JP5124038B2 - Pressure regulator and vibration isolator - Google Patents

Description

  The present invention relates to a pressure regulator that maintains a constant pressure and an air spring vibration isolator using the pressure regulator.

  The gas pressure control is indispensable in the control of inert gas in the semiconductor manufacturing process, the air spring type vibration isolation table that is the foundation of the exposure apparatus for semiconductor manufacturing, and the analyzers of various gases. Precise pressure control is required in many fields including such devices used for semiconductor manufacturing.

  Pressure regulators that maintain a constant pressure are sold at low cost using a mechanical feedback mechanism.For example, a pilot-type precision regulator with a mechanical feedback function is often used. Since it was affected by flow, there was a big problem in precise measurement and control. In order to avoid this, a method has been adopted in which a container having a large volume is provided as a buffer to reduce the influence of fluctuations in the flow rate used. However, when a container having a large volume is installed, there is a problem that a large space is occupied for the installation.

In view of this, the inventors of the present application disclosed in Patent Document 1 (paragraphs 0016 to 0021, FIG. 1 and FIG. 2) , by regulating the amount of air flowing into the pressure vessel with a pneumatic servo valve, the pressure in the pressure vessel was reduced. In a pressure control device that performs constant control, a flow meter is arranged at the gas outlet of the pneumatic servo valve to measure the inflow flow rate of air flowing into the pressure vessel, and a pressure gauge is arranged in the pressure vessel, We proposed a pressure control device with a cascade control mechanism that consists of a main loop that measures the pressure of air and feedback controls the pressure measured by the pressure gauge, and a minor loop that feedback controls the inflow rate measured by the flow meter. As a result, the pressure of the air flowing out through the pneumatic servo valve can be controlled at high speed.

Further, the inventors of the present application have proposed a vibration isolator using an air spring using a flow control type servo valve as a support leg in Patent Document 2 (paragraphs 0024 to 0044, FIG. 10) .

JP 2004-310478 A JP 2006-144859 A

The pressure control device proposed in Patent Document 1 realizes high-speed pressure control by feedback control of the inflow flow rate of air flowing into the pressure vessel. Furthermore, even when flow rate fluctuations occur downstream, In order to perform pressure control, it was necessary to detect and control the outflow rate of air flowing out from the pressure vessel.
For this purpose, for example, a method of measuring the outflow flow rate flowing out of the pressure vessel by arranging a flow meter on the downstream side of the pressure vessel can be considered, but pressure loss occurs due to the arranged downstream flow meter. It was difficult to precisely control the pressure.

  In order to further improve the response and accuracy of the vibration isolator proposed in Patent Document 2, not only the pressure control of the air spring but also the pressure of the air supply source supplied to the air spring is high speed and high accuracy. There was a need to control.

In view of these problems, an object of the present invention is to provide a pressure regulator capable of performing pressure control with high response and high accuracy even when a flow rate fluctuation occurs on the downstream side.
Another object of the present invention is to provide an air spring type vibration isolator capable of high-speed response and highly accurate position setting.

The present invention was devised to achieve the above object, and the pressure regulator according to claim 1 is a servo valve that regulates an inflow flow rate of a compressive fluid supplied from a compressible fluid supply source; An isothermal pressure vessel that holds the compressible fluid flowing in through the servo valve in an isothermal state, a pressure detection means that detects the pressure of the compressible fluid in the isothermal pressure vessel, and an isothermal pressure vessel Pressure differential value detecting means for detecting a pressure differential value of the compressive fluid, and pressure control means for operating the servo valve to control the compressible fluid in the isothermal pressure vessel to a predetermined constant pressure, and the pressure control means includes a pressure control system for feedback-controlling the pressure detected by said pressure detecting means, the isothermal inflow rate control system of the inflow rate control Gosuru the compressive fluid flowing into the pressure vessel, the pressure differential value A pressure differential value detected by the detecting means, flows out rate being the difference between the outflow rate of the compressive fluid flowing inlet flow of the compressible fluid flowing into the isothermal pressure vessel from the isothermal pressure vessel the anda inflow out flow rate difference estimating means for estimating, as well as configuration inside the control loop of the pressure control system, the inflow of the estimated inflow out flow rate difference by the influx out flow rate difference estimating means A model following control system that feeds back to the flow control system is configured.

According to such a configuration, the pressure regulator uses the isothermal pressure vessel as a buffer, so that the inflow process and the outflow process of the compressible fluid typified by a gas such as air to the isothermal pressure vessel can be performed at an equal volume and isotherm. Since it can be regarded as a change, pressure control can be easily performed.
In order to control the compressive fluid in the isothermal pressure vessel to a predetermined pressure, the flow rate of the compressive fluid supplied from the compressive fluid supply source to the isothermal pressure vessel is regulated by a servo valve. At this time, the pressure regulator operates the servo valve to regulate the inflow flow rate by pressure control means having a pressure control system for feedback control of the pressure of the compressible fluid in the isothermal pressure vessel as the main loop, and the isothermal pressure The compressible fluid in the container is controlled to a predetermined pressure.

Here, the pressure control means, the inlet flow control system is a minor loop that is configured on the inside of the pressure control system, in order to feedback control the flow out rate difference of the compressible fluid in the isothermal pressure vessel, inflow out flow the difference estimating means, on the basis of the pressure differential value of the compressive fluid in the isothermal pressure vessel, to estimate the inflow out flow differential of the compressible fluid in the isothermal pressure vessel, inlet flow the estimated inflow out flow rate difference Compensation is provided by a model following control system that feeds back to the control system.

A pressure regulator according to a second aspect is the pressure regulator according to the first aspect , wherein the servo valve is a spool type servo valve.

  According to such a configuration, the pressure regulator controls the inflow flow rate using the spool type servo valve that is a flow rate control type servo valve, and therefore, for example, compared with the case where the pressure control type nozzle flapper type servo valve is used, exhaust pressure is controlled. The amount can be reduced.

The pressure regulator according to claim 3 is the pressure regulator according to claim 1 or 2 , wherein the pressure differential value detecting means includes a pressure chamber, a diaphragm type differential pressure gauge or an anemometer, and the isothermal pressure vessel. And a pressure differential meter provided with a cylindrical slit channel communicating with the pressure chamber.

  According to such a configuration, since the pressure differential meter using the cylindrical slit channel is used, the channel cross-sectional area can be increased and the time constant can be decreased. For this reason, it can be set as the pressure differential meter which responds at high speed.

ここで、Ｒはガス定数［Ｊ／（ｋｇ・Ｋ）］、Ｖは等温化圧力容器の容積［ｍ^３］、θは等温化圧力容器内の空気の温度［Ｋ］、Ｐは等温化圧力容器内の圧力［Ｐａ］、ｔは時間［ｓ］である。 The pressure regulator of claim 4, in the pressure regulator according to any one of claims 1 to 3, wherein the influx out flow difference estimation means is detected by previous SL pressure differential value detection means Based on the pressure differential value (dP / dt ) of the compressible fluid in the isothermal pressure vessel, the inflow / outflow flow rate difference (Gin−Gout) is calculated by the following equation (7) .

Here, R is the gas constant [J / (kg · K)], V is the volume of the isothermal pressure vessel [m ³ ], θ is the temperature of the air in the isothermal pressure vessel [K], and P is the isothermal pressure. Pressure [Pa] in the container, t is time [s].

According to this configuration, by forming the model following control system for feedback inflow out flow difference (Gin-Gout) to the summing junction of the inflow rate control system, corresponding to a slight change in the outflow rate in the downstream Thus, pressure control is performed, and a highly responsive pressure regulator resistant to disturbance can be configured.

The vibration isolator according to claim 5 is supplied from a surface plate, an air spring that supports the surface plate, a servo valve that regulates an inflow flow rate and an outflow flow rate of air to the air spring, and an air supply source. The pressure regulator according to any one of claims 1 to 4 , wherein air is controlled to a predetermined pressure and supplied to the servo valve, position detecting means for detecting the position of the surface plate, and the surface plate Based on the acceleration detecting means for detecting the acceleration of the motor, the position detected by the position detecting means and the acceleration detected by the acceleration detecting means, the servo valve is operated to control the surface plate to a predetermined position. And an air spring control means.

  According to such a configuration, the vibration isolator supplies air controlled to a predetermined pressure by the pressure regulator to the servo valve, and the position of the surface plate detected by the position detector and the acceleration detector by the air spring controller. Based on the detected acceleration of the surface plate, the surface plate is controlled to a predetermined position by operating the servo valve to regulate the inflow rate and the outflow rate with respect to the air spring.

