JP4860506B2 - Control valve - Google Patents

Description

  The present invention relates to a control valve used for fluid control.

  Conventionally, in production lines for semiconductors, pharmaceuticals, etc., control valves have been used to control fluids such as pure water, acid, and alkali. The control valve may be designed to be metal-free so that it can be applied even when the object to be controlled is acid, alkali, or the like.

FIG. 5 is a cross-sectional view of a conventional control valve 100, in which the fully closed state is indicated by a solid line, and the position of the indicator 107 when fully opened is indicated by a two-dot chain line.
In the conventional control valve 100, a body is composed of a body 101, a cylinder 102 and a cover 103. A piston rod 104 is slidably loaded in the cylinder 102. A diaphragm 105 is attached to the lower end of the piston rod 104, and the diaphragm 105 is brought into contact with or separated from a valve seat 106 provided on the body 101. An indicator 107 is fixed to the upper end portion of the piston rod 104. The indicator 107 protrudes to the outside from a through hole 108 formed in the cover 103, and its position is detected by a photo sensor 109 fixed to the cover 103.

  In such a control valve 100, when the diaphragm 105 is in contact with the valve seat 106, the indicator 107 protrudes from the cover 103 by a predetermined amount while the diaphragm 105 is separated from the valve seat 106, as shown by the solid line in the figure. The indicator 107 protrudes from the cover 103 larger than when fully closed, as indicated by a two-dot chain line in the figure. Therefore, if the amount of protrusion of the indicator 107 is detected by the photosensor 109, the valve opening / closing state of the control valve 100 can be detected (see, for example, Patent Document 1).

JP 2001-153261 A

  However, when the conventional control valve 100 is a metal-free design in which the material of the valve portion including the diaphragm 105, the valve seat 106, and the like is made of resin, the valve portion changes over time as the valve opening / closing operation is repeated. Or creep. When secular change or creep occurs, the piston rod 104 is lowered from the initial state to bring the diaphragm 105 into contact with the valve seat 106, so that the position of the indicator 107 when fully closed is lower than the initial position. Even in this case, the conventional control valve 100 detects the valve closed state based on the initial position of the indicator 107. Therefore, when the indicator 107 moves to the initial position, the valve is slightly opened. The fully closed state was detected. This is not preferable because, for example, when the control valve 100 is used for drainage control of acid and alkali, the acid and alkali are mixed.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a control valve that can reliably detect the fully closed state of the valve portion.

The control valve according to the present invention has the following configuration.
(1) A valve for detecting a valve open / closed state, by reciprocating a piston rod in a piston chamber formed in a valve body, thereby bringing a valve body connected to the piston rod into contact with or separating from a valve seat. In the control valve having an open / close detection mechanism, the piston rod includes a first piston member slidably housed in the piston chamber, a rod portion to which the valve body is coupled, and a piston having a larger diameter than the rod portion. And a second piston member in which the piston portion is housed in the piston chamber in a state where the rod portion is slidably penetrated through the first piston member, and the valve body is the valve seat. A gap is formed between the first piston member and the second piston member when the first piston member is in contact with the piston. The locked are locked position when in tons chamber moves to the valve seat side is for detecting a fully closed state of the valve unit.

(2) In the invention described in (1), the first piston member is formed with a recess for accommodating the piston portion, and a seal member is provided between the inner peripheral surface of the recess and the outer peripheral surface of the piston portion. Has been placed.

(3) In the invention described in (1) or (2), a first urging member that urges the first piston member toward the valve seat, and a urging the second piston member toward the valve seat. A second urging member that is provided in the valve body, and an operation port that supplies and exhausts operation air that acts on the end face of the first piston member on the valve seat side.

(4) In the invention described in (3), the first urging member has a smaller urging force than the second urging member.

  In the control valve of the present invention, the piston rod is divided into the first piston member and the second piston member, and when the valve body is in contact with the valve seat, a gap is provided between the first piston member and the second piston member. Is formed. Therefore, for example, when the valve portion composed of a valve body, a valve seat, and the like has changed over time or creeped, the valve closing position where the second piston member contacts the valve body with the valve seat has changed from the initial time. However, the first piston member moves to the valve seat side in the piston chamber and stops at the same locking position as in the initial stage. Since the valve opening / closing detection mechanism detects the locking position of the first piston member as a fully closed state of the valve portion, even if the valve closing position changes from the initial time, the valve position is determined based on the locking position of the first piston member. Continue to detect the fully closed state of the part at one point. Therefore, according to the control valve of the present invention, the fully closed state of the valve portion can be reliably detected.

