JP2003185035A - Gate valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of a bellows for cutting off communication of a fluid passage with other spaces. <P>SOLUTION: A pressing mechanism 64 is installed so as to be integrally deformed with a pressing plate 74 and provided with the bellows 90a, 90b for cutting off communication of the communicating chamber 24 formed between a first opening 12 and a second opening 14 with a gate chamber 26 of other spaces, and a cylindrical member 92 installed at the inner peripheral side of the bellows 90b, preventing the fluid passing through the communicating chamber 24 from flowing into the bellows 90b side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate valve that can be used, for example, in a high-purity gas system or an ultra-high vacuum system such as a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art Conventionally, gate valves have been used in high-purity gas systems and ultra-high vacuum systems such as semiconductor manufacturing equipment. This gate valve includes a valve box, a valve seat formed in the valve box, a valve plate that opens and closes a fluid passage by being seated on the valve seat or separated from the valve seat, and opening and closing the valve plate. In order to do so, a valve plate drive mechanism provided in the valve box is provided.

By the way, in the gate valve according to the prior art, when the processing gas is introduced into the fluid passage, the processing gas enters into the space of the valve plate drive mechanism and is adsorbed to the outer surface and the space of the valve plate drive mechanism. Since it adheres to the inner wall of the valve box that forms the above, there is a problem that it is difficult to remove the adhered gas.

Therefore, in the gate valve according to the prior art, the valve piston facing the inside of the valve box is swung by the drive piston mechanism provided outside the valve box, and the valve plate connected to the end of the valve box is moved. A configuration is adopted in which the fluid passage is opened and closed by performing a pendulum motion (for example, Japanese Patent Laid-Open No. 3-23).
(See Japanese Patent Publication No. 9884).

In this case, in the gate valve disclosed in Japanese Patent Laid-Open No. 3-239884, a ring-shaped bellows that expands and contracts along the axial direction under the action of the pressure fluid supplied through the pressure passage, A valve plate retainer is provided which is interlocked with the bellows and is integrally displaced toward the valve seat side.

That is, in the gate valve disclosed in JP-A-3-239884, when the fluid passage of the valve box is closed by the valve plate, the bellows and the valve plate are introduced by introducing the pressure fluid through the pressure passage. The presser is integrally displaced toward the valve seat side, and the valve plate presser is brought into contact with the valve plate. Further, the valve plate seated on the valve seat is pressed toward the valve seat side by the valve plate retainer to close the fluid passage.

On the other hand, when the valve plate swings and the fluid passage of the valve box is opened from the closed state, the bellows and the valve plate retainer are located closer to the valve seat side than in the closed state. The valve plate retainer is directly seated on the valve seat.

As a result, the gas flowing through the fluid passage is sealed by the bellows so as not to flow into the other space in the valve box. In other words, the space occupied by the valve plate drive mechanism in the valve box is provided so as to be completely cut off from the fluid passage by the bellows.

[0009]

However, in the conventional gate valve disclosed in Japanese Patent Laid-Open No. 3-239884, the by-product flowing in the fluid passage constitutes the inner wall surface of the metal bellows. Attached to the folds, the attached by-product is cooled and solidified. When the bellows shrinks, the solidified by-product may be sandwiched between the folds of the bellows to damage the bellows. As a result, there is a problem that the durability of the bellows deteriorates and the function of blocking the fluid passage from the space occupied by the valve plate drive mechanism deteriorates.

The present invention has been made in view of the above problems, and provides a gate valve capable of improving the durability of a blocking member for blocking communication between a fluid passage and another space. With the goal.

[0011]

In order to achieve the above-mentioned object, the present invention is directed to a drive mechanism and a main body portion having a fluid passage for communicating one first port with the other second port. The first port and the second port are connected to a valve disc that is swingably provided in an arc shape under biasing action and that opens and closes the fluid passage, and a pressing member that presses the valve disc or seats on a seat portion. A pressing mechanism provided with a blocking member for blocking communication between the communication chamber formed between the port and the other space, and a fluid provided in the communication chamber, which is provided on the inner peripheral side of the blocking member. And a protective member that prevents the member from entering the member side.

In this case, the blocking member may be formed of a ring-shaped metal bellows, and the protection member may be formed of a cylindrical member arranged on the inner peripheral side of the bellows.

