generator for compressive fluid according to claim 1 or 2 is introduced into the flow meter to be tested, and the flow meter A flowmeter verification device for compressible fluid characterized by verifying the measurement accuracy of the flow rate.

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