JP2006018599A - Mass flow rate controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mass flow rate controller capable of miniaturizing the entire device and substantially reducing an occupancy area especially. <P>SOLUTION: The mass flow rate controller for controlling a mass flow rate comprises: a casing body 42 extended in a vertical direction, whose inside is made hollow; a flow rate control valve 10 provided with a valve which can be seated to a valve port communicated with a fluid exit through a secondary side space; an actuator mechanism 26 for pressurizing the valve; a bypass flow path 12 arrayed in the vertical direction in parallel with the actuator mechanism; a fluid introducing path 74 for communicating an entrance head space and a fluid entrance; a sensor pipe 14 communicated between the entrance header space and an exit header space and provided so as to be extended upwards along the actuator mechanism and then bent downwards; a communicating path 48 for communicating the exit header space and the primary side space of the flow rate control valve; and a control circuit part 16 provided above the actuator mechanism so as to drive the actuator mechanism such that a detected mass flow rate matches with a set flow rate inputted from the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mass flow controller for controlling a mass flow rate of a fluid having a relatively small flow rate such as a gas.

In general, in order to manufacture a semiconductor product such as a semiconductor integrated circuit, for example, CVD film formation and etching operations are repeatedly performed on a semiconductor wafer or the like in various semiconductor manufacturing apparatuses. For example, a mass flow controller such as a mass flow controller is used (for example, Patent Document 1, Patent Document 2, Patent Document 3).
This type of mass flow control device has a flow control valve having a diaphragm or the like that can be bent as a valve body, and a flow rate is branched at a constant ratio in order to detect a mass flow rate of flowing gas or the like. A mass flow rate detector having a sensor tube and a bypass flow path is provided. Of the four resistance wires forming the bridge circuit, two resistance wires connected in series are sequentially wound around the sensor tube along the fluid flow direction, and the fluid flows from the upstream side. The amount of heat transferred to the downstream side is grasped as a voltage change for balancing the bridge circuit, and the mass flow rate of the flowing fluid is thereby detected. And the control circuit part which consists of a computer etc. controls the valve opening degree of the said flow control valve so that the value of this detected mass flow volume may correspond with the setting flow volume input from the outside.

JP 2001-184127 A Japanese Patent Laid-Open No. 2-138582 US Pat. No. 6,543,466

By the way, in the field of semiconductor manufacturing technology and the like, the size of the wafer substrate has become larger and the unit floor area of the clean room is very expensive. There is an increasing demand for miniaturization of manufacturing equipment. Under such circumstances, further miniaturization of each member constituting the semiconductor manufacturing apparatus is also demanded, and the mass flow control apparatus frequently used in the semiconductor manufacturing apparatus is no exception.
However, each mass flow control device disclosed in each of the above-mentioned Patent Documents 1 to 3 is not produced by the design concept of downsizing as described above. There was a problem that the area (foot space) has become considerably large.
The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a mass flow control device capable of downsizing the entire device and particularly greatly reducing the occupied area.

  The invention according to claim 1 is a mass flow control device that detects a mass flow rate of a fluid and controls the mass flow rate so that the detected flow rate matches a set flow rate input from the outside. A casing main body provided with a fluid inlet and a fluid outlet at the bottom, and a valve port provided at the bottom of the casing main body and communicated with the fluid outlet via a secondary space. A flow control valve having a valve body that can be seated on the actuator, an actuator mechanism that is provided along the vertical direction to press the valve body, and is arranged in the vertical direction in parallel with the actuator mechanism. A bypass flow path having an inlet header space formed on the inlet side and an outlet header space formed on the lower outlet side, and a fluid introduction path communicating the inlet header space and the fluid inlet A sensor tube that is communicated between the inlet header space and the outlet header space and that extends upward along the actuator mechanism and is bent downward; and the outlet The actuator mechanism is driven so that the mass flow detected through the communication path communicating with the header space and the primary space of the flow rate control valve and the sensor pipe matches the set flow rate input from the outside. Therefore, a mass flow control device comprising a control circuit unit provided above the actuator mechanism.

