JP7382054B2 - Valve devices and flow control devices - Google Patents

Description

The present invention relates to a valve device and a flow rate control device, and more particularly to a valve device and a flow rate control device that are suitably used in gas supply systems used in semiconductor manufacturing equipment, drug manufacturing equipment, chemical plants, and the like.

BACKGROUND ART In semiconductor manufacturing equipment, chemical plants, etc., it is required to supply gas to a process chamber or the like at an appropriate flow rate. Mass flow controllers (thermal mass flow controllers) and pressure flow controllers are known as gas flow rate control devices.

Pressure flow control devices are widely used because they can control the mass flow rate of various fluids with high precision using a relatively simple mechanism that combines a control valve and a restrictor (for example, an orifice plate or critical nozzle). . The pressure-type flow rate control device has excellent flow rate control characteristics that allow stable flow rate control even when the primary side supply pressure fluctuates greatly.

Some pressure-type flow rate control devices adjust the flow rate by controlling the fluid pressure on the upstream side of the restrictor (hereinafter sometimes referred to as upstream pressure _PU ). The upstream pressure P _U is controlled by adjusting the opening degree of a control valve disposed upstream of the throttle section.

A piezoelectric element-driven valve configured to open and close a metal diaphragm valve body using a piezoelectric element driving device (hereinafter sometimes referred to as a piezo actuator) is used as a control valve used in a pressure-type flow rate control device. . Patent Document 1 discloses a piezoelectric element-driven valve used as a control valve. A piezoelectric element-driven valve is capable of high-speed operation, and can control upstream pressure and flow rate by feedback controlling its opening degree based on the output of a pressure sensor.

Japanese Patent Application Publication No. 2007-192269 Patent No. 6336692 International Publication No. 2004/079243

A piezoelectric element-driven valve can accurately control the flow rate of a small flow rate of gas, but on the other hand, it may be difficult to flow a large flow rate of gas. This is because there is a limit to the range of valve opening and closing that can be controlled by expanding the piezoelectric element. The lift amount of the piezoelectric element-driven valve is set, for example, to about 35 to 40 μm, but with such a displacement amount, it is difficult to flow gas of 10 slm (standard liter/min) or more.

For this reason, in recent applications where a large flow rate is required, the flow rate has sometimes been insufficient with conventional piezoelectric element-driven valves. It is also possible to compensate for the lack of flow rate by providing two parallel flow paths with control valves for one line, but in this case, this may result in increased costs and the complexity and enlargement of the equipment. become.

Patent Document 2 discloses a valve device that combines a main actuator that performs opening/closing operations using air pressure and a piezo actuator for adjusting the opening degree. The valve device configured in this manner is installed in the flow path in front of the process chamber, and is suitably used as an on-off valve for supplying gas in pulses when performing a process such as ALD (Atomic Layer Deposition). can do.

However, although the valve device described in Patent Document 2 can ensure the maximum flow rate, it is basically intended to be used as an on-off valve, so the flow rate can be accurately controlled over a wide flow range from small flow rates to large flow rates. Control was sometimes difficult. For this reason, it has been difficult to use it as a control valve for a pressure-type flow rate control device.

The present invention has been made to solve the above problems, and provides a valve device and a valve device that can accurately control the flow rate from a small flow rate to a large flow rate, and can also be used as a control valve of a pressure-type flow rate control device. The main objective is to provide a flow control device equipped with this.

A valve device according to an embodiment of the present invention includes a valve body that can be placed in and out of a valve seat, an operation member connected to the valve body, and a main actuator that moves the operation member and that is operated by a driving fluid. a pressure regulator that adjusts the pressure of the driving fluid supplied to the main actuator; a sub-actuator that is movable together with the operating member by the main actuator and is extendable by electrical drive; and the sub-actuator an elastic member that urges the valve body toward the valve body.