A vibration isolator according to claim 6 is the vibration isolator according to claim 5 , wherein the servo valve is a spool type servo valve.

  According to this configuration, since the spool type servo valve that is a flow rate control type is used as the servo valve that supplies and exhausts air to the air spring, the amount of exhaust can be reduced. Furthermore, the displacement of the servo valve used in the pressure regulator can be further reduced by using a spool type servo valve.

According to the first aspect of the present invention, since pressure control is performed in response to a slight change in the downstream outflow rate, the pressure regulator is resistant to disturbance and has high response. Also, to estimate based on the inflow out flow rate difference to the pressure differential value, in comparison with the case of measuring the flow rate directly, it is possible to perform the pressure control with high accuracy.
According to the second aspect of the present invention, the amount of exhaust can be reduced, so that the environmental load can be reduced.
According to the invention described in claim 3 , since the pressure differential meter that responds at high speed is used, the responsiveness of the pressure regulator can be further improved.
According to the invention described in 請 Motomeko 4 can be correspondingly pressure control to a slight change in the outflow rate in the downstream performed, it constitutes a pressure regulator of a strong high response to a disturbance.
According to the fifth aspect of the present invention, since the pressure of the air supply source supplied to the air spring by the pressure regulator is maintained with high response and high accuracy, the vibration isolator can quickly position the surface plate. In addition, it can be set with high accuracy.
According to the invention described in claim 6 , it is possible to reduce the environmental load due to the use of the vibration isolator.

It is a block diagram which shows typically the structure of the pressure regulator of 1st Embodiment. It is sectional drawing which shows typically the structure of the pressure differential meter of 1st Embodiment. It is a block diagram which shows the control system of the pressure regulator of 1st Embodiment. It is a block diagram which shows typically the structure of the pressure regulator of 2nd Embodiment. It is a block diagram which shows the control system of the pressure regulator of 2nd Embodiment. It is a block diagram which shows the structure of the experimental apparatus of Experiment 1 typically. 6 is a graph showing changes in supply pressure in Experiment 1. 6 is a graph showing an experimental result of Experiment 1. It is a block diagram which shows typically the structure of the experimental apparatus of Experiment 2. FIG. It is a graph which shows the measured value and estimated value of the outflow flow rate in Experiment 2. 10 is a graph showing an experimental result of Experiment 2. 10 is a graph showing an experimental result of Experiment 3. It is a graph which shows the pressure differential value calculated | required by carrying out discrete differentiation of the pressure differential value measured with the pressure differential meter, and the pressure value measured with the pressure gauge. 1 is a configuration diagram schematically showing the configuration of an air spring type vibration isolator using a pressure regulator of the present invention.

Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
(First embodiment)
<Configuration of pressure regulator>
FIG. 1 is a configuration diagram schematically showing the configuration of the pressure regulator according to the first embodiment of the present invention.
A pressure regulator 1 shown in FIG. 1 includes a servo valve 11, a flow meter 12, an isothermal pressure vessel 13, a pressure gauge 14, a pressure differential meter 15, a computer 16, and an A / D (analog / digital). A converter 17 and a D / A (digital / analog) converter 18 are provided. Each pressure device is connected by conduits 19a, 19b, 19c, 19d.

The pressure regulator 1 according to the first embodiment of the present invention regulates the flow rate of the gas supplied from the gas supply source 10 to the isothermal pressure vessel 13 by the servo valve 11, thereby allowing the flow of the isothermal pressure vessel 13 to flow. The gas output from the outlet 13b through the conduit 19d is held at a predetermined constant pressure.
In the first embodiment of the present invention, air will be described as an example of the compressible fluid, but the present invention is applied to compressible fluids other than air, for example, gases such as nitrogen, hydrogen, carbon dioxide, and the like. be able to.

The main symbols used in the description of the first embodiment of the present invention are as follows.
fc: Cut-off frequency [Hz]
Gin: Inflow flow rate [kg / s]
Gout: Outflow flow rate [kg / s]
Kgi: integral gain [Pa · s / kg]
Kp: proportional gain of pressure control loop [kg / (Pa · s)]
Kv: Voltage of spool type servo valve-flow rate gain [kg / (Pa · s)]
L: Length of cylindrical slit channel [m]
P: pressure in isothermal pressure vessel [Pa]
Pc: Pressure in the container of the pressure differential meter [Pa]
Pj: differential pressure [Pa] applied to the differential pressure gauge of the pressure differential meter
Pref: Target set pressure [Pa]
Ps: Supply pressure [Pa] of air supplied from a gas supply source
R: Gas constant [J / (kg · K)]
r1: outer diameter (radius) of slit channel [m]
r2: inner diameter (radius) [m] of the slit channel
T: Time constant [s]
V: Volume of isothermal pressure vessel [m ³ ]
Vd: Volume of pressure differential container [m ³ ]
θ: temperature of the air in the isothermal pressure vessel [K]
μ: Air viscosity [Pa · s]
ρa: density of air [kg / m ³ ]

(Gas supply source)
The gas supply source (compressible fluid supply source) 10 is a supply source that supplies air that is a compressive fluid, and a cylinder filled with high-pressure air can be used. Moreover, you may make it supply compressed air using pumps, such as a compressor.

(Servo valve)
The servo valve 11 regulates the flow rate of air supplied from the gas supply source 10 through the conduit 19a to the isothermal pressure vessel 13, and the flow rate of air flowing back from the isothermal pressure vessel 13 (negative inflow). This is a flow control servo valve that regulates the flow rate). Preferably, a spool type servo valve with low pressure loss can be used.

  The servo valve 11 according to the first embodiment of the present invention is a spool type three-way valve provided with an intake port 11a, an exhaust port 11b, and a control port 11c, and is connected from the computer 16 via a D / A converter 18. By controlling the connection and opening degree of the control port 11c and the intake port 11a or the exhaust port 11b by the output control signal (control voltage Ei1), the inflow flow rate and its direction are regulated.

The intake port 11a is connected to the gas supply source 10 via a conduit 19a, and the exhaust port 11b is open to the atmosphere. The control port 11c is connected to the flow meter 12 via a conduit 19b.
In addition, for example, when using a gas that is toxic, flammable, odor, etc. and is not preferable to be exhausted into the atmosphere, the exhaust port 11b is not opened to the atmosphere but is exhausted by appropriately connecting a conduit. The gas may be collected and disposed of so as not to affect the human body or the like.

(Flowmeter)
The flow meter (inflow rate acquisition means) 12 measures the inflow rate of air supplied from the gas supply source 10 to the isothermal pressure vessel 13 through the servo valve 11. A detection signal related to the measured air inflow rate is transmitted to the computer 16 via the A / D converter 17.
In addition, when the air in the isothermal pressure vessel 13 flows out from the exhaust port 11b of the servo valve 11, it is measured as a negative inflow rate. Hereinafter, the “inflow rate” to the isothermal pressure vessel 13 will be described as including the negative inflow rate.

As the 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. Further, a differential pressure gauge that measures the differential pressure across the servo valve 11 of the compressible fluid flowing into the isothermal pressure vessel 13 via the servo valve 11 may be used as the flow meter.
As the laminar flow meter, for example, the laminar flow meter proposed by the inventors of the present application in Reference Document 1 can be used.
(Reference 1)
Tatsuya Kashiwagi, Kengo Kawashima, Toshiharu Kagawa, “Characteristic analysis of laminar flow meter for gas with high-speed response”, Transactions of the Society of Instrument and Control Engineers, Vol.40, No.10, pp.1008-1013 (2004)

(Isothermal pressure vessel)
The isothermal pressure vessel 13 holds the gas flowing from the inlet 13a through the conduit 19c in an isothermal state. The isothermal pressure vessel 13 is usually made of metal.
As the shape of the isothermal pressure vessel 13, various shapes such as a cylindrical shape, a polygonal column, a sphere, and an ellipsoid can be adopted. For example, in the case of a cylindrical shape, air is caused to flow in from an inflow port 13a provided on one bottom surface side, and air is flowed out from an outflow port 13b provided on the other bottom surface. At this time, it is preferable that the depth in the air inflow direction (the height of the cylinder) is not more than twice the maximum width of the cross section (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 air 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 isothermal pressure vessel 13 functions as a buffer tank, the internal volume V of the isothermal pressure vessel 13 is 5.0 × 10 ⁻⁶ Qout with respect to the volume outflow flow rate Qout [NL / min] of air. Although it is preferably in the range of ˜7.0 × 10 ⁻⁵ Qout [m ³ ], it can be appropriately determined according to the response specification of the pressure regulator 1.