  In this way, the bypass passage that takes up a relatively large occupied space is installed along the same vertical direction as the length direction of the actuator mechanism, and the sensor tube is also bent along the length direction of the actuator mechanism. Since it is arranged, the entire apparatus can be reduced in size, and in particular, the occupied area can be greatly reduced.

In this case, for example, as defined in claim 2, the actuator mechanism includes a laminated piezoelectric element, a pressing member in contact with the upper surface of the valve body, and a connecting member that connects the laminated piezoelectric element and the pressing member. It is configured.
For example, as defined in claim 3, the bypass passage is arranged in a ring shape so as to surround the connection member and the laminated piezoelectric element.
For example, as defined in claim 4, the bypass passages are arranged in a ring shape so as to surround the periphery of the connecting member.

For example, as defined in claim 5, the communication path is a through hole formed in the valve body.
For example, as defined in claim 6, the communication path is a ring-shaped channel formed along the inner peripheral surface of the bottom of the casing body.
Further, for example, as defined in claim 7, the valve body is made of a diaphragm which is elastically bendable.

  According to an eighth aspect of the present invention, there is provided a mass flow controller for detecting a mass flow rate of a fluid and controlling the mass flow rate so that the detected flow rate coincides with a set flow rate inputted from the outside. And a casing body provided with a fluid inlet and a fluid outlet at the bottom, and arranged in the casing body along the vertical direction, and communicated with the fluid inlet on the lower inlet side. An inlet header space is formed, and a bypass passage having an outlet header space formed on the upper outlet side is provided above the bypass passage, and communicated with the outlet header space via a primary side space. A flow control valve having a valve body that can be seated on the valve port, an actuator mechanism provided along a vertical direction to press the valve body, the inlet header space, and the outlet port. A sensor pipe provided so as to be bent downward after extending upward along the actuator mechanism, and a secondary side space of the flow control valve; In order to drive the actuator mechanism so that the mass flow rate detected via the sensor tube and the fluid flow path communicating with the fluid outlet matches the set flow rate input from the outside, the actuator mechanism is disposed above the actuator mechanism. And a control circuit unit provided.

According to the mass flow control device of the present invention, the following excellent effects can be achieved.
A bypass passage that takes up a relatively large occupied space is installed along the same vertical direction as the length direction of the actuator mechanism, and the sensor tube is also bent along the length direction of the actuator mechanism. Therefore, the entire apparatus can be reduced in size, and the occupied area can be significantly reduced.

Hereinafter, an embodiment of a mass flow controller according to the present invention will be described in detail with reference to the accompanying drawings.
<First embodiment>
First, a first embodiment of the present invention will be described.
1 is a cross-sectional configuration diagram showing a first embodiment of a mass flow control device of the present invention, FIG. 2 is a plan view showing a diaphragm which is a valve body, FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a principle explanatory diagram for explaining the principle of a general mass flow controller, and FIG. 5 is a principle explanatory diagram for explaining the principle of a sensor unit.

First, prior to describing the device of the present invention, the principle of a general mass flow control device will be described with reference to FIGS. 4 and 5.
As shown in the figure, the mass flow rate control device 2 is arranged in the middle of a fluid passage for flowing a fluid such as liquid or gas, for example, a gas pipe 4 to control the mass flow rate. The semiconductor manufacturing apparatus connected to one end of the gas pipe 4 is evacuated, for example. The mass flow control device 2 has a flow path 6 formed of, for example, stainless steel, and the uppermost stream of the flow path 6 is a fluid inlet 6A and the lowermost stream is a fluid outlet 6B. Then, both ends of the flow path 6 are connected to the gas pipe 4. The mass flow control device 2 includes a sensor unit 8 located on the front stage side of the flow path 6 and a flow control valve 10 located on the rear stage side.