In one embodiment, in the above-mentioned valve device, the main actuator moves the operating member against the urging force of the elastic member by a driving fluid whose pressure is adjusted by the pressure regulator, and the sub-actuator moves the operating member. The elastic member is configured to increase the biasing force of the elastic member and move the operating member as the elastic member expands.

In one embodiment, the above-mentioned valve device is capable of controlling the valve opening to any desired degree between close and maximum opening by adjusting the pressure of the driving fluid and adjusting the degree of extension of the auxiliary actuator. It is configured.

In some embodiments, the primary actuator includes a pneumatic actuator having a piston that engages the operating member, the secondary actuator includes a piezo actuator, and the pressure regulator includes an electropneumatic regulator.

In one embodiment, the above valve device further includes a main elastic member that biases the flange portion of the operating member toward the valve body.

A flow rate control device according to an embodiment of the present invention includes a constriction section provided in a flow path, a control valve provided upstream of the constriction section and constituted by any one of the valve devices described above, and the constriction section. The control valve includes a pressure sensor that measures fluid pressure between the control valve and the control valve, and a control unit that controls opening and closing operations of the control valve based on the output of the pressure sensor.

According to the valve device and flow rate control device of the embodiment of the present invention, it is possible to appropriately control the flow rate from a small flow rate to a large flow rate.

FIG. 1 is a cross-sectional view showing a valve device according to an embodiment of the present invention. 2 is a diagram showing a valve drive system including the valve device of FIG. 1. FIG. It is a graph showing the relationship between the operating pressure of the main actuator and the Cv value. FIG. 1 is a diagram showing a flow control device including a valve device according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 shows a valve device 100 according to an embodiment of the invention. The valve device 100 includes an operating member 30 for opening and closing a diaphragm valve body 34, a main actuator 10 for moving the operating member 30 relatively large, and a sub actuator 20 for moving the operating member 30 relatively small. It is equipped with

The valve device 100 is a normally closed type valve, and when the main actuator 10 and the sub actuator 20 are not driven, the diaphragm valve body 34 is connected to the main elastic member 42 (here, a coil spring) etc. via the operating member 30. It is pressed against the valve seat (not shown) by the urging force received from the valve seat. The valve seat is usually provided as an annular protruding surface facing the center of the diaphragm valve body 34.

The main actuator 10, the sub actuator 20, and the operating member 30 are all arranged inside the valve housing 40. In this embodiment, the valve housing 40 includes a bonnet 40a, an intermediate housing 40b, an upper housing 40c, and an upper cover 40d, which are fixed to each other with screws. Of these, the bonnet 40a is screwed and fixed to a flow path block (not shown), so that the entire valve housing 40 is fixed to the flow path block.

In the valve device 100, the operating member 30 includes a cylinder made of stainless steel, and is arranged to be movable in the vertical direction (the opening/closing direction of the valve body) with respect to the valve housing 40. A diaphragm presser 32 is fixed to the lower tip of the operating member 30 and is in contact with the center of the diaphragm valve element 34. By moving the operating member 30 up and down, the diaphragm valve element 34 is pressed against the valve seat, and the diaphragm valve element 34 is pressed against the valve seat. can be moved away from the valve seat. Note that as the material for the operating member 30, in addition to stainless steel, it is also possible to use an invar material, etc., and the material is not particularly limited, and the material to be used may be selected depending on the situation. The diaphragm retainer 32 may be made of, for example, synthetic resin (eg, tetrafluoroethylene resin), synthetic rubber, aluminum, stainless steel, Invar material, or the like.

The diaphragm valve body 34 is, for example, a circular thin plate (for example, 15 to 100 μm thick) made of stainless steel or cobalt-nickel alloy, and is formed into an inverted dish shape with a slightly bulged upward in the center. good. The diaphragm valve body 34 may be formed from a single diaphragm, or may be formed from a stack of 2 to 4 diaphragms. The peripheral edge of the diaphragm valve body 34 is fixed between the bonnet 40a and the flow path block with a stainless alloy holding adapter 36 in between.