  In the control valve of the present invention, the piston portion of the second piston member is housed in the recess formed in the first piston member, and the seal member is disposed between the recess and the piston portion. It is possible to prevent fluid leakage from between the piston member.

  The control valve of the present invention includes a resultant force of the first and second urging members that urges the first and second piston members toward the valve seat side, an end face on the valve seat side of the first piston member from the operation port, and a piston chamber. The valve is opened and closed by a balance with the pressure of the operating air supplied between the inner wall and the first piston member and acting on the first piston member in the direction opposite to the valve seat. The valve closing force is secured by the second biasing member, and the force for moving the first piston member to the locking position is secured by the first biasing member. Therefore, according to the control valve of the present invention, the first piston member can be returned to the locking position while maintaining the conventional valve closing force with a simple structure.

  In the control valve of the present invention, the first urging member has a smaller urging force than the second urging member and can move the first piston member with a force smaller than the second piston member. Even if the member is divided, the response of the valve opening / closing operation is hardly affected.

  Next, an embodiment of a control valve according to the present invention will be described with reference to the drawings.

<Overall configuration>
FIG. 1 is a sectional view of the control valve 1 and shows a fully closed state. FIG. 2 is a cross-sectional view of the control valve 1 and shows a state in which only the first piston member 14 is operating. FIG. 3 is a sectional view of the control valve 1 and shows a fully opened state.
The control valve 1 shown in FIGS. 1-3 is assembled | attached to a semiconductor manufacturing apparatus via the resin mounting plates 33, for example, and is used in order to discharge | emit waste liquids, such as an alkali and an acid. In the control valve 1, a body 2, a cylinder 3, and a cover 4 are fixed with bolts or the like (not shown) to constitute a “valve body”.

  The body 2 is formed by molding a resin into a rectangular parallelepiped shape. As for the body 2, the 1st port 5 and the 2nd port 6 are opened from the opposing side surface. On the inner peripheral surfaces of the first and second ports 5 and 6, female threads for connecting pipes (not shown) are formed. The body 2 has an opening 8 formed in a cylindrical shape from the upper surface, and an attachment step 9 is formed along the outer periphery of the opening 8. The diaphragm 10, which is an example of a “valve element”, is positioned by fitting the peripheral edge portion to the attachment stepped portion 9, and the peripheral edge portion is held between the body 2 and the cylinder 3. Thereby, the opening 8 is hermetically partitioned by the diaphragm 10, and the valve chamber 7 is formed by the inner wall of the opening 8 and the pressure receiving surface of the diaphragm 10.

  A valve seat 11 for communicating the first port 5 and the second port 6 is provided at the bottom of the valve chamber 7 so that the diaphragm 10 contacts or separates. In the present embodiment, the valve seat 11 is integrally formed with the body 2, but the valve seat 11 may be detachably attached to the body 2 as a separate member so that only the deteriorated valve seat 11 can be replaced.

  The cylinder 3 is formed by molding a resin into a rectangular parallelepiped shape. The cylinder 3 has a large-diameter cylindrical hollow hole and a small-diameter cylindrical hollow hole formed on the same axis. The cover 4 is a square plate-like resin molded product, and has a cylindrical boss portion 25 protruding therefrom. The cylinder 3 is fitted with a cover 4 so that the boss portion 25 is fitted into the opening of the large-diameter hollow hole without any gap to close the large-diameter hollow hole, and a piston chamber 12 is formed between the cover 4 and the cylinder 3. Yes. A piston rod 13 is slidably loaded in the piston chamber 12.

  The piston rod 13 includes a first piston member 14 and a second piston member 15, and a gap S is formed between the first piston member 14 and the second piston member 15 when the valve shown in FIG. The piston members 14 and 15 are formed by a first coil spring 26 that is an example of a “first urging member” and a second coil spring 27 that is an example of a “second urging member” (downward in the drawing). ). The piston structure will be described later.

  As shown in FIGS. 1 to 3, the piston chamber 12 is airtightly divided into an upper chamber and a lower chamber by a piston rod 13. An operation port 28 opened in the cylinder 3 communicates with the lower chamber of the piston chamber 12 to supply and exhaust operation air. On the other hand, the upper chamber of the piston chamber 13 communicates with a breathing hole 29 provided in the cover 4 and is opened to the atmosphere.