  First, the sensor unit 8 has a bypass flow path 12 provided on the upstream side of the flow direction of the gas fluid in the flow path 6 and formed by bundling a plurality of bypass pipes. Sensor pipes 14 are connected to both ends of the bypass flow path 12 so as to bypass it, so that a small amount of gas fluid can flow at a constant ratio as compared with the bypass flow path 12. It has become. That is, a part of the gas having a constant ratio with respect to the total gas flow rate is always supplied to the sensor tube 14. A pair of control resistance wires R1 and R4 connected in series are wound around the sensor tube 14, and the resistance wires R1 and R4 are connected to a sensor circuit 18 of the control circuit unit 16, and this sensor circuit 18, a flow rate signal S1 indicating a mass flow rate value is output.

  The flow rate signal S1 is introduced into the control unit 20 made of, for example, a microcomputer, and the mass flow rate of the currently flowing gas is obtained based on the flow rate signal S1, and the mass flow rate is input from the outside. The flow rate control valve 10 is controlled to match the set flow rate represented by the set signal S0. The flow control valve 10 has a diaphragm 22 made of, for example, a metal plate that can be bent elastically as a valve body for directly controlling the mass flow rate of the gas fluid.

  The valve opening degree of the valve port 24 can be arbitrarily controlled by appropriately bending and moving the diaphragm 22 toward the valve port 24. The upper surface of the diaphragm 22 is connected to, for example, a lower end portion of an actuator mechanism 26 including a laminated piezoelectric element (piezo element), so that the valve opening can be adjusted as described above. . The actuator mechanism 26 operates by the valve drive voltage S2 output from the valve drive circuit 28 in response to the drive signal from the control unit 20. Note that an electromagnetic actuator may be used as the actuator mechanism 26 instead of the laminated piezoelectric element.

The relationship between the resistance lines R1 and R4 and the sensor circuit 16 is shown in FIG. That is, a series connection circuit of two reference resistors R2 and R3 is connected in parallel to the series connection of the resistance lines R1 and R4 to form a so-called bridge circuit. A constant current source 30 for flowing a constant current is connected to the bridge circuit. Also, a differential circuit 32 is provided by connecting the connection point between the resistance lines R1 and R4 and the connection point between the reference resistors R2 and R3 to the input side, and obtains the potential difference between the connection points. The potential difference is output as a flow rate signal S1.
Here, the resistance wires R1 and R4 are made of a material whose resistance value changes according to the temperature. The resistance wire R1 is wound on the upstream side in the gas flow direction, and the resistance wire R4 is on the downstream side. It is wound. Further, it is assumed that the reference resistors R2 and R3 are maintained at a substantially constant temperature.

In the mass flow control device 2 configured in this way, when the gas fluid does not flow through the sensor tube 14, the temperature of both the resistance lines R1 and R4 is the same, so the bridge circuit is balanced. The potential difference that is the detection value of the differential circuit 32 is, for example, zero.
Assuming that the gas fluid flows in the sensor pipe 14 at the mass flow rate Q, the gas fluid is heated by the heat generated by the resistance wire R1 located on the upstream side, and the downstream resistance wire R4 is wound in this state. As a result, a heat transfer occurs, resulting in a temperature difference between the resistance wires R1 and R4, that is, a difference in resistance value between the resistance wires R1 and R4, and a potential difference generated at this time. Is approximately proportional to the mass flow rate of the gas. Therefore, by applying a predetermined gain to the flow rate signal S1, the mass flow rate of the gas flowing at that time can be obtained. Further, the valve opening degree of the flow rate control valve 10 is controlled so that the detected mass flow rate of the gas matches the mass flow rate represented by the flow rate setting signal S0 (actually a voltage value). Here, the control circuit unit 16 includes an electric circuit, that is, a sensor circuit 18, a control unit 20, and a valve drive circuit 28.