In this specification, for convenience, the opening/closing direction of the diaphragm valve body 34 (or the moving direction of the operating member 30) is defined as the vertical directions D1 and D2. However, depending on the attitude of the valve device 100, the opening/closing direction of the valve body may be horizontal or diagonal, and the vertical directions D1 and D2 in this specification may be different from the actual vertical direction. . Moreover, the top and bottom may be reversed.

In this embodiment, the main actuator 10 that moves the operating member 30 is an air-driven actuator that moves the operating member 30 up and down using compressed air as a driving fluid. The main actuator 10 includes first to third annular pistons 12a, 12b, and 12c. The first to third pistons 12a, 12b, and 12c are fitted around the operating member 30 so as to come into contact with a stepped portion provided on the outer peripheral surface of the operating member 30. It is movable along D1 and D2.

Between the inner circumferential surfaces of the first to third pistons 12a, 12b, 12c and the operating member 30, and between the outer circumferential surfaces of the first to third pistons 12a, 12b, 12c and the outer valve housing 40. An O-ring 16 is provided between them. Furthermore, first to third piston pressure chambers 14a, 14b, and 14c are provided on the lower surface side of the first to third pistons 12a, 12b, and 12c. On the other hand, gaps communicating with the outside are provided on the upper surfaces of the first to third pistons 12a, 12b, and 12c, and these gaps are typically maintained at atmospheric pressure. The pressure chambers 14a, 14b, 14c on the lower surface side of the first to third pistons and the above-mentioned gap are separated by an O-ring 16, and the pressure chambers 14a, 14b, 14c are in a sealed state.

Compressed air from an air source is sent to the pressure chambers 14a, 14b, and 14c via a supply pipe 50. As can be seen from FIG. 1, the air from the supply pipe 50 passes through a small hole provided in the valve housing 40 and a small hole provided in the operating member 30, and is arranged around the operating member 30 and its inner circumference. It flows into the gap between the tubular wall member 38 and reaches the first and second pressure chambers 14a, 14b.

The main actuator 10 can move the engaged operating member 30 in the upward direction D1 by pushing up the first to third pistons 12a, 12b, and 12c using air pressure. Further, compressed air at an arbitrary pressure is supplied to the supply pipe 50 and the pressure chambers 14a, 14b, and 14c via an electropneumatic regulator 55 (see FIG. 2). The electropneumatic regulator 55 has a function of adjusting the operating pressure of the main actuator 10 to an arbitrary level. Note that an air-driven valve including an electropneumatic regulator 55 is disclosed in Patent Document 3.

Furthermore, a piezo actuator is used as the sub actuator 20 that moves the operating member 30. The sub actuator 20 is arranged inside the operating member 30 so as to be slidable with respect to the operating member 30.

In the sub actuator 20, the degree of expansion thereof is controlled by controlling the voltage applied to the piezo element (also referred to as a piezoelectric element). As the sub-actuator 20, a metal-sealed laminated piezo actuator (for example, manufactured by Nippon Tokushu Togyo Co., Ltd.) in which a stack of piezoelectric elements is sealed in a metal container, or a piezo actuator constituted by a single piezoelectric element is used. A voltage is applied to the piezoelectric element via a wiring 24 extending from the top.

A hemispherical protrusion 22 is provided at the lower end of the sub-actuator 20 , and the protrusion 22 is supported by a pedestal 33 fixed to the operating member 30 . Further, an upper elastic member (here, a disc spring) 25 is provided above the sub-actuator 20.

The upper elastic member 25 is disposed between a lid member 26 that covers the upper surface of the sub-actuator 20 and the lower surface of the upper cover 40d of the valve housing 40, and urges the lid member 26 and the sub-actuator 20 downward. can do. The upper elastic member 25 is provided to push the sub actuator 20 downward with a force of, for example, 100 to 400 N when the valve is in the closed state.