  The inside of the isothermal pressure vessel 13 is filled with a heat 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 isothermal pressure vessel 13 with this heat conductive material, the heat transfer area in the inside can be increased. The heat conductive material suppresses the temperature change of the air in the isothermal pressure vessel 13 when the gas flows into the isothermal pressure vessel 13 and when the air flows out of the isothermal pressure vessel 13. And suppression of the temperature change by this heat conductive material is further effective if the isothermal pressure vessel 13 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, the one having a fiber diameter in the range of 10 to 50 [μm] can increase the heat transfer area. preferable. Moreover, it is preferable that this heat conductive material is 0.05 [W / mK] or more in thermal conductivity. The material of the heat conductive material and the filling amount of the isothermal pressure vessel 13 are adjusted so that the temperature change of the air held in the isothermal pressure vessel 13 can be suppressed to about 3 [K]. Thus, the heat transfer area of the isothermal pressure vessel 13 can be increased by filling the isothermal pressure vessel 13 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 of the air in the isothermal pressure vessel 13 can be sufficiently suppressed.

(Pressure gauge)
The pressure gauge (pressure detection means) 14 measures the pressure P of the air in the isothermal pressure vessel 13 and transmits a detection signal related to the measurement result (pressure value) to the computer 16 via the A / D converter 17. To do. The pressure gauge 14 is not particularly limited as long as it can output the pressure value of air as an electric signal. For example, a semiconductor pressure sensor or the like can be used. The measurable range of the pressure gauge 14 preferably covers the range from the atmospheric pressure to the supply pressure Ps of air supplied from the gas supply source 10.

(Pressure differential meter)
The pressure differential meter (pressure differential value detection means) 15 measures the differential value dP / dt of the air pressure P in the isothermal pressure vessel 13 and outputs a detection signal related to the measurement result (pressure differential value) as A / D. The data is transmitted to the computer 16 via the converter 17.

As the pressure differential meter 15, for example, the pressure differential meter proposed in Reference Document 2 by the present inventors can be used.
(Reference 2)
JP 2005-98991 A

In the first embodiment of the present invention, a pressure differential meter having a higher response is used than the pressure differential meter using the flat plate slit type channel proposed in Reference Document 2 described above.
Hereinafter, with reference to FIG. 2, the structure of the pressure differential meter 15 in 1st Embodiment of this invention is demonstrated.
FIG. 2 is a cross-sectional view schematically showing the configuration of the pressure differential meter according to the first embodiment of the present invention.

  The pressure differential meter 15 shown in FIG. 2 includes an isothermal pressure vessel 151, a slit channel 152, and a differential pressure meter 153.

  In FIG. 2, the pressure differential meter 15 has a cylindrical outer shape having a bottom surface with a radius r1 at the left and right ends, and an opening 154 is formed on the bottom surface on the left end side. This opening 154 is connected to the isothermal pressure vessel 13.

  A cylindrical isothermal pressure vessel 151 having a bottom surface with a radius r2 is provided on the right side of the opening 154, and a cylindrical slit channel 152 is formed by a side surface of the pressure differential meter 15 and a side surface of the isothermal pressure vessel 151. Is configured. The air pressure in the opening 152a at the left end of the slit channel 152 becomes the air pressure P in the isothermal pressure vessel 13 to be measured. Further, the right end opening 152b separated from the opening 152a by the flow path length L communicates with the inside of the isothermal pressure vessel 151, and the air pressure in the opening 152b is the air in the isothermal pressure vessel 151. Pressure Pc. In addition, a differential pressure gauge 153 for measuring an air pressure difference Pj between the opening 152a and the opening 152b of the slit channel 152 is provided on the side surface of the pressure differential meter 15.

As in the isothermal pressure vessel 13 of the pressure regulator 1 shown in FIG. 1, the isothermal pressure vessel (pressure chamber) 151 is filled with a thermally conductive material such as a copper wire, When air flows in or out, the amount of heat is quickly absorbed or supplied, and the temperature of the air in the isothermal pressure vessel 151 is kept constant. The volume of the isothermal pressure vessel 151 is preferably in the range of 1.0 × 10 ^{−8 to} 1.0 × 10 ⁻⁴ [m ³ ]. When the volume is 1.0 × 10 ⁻⁸ [m ³ ] or more, there is an advantage that the isothermal pressure vessel 151 can be easily configured. Further, when the volume is 1.0 × 10 ⁻⁴ [m ³ ] or less, high response measurement is possible.
The heat conductive material can be used by filling the same material as that of the isothermal pressure vessel 13 at the same volume ratio.

  The slit channel 152 is a cylindrical channel surrounded by the side surface of the pressure differential meter 15 and the side surface of the isothermal pressure vessel 151. It is preferable that the air flowing in the slit channel 152 at the time of measurement is a laminar flow. Accordingly, a proportional relationship is established between the pressure and the flow rate, and the pressure differential value can be measured with high accuracy.

The differential pressure gauge 153 is a diaphragm type differential pressure gauge having a diaphragm 153a, and a signal corresponding to the pressure difference Pj applied to both surfaces of the diaphragm 153a is output.
In addition, for example, other types of differential pressure gauges such as a differential pressure gauge using a bellows may be used.

Here, the operation principle of the pressure differential meter 15 will be described.
When the measurement pressure P changes, the air flows through the slit channel 152 to the isothermal pressure vessel 151, and the pressure Pc in the isothermal pressure vessel 151 changes with a slight delay. When the differential pressure Pj (= P−Pc) generated at this time is measured, the pressure differential value dP / dt and the differential pressure Pj are expressed by a first-order lag relationship as shown in Equation (1) (Reference 3).
(Reference 3)
Kengo Kawashima, Toshinori Fujita, Toshiharu Kagawa, “Measurement of flow rate of compressible fluid by pressure change in container”, Transactions of the Society of Instrument and Control Engineers, Vol.32, No.11, pp.1485-1492 (1996)

  Here, the time constant T is expressed by Expression (2).

In addition, r1 and r2 represent the outer diameter (radius) and inner diameter (radius) of the cylindrical slit flow path 152, respectively.
From the above, the cut-off frequency fc is as shown in Expression (3).

  Since the pressure differential meter 15 of the first embodiment of the present invention uses a cylindrical slit flow channel, the cross-sectional area of the flow channel is compared with the pressure differential meter using the flat plate slit flow channel proposed in Reference 2. Can be increased. For this reason, the time constant T can be made small and it can be set as a highly responsive pressure differential meter.

Returning to FIG. 1, the description of the configuration of the pressure regulator 1 will be continued.
(conduit)
The conduit 19a, the conduit 19b, the conduit 19c and the conduit 19d are respectively connected to the gas supply source 10 and the intake port 11a of the servo valve 11, the control port 11c and the flow meter 12, the flow meter 12 and the isothermal pressure vessel 13 of the servo valve 11. The inlet 13a, the outlet 13b of the isothermal pressure vessel 13, and an external device such as a vibration isolator are connected.

  The cross-sectional areas of the conduits 19a, 19b, 19c, and 19d are preferably four times or more the effective cross-sectional area of the servo valve 11. This is because when the cross-sectional areas of the conduits 19a, 19b, 19c, and 19d are within this range, the pressure drop caused by the conduits can be almost ignored.

(A / D converter, D / A converter)
The A / D converter 17 converts an analog signal detected by the flow meter 12, the pressure gauge 14 and the pressure differential meter 15 into a digital signal and outputs the digital signal to the computer 16. The D / A converter 18 converts a digital signal from the computer 16 regarding the opening / closing or opening of the servo valve 11 into an analog signal and outputs the analog signal to the servo valve 11.

(Computer)
The computer (pressure control means) 16 includes a detection signal related to the inflow flow rate Gin of air measured by the flow meter 12, a detection signal related to the pressure P of air in the isothermal pressure vessel 13 measured by the pressure gauge 14, and a pressure The detection signal related to the differential value dP / dt of the pressure in the isothermal pressure vessel 13 measured by the differentiator 15 is received as a digital signal via the A / D converter 17, and based on those detection signals, A control voltage Ei1 for controlling the inflow flow rate Gin of air flowing into the isothermal pressure vessel 13 via the servo valve 11 (including the case of “negative inflow flow rate” for flowing out air from the exhaust port 11b of the servo valve 11). The signal is transmitted to the servo valve 11 via the D / A converter 18.

  In this computer 16, the air inflow flow rate Gin measured by the flow meter 12, the air pressure P in the isothermal pressure vessel 13 measured by the pressure gauge 14, and the isothermal pressure measured by the pressure differential meter 15. An operation for controlling the opening / closing or opening of the servo valve 11 is performed using the pressure differential value dP / dt of the air in the container 13 as appropriate.