Next, a first embodiment of the device of the present invention will be described with reference to the principle diagram as described above. The same components as those shown in FIGS. 4 and 5 are denoted by the same reference numerals, and the description thereof is omitted.
The feature of the present invention is that the bypass flow path is provided along the length direction (vertical direction) of the actuator mechanism, and the sensor tube is also bent in the length direction of the actuator mechanism, thereby greatly eliminating the occupied area. This is the point. As shown in FIG. 1, the mass flow controller 40 of the first embodiment has a casing body 42 that extends in the vertical direction and is hollow. The casing main body 42 is opened at the top and is provided with the fluid inlet 6A and the fluid outlet 6B described above at the bottom. The casing body 42 is formed of, for example, stainless steel and has a substantially square cross section.

  The upstream side of the gas pipe 4 (see FIG. 4) is connected to the fluid inlet 6A, and the downstream side of the gas pipe 4 is connected to the fluid outlet 6B. A flow rate control valve 10 for controlling the flow rate of gas (fluid) is provided at the bottom of the casing main body 42. Specifically, the flow control valve 10 includes a circular ring-shaped valve port 24 and a diaphragm 22 as a valve body that can be seated on the valve port 24. The valve port 24 communicates with the fluid outlet 6B through a secondary space 44 that is a fluid outlet side. The diaphragm 22 is made of a thin metal plate, and its peripheral portion is fixed to the inner peripheral surface side of the casing body 42, and a corrugation 45 is formed in a ring shape as shown in FIG. It can be bent in the direction of the valve port 24 and is seated on the valve port 24.

A space below the periphery of the diaphragm 22 is formed as a primary space 46 that is the inlet side of the valve port 24. A plurality of through holes 48 (see FIG. 2) are formed in the diaphragm 22 as communication passages that connect the primary side space 46 and an outlet header space, which will be described later, which is above the space. Gas is flowing.
An actuator mechanism 26 is provided above the diaphragm 22 so as to stand along the vertical direction and press the diaphragm 22. Specifically, the actuator mechanism 26 has a laminated piezoelectric element 50 such as a piezo element, and is connected to a pressing member 54 in contact with the upper surface of the diaphragm 22 via a connecting member 52 below the actuator element 26. .

  The laminated piezoelectric element 50 is accommodated in a cylindrical element accommodating case 56 disposed in the casing body 42, and the center of the bottom of the element accommodating case 56 is opened. A ring-shaped support flange 58 is formed on the outer periphery of the central portion of the element housing case 56. By supporting the support flange 58 on the inner step of the upper portion of the casing body 42, the entire actuator mechanism 26 is provided. Support. A circular ring-shaped fixing screw 60 is screwed and tightened to the upper end portion of the casing body 42 to fix the support flange 58 from above. The cylindrical element housing case 56 can be divided into an upper case 56A and a lower case 56B vertically by means of a screw connection 62 at the center, and the laminated piezoelectric element 50 can be taken in and out by separating them. It can be done.

  At the lower end of the laminated piezoelectric element 50, for example, a hemispherical hard sphere 64 for uniformly distributing the downward pressing force and a receiving member 66 for receiving the same are provided. Further, a disc spring 68 is provided on the lower surface of the receiving member 66 so that the peripheral edge portion is supported by the peripheral portion of the bottom portion of the element housing case 56. The disc spring 68 is provided in an inverted eight-shaped cross section, and the connecting member 52 is connected to the lower surface of the central portion of the disc spring 68. Therefore, when no drive signal is sent to the laminated piezoelectric element 50, the disc spring 68 presses the diaphragm 22 downward, so that the valve port 24 is closed, and when the drive signal is sent, the laminated piezoelectric element 50 moves downward. As a result of pushing the peripheral edge of the disc spring 68 downward, the central portion of the disc spring 68 moves upward, so that the diaphragm 22 also rises upward and the valve port 24 opens. As a result, a so-called normally closed operation can be realized.