It should be noted that one end of the cylindrical member along the axial direction is fixed to the pressing member and the other end is a free end extending along the fluid passage, and the cylindrical member is displaced integrally with the pressing member. It should be provided freely.

Further, the plate on which a seal member surrounding the first port or the second port is mounted is
By detachably holding the inner wall surface of the main body portion near the port or the second port, the plate can be easily replaced, and maintenance work time can be shortened.

According to the present invention, when the blocking member blocks the communication between the communication chamber and another space, the protective member prevents the fluid flowing into the communication chamber from entering the blocking member side. Therefore, by-products contained in the fluid are prevented from adhering to the blocking member and the durability of the blocking member is prevented from being deteriorated.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a gate valve according to the present invention will be described below with reference to the accompanying drawings.

1 and 2, reference numeral 10
FIG. 3 shows a gate valve according to the first embodiment of the present invention. The gate valve 10 is formed with a first opening (first port) 12 communicating with the chamber side and a second opening (second port) 14 communicating with the vacuum pump side facing each other. A body (main body) 18 in which a fluid passage that connects the first opening 12 and the second opening 14 is formed;
A valve disk 22 is provided so as to be swingable within a range of a predetermined angle within the internal space of the body 18 about a pivot 20 as a rotation center.

In the internal space of the body 18, the first chamber 12 on the chamber side and the second chamber 14 on the vacuum pump communicate with each other, and a communication chamber 24 through which a negative pressure fluid flows, and the communication chamber. And a gate chamber 26 that is provided on the upper side of 24 and functions as another space formed by the inner wall surface of the body 18.

The valve disc 22 has a shaft portion 28 pivotally attached to the pivot shaft 20 and a disc portion 30 formed in a substantially disc shape, which are integrally formed. As shown in FIG. When viewed, the axis of the shaft portion 28 is provided so as to intersect the axis of the disk portion 30 at a predetermined angle. A first seal member 32 is attached to the disk portion 30 along a substantially circular annular groove, and the first seal member 32 is seated on a seat portion 34 formed on the inner wall surface of the body 18, The first opening 12 is airtightly closed.

A cylinder mechanism 36 functioning as a drive mechanism is provided on the upper portion of the body 18, and the cylinder mechanism 36 has a set of pressure fluid inlet / outlet ports (not shown) communicating with the cylinder chamber. Cylinder tube 38
A piston (not shown) that reciprocates along the cylinder chamber, and a piston rod 40 having one end connected to the shaft portion 28 of the valve disc 22 and the other end connected to the piston.

In this case, as shown in FIGS. 1 and 2, a rectangular connecting portion 44 having a long groove 42 is provided at one end of the shaft portion 28 of the valve disc 22, and the one end portion of the shaft portion 28 is provided. And one end of the piston rod 40, which has a semicircular cross section, are connected via a pin member 46. That is, the shaft portion 28 of the valve disc 22 is provided so as to be vertically displaceable via the long groove 42 that engages with the pin member 46, and is also provided by the locking portion 48 formed at one end of the pin member 46. It is provided so as to be slightly separated from one end of the piston rod 40 along a substantially horizontal direction.

Further, a hole portion 50 facing the shaft portion 28 of the valve disc 22 is formed on the upper side of the body 18, and the hole portion 50 covers a part of the shaft portion 28 so as to be swingable. The metal bellows 52 is closed. One end of the bellows 52 is locked to a first plate 54a fixed to the body 18, and the other end is locked to a second plate 54b fitted to the shaft 28. The bellows 52 is formed so as to be expandable and contractable along the shaft portion 28 that swings integrally with the disc portion 30 when the disc portion 30 of the valve disc 22 swings in an arc shape.

The pivot 20 is a shaft portion 28 of a valve disc 22.
The one end portion 20a of the pivot 20 is provided so as to be exposed to the outside by a predetermined length by penetrating the elongated hole 56 formed in the body 18 (see FIG. 2). A spherical portion 58 is formed at the other end of the pivot 20, and the spherical portion 58 is inserted into a spherical hole formed on the inner wall surface of the body 18, and the spherical portion 58 serves as a fulcrum for the body 18. One end 20a of the pivot 20 exposed to the outside is provided so as to be displaceable. A spring member 60 is attached to one end portion 20a of the pivot shaft 20 exposed to the outside of the body 18, and the spring member 60 is attached to a convex portion 62 formed by protruding a predetermined length from the body 18 in a substantially horizontal direction. It

Therefore, the pivot shaft 20 is always biased upward by the spring force of the spring member 60, and by overcoming the spring force of the spring member 60, the pivot shaft 20 is inserted into the elongated hole 56. It is provided so that it can be tilted along it.