<Pressure control method>
Next, referring to FIG. 3 (refer to FIG. 1 as appropriate), the pressure control by the pressure regulator 1 according to the first embodiment of the present invention will be described. Here, FIG. 3 is a block diagram showing a control system of the pressure regulator according to the first embodiment of the present invention.

As shown in FIG. 3, the control system of the pressure regulator 1 according to the first embodiment of the present invention feeds back the pressure P of the air in the isothermal pressure vessel 13 with respect to the target set pressure Pref and performs PI (proportional operation, (Integral operation) The pressure control system 20 to be controlled is configured as a main loop.
Inside this main loop, an inflow flow rate control system 23 that feedback-controls the inflow flow rate Gin of the air flowing into the isothermal pressure vessel 13 through the servo valve 11 is configured as one minor loop, and is also isothermal with the inflow flow rate Gin. An observer (inflow rate estimating means) 27 for estimating the outflow flow rate Gout flowing out from the isothermal pressure vessel 13 based on the pressure differential value dP / dt of the air in the gasification pressure vessel 13 is configured, and the outflow estimated by the observer 27 A model follow-up control system 28 that feeds back and compensates the flow rate Gout (hat on top) to the inflow flow rate control system 23 is configured as another minor loop.

  In the pressure control system 20, the pressure P that is a control amount is fed back, and a deviation from the target value Pref is calculated at the addition junction 21. Here, the pressure P is measured by the pressure gauge 14.

  The calculated pressure deviation is transmitted to the control element 22, and the control element 22 performs PI control with the proportional gain as Kp. Thereby, a target value of the inflow flow rate of air into the isothermal pressure vessel 13 for eliminating the deviation of the pressure P is calculated, and becomes a target value Gref of the inflow flow rate Gin, which is a control amount of the inflow flow rate control system 23. Note that the control element 22 of the pressure control system 20 may perform PID (proportional operation, integral operation, differential operation) control instead of PI control.

The inflow flow rate control system 23 is a cascade loop configured inside the pressure control system 20 that is a main loop, and performs feedback control of the inflow flow rate Gin.
In the inflow flow rate control system 23, first, the inflow rate Gin measured by the flow meter 12 is fed back, and a deviation from the inflow rate target value Gref, which is the output of the control element 22, is calculated at the addition junction 231. . In addition, an estimated value Gout (outward hat) of the outflow rate output by the observer 27 is added to the addition junction 231, and a deviation of the inflow rate Gin in anticipation of the estimated outflow rate value Gout (upward hat) is obtained. Calculated.

  The deviation of the inflow flow rate Gin calculated at the addition junction 231 is transmitted to the control element 232, multiplied by the integral gain Kgi by the control element 232, and the servo valve that gives the inflow flow rate Gin for eliminating the deviation of the inflow flow rate Gin. 11 control voltages Ei1 are calculated. By transmitting this control voltage Ei1 to the servo valve 11 via the D / A converter 18, the servo valve 11 opens the valve at an opening corresponding to the control voltage Ei1, and flows air into the isothermal pressure vessel 13. Let

When a spool type servo valve is used as the servo valve 11, there is an approximately proportional relationship between the control voltage Ei1 and the inflow flow rate Gin with Kv as a voltage-flow rate gain as shown in the equation (4). is there.
Gin = Kv · Ei1 (4)
Therefore, instead of measuring the inflow flow rate Gin by the flow meter 12, the inflow flow rate Gin can be calculated and obtained by the expression (4) using the control voltage Ei1.

  Thus, by performing feedback control of the inflow flow rate Gin, it is possible to compensate for nonlinearity that deviates from the proportional relationship of the voltage-flow rate characteristics, and to improve the accuracy of pressure control by the pressure control system 20.

By transmitting the control voltage Ei1 to the servo valve 11, air of the inflow flow rate Gin corresponding to the control voltage Ei1 flows into the isothermal pressure vessel 13 from the inflow port 13a, while a conduit 19d to which an external device is connected. The outflow rate Gout flowing out from the outflow port 13b is added as a disturbance. In FIG. 3, this disturbance is represented by the addition junction 24.
In order to perform pressure control with high response and high accuracy, the pressure control system 20 needs to compensate for the outflow flow rate Gout.

  The outflow flow rate Gout can be detected by connecting a flow meter to the downstream side of the outlet 13b of the isothermal pressure vessel 13 and measuring it. However, when the flow meter is connected, the pressure loss due to the flow meter becomes a new disturbance, and thus there is a problem that the pressure control does not necessarily contribute to high response and high accuracy. For example, even when a laminar flow meter with a small pressure loss is used, it is not preferable to install a flow meter on the downstream side because a pressure loss of several hundred Pascals is generated by a laminar resistance tube.

  Therefore, in the present invention, an observer 27 for estimating the outflow flow rate Gout is provided based on the pressure differential value dP / dt measured by the pressure differential meter 15 with less pressure loss than the flow meter and the inflow flow rate Gin. I made it.

Here, the estimation method of the outflow flow rate Gout will be described.
First, the relationship among the inflow flow rate Gin from the servo valve 11 to the isothermal pressure vessel 13, the outflow rate Gout from the isothermal pressure vessel 13, and the pressure P in the isothermal pressure vessel 13 will be described.
The gas equation of state is as shown in equation (5). However, V represents the volume of the isothermal pressure vessel 13 and W represents the mass of air in the isothermal pressure vessel 13.
PV = WRθ (5)

  When equation (5) is fully differentiated, equation (6) is obtained. However, G = dW / dt.

  Here, in consideration of the fact that the air in the isothermal pressure vessel 13 undergoes an isovolume change (dV / dt = 0) and an isothermal change (dθ / dt = 0), the inflow flow rate Gin and the outflow to the isothermal pressure vessel 13 There is a relationship of the formula (7) between the flow rate Gout and the pressure P in the isothermal pressure vessel 13.

  Therefore, based on the inflow flow rate Gin and the pressure differential value dP / dt in the isothermal pressure vessel 13, the estimated value Gout (upper hat) of the outflow flow rate can be calculated by Equation (8).

  Therefore, the observer 27 calculates “Gin−Gout” by multiplying the pressure change (pressure differential value) dP / dt associated with the inflow flow rate Gin and the outflow flow rate Gout by V / (Rθ) by the control element 271, and adds it. By subtracting from the inflow flow rate Gin at the junction point 272, an estimated value Gout (upper hat) of the outflow flow rate can be calculated.

  By constructing the model follow-up control system 28 that feeds back the estimated value Gout of the outflow flow rate (hat on top) to the addition junction 231 of the inflow flow rate control system 23, it is possible to cope with slight changes in the outflow flow rate downstream. Pressure control is performed, and a highly responsive pressure regulator 1 that is resistant to disturbance can be configured.

  The pressure differential value dP / dt can also be obtained by discrete differentiation (numerical differentiation) of the pressure P measured by the pressure gauge 14. However, in the discrete differentiation of the pressure P, it is difficult to obtain a good feedback signal including a large noise component with respect to a slight pressure fluctuation.

  The calculation of the pressure control system 20 of the pressure regulator 1 described above is performed by the computer 16, and the control voltage Ei1 calculated by the computer 16 is transmitted to the servo valve 11 via the D / A converter 18. The air in the isothermal pressure vessel 13 can be controlled to a predetermined constant pressure.

  The calculation of the pressure control system 20 may be performed using a general-purpose computer such as a PC (Personal Computer), or may be performed by configuring a dedicated calculation circuit.

<Operation of pressure regulator>
Next, the operation of the pressure regulator 1 will be described with reference to FIG.

  First, it is assumed that the pressure regulator 1 is activated and the pressure P of air in the isothermal pressure vessel 13 is set to a predetermined target value Pref. At this time, the servo valve 11 is adjusted to an opening that balances the outflow rate Gout flowing out from the outlet 13b of the isothermal pressure vessel 13 and the inflow rate Gin flowing in from the inlet 13a.

  Here, when fluctuation occurs in the pressure Ps of the gas supply source 10 or the outflow flow rate Gout flowing out of the isothermal pressure vessel 13 and the pressure P in the isothermal pressure vessel 13 changes from the target value Pref, the pressure regulator 1 In order to compensate for the pressure fluctuation, the computer 16 calculates the inflow flow rate Gin measured by the flow meter 12, the pressure P measured by the pressure meter 14, and the pressure differential value dP / dt measured by the pressure differential meter 15 by A The control voltage Ei1 for the servo valve 11 is calculated based on the received measurement data received via the / D converter 17, and the calculated control voltage Ei1 is calculated via the D / A converter 18 for the servo valve 11 Send to.