  A cylindrical bellows 70 is provided between the lower surface of the element housing case 56 and the pressing member 54 so as to hermetically seal the inner and outer spaces. ing. In the space between the outer peripheral surface of the lower surface of the element housing case 56 and the inner peripheral surface of the casing main body 42, the upper and lower portions that are parallel to the actuator mechanism 26 and that are longitudinal in the outer peripheral portion thereof. Bypass channels 12 are arranged along the direction. It is desirable that the bypass flow path 12 is arranged in a ring shape along the vertical direction so as to surround the outer periphery of the actuator mechanism 26. The bypass flow path 12 is not formed in a ring shape as described above, but may be provided by being arranged along the vertical direction on the outer periphery so as to be in parallel with the actuator mechanism 26. The upper inlet side of the bypass passage 12 is formed as an inlet header space 72A through which gas flows in, and the lower outlet side is formed as an outlet header space 72B through which gas flows out. A fluid introduction path 74 is formed so as to communicate between the inlet header space 72 </ b> A and the fluid inlet 6 </ b> A provided at the bottom of the casing body 42.

  The sensor pipe 14 is provided so as to communicate between the inlet header space 72A and the outlet header space 72B. Specifically, the sensor tube 14 extends upward along the actuator mechanism 26 from the inlet header space 72A, then bends downward in a U shape (see also FIG. 3), and further extends downward. The front end of the support flange 58 passes through the outlet header space 72B. And resistance wire R1, R4 is wound in the middle of this sensor pipe | tube 14. As shown in FIG. In addition, the control circuit unit 16 that controls the entire apparatus is installed above the actuator mechanism 26, and the entire upper part of the apparatus is covered with an outer casing 76.

Next, the operation of the first embodiment will be described.
First, a gas as a fluid enters the fluid inlet 6A and then moves up the fluid introduction path 74 to reach the ring-shaped inlet header space 72A. Here, a part of the gas passes through the sensor tube 14 and forms a ring-shaped outlet header. It reaches the space 72B. Most of the gas in the inlet header space 72A passes through the bypass flow path 12 and reaches the outlet header space 72B. The gas in the outlet header space 72B flows into the primary space 46 below the diaphragm 22 through the communication hole 48 formed in the diaphragm 22 as shown in FIG. 2, and this gas further flows into the diaphragm. The flow rate is controlled through the valve port 24 whose valve opening degree is controlled by the vertical movement of the valve 22 and flows into the secondary space, and finally flows out from the fluid outlet 6B.

As a matter of course, the mass flow rate is detected by the gas flowing into the sensor tube 14, and the control circuit unit 16 converts the detected mass flow rate into a set flow rate (flow rate setting signal S0) input from the outside. The actuator mechanism 26 is driven so as to match, and the valve opening degree of the flow control valve 10 is controlled.
In this way, the bypass passage that takes up a relatively large occupied space is installed along the same vertical direction as the length direction of the actuator mechanism, and the sensor tube is also bent along the length direction of the actuator mechanism. Since it is arranged, the entire apparatus can be reduced in size, and in particular, the occupied area can be greatly reduced. Actually, in the conventional mass flow control device, the occupied area is 105 mm × 28.6 mm, but in the case of the first embodiment of the present invention having the same performance, the size is 28.6 mm × 28.6 mm. It was confirmed that the occupied area could be greatly deleted.

<Second embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 6 is a cross-sectional view showing a second embodiment of the mass flow control device of the present invention, and FIG. 7 is a cross-sectional view taken along line BB in FIG. In addition, the same code | symbol is attached | subjected about the same component as the component shown in FIG.1 and FIG.2, and the description is abbreviate | omitted.
In the second embodiment, in order to control a fluid having a larger flow rate than in the case of the first embodiment, the connection is made to connect the laminated piezoelectric element 50 side and the pressing member 54 on the upper surface of the diaphragm 22 which is a valve body. The member 52 is formed into a rod shape with a small radius and is formed long, whereby the accommodation cross-sectional area of the bypass flow path 12 is set to be large, and the cross-sectional area of the bypass flow path 12 is set to be large. Further, as shown in FIG. 7, the sensor tube 14 is bent in a semicircular shape along the circumferential direction in the middle of the laminated piezoelectric element 50 in the length direction. Further, here, the fixing screw 60 and the upper case 56A in the first embodiment are integrated, and the lid case 56C is screwed onto the upper part of the upper case 56A. Also in this case, the same effect as the first embodiment can be exhibited.