In the above configuration, when the main actuator 10 and the sub actuator 20 are not driven, the diaphragm valve body 34 receives the urging force of the main elastic member 42 that presses the flange portion 35 of the operating member 30 downward, and the sub actuator 20 is pressed against the valve seat by the urging force of the upper elastic member 25 that presses the valve downward. The main elastic member 42 is set to apply a relatively large spring load (for example, 300 to 600 N) downward in the closed state in order to provide sufficient pressing force against the valve body in the closed state. There is.

On the other hand, when opening the valve, compressed air having an operating pressure corresponding to the opening degree is supplied to the main actuator 10, and the first to third pistons 12a are moved against the urging force of the main elastic member 42 and the upper elastic member 25. , 12b, 12c lift the operating member 30 upward. At this time, since the load is balanced, the operation member 30 moves relatively smoothly, and the displacement of the operation member 30 is easily adjusted by the operation pressure. In particular, since it is relatively easy to adjust the elastic force of the upper elastic member 25 by adjusting the number of disc springs during assembly, etc., the upper elastic member 25 has an appropriate elastic force that matches the actual operating pressure of the main actuator 10. It has the advantage of being easy to adjust to the force.

According to this configuration, the operating pressure of the main actuator 10 and the valve opening can be in a generally linear relationship, and the displacement of the operating member 30 can be increased to a magnitude corresponding to the maximum displacement of the upper elastic member 25. can be done. Thereby, the maximum opening degree of the diaphragm valve body 34 can be increased, and it becomes possible to flow gas from a small flow rate to a large flow rate at a flow rate corresponding to the operating pressure of the driving fluid.

Further, as the operating member 30 moves by the main actuator 10, the sub actuator 20 disposed inside the operating member 30 also moves upward while being urged downward by the upper elastic member 25. At this time, if a voltage is applied to the sub-actuator 20 to extend the sub-actuator 20, a downward biasing force is generated while increasing the displacement of the upper elastic member 25 (that is, while further contracting the upper elastic member 25). can be increased. Thereby, the displacement of the operating member 30 can be finely adjusted downward.

Therefore, by controlling both the operating pressure of the main actuator 10 and the applied voltage of the sub-actuator 20 in combination, it becomes possible to accurately control the flow rate over a wide range from small flow rates to large flow rates.

Further, when the valve device 100 is used as a control valve of a pressure-type flow rate control device, the valve opening degree is adjusted by feedback control based on the output (upstream pressure P _U ) of a pressure sensor on the upstream side of the throttle portion. At this time, continuous fine adjustment of the valve opening may be required due to pressure fluctuations. Even at this time, in the valve device 100, the valve opening can be made to appropriately follow pressure fluctuations by controlling the voltage of the sub actuator 20, which has excellent responsiveness, while maintaining the operating pressure of the main actuator 10 constant.

FIG. 2 shows a valve drive system 150 that includes the valve device 100. The valve drive system 150 includes a gas source GS for supplying compressed air to the valve device 100, an electro-pneumatic regulator 55 interposed in a flow path between the gas source GS and the valve device 100, and a gas source GS for supplying compressed air to the valve device 100. The controller 60 controls the operation of the regulator 55.

The electropneumatic regulator 55 is provided to control the pressure of compressed air supplied to the main actuator 10 of the valve device 100. The electro-pneumatic regulator 55 is a type of proportional control valve, and controls the compression from the gas source GS by driving the air supply valve and the exhaust valve so that the difference between the input signal indicating the set pressure and the pressure sensor signal is eliminated. It is configured to adjust the pressure of air G0 and output compressed air G1 controlled to a set pressure. However, the present invention is not limited to the electropneumatic regulator 55, and various other types of pressure regulators may be used as long as the pressure (operating pressure) of the compressed air supplied to the main actuator 10 can be arbitrarily adjusted.