  The servo valve 11 adjusts the valve to an opening corresponding to the control voltage Ei1 calculated by the computer 16, and flows air into the isothermal pressure vessel 13 at an inflow flow rate Gin corresponding to the opening. Thus, control is performed so that the pressure P of the air in the isothermal pressure vessel 13 is set to the target value Pref.

(Second Embodiment)
FIG. 4 is a configuration diagram schematically showing the configuration of the pressure regulator according to the second embodiment of the present invention. In FIG. 4, the same components and parts as those of the pressure regulator 1 shown in FIG.
The pressure regulator 41 shown in FIG. 4 is the same as that of the first embodiment except that the flow meter 12 is not provided in the conduit 19b between the servo valve 11 and the isothermal pressure vessel 13, and the calculation in the computer 46 is different. The pressure regulator 1 has the same configuration. Therefore, hereinafter, servo valve 11, isothermal pressure vessel 13, pressure gauge 14, pressure differential meter 15, A / D (analog / digital) converter 17, D / A (digital / analog) converter 18, and conduit 19a. , 19b, 19d are not described here.

The pressure regulator 41 of the second embodiment of the present invention regulates the flow rate of the isothermal pressure vessel 13 by regulating the flow rate of the gas supplied from the gas supply source 10 into the isothermal pressure vessel 13 by the servo valve 11. The gas output from the outlet 13b through the conduit 19d is held at a predetermined constant pressure.
Also in the second embodiment of the present invention, as in the first embodiment, air will be described as an example of a compressible fluid, but representative examples include gases other than air, such as nitrogen, hydrogen, carbon dioxide, and the like. It can be applied to a compressible fluid.

  The main symbols (fc, Gin, Gout, Kgi, Kp, Kv, L, P, Pc, Pj, Pref, Ps, R, r1, r2, T, V used in the description of the second embodiment of the present invention. , Vd, θ, μ, ρa) are the same as described above.

(Computer)
In the second embodiment of the present invention, the computer (pressure control means) 46 detects the detection signal related to the pressure P of the air in the isothermal pressure vessel 13 measured by the pressure gauge 14 and the isothermal measured by the pressure differential meter 15. The detection signal related to the differential value dP / dt of the pressure in the pressure vessel 13 is received as a digital signal via the A / D converter 17 and is isothermalized via the servo valve 11 based on these detection signals. A control voltage Ei2 for controlling the inflow flow rate Gin of air flowing into the pressure vessel 13 (including the case of “negative inflow flow rate” for flowing out air from the exhaust port 11b of the servo valve 11) is supplied to the D / A converter 18. Via the servo valve 11.

  In the computer 46 according to the second embodiment of the present invention, the air pressure P in the isothermal pressure vessel 13 measured by the pressure gauge 14 and the air pressure in the isothermal pressure vessel 13 measured by the pressure differential meter 15. Using the differential value dP / dt as appropriate, an operation for controlling the opening / closing or opening of the servo valve 11 is performed.

<Pressure control method>
Next, referring to FIG. 5 (refer to FIG. 4 as appropriate), control of pressure by the pressure regulator 41 according to the second embodiment of the present invention will be described. Here, FIG. 5 is a block diagram showing a control system of the pressure regulator of the second embodiment of the present invention.

As shown in FIG. 5, the control system of the pressure regulator 41 according to the second embodiment of the present invention feeds back the pressure P of the air in the isothermal pressure vessel 13 to the target set pressure Pref to provide PI (proportional operation, (Integral operation) The pressure control system 50 to be controlled is configured as a main loop.
Inside this main loop, an observer (outflow flow rate estimating means) for estimating an outflow flow rate Gout (hatted upward) flowing out from the isothermal pressure vessel 13 based on the pressure differential value dP / dt of air in the isothermal pressure vessel 13. ) 57, and the model follow-up control system 58 that compensates the inflow flow rate Gout (hatted above) estimated by the observer 57 by feeding it back to the inflow rate control system 53 is configured as a minor loop.

  In the pressure control system 50, the pressure P that is a control amount is fed back, and a deviation from the target value Pref is calculated at the addition junction 51. Here, the pressure P is measured by the pressure gauge 14.

  The calculated pressure deviation is transmitted to the control element 52, and the control element 52 performs PI control with the proportional gain as Kp. Thereby, the target value of the inflow flow rate of the air in the isothermal pressure vessel 13 for eliminating the deviation of the pressure P is calculated, and becomes the target value Gref of the inflow rate Gin which is the control amount of the outflow rate control system 53. Note that the control element 52 of the pressure control system 50 may perform PID (proportional operation, integral operation, differential operation) control instead of PI control.

The inflow flow rate control system 53 is a cascade loop configured inside the pressure control system 20 that is the main loop, and performs feedback control of the inflow flow rate Gin.
In the inflow flow rate control system 53, a deviation from the target value Gref of the inflow rate that is the output of the control element 52 is calculated at the addition junction 531. Further, an estimated value Gout (outward hat) of the outflow rate output by the observer 57 is added to the summing junction 531, and the deviation of the inflowing flow rate Gin expecting the outflow rate estimated value Gout (upward hat) is added. Calculated.

  The deviation of the inflow flow rate Gin calculated at the summing junction 531 is transmitted to the control element 532, multiplied by the integral gain Kgi by the control element 532, and the servo valve that gives the inflow flow rate Gin for eliminating the deviation of the inflow flow rate Gin. 11 control voltage Ei2 is calculated. By transmitting this control voltage Ei2 to the servo valve 11 via the D / A converter 18, the servo valve 11 opens at a degree of opening corresponding to the control voltage Ei2, and air flows into the isothermal pressure vessel 13. Let

When a spool type servo valve is used as the servo valve 11, there is an approximately proportional relationship between the control voltage Ei2 and the inflow flow rate Gin with Kv as a voltage-flow rate gain as shown in the equation (4). is there.
Gin = Kv · Ei2 (4)
Therefore, the inflow flow rate Gin can be calculated and obtained by the equation (4) using the control voltage Ei2.

  Thus, by performing feedback control of the inflow flow rate Gin, it is possible to compensate for nonlinearity that deviates from the proportional relationship of the voltage-flow rate characteristics, and to improve the accuracy of pressure control by the pressure control system 50.

By transmitting the control voltage Ei2 to the servo valve 11, air of the inflow flow rate Gin corresponding to the control voltage Ei2 flows into the isothermal pressure vessel 13 from the inflow port 13a, while a conduit 19d to which an external device is connected. The outflow rate Gout flowing out from the outflow port 13b is added as a disturbance.
In order to perform pressure control with high response and high accuracy, the pressure control system 50 needs to compensate for the outflow flow rate Gout.

  In the second embodiment of the present invention, the observer 57 for estimating the outflow flow rate Gout is provided based on the pressure differential value dP / dt measured by the pressure differential meter 15 having a pressure loss smaller than that of the flow meter.

Here, a method for estimating the outflow flow rate Gout in the second embodiment of the present invention will be described.
First, the relationship among the inflow flow rate Gin of the isothermal pressure vessel 13, the outflow flow rate Gout from the isothermal pressure vessel 13 and the pressure P in the isothermal pressure vessel 13 will be described.
First, the gas equation of state is as shown in equation (5) as described above. However, V represents the volume of the isothermal pressure vessel 13 and W represents the mass of air in the isothermal pressure vessel 13.
PV = WRθ (5)

Then, when the equation (5) is fully differentiated, the equation (6) is obtained.
Here, considering that the air in the isothermal pressure vessel 13 undergoes an isovolume change (dV / dt = 0) and an isothermal change (dθ / dt = 0), the inflow flow rate Gin to the isothermal pressure vessel 13 and the outflow Between the flow rate Gout and the pressure P in the isothermal pressure vessel 13, there is a relationship of the above formula (7).

Accordingly, the observer (inflow / outflow flow rate difference estimation means) 57 multiplies the pressure change (pressure differential value) dP / dt associated with the inflow flow rate Gin and the outflow flow rate Gout by V / (Rθ) by the control element 571 to obtain “Gin”. -Gout "can be calculated.

By constructing a model following control system 58 that feeds back this inflow / outflow flow rate difference “Gin−Gout” to the addition junction 531 of the inflow flow rate control system 53, pressure control is performed in response to slight changes in the downstream outflow rate. Thus, it is possible to configure the pressure regulator 41 having a high response to disturbance.

  The pressure differential value dP / dt can also be obtained by discrete differentiation (numerical differentiation) of the pressure P measured by the pressure gauge 14. However, since the discrete differentiation of the pressure P includes a large noise component with respect to a slight pressure fluctuation and it is difficult to obtain a good feedback signal, it is preferable to measure by providing the pressure differential meter 15.