<Third embodiment>
Next, a third embodiment of the present invention will be described.
FIG. 8 is a sectional view showing a third embodiment of the mass flow control device of the present invention, and FIG. 9 is a plan view showing a diaphragm. In addition, the same code | symbol is attached | subjected about the same component as the component shown in FIG.1 and FIG.2, and the description is abbreviate | omitted.

  In the first embodiment, the diaphragm 22 is fixed to the casing body 42 side, and the through-hole 48 (see FIG. 2) is formed in the diaphragm 22 as a communication path. In the third embodiment, the diaphragm 22 is formed as an element. The housing case 56 is fixed to the lower case 56B side.

  That is, as shown in FIG. 8, in the third embodiment, the lower case 56B of the element housing case 56 is extended to the lower side, and a circular ring-shaped mounting bracket 80 is screwed to the lower end portion of the lower case 56B. The diaphragm 22 is fastened and fixed. A communication passage 82 that communicates the outlet header space 72B on the outlet side of the bypass passage 12 and the primary space 46 on the lower surface of the diaphragm 22 is formed along the inner peripheral surface of the bottom portion of the casing body 42. It is constituted by a ring-shaped space formed between the inner peripheral surface and the outer peripheral surface of the mounting bracket 80. Therefore, as shown in FIG. 9, the diaphragm 22 is not provided with the communication hole 48 provided in FIG. Also in this case, the same effect as the first embodiment can be exhibited.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described.
FIG. 10 is a front cross-sectional configuration diagram showing a fourth embodiment of the mass flow controller of the present invention, and FIG. 11 is a side cross-sectional configuration diagram. In addition, the same code | symbol is attached | subjected about the same component as the component shown in FIG.1 and FIG.2, and the description is abbreviate | omitted.
In the fourth embodiment, the arrangement positions of the flow control valve 10 and the bypass passage 12 in the first embodiment are provided upside down. That is, as shown in FIGS. 10 and 11, the bypass passages 12 are bundled together at the center, and the inlet header space 72 </ b> A on the lower inlet side communicates with the fluid inlet 6 </ b> A directly below. .

  Further, a flow rate control valve 10 having a diaphragm 22 (see FIG. 9) in which no through hole is provided is provided above the bypass passage 12, and a fluid inlet side below the central portion of the diaphragm 22 is provided. Is formed with a primary space 46, and the primary space 46 communicates with an outlet header space 72 B on the outlet side above the bypass passage 12. The outlet header space 72 </ b> B and the fluid outlet 6 </ b> B provided in the lower portion of the casing body 42 are communicated with each other through a fluid discharge path 86. An actuator mechanism 26 having a laminated piezoelectric element 50 is provided above the flow rate control valve 10 so that the valve opening degree of the diaphragm 22 can be controlled.

  The sensor pipe 14 is provided so as to communicate the inlet header space 72A and the outlet header space 72B of the bypass flow path 12. The sensor tube 14 extends upward along the actuator mechanism 26 in the same manner as in the second embodiment, and is bent in a semicircular shape along the circumferential direction in the middle of the actuator mechanism 26. It is provided so as to be bent downward. Also in this case, the same effect as the first embodiment can be exhibited.

It is a section lineblock diagram showing the 1st example of a mass flow control device of the present invention. It is a top view which shows the diaphragm which is a valve body. It is an AA arrow directional cross-sectional view in FIG. It is principle explanatory drawing for demonstrating the principle of a general mass flow control apparatus. It is principle explanatory drawing for demonstrating the principle of a sensor part. It is sectional drawing which shows 2nd Example of the mass flow control apparatus of this invention. FIG. 7 is a cross-sectional view taken along line B-B in FIG. 6. It is a section lineblock diagram showing the 3rd example of a mass flow control device of the present invention. It is a top view which shows a diaphragm. It is a front section lineblock diagram showing the 4th example of a mass flow control device of the present invention. It is a side section lineblock diagram showing the 4th example of a mass flow control device of the present invention.