When a valve opening control signal is input from the outside, the controller 60 outputs a rough adjustment operating pressure command A1 to the electropneumatic regulator 55, and outputs a fine adjustment piezo command A2 to the sub actuator 20 of the valve device 100. do. Thereby, the valve can be adjusted to an opening degree corresponding to the operating pressure of the main actuator 10 and the drive voltage of the sub actuator 20. The controller 60 typically has a built-in CPU, a memory (storage unit) M such as ROM or RAM, an A/D converter, etc., and includes a computer program configured to execute valve control. Often, it can be implemented by a combination of hardware and software.

The controller 60 receives the outputs of flow meters and various sensors provided in the flow path in which the valve device 100 is installed, updates the command A1 or the command A2, and adjusts the valve opening of the valve device 100 by feedback control. It may be configured to do so. In addition, if the relationship between the operating pressure of the main actuator 10 and the valve opening is not linear, a rough estimate may be made based on a table that shows the relationship between the operating pressure and the valve opening (or flow rate, etc.) stored in memory in advance. In addition to outputting the adjustment operating pressure command A1, the fine adjustment piezo command A2 may also be output as necessary.

FIG. 3 is a graph showing the relationship between the operating pressure of the main actuator 10 and the Cv value (Coefficient of flow). The Cv value is an index indicating the ease of fluid flow in the valve, and specifically, it is given by the following formula.
Cv=(Q/6900)×(Gg・T/(P1-P2)・P2) ^1/2

In the above formula, Q is the flow rate (sccm), Gg is the specific gravity of the gas, P1 is the valve primary pressure (kPa abs), P2 is the valve secondary pressure (kPa abs), and T is the temperature (K). . The Cv value corresponds to the flow rate when the pressure difference between the primary side and the secondary side of the valve is constant, and in the case of a proportional valve, it generally corresponds to the valve opening degree.

As shown by line B1 in FIG. 3, the operating pressure of the main actuator 10 is smaller than the starting pressure P0, and the force that lifts the operating member 30 upward is smaller than the sum of the biasing forces of the main elastic member 42 and the upper elastic member 25. When the valve is closed, the valve remains closed. On the other hand, when the operating pressure exceeds the starting pressure P0, the Cv value increases linearly as the operating pressure increases. In addition, in this embodiment, the line B1 also corresponds to the relationship between the lift amount of the sub actuator 20 (or the increased displacement amount of the upper elastic member 25) and the operating pressure.

Furthermore, as shown by arrow B3 in FIG. 3, by varying the voltage applied to the piezo element of the sub-actuator 20 between, for example, 0 to 100V, the Cv value can be adjusted even when the operating pressure of the main actuator 10 is constant. It can be changed within a predetermined range. That is, by combining the main actuator 10 and the sub actuator 20, the Cv value can be adjusted within the Cv value adjustment range B2 shown by hatching. In this way, by using the sub-actuator 20, it becomes possible to perform delicate valve opening adjustments that cannot be controlled by the main actuator 10.

Note that FIG. 3 shows a case where no voltage is applied to the piezo element in the steady state of the sub-actuator 20. In this case, the application of voltage to the sub-actuator 20 pushes down the operating member 30, and the Cv value adjustment range B2 is provided below line B1. However, the present invention is not limited to this, and a predetermined voltage may be applied when the sub actuator 20 is in a steady state. In this case, the Cv value adjustment range B2 is provided so as to cover the upper and lower sides of the line B1, or above the line B1.

Further, as described above, when the operating pressure is less than the starting pressure P0, the valve device 100 maintains the closed state. Therefore, even in the closed state, if a predetermined pressure lower than the starting pressure P0 is always applied to the main actuator 10, the response of startup can be improved.

FIG. 4 shows the configuration of a pressure-type flow control device 200 that includes the valve device 100. The flow control device 200 is provided between a throttle section 1 having a fine opening (orifice), a valve device 100 serving as a control valve provided upstream of the throttle section 1, and the throttle section 1 and the valve device 100. A pressure sensor 2 and a temperature sensor 3 are provided. In addition to an orifice member such as an orifice plate, a critical nozzle or a sonic nozzle may be used as the constriction part 1. The diameter of the orifice or nozzle is set to, for example, 10 μm to 2500 μm. A plurality of orifices may be provided. Further, the downstream side of the flow rate control device 200 is connected to a process chamber (not shown) via a cutoff valve 5.