  Therefore, the piston rod 13 has a resultant force acting on the valve seat 11 side of the first and second coil springs 26 and 27 and an operating air supplied to the lower chamber of the piston chamber 12 and acting in the opposite direction to the valve seat 11. The piston chamber 12 reciprocates in accordance with the balance with the pressure. The piston rod 13 is connected to the diaphragm 10 and reciprocates in the piston chamber 12 to bring the diaphragm 10 into contact with or away from the valve seat 11. The valve opening / closing state in this case is detected by the valve opening / closing detection mechanism 32. The valve opening / closing detection mechanism 32 will be described later.

<Piston structure>
Next, the piston structure described above will be described. The piston rod 13 is divided into a first piston member 14 and a second piston member 15, and the first piston member 14 is closed when the second piston member 15 closes the diaphragm 10 against the valve seat 11. A movable gap S is provided.

  The first piston member 14 is a resin molded product and is slidably accommodated in the first piston chamber 12. The first piston member 14 has a cylindrical shape, and a recess 16 is formed in a cylindrical shape from the upper end surface in the drawing. Two annular grooves are formed in parallel on the outer peripheral surface of the first piston member 14. One (upper side in the figure) is provided with an O-ring 17 made of an elastic material such as rubber or resin to seal between the outer peripheral surface of the first piston member 14 and the inner peripheral surface of the piston chamber 12. ing. An annular magnet 18 is attached to the other (lower side in the figure) annular groove.

  The annular magnet 18 is fixed to the first piston member 14 by insert molding or an adhesive. The annular magnet 18 is disposed slightly inside the outer peripheral surface of the first piston member 14 so as not to damage the inner peripheral surface of the piston chamber 12.

  The second piston member 15 is a resin molded product. The second piston member 15 includes a rod portion 21 to which the diaphragm 10 is coupled, and a piston portion 20 having a larger diameter than the rod portion 21. The rod portion 21 and the piston portion 20 are integrally formed by injection molding or the like. The piston portion 20 has a cylindrical shape, and has an outer diameter that is substantially the same as the inner diameter of the concave portion 16, and is provided so as to overlap a part of the front end surface (lower end surface in the drawing) of the boss portion 25.

  The second piston member 15 slidably penetrates the rod portion 21 through a through hole formed in the central portion of the first piston member 14, and the piston portion 20 is fitted in the recess 16 of the first piston member 14. The piston part 20 is accommodated in the piston chamber 12. The rod portion 21 protrudes from the small diameter hollow hole of the cylinder 3 into the opening portion 8 of the body 2, and the diaphragm 10 is screwed. An O-ring 22 is disposed at the sliding contact portion between the rod portion 21 and the cylinder 3 to center the second piston member 15 and to seal the operation air.

  When the piston rod 13 is assembled by engaging the first and second piston members 14 and 15 in this way, the upper end surface of the first piston member 14 is around the piston portion 20 provided on the second piston member 15. And a step is provided between the first and second piston members 14 and 15. Further, the upper end surface of the first piston member 14 faces the front end surface (lower end surface in the drawing) of the boss portion 25 of the cover 4. The first coil spring 26 is contracted between the upper end surface of the first piston member 14 and the lower end surface of the boss portion 25 provided on the cover 4 so that the first piston member 14 faces the valve seat 11 (downward in the figure). ) Is always on. Due to the urging force of the first coil spring 26, the first piston member 14 is abutted against the bottom of the piston chamber 12 and locked. Accordingly, the bottom of the piston chamber 12 serves as a stopper that restricts the movement of the first piston member 14 toward the valve seat 11. A position where the first piston member 14 moves to the valve seat 11 side in the piston chamber 12 and is locked to the bottom of the piston chamber 12 is referred to as a “locking position”.

  In the second piston member 15, the piston part 20 fitted in the recess 16 of the first piston part 14 faces the cover 4. The second coil spring 27 is disposed inside the boss portion 25 and is contracted between the cover 4 and the piston portion 20. Therefore, the second coil spring 27 constantly urges the second piston member 15 toward the valve seat 11 (downward in the drawing). Due to the urging force of the second coil spring 27, the second piston member 15 brings the diaphragm 10 into contact with the valve seat 11. The second piston member 15 is disposed so that the piston portion 20 overlaps a part of the boss portion 25, and is provided so as to be able to contact and separate from the boss portion 25. Therefore, the lower limit of the stroke of the second piston member 15 is determined by the position of the valve seat 11 as shown in FIG. 1, and the upper limit is determined by the position of the tip surface (lower end surface) of the boss portion 25 as shown in FIG. It is done.