In the body 18, the pressing mechanism 6 for seating the first seal member 32 on the seat portion 34 by pressing the disk portion 30 of the valve disc 22 in a substantially horizontal direction.
4 are provided.

As shown in FIG. 2, the pressing mechanism 64 is fixed to one side surface of the body 18 having the second opening 14, and a hole portion that allows the first opening 12 and the second opening 14 to communicate with each other. A fixed plate 68 on which 66 is formed, and the hole 6
A substantially donut-shaped actuator 70 provided so as to surround 6 and an annular pressing plate (pressing member) 74 that advances and retreats toward the disk portion 30 of the valve disc 22 under the driving action of the actuator 70. .

An opening 72 having a substantially circular cross section is formed in the pressing plate 74, and the opening 7 is formed.
The second seal member 76 is mounted along the annular groove that surrounds 2. The second seal member 76 has a sealing function by sitting on the seat portion 34 formed on the inner wall surface of the body 18 (see FIG. 5), and the second seal member 76 contacts the disk portion 30. A shock absorbing function is absorbed to absorb the impact.

The actuator 70 is formed by combining an annular recess having a rectangular cross section of the fixed plate 68 and an annular recess having a rectangular cross section of the body 18, and a pressure fluid is supplied through a pressure fluid supply port 78. Annular pressure chamber 80
An annular pressing piston 82 that is slidably displaced along the axial direction of the pressure chamber 80, and the annular pressing piston 82.
A plurality of pressing rods 84 that are connected to each other at a predetermined angle.
And an annular spring member 8 for urging the pressing piston 82.
6 and 6, respectively.

An annular pressing plate 74 is connected to an end portion of the pressing rod 84, and the pressing piston 82, the pressing rod 84 and the pressing plate 74 are provided so as to be integrally displaced.

Further, as shown in FIG. 3, a pair of ring-shaped bellows (blocking members) 90a, 90b having one end connected to the pressing plate 74 and the other end connected to the fixed plate 88. Is provided. This bellows 9
0a and 90b are made of metal materials having different diameters, and have a double structure of an outer peripheral bellows 90a and an inner peripheral bellows 90b. A plurality of pressing rods 84 are disposed between the pair of bellows 90a and 90b, and the pressing rods 84 are sealed by the bellows 90a and 90b. The bellows 90a and 90b have a function of blocking communication between the communication chamber 24 and the gate chamber 26, as described later.

Further, on the inner peripheral side of the bellows 90b, as shown in FIG. 3, the first opening 12 and the second opening 14 are formed.
A cylindrical member (protective member) 92 is provided that extends along a fluid passage communicating with and. One end portion 92a of the cylindrical member 92 is fixed to the pressing plate 74 and is provided so as to be integrally displaced with the pressing plate 74. The other end 92b of the cylindrical member 92 is formed at a free end movably provided on the inner wall surface of the second opening 14 through a predetermined clearance. Since the fluid flowing through the fluid passage flows from the first opening 12 on the chamber side toward the second opening 14 on the vacuum pump side, the second opening 14 side of the cylindrical member 92 may be a free end. Because.

By providing the cylindrical member 92, the fluid flowing through the fluid passage is prevented from being introduced to the bellows 90a, 90b side, and by-products are prevented from adhering to the folds of the bellows 90a, 90b. be able to.

In this case, the pressing piston 82, the pressing rod 84 and the pressing plate 74 are attached so as to be integrally displaced toward the seating portion 34 (the disc portion 30 of the valve disc 22) by the spring force of the spring member 86. On the other hand, the pressure fluid is supplied from the pressure fluid supply port 78 to the pressure chamber 80, so that the pressing piston 82, the pressing rod 84, and the pressing plate 74 resist the spring force of the spring member 86. 34 (disc part 30 of the valve disc 22) is provided so as to be integrally displaced in a direction away from it.

The gate valve 10 according to the first embodiment of the present invention is basically constructed as described above. Next, its operation, function and effect will be explained.

First, the first opening 12 on the chamber side and the second opening 14 on the vacuum pump side are set to communicate with each other, and a pressure fluid