The control unit 4 is connected to the pressure sensor 2 and the temperature sensor 3 via an AD converter, and is an electro-pneumatic regulator that supplies compressed air at an arbitrary pressure to the sub actuator 20 of the valve device 100 and the main actuator 10 of the valve device 100. (Pressure regulator) 55 is also connected. The control unit 4 generates a control signal based on the outputs of the pressure sensor 2 and the temperature sensor 3, and controls the operation of the valve device 100.

The flow rate control device 200 satisfies the critical expansion condition P _U /P _D ≧ approximately 2 (where P _U is the gas pressure on the upstream side of the constriction section (upstream pressure), P _D is the gas pressure on the downstream side of the constriction section (downstream pressure). (approximately 2 for nitrogen gas), the flow velocity of the gas passing through the constriction part 1 is fixed at the sonic velocity, and the flow rate is determined by the upstream pressure P _U and not by the downstream pressure P _D. Performs flow control. When the critical expansion condition is satisfied, the flow rate Q on the downstream side of the throttle section 1 is given by Q = K1 · P _U (K1 is a constant that depends on the type of fluid and the fluid temperature), and the flow rate Q is determined by the pressure sensor 2. It is proportional to the measured upstream pressure P _U . Further, in another embodiment, when a pressure sensor (not shown) is provided on the downstream side of the throttle part 1, the difference between the upstream pressure P _U and the downstream pressure P _D is small and the critical expansion condition is not satisfied. can also calculate the flow rate, and based on the measured upstream pressure P _U and downstream pressure P _D , Q = K2 P _D ^m (P _U - P _D ) ⁿ (where K2 is the fluid type and The flow rate Q can be calculated from temperature-dependent constants (m and n are indices derived based on the actual flow rate). Further, the flow rate Q may be calculated by also taking into account the temperature output from the temperature sensor 3.

A target flow rate is input to the control unit 4 in order to perform flow rate control. The control unit 4 calculates the flow rate based on the output of the pressure sensor 2 (upstream pressure _PU ), etc., and performs feedback control of the valve device 100 so that the calculated flow rate approaches the input target flow rate. More specifically, a control signal for the operating pressure is sent to the electropneumatic regulator 55 and a control signal for the voltage applied to the piezo element of the sub-actuator 20 is sent to correspond to the target flow rate.

The actual operation control of the valve device 100 may be performed in various ways. To give an example, first, based on the input target flow rate, an appropriate one of a plurality of preset operating pressure values is selected, and the electropneumatic regulator 55 is set to the selected operating pressure ( stepwise control). After the operating pressure reaches the set pressure, the calculated flow rate is calculated based on the output of the pressure sensor 2, and the piezo element drive voltage of the sub-actuator 20 is feedback-controlled so that the calculated flow rate matches the target flow rate. do. As a result, it is possible to appropriately control the flow rate from a small flow rate to a large flow rate while taking advantage of the features of the sub actuator 20 having excellent responsiveness and control accuracy. Note that the calculated flow rate may be displayed as a flow rate output value.

Although the embodiments of the present invention have been described above, various modifications are possible. For example, although the embodiment in which a piezo actuator is used as a sub-actuator is described above, the present invention is not limited to this, and an actuator that includes a material that can be deformed by electrical drive, such as an electrically driven polymer material or an electroactive polymer material, can also be used. It can also be used. Note that electrical driving includes applying a voltage to the element, passing a current through the element, or forming an electric field around the element. Further, instead of the piezo actuator, an actuator including a solenoid that utilizes magnetic force may be used.