  As shown in FIG. 1, when the diaphragm 10 is in contact with the valve seat 11, the piston chamber 12 forms a gap S between the bottom of the recess 16 and the lower end surface of the piston 20 in the drawing. The bottom is provided. Therefore, the first piston member 14 is provided with a play that can move to the locking position after the second piston member 15 closes the valve in which the diaphragm 10 contacts the valve seat 11.

  A seal member 23 seals between the inner peripheral surface of the concave portion 16 of the first piston member 14 and the outer peripheral surface of the piston portion 20 of the second piston member 15. The seal member 23 is set to have a frictional resistance so as not to hinder the movement of the first piston member 14 relative to the second piston member 15 by the gap S.

  The first coil spring 26 has a smaller urging force than the second coil spring 27. That is, the second coil spring 27 is set to an urging force necessary to ensure the valve closing force. On the other hand, the first coil spring 26 is set to an urging force necessary to move the first piston member 14 to the locking position after the valve is closed.

<Valve open / close detection mechanism>
As shown in FIGS. 1 to 3, the valve opening / closing detection mechanism 32 includes an annular magnet 18 attached to the first piston member 14 and an MR element sensor 30 attached to the cylinder 3. The MR element sensor 30 is connected to a control device (not shown) via a wiring 31 and transmits a detection signal of a valve open / close state. The detection area of the MR element sensor 30 is set so as to cover the area in which the annular magnet 18 moves in the axial direction when the first piston member 14 reciprocates in the piston chamber 12.

  The MR element sensor 40 detects the position of the first piston member 14 from the position of the annular magnet 18 and detects the valve open / closed state. That is, the MR element sensor 30 detects the locking position of the first piston member 14 shown in FIG. 1 as a fully closed state of the valve portion, and the second piston member 15 contacts the boss portion 25 as shown in FIG. The position of the first piston member 14 when the upward movement is restricted by contact is detected as a fully opened state of the valve portion. Then, the MR element sensor 40 detects the valve open / closed state according to the movement amount of the first piston member 14 with reference to the locking position.

<Description of operation>
As shown in FIG. 1, in the control valve 1 having the above configuration, when the operation air is not supplied to the operation port 28, the first and second piston members 14 and 15 are connected to the first and second coil springs 26. , 27 are pushed downward in the figure. The first piston member 14 is urged by the first coil spring 26 to be pushed down to the locking position, while the second piston member 15 is urged by the second coil spring 27 to cause the diaphragm 10 to move to the valve seat 11. It is pushed down to the position where it abuts against Therefore, the valve closing force is secured only by the second coil spring 27. In this case, the control valve 1 is disconnected between the first port 5 and the second port 6, and the drainage supplied to the first port 5 is not discharged from the second port 6.

  At this time, the valve opening / closing detection mechanism 32 detects that the MR element sensor 30 is in the locking position based on the position of the annular magnet 18 and detects the fully closed state of the valve portion. This detection result is transmitted from the MR element sensor 30 to a control device (not shown) via the wiring 31.

  On the other hand, when the operation air is supplied to the operation port 28 and the pressure of the operation air acting on the lower surface of the first piston member 14 overcomes the urging force of the first coil spring 26, the first piston member 14 is shown in the figure. Start moving upward. While the first piston member 14 moves through the gap S, the upward force in the figure does not act on the second piston member 15 and the valve closed state is maintained.

  After that, as shown in FIG. 2, when the first piston member 14 is raised by the gap S and the bottom portion of the recess 16 is brought into contact with the piston portion 20 of the second piston member 15, the pressure of the operation air is changed to the first piston. It acts on the second piston member 15 via the member 14. When the pressure of the operation air overcomes the resultant force of the first and second coil springs 26 and 27, the first piston member 14 pushes up the second piston member 15 as shown in FIG. That is, the first and second piston members 14 and 15 rise integrally.

  Along with this, the second piston member 15 pulls up the diaphragm 10 and separates it from the valve seat 11. The first and second piston members 14 and 15 rise to a position where the pressure of the operating air and the resultant force of the first and second coil springs 26 and 27 are balanced. As a result, the drainage supplied to the first port 5 is adjusted to a flow rate corresponding to the valve opening and discharged from the second port 6.