The calculation of the pressure control system 50 of the pressure regulator 41 described above is performed by the computer 46, and the control voltage Ei2 calculated by the computer 46 is transmitted to the servo valve 11 via the D / A converter 18. The air in the isothermal pressure vessel 13 can be controlled to a predetermined constant pressure.

  The calculation of the pressure control system 50 may be performed using a general-purpose computer such as a PC (Personal Computer), or may be performed by configuring a dedicated calculation circuit.

<Operation of pressure regulator>
Next, the operation of the pressure regulator 41 will be described with reference to FIG.

  First, it is assumed that the pressure regulator 41 is activated and the pressure P of the air in the isothermal pressure vessel 13 is set to a predetermined target value Pref. At this time, the servo valve 11 is adjusted to an opening that balances the outflow rate Gout flowing out from the outlet 13b of the isothermal pressure vessel 13 and the inflow rate Gin flowing in from the inlet 13a.

Here, when fluctuation occurs in the pressure Ps of the gas supply source 10 or the outflow flow rate Gout flowing out of the isothermal pressure vessel 13, and the pressure P in the isothermal pressure vessel 13 changes from the target value Pref, the pressure regulator 41 In order to compensate for the pressure fluctuation, the computer 46 receives the pressure P measured by the pressure gauge 14 and the pressure differential value dP / dt measured by the pressure differential meter 15 via the A / D converter 17, Based on the received measurement data, the control voltage Ei2 for the servo valve 11 is calculated, and the calculated control voltage Ei2 is transmitted to the servo valve 11 via the D / A converter 18.

  The servo valve 11 adjusts the valve to an opening degree corresponding to the control voltage Ei2 calculated by the computer 16, and flows air into the isothermal pressure vessel 13 with an inflow flow rate Gin corresponding to the opening degree. Thus, control is performed so that the pressure P of the air in the isothermal pressure vessel 13 is set to the target value Pref.

<Experimental example>
Next, an experimental result of evaluating the response to the pressure fluctuation on the upstream side of the pressure regulator 1 and the fluctuation of the outflow flow rate on the downstream side using the pressure regulator 1 according to the present invention will be described.
(Configuration of pressure regulator)
The pressure regulator shown in FIG. 1 was configured. Detailed specifications of each part are shown below.

(Servo valve 11):
As the spool type servo valve, 5-port FESTO MYPE-5-M5-SA was used. Two unused ports were closed, and three ports of intake, exhaust and control were used.
(Isothermal pressure vessel 13):
A container manufactured by Tokyo Meter Co., Ltd. with a volume of 1.0 × 10 ⁻³ [m ³ ] filled with 5% copper wire with a wire diameter of 50 μm was used. The surface of the copper wire is coated.
(Flow meter 12):
A laminar flow meter was used in which a laminar flow element was constructed by inserting about 320 thin tubes having an outer diameter of 0.5 [mm], an inner diameter of 0.3 [mm] and a length of 50 [mm] (details). (See Reference 1).
(Pressure gauge 14):
As the pressure gauge, a semiconductor type PD-64S500K manufactured by Toyota Koki Co., Ltd. was used.
(Pressure differential meter 15):
The pressure differential meter provided with the cylindrical slit channel shown in FIG. 2 was used. Slit channel outer diameter r1 = 1.0 × 10 ⁻² [m], inner diameter r2 = 0.99 × 10 ⁻² [m], channel length L = 2.5 × 10 ⁻² [m], isothermal The capacity Vd of the chemical pressure vessel is 8.06 × 10 ⁻⁶ [m ³ ]. The theoretical value of the cut-off frequency fc is 67 [Hz] at the pressure P = 300 [kPa] from the equation (3). A differential pressure gauge having a measurement range of ± 1 inch H 2 O (249 [Pa]) manufactured by Allsensors was used. In addition, it has been confirmed that this pressure differential meter sufficiently responds to about 30 [Hz] by a preliminary experiment in which a sinusoidal pulsating flow is generated.

(Control parameter setting):
The control parameters were set as follows.
In the block diagram shown in FIG. 3, when it is assumed that the control of the inflow flow rate Gin is sufficiently faster than the pressure control, the transfer function of the pressure control is as shown in Expression (9).

The pressure recovery settling time (time to reach 95% of the target value) when a disturbance such as pressure fluctuation on the upstream side or downstream side occurs is targeted within 0.3 [s], and Tp = 0.1 [s] Thus, Kp = 1.19 × 10 ⁻⁷ [kg / (Pa · s)] was set as the proportional gain of the pressure control system 20.

  Next, in the inflow flow rate control system 23, if the input from the control element 22 of the pressure control system 20 is Gref, the flow rate gain for the control voltage Ei1 of the servo valve 11 is Kv, and the integral gain of the inflow flow rate control system 23 is Kgi, The transfer function of the inflow flow rate control is as shown in Equation (10).

The spool type servo valve 11 used in this experiment is strictly non-linear, but the supply pressure Ps = 500 [kPa (abs)] on the upstream side of the servo valve 11 and the pressure P = 300 [ Under the experimental condition of kPa (abs)], linear approximation was performed with Kv = 2.155 × 10 ⁻⁴ [kg / (s · V)] based on the static characteristics measured in advance. Since the loop of the inflow flow rate control system 23 is a minor loop of the loop of the pressure control system 20, the control cycle needs to be sufficiently faster than that of the pressure control system 20. Therefore, Kgi = 6.19 × 10 ⁵ [s ² · V / kg] was set so that Tgi = 0.005 [s] (Tp: TG = 15: 1). Also in Experiment 2 described later, Pref = 300 [kPa (abs)].

For comparison, an experiment was conducted by replacing the pressure regulator 1 of the present invention with a commercially available precision regulator (pilot pressure regulator) and an electropneumatic regulator.
(Precision regulator):
IR2010-02G manufactured by SMC was used.
(Electro-pneumatic regulator):
STV ITV2050-212BL5 was used.

(Experiment 1: Upstream pressure fluctuation experiment)
In Experiment 1, a pressure fluctuation was caused on the upstream side of the pressure regulator 1, and the state in which the pressure was stabilized by the pressure regulator 1 was measured.

As shown in FIG. 6, the experimental apparatus is provided with a branch pipe 30 and a pressure gauge 32 in a conduit 19a that connects the gas supply source 10 and the servo valve 11 to the pressure regulator 1 shown in FIG. . The exhaust flow rate Gout_up from the branch pipe 30 can be adjusted with a variable throttle, and a laminar flow meter 31 is provided on the downstream side of the branch pipe 30. The supply pressure Ps was varied by exhausting part of the air supplied to the servo valve 11 through the branch pipe 30.
The exhaust gas flow rate Gout_up and the pressure Ps of the air supplied to the servo valve 11 were measured by the flow meter 31 and the pressure meter 32, respectively.

  In FIG. 6, the description of the computer 16, the A / D converter 17, and the D / A converter 18 (see FIG. 1) that are control means of the pressure regulator 1 is omitted. In addition, measurement data obtained by the pressure gauge 32 and the flow meter 31 of this experimental apparatus is transmitted to the computer 16 via the A / D converter 17, and the computer 16 uses the flow meter 12, the pressure gauge 14, and the pressure differential meter 15. Data processing was performed along with the measurement data.

(Experimental operation)
In the experimental apparatus shown in FIG. 6, after the pressure P is sufficiently settled, the hand valve of the branch pipe 30 upstream of the servo valve 11 is opened at t ≧ 30 [s], and Gout_up = 6.47 × 10 ^{− 3} [kg] of air was released. The change in the supply pressure Ps at that time is shown in FIG. For comparison, the same experiment was performed using the above-described commercially available precision regulator and electropneumatic regulator.

(Experimental result)
FIG. 8 is a graph showing the experimental results of Experiment 1. In FIG. 8, “A” indicates a change in pressure when the pressure regulator 1 according to the present invention is used, “B” indicates a case where a precision regulator is used, and “C” indicates a change in pressure when an electropneumatic regulator is used.

  As shown in FIG. 8, when the pressure regulator 1 according to the present invention is used, the pressure P is set to the target value of 300 [kPa] without deviation and is hardly affected by fluctuations in the supply pressure Ps. On the other hand, when a precision regulator and an electropneumatic regulator are used, a steady offset is seen with respect to the target pressure value. When the precision regulator is used, the pressure P on the downstream side is also decreased due to the decrease in the supply pressure Ps. On the other hand, when the electropneumatic regulator is used, the influence of fluctuations in the supply pressure Ps is not observed, but the pressure P increases at t ≧ 39 [s]. This is considered to be because the supply pressure Ps falls below the threshold value of the electropneumatic regulator at t = 39 [s], and the regulator switch is activated.