Explanation of symbols

6A Fluid inlet 6B Fluid outlet 8 Sensor part 10 Flow control valve 12 Bypass flow path 14 Sensor pipe 16 Control circuit part 22 Valve body (diaphragm)
24 Valve 26 Actuator Mechanism 40 Mass Flow Control Device 42 Casing Body 44 Secondary Side Space 46 Primary Side Space 48 Communication Hole (Communication Path)
DESCRIPTION OF SYMBOLS 50 Multilayer piezoelectric element 52 Connection member 54 Press member 56 Element accommodation case 72A Inlet header space 72B Outlet header space 74 Fluid introduction path

Claims (8)

In a mass flow controller for detecting a mass flow rate of a fluid and controlling the mass flow rate so that the detected flow rate matches a set flow rate input from the outside,
A casing body that extends in the vertical direction and has a hollow inside, and is provided with a fluid inlet and a fluid outlet at the bottom,
A flow rate control valve having a valve body provided at a bottom portion in the casing body and configured to be seated on a valve port communicated with the fluid outlet via a secondary side space;
An actuator mechanism provided along the vertical direction to press the valve body;
A bypass channel that is arranged in the vertical direction in parallel with the actuator mechanism, an inlet header space is formed on the upper inlet side, and an outlet header space is formed on the lower outlet side;
A fluid introduction path communicating the inlet header space and the fluid inlet;
A sensor tube that is communicated between the inlet header space and the outlet header space and is provided to be bent downward after extending upward along the actuator mechanism;
A communication path communicating the outlet header space and the primary side space of the flow control valve;
A control circuit unit provided above the actuator mechanism for driving the actuator mechanism so that a mass flow rate detected via the sensor tube matches a set flow rate input from the outside;
A mass flow control device comprising:   The said actuator mechanism is comprised by the laminated piezoelectric element, the press member which touches the upper surface of the said valve body, and the connection member which connects the said laminated piezoelectric element and the said press member. Mass flow control device.   The mass flow rate control device according to claim 1, wherein the bypass flow path is arranged in a ring shape so as to surround the connection member and the multilayer piezoelectric element.   The mass flow controller according to claim 1, wherein the bypass flow path is arranged in a ring shape so as to surround the periphery of the connecting member.   The mass flow control device according to claim 1, wherein the communication path is a through hole formed in the valve body.   5. The mass flow controller according to claim 1, wherein the communication path is a ring-shaped flow path formed along an inner peripheral surface of a bottom portion of the casing body.   The mass flow control device according to claim 1, wherein the valve body is made of a diaphragm that is elastically bendable. In a mass flow controller for detecting a mass flow rate of a fluid and controlling the mass flow rate so that the detected flow rate matches a set flow rate input from the outside,
A casing body that extends in the vertical direction and has a hollow inside, and is provided with a fluid inlet and a fluid outlet at the bottom,
A bypass flow path which is arranged in the casing body along the vertical direction, and has an inlet header space communicating with the fluid inlet on the lower inlet side and an outlet header space formed on the upper outlet side; ,
A flow rate control valve provided above the bypass flow path and having a valve body that can be seated on a valve port communicated with the outlet header space via a primary side space;
An actuator mechanism provided along the vertical direction to press the valve body;
A sensor tube that is communicated between the inlet header space and the outlet header space and is provided to be bent downward after extending upward along the actuator mechanism;
A fluid discharge passage communicating the secondary side space of the flow control valve and the fluid outlet;
A control circuit unit provided above the actuator mechanism for driving the actuator mechanism so that a mass flow rate detected via the sensor tube matches a set flow rate input from the outside;
A mass flow control device comprising:

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