  When the valve is opened, the MR element sensor 30 detects the movement of the first piston member 14 based on the annular magnet 18 and detects the valve opening according to the amount of movement from the locking position.

  Thereafter, the operation air is discharged from the operation port 28, and the resultant force of the first and second coil springs 26, 27 acting downward on the upper surfaces of the first and second piston members 14, 15 is the lower surface of the first piston member 14. When the pressure of the operating air acting upward is overcome, the first and second piston members 14 and 15 begin to descend integrally. Since the urging force of the first coil spring 26 is smaller than the urging force of the second coil spring 27, the first piston member 14 is lowered in such a manner that the bottom portion of the recess 16 is pushed down by the piston portion 20 of the second piston member 15.

  When the diaphragm 10 is brought into contact with the valve seat 11, the second piston member 15 is restricted from moving downward and stops. At this time, the first piston member 14 has not reached the locking position, and the downward movement is not restricted. Therefore, the first piston member 14 is separated from the second piston member 15 by the urging force of the first coil spring 26, is pushed down toward the valve seat 11, and continues to descend. The first piston member 14 descends by the gap S and stops descending when it is locked to the bottom of the piston chamber 12 as shown in FIG. That is, the first piston member 14 reaches the locking position.

  As shown in FIG. 1, the valve opening / closing detection mechanism 32 detects the fully closed state of the valve portion when detecting that the first piston member 14 is in the locking position, and transmits the detection result to a control device (not shown). . In the control valve 1, the second piston member 15 brings the diaphragm 10 into contact with the valve seat 11 before the first piston member 14 reaches the locking position. When the closed state is detected, the valve portion closes to shut off the drainage.

<Effect>
As described above, the control valve 1 of the present embodiment is the first when the piston rod 13 is divided into the first piston member 14 and the second piston member 15 and the diaphragm 10 is in contact with the valve seat 11. A gap S is formed between the piston member 14 and the second piston member 15 (see FIG. 1). For this reason, for example, when the valve portion including the diaphragm 10 and the valve seat 11 undergoes secular change or creep, the valve closing position where the second piston member 15 contacts the diaphragm 10 with the valve seat 11 is the initial position. The first piston member 14 moves to the valve seat side in the piston chamber 12 and stops at the same locking position as the initial stage. Since the valve opening / closing detection mechanism 32 detects the locking position of the first piston member 14 as a fully closed state of the valve portion, even if the valve closing position changes from the initial time, the locking position of the first piston member 14 is changed. As a reference, the fully closed state of the valve part is continuously detected at one point. Therefore, according to the control valve 1 of the present embodiment, the fully closed state of the valve portion can be reliably detected.

  In addition, since the conventional control valve 100 detects the piston rod 104 connected to the diaphragm 105, for example, if the stroke of the diaphragm 105 is as small as 0.2 to 0.3 mm, the displacement of the piston rod 104 can be detected. Therefore, it was difficult to detect the open / closed state of the valve part. However, since the control valve 1 of this embodiment has the clearance S between the first piston member 14 and the second piston member 15, the stroke of the diaphragm 10 is as small as 0.2 to 0.3 mm. Even if it exists, the stroke of the 1st piston member 14 can be ensured larger than the stroke of the diaphragm 10, and the valve opening / closing detection mechanism 32 can detect the displacement of the 1st piston member 14. FIG. Therefore, according to the control valve 1 of this embodiment, even when the stroke of the diaphragm 10 is small, the open / closed state of the valve portion can be reliably detected.

  In addition, the control valve 1 of the present embodiment houses the piston portion 20 of the second piston member 15 in the recess 16 formed in the first piston member 14, and places the seal member 23 between the recess 16 and the piston portion 20. Since it arrange | positions (refer FIGS. 1-3), it can prevent that a fluid leak arises between the 1st piston member 14 and the 2nd piston member 15. FIG.

  In addition, the control valve 1 of the present embodiment is configured so that the resultant force of the first and second coil springs 26 and 27 that urge the first and second piston members 14 and 15 toward the valve seat 11 and the operation port 28 are the first to the first. The valve opening / closing operation is performed by a balance with the pressure of the operation air supplied between the end surface of the piston member 14 on the valve seat 11 side and the inner wall of the piston chamber 12 and acting on the first piston member 14 in the direction opposite to the valve seat 11. (See FIGS. 1 to 3). The valve closing force is secured by the second coil spring 27, and the force for moving the first piston member 14 to the locking position is secured by the first coil spring 26. Therefore, according to the control valve 1 of the present embodiment, the first piston member 14 can be returned to the locking position while maintaining the conventional valve closing force with a simple structure. That is, the fully closed state of the valve portion can be reliably detected with a structure substantially similar to the conventional spring structure.