(Experiment 2: Downstream flow fluctuation experiment)
In Experiment 2, the usage flow rate (outflow flow rate) fluctuated on the downstream side of the pressure regulator 1 and the state in which the pressure was regulated by the pressure regulator 1 was measured.

  As shown in FIG. 9, the experimental apparatus has a spool type servo valve 33 connected to the downstream end of the conduit 19d on the output side of the pressure regulator 1 with respect to the pressure regulator 1 shown in FIG. A laminar flow meter 34 was connected to the downstream side. A control voltage E2 was applied to the servo valve 33, and the opening degree of the servo valve 33 was adjusted to vary the outflow flow rate Gout. The outflow flow rate Gout was measured by the flow meter 34.

  In FIG. 9, the computer 16, the A / D converter 17 and the D / A converter 18 (see FIG. 1) which are the control means of the pressure regulator 1 are omitted. In addition, the measurement data obtained by the flow meter 34 of this experimental apparatus is transmitted to the computer 16 via the A / D converter 17, and the computer 16 transmits the data together with the measurement data obtained by the flow meter 12, the pressure gauge 14 and the pressure differential meter 15. Processed. Further, the computer 16 transmits the control voltage E2 to the servo valve 33 via the D / A converter 18 to drive the servo valve 33.

(Experimental operation)
In the experimental apparatus shown in FIG. 9, the control voltage E2 to the servo valve 33 installed on the downstream side of the pressure regulator 1 is
When t <20 [s], E2 = 6.5 [V]
When t ≧ 20 [s], E2 = 8.0 [V]
As a result, disturbance was generated on the downstream side of the pressure regulator 1.

  FIG. 10 is a graph showing the measured value and estimated value of the outflow rate in Experiment 2. In FIG. 10, “A” indicates the outflow flow rate Gout measured by the flow meter 34, and “B” indicates the outflow flow rate estimated value Gout (hatted above) estimated by the equation (8). Moreover, also in Experiment 2, the same experiment was conducted using the above-mentioned commercially available precision regulator and electropneumatic regulator as a comparison object.

(Experimental result)
FIG. 11 is a graph showing the experimental results of Experiment 2. In FIG. 11, “A” indicates a change in pressure when the pressure regulator 1 according to the present invention is used, “B” indicates a case where a precision regulator is used, and “C” indicates a change in pressure when an electropneumatic regulator is used.

  Also in the result of Experiment 2, when the pressure regulator 1 according to the present invention is used, the pressure is set to the target value of 300 [kPa] without offset, and the influence of the disturbance on the downstream side is about 0.3 [s]. It is quickly compensated and shows an advantage over commercially available regulators.

(Experiment 3: Control experiment using discrete differentiation of pressure gauge measurement value)
In Experiment 3, the pressure differential value dP / measured by the pressure differential meter 15 is used to calculate the estimated value Gout (upper hat) of the outflow flow rate according to Equation (8) using the experimental apparatus shown in FIG. Instead of dt, the pressure P measured by the pressure gauge 14 was obtained by discrete differentiation, and the pressure differential value was used. The digital filter for discretely differentiating the pressure P was an incomplete differentiator similar to the pressure differentiator 15, and the cut-off frequency fc was 67 [Hz].
Other experimental conditions are the same as those in Experiment 2.

(Experimental result)
FIG. 12 is a graph showing the experimental results of Experiment 3. In FIG. 12, “A” indicates the case where the pressure differential value measured by the pressure differential meter is used, and “B” indicates the case where the discrete differential of the pressure value measured by the pressure gauge is used.

  As shown in FIG. 12, it can be seen that the steady fluctuation is larger when the discrete derivative is used than when the measured value by the pressure differential meter is used. This is considered to be caused by amplification of noise components due to discrete differentiation of the measurement value of the pressure gauge 14.

  FIG. 13 is a graph showing a pressure differential value measured by a pressure differential meter and a pressure differential value obtained by discrete differentiation of the pressure value measured by the pressure meter. In FIG. 11, “A” indicates a pressure differential value measured by a pressure differential meter, and “B” indicates a pressure differential value obtained by discrete differentiation of the pressure value measured by the pressure meter.

  As shown in FIG. 13, the pressure differential value measured using the pressure differential meter 15 has a smaller fluctuation and the noise component is smaller than the pressure differential value obtained by discrete differentiation of the measurement value obtained by the pressure gauge 14. I understand that there are few things. Accordingly, it can be seen that it is effective to use the pressure differential meter 15 in order to perform pressure control with high accuracy.

<Configuration of vibration isolation device>
Next, an air spring vibration isolator 100 using the pressure regulator 1 will be described as an application example of the pressure regulator 1 according to the present invention with reference to FIG. Here, FIG. 14 is a block diagram schematically showing the configuration of an air spring type vibration isolator using the pressure regulator of the present invention.

As shown in FIG. 14, the vibration isolation device 100 includes a vibration isolation table 110 and an air spring control unit 120.
The vibration isolator 100 controls the supply and exhaust of air to the air spring 111 by the servo valve 115 so that the position of the surface plate 112 that is displaced by vibration or the like is set to a set displacement. In addition, the air supplied to the servo valve 115 is configured to be supplied from the air supply source 10 </ b> A through the pressure regulator 1 while being maintained at a constant pressure with high accuracy.
In the embodiment of the present invention, the position and acceleration of the surface plate 112 are feedback-controlled by the air spring control unit 120, the control voltage E3 for the servo valve 115 is calculated, and the servo valve 115 is operated.

(Vibration isolation table)
The vibration isolation table 110 includes an air supply source 10A, a pressure regulator 1, a servo valve 115, an air spring 111, a surface plate 112, a position detector 113, and an acceleration detector 114.

  The air supply source 10A is a supply source for supplying air to the air spring 111, and supplies compressed air using pumps such as a compressor. A cylinder filled with high-pressure air to be supplied can also be used. The air supplied from the air supply source 10A flows into the pressure regulator 1 and is adjusted to a predetermined pressure.

  The pressure regulator 1 adjusts the air supplied from the air supply source 10A to a predetermined pressure and supplies it to the air spring 111 via the servo valve 115. The pressure regulator 1 according to the present invention shown in FIG. It is a regulator.

The servo valve 115 regulates air supply and exhaust to the air spring 111. The servo valve 115 of this embodiment shown in FIG. 14 is a spool type servo valve having an intake port 115a, an exhaust port 115b, and a control port 115c, and is similar to the servo valve 11 of the pressure regulator 1 shown in FIG. Servo valves can be used.
As the servo valve 115, for example, a nozzle flapper type servo valve can be used as long as it can regulate the supply and exhaust of air to the air spring 111. In particular, the servo valve 115 is a flow control type servo valve with a small exhaust flow rate. It is preferable to use a certain spool type servo valve in order to reduce the environmental load.

  The control port 115c of the servo valve 115 is connected to the air spring 111, the intake port 115a is connected to the pressure regulator 1, the exhaust port 115b is opened to the atmosphere, and the D / A converter ( Based on a control voltage E3 transmitted via a not-shown switch, the connection between the control port 115c and the intake port 115a or the exhaust port 115b is switched, and the opening of the valve is adjusted. Thereby, supply and exhaust of air to the air spring 111 can be regulated.

The air spring 111 is composed of a buffer tank portion 111a and a rubber bellows portion 111b. The air bellows portion 111b is an actuator that expands and contracts according to the internal air pressure, and is a support leg that supports the surface plate 112.
The air spring 111 is connected to the control port 115c of the servo valve 115, and air is supplied to and exhausted from the air spring 111 according to the connection direction and opening degree of the servo valve 115.

  The surface plate 112 is a mounting table that is used in a state where vibration is removed, for example, for mounting a device such as an exposure apparatus. The surface plate 112 is supported by the air spring 111, and the position (displacement) and acceleration of the surface plate 112 are detected by the position detector 113 and the acceleration detector 114.

  The position detector 113 detects the position (displacement) of the surface plate 112 and outputs the detected signal to the air spring control unit 120 via an A / D converter (not shown). As the position detector 113, an eddy current displacement sensor, a capacitance sensor, a position detection sensor using a photoelectric conversion element, or the like can be used.

  The acceleration detector 114 detects the acceleration of the surface plate 112 and outputs the detected signal to the air spring control unit 120 via an A / D converter (not shown). As the acceleration detector 114, a piezoelectric acceleration sensor, a capacitive acceleration sensor, or the like can be used.