Further, although a normally closed type valve device has been described above, a normally open type valve device may be used. In this case as well, the opening degree of the valve can be adjusted by controlling the operating pressure of the main actuator and the driving voltage of the auxiliary actuator. Furthermore, although the above description does not specifically mention the operating temperature of the valve device, by using appropriate materials, it is possible to create a structure that can be used at high or low temperatures. In addition, by creating a structure in which an extension (separation member, not shown) can be inserted between the lower end of the piezo element and the diaphragm holder, it is possible to prevent the piezo element from being affected by temperature (high or low temperature). You can also do it.

Furthermore, although a pressure-type flow rate control device has been described above, the above-mentioned valve device can also be used as a control valve for other types of flow rate control devices, such as a thermal mass flow controller equipped with a thermal type flow rate sensor. It is possible. Furthermore, in an ALD process or the like, it is also possible to utilize the above-mentioned valve device as a high-speed opening/closing valve provided downstream of a flow rate control device.

The valve device according to the embodiment of the present invention is suitably used, for example, as a control valve of a pressure-type flow rate control device.

10 Main actuator 12a, 12b, 12c Piston 14a, 14b, 14c Pressure chamber 20 Sub-actuator 22 Projection 24 Wiring 25 Upper elastic member 26 Lid material
30 Operating member 32 Diaphragm presser 34 Diaphragm valve body 36 Holder adapter 38 Cylindrical wall member 40 Valve housing 40a Bonnet 40b Middle housing 40c Upper housing 40d Upper cover 42 Main elastic member 50 Supply pipe 55 Electropneumatic regulator (pressure regulator) )
60 controller 100 valve device 150 valve drive system 200 flow rate control device

Claims (6)

a valve body that can be moved into and out of the valve seat;
an operating member connected to the valve body;
a main actuator for moving the operating member, the main actuator being operated by a driving fluid;
a pressure regulator that adjusts the pressure of the driving fluid supplied to the main actuator;
a sub-actuator that is provided movably together with the operating member by the main actuator and that is extendable by electrical drive;
an elastic member that biases the sub-actuator in the direction of the valve body ;
A lid member interposed between the elastic member and the sub-actuator, which does not restrict movement in the direction of the valve element even when the valve element is seated on the valve seat, and the elastic member a lid member arranged so as to be able to transmit the biasing force of the member to the sub-actuator;
Equipped with
A valve device configured to be able to continuously control the valve opening to any desired valve opening between closed and maximum opening by adjusting the pressure of the driving fluid and adjusting the extension of the sub-actuator. further comprising: a valve housing fixed to the flow path block, the valve housing including an upper cover that accommodates a portion of the sub-actuator, the lid member, and the elastic member;
The lid material is slidable along the inner peripheral surface of the upper cover, and the inner peripheral surface of the upper cover does not restrict movement of the lid material even when the valve body is seated on the valve seat. It is configured as follows.
Claim: The valve body is configured such that the pressing force of the valve body in a state where the valve body is seated on the valve seat can be adjusted by adjusting the position of the upper cover or the biasing force of the elastic member. 1. The valve device according to 1. The main actuator moves the operating member against the biasing force of the elastic member by the driving fluid whose pressure is adjusted by the pressure regulator, and the biasing force of the elastic member is increased by elongation of the sub-actuator. The valve device according to claim 1 or 2 , wherein the valve device is configured to move the operating member by moving the operating member. The main actuator includes an air-driven actuator having a piston that engages the operating member,
The sub-actuator includes a piezo actuator,
The valve device according to any one of claims 1 to 3, wherein the pressure regulator includes an electropneumatic regulator. The valve device according to any one of claims 1 to 4, further comprising a main elastic member that biases the flange portion of the operating member toward the valve body. A constriction section provided in the flow path;
A control valve provided on the upstream side of the throttle portion and configured by the valve device according to any one of claims 1 to 5;
a pressure sensor that measures fluid pressure between the throttle section and the control valve;
A flow control device comprising: a control section that controls opening and closing operations of the control valve based on the output of the pressure sensor.