  Further, in the control valve 1 of the present embodiment, the first coil spring 26 has a smaller urging force than the second coil spring 27 and can move the first piston member 14 with a force smaller than the second piston member 15. Even if the first and second piston members 14 and 15 are divided, the responsiveness of the valve opening / closing operation is hardly affected.

  In addition, this invention is not limited to the said embodiment, Various application is possible.

(1) For example, in the above embodiment, the bottom of the piston chamber 12 is a stopper that determines the locking position. On the other hand, as shown in FIG. 4, a cylindrical stopper 45 is erected at a step portion between the large diameter hollow hole and the small diameter hollow hole of the cylinder 44, and the first piston member 45 is engaged by the stopper 45. A stop position may be determined.

(2) For example, in the above embodiment, a joint member or the like is screwed into the first and second ports 5 and 6 of the body 2. On the other hand, as shown in FIG. 4, one-touch joints (not shown) may be attached to the outer circumferences of the first and second ports 42 and 43.

(3) For example, in the above embodiment, the normally closed type control valve 1 has been described as an example, but the piston rod 13 of the above embodiment may be applied to a normally open type control valve.

(4) For example, in the said embodiment, the 1st and 2nd coil springs 26 and 27 were mentioned as an example of a 1st and 2nd biasing member. On the other hand, for example, the first coil spring 26 may be a leaf spring. Further, for example, the valve closing force may be secured by pressurizing the second piston member 15 by operating air instead of the second coil spring 26.

(5) For example, in the above embodiment, the valve opening / closing detection mechanism 32 is provided by the annular magnet 18 and the MR element sensor 30, but a valve opening / closing detection mechanism that detects the valve opening / closing state by an optical sensor is applied to the control valve 1. May be.

(6) For example, in the said embodiment, although the piston part 20 and the rod part 21 of the 2nd piston member 15 were integrally molded, a piston part and a rod part are provided separately and connected, and it can also serve as a 2nd piston member. Good.

It is sectional drawing of the control valve which concerns on embodiment of this invention, Comprising: A fully closed state is shown. It is sectional drawing of the control valve which concerns on embodiment of this invention, Comprising: It is a figure which shows the state which only the 1st piston member is operating. Similarly, it is sectional drawing of a control valve, Comprising: A full open state is shown. It is a modification of the control valve of this embodiment. It is sectional drawing of the conventional control valve, Comprising: A fully closed state is shown as a continuous line, and a fully open state is shown with a dashed-two dotted line.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control valve 2 Body 3 Cylinder 4 Cover 10 Diaphragm 11 Valve seat 13 Piston rod 14 1st piston member 15 2nd piston member 16 Recessed part 20 Piston part 21 Rod part 23 Seal member 26 1st coil spring (1st biasing member)
27 Second coil spring (second biasing member)
28 Operation port 32 Valve open / close detection mechanism S Clearance

Claims (4)

A valve opening / closing detection mechanism for detecting a valve opening / closing state by reciprocating a piston rod in a piston chamber formed in a valve body to bring a valve body connected to the piston rod into contact with or away from a valve seat. In a control valve having
The piston rod is
A first piston member slidably housed in the piston chamber;
A rod portion connected to the valve body; and a piston portion having a diameter larger than that of the rod portion, and the piston portion is slidably penetrated through the first piston member. A second piston member to be housed,
When the valve body is in contact with the valve seat, a gap is formed between the first piston member and the second piston member,
The valve opening / closing detection mechanism is
A control valve that detects a locking position that is locked when the first piston member moves toward the valve seat in the piston chamber as a fully closed state of a valve portion. The control valve according to claim 1,
The first piston member is formed with a recess for accommodating the piston portion,
A control valve, wherein a seal member is disposed between an inner peripheral surface of the concave portion and an outer peripheral surface of the piston portion. In the control valve according to claim 1 or 2,
A first biasing member that biases the first piston member toward the valve seat;
A second biasing member that biases the second piston member toward the valve seat;
An operation port that is opened in the valve body and that supplies and exhausts operation air that acts on an end surface of the first piston member on the valve seat side;
A control valve characterized by comprising: The control valve according to claim 3,
The control valve according to claim 1, wherein the first urging member has a smaller urging force than the second urging member.

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