(Air spring control unit)
The air spring control unit (air spring control means) 120 includes a filter 121, a filter 122, a comparator 123, a PI compensator 124, and a subtractor 125, and the position of the vibration isolation table 110. The position and acceleration of the surface plate 112 measured by the detector 113 and the acceleration detector 114 are received via an A / D converter (not shown), and the received position and acceleration are feedback-controlled to the servo valve 115. A control voltage E3 is calculated and transmitted to the servo valve 115 via a D / A converter (not shown). As a result, the position of the surface plate 112 is set to a set displacement that is a target value, and the servo valve 115 is controlled so as to suppress a change in acceleration to a minimum.

  The air spring control unit 120 can be realized using a computer in the same manner as the control system of the pressure regulator 1. Further, the computer 16 (see FIG. 1) of the pressure regulator 1 may also be used as the air spring control unit 120.

  The filter 121 performs filtering on the position signal of the surface plate 112 detected by the position detector 113 with an appropriate amplification degree and time constant, and outputs the result to the comparator 123.

  The filter 122 performs a filtering process on the acceleration signal of the surface plate 112 detected by the acceleration detector 114 with an appropriate amplification degree and time constant, and outputs the filtered signal to the subtractor 125.

  The comparator 123 compares the set displacement, which is a target value of the position of the surface plate 112, with the position signal (displacement signal) of the surface plate 112 filtered by the filter 121, and calculates a deviation from the set displacement of the position signal. Calculate and output to the PI compensator 124.

  The PI compensator 124 calculates a control voltage for the servo valve 115 for eliminating the deviation based on the deviation of the position of the surface plate 112 which is a control amount of the PI control, and outputs it to the subtractor 125.

  The subtractor 125 subtracts the signal obtained by filtering the acceleration signal using the filter 122 from the control voltage calculated by the PI compensator 124 to calculate the control voltage E3. As a result, since the acceleration is negatively fed back and the control system loop is provided with damping, the control mechanism can be stabilized. The calculated control voltage E3 is transmitted to the servo valve 115 via a D / A converter (not shown), and the opening degree of the servo valve 115 is adjusted.

  In the present embodiment, the feedback loop of the PI control system is configured, but a feedback loop of the PID control system may be configured. In addition, the position and acceleration of the surface plate 112 are feedback-controlled, but the control amount to be feedback-controlled is not limited to these. For example, the air pressure in the air spring 111 or a differential value of the air pressure is further measured. Thus, a feedback control system may be configured.

  The control of the vibration isolator is described in detail in the vibration isolator proposed by the present inventors in Patent Document 2.

<Operation of vibration isolator>
Next, the operation of the vibration isolation device 100 will be described with reference to FIG. 14 (refer to FIG. 1 as appropriate).
First, it is assumed that a sufficient amount of time has elapsed after the vibration isolator is activated and the surface plate 112 has been set to the set displacement. At this time, the servo valve 115 is in a closed state, and air does not flow into or out of the air spring 111.

  Here, if a change occurs in the position of the surface plate 112 due to vibration from the installation surface of the vibration isolation table 110 or operation of equipment installed on the surface plate 112, an A / D converter (not shown) is used. Based on the position signal and acceleration signal detected by the position detector 113 and the acceleration detector 114 received in this way, the control voltage E3 for setting the position of the surface plate 112 to the set displacement is calculated by the air spring control unit 120, It outputs to the servo valve 115 via a D / A converter (not shown).

  The servo valve 115 opens at an opening corresponding to the control voltage E3 calculated by the air spring control unit 120, and supplies air to the air spring 111 from the intake port 115a or air to the exhaust port 115b. Exhaust. Thereby, the air pressure in the air spring 111 is adjusted, and the position of the surface plate 112 supported by the air spring 111 is controlled to be set to the set displacement.

  On the other hand, when air is supplied from the air supply source 10 </ b> A to the air spring 111 via the pressure regulator 1, the air pressure in the pressure regulator 1 varies. For this reason, the pressure regulator 1 adjusts the inflow flow rate Gin, the pressure P, and the pressure differential value dP / dt, which are measured by the flow meter 12, the pressure gauge 14, and the pressure differential meter 15, respectively, in order to compensate for fluctuations in air pressure. Based on this, the computer 16 calculates a control voltage Ei1 for the servo valve 11 and transmits it to the servo valve 11.

  The servo valve 11 opens the valve at an opening degree corresponding to the transmitted control voltage Ei1, and allows air to flow into the isothermal pressure vessel 13. Thus, control is performed so that the pressure P of the air in the isothermal pressure vessel 13 is set to the target value Pref.

  As described above, the vibration isolation device 100 according to the present embodiment controls the pressure of the air supplied to the air spring 111 so that the pressure regulator 1 maintains a predetermined pressure. For this reason, the vibration isolator 100 receives the supply of air with a stable pressure, controls the air spring 111, and can quickly and accurately set a displacement deviation due to vibration of the surface plate 112 or the like.

1 Pressure regulator 10 Gas supply source (compressible fluid supply source)
10A Air supply source 11 Servo valve 12 Flow meter (Inflow rate acquisition means)
13 Isothermal pressure vessel 14 Pressure gauge (pressure detection means)
15 Pressure differential meter (pressure differential value detection means)
16 Computer (pressure control means, air spring control means)
20 Pressure control system 23 Inflow flow rate control system 27 Observer (outflow flow rate estimation means)
28 Model following control system 46 Computer (pressure control means)
DESCRIPTION OF SYMBOLS 100 Anti-vibration apparatus 110 Anti-vibration stand 111 Air spring 112 Surface plate 113 Position detector (position detection means)
114 Acceleration detector (acceleration detection means)
115 Servo Valve 120 Air Spring Control Unit (Air Spring Control Unit)
151 Isothermal pressure vessel (pressure chamber)
152 Slit channel 153 Differential pressure gauge

Claims (6)

A servo valve that regulates the flow rate of the compressive fluid supplied from the compressible fluid supply source;
An isothermal pressure vessel that holds the compressible fluid flowing through the servo valve in an isothermal state;
Pressure detecting means for detecting the pressure of the compressible fluid in the isothermal pressure vessel;
Pressure differential value detection means for detecting the pressure differential value of the compressible fluid in the isothermal pressure vessel;
Pressure control means for operating the servo valve to control the compressible fluid in the isothermal pressure vessel to a predetermined constant pressure, and
The pressure control means includes
A pressure control system for feedback-controlling the pressure detected by the pressure detection means;
An inlet flow control system that control the inflow rate of the compressive fluid flowing into the isothermal pressure vessel,
An inflow that is a difference between an inflow flow rate of the compressible fluid flowing into the isothermal pressure vessel and an outflow rate of the compressive fluid flowing out of the isothermal pressure vessel from the pressure differential value detected by the pressure differential value detecting means. has a inflow out flow rate difference estimating means for estimating the output flow rate difference, a,
Wherein together constituting the inside of the control loop of the pressure control system, constituting a model following control system for feeding back the inflow out flow rate difference that is estimated by the influx out flow rate difference estimating means to said inlet flow control system And pressure regulator.
The pressure regulator according to claim 1, wherein the servo valve is a spool type servo valve. The pressure differential value detection means is a pressure differential meter provided with a pressure chamber, a diaphragm type differential pressure gauge or a flowmeter, and a cylindrical slit channel communicating the isothermal pressure vessel and the pressure chamber. The pressure regulator according to claim 1 or 2 , characterized in that. The influx out flow difference estimation means, based on the previous SL pressure differential value the pressure differential value of the compressive fluid in the isothermal pressure vessel detected by the detecting means (dP / dt), by the following formula (7) The pressure regulator according to any one of claims 1 to 3 , wherein the inflow / outflow flow rate difference (Gin-Gout) is calculated.

Here, R is the gas constant [J / (kg · K)], V is the volume of the isothermal pressure vessel [m ³ ], θ is the temperature of the air in the isothermal pressure vessel [K], and P is the isothermal pressure. Pressure [Pa] in the container, t is time [s]. A surface plate,
An air spring that supports the surface plate;
A servo valve that regulates an inflow flow rate and an outflow flow rate of air to the air spring;
The pressure regulator according to any one of claims 1 to 4 , wherein a pressure of air supplied from an air supply source is held constant and supplied to the servo valve.
Position detecting means for detecting the position of the surface plate;
Acceleration detecting means for detecting the acceleration of the surface plate;
An air spring control means for operating the servo valve to control the surface plate to a predetermined position based on the position detected by the position detection means and the acceleration detected by the acceleration detection means;
An anti-vibration device comprising: The vibration isolator according to claim 5 , wherein the servo valve is a spool type servo valve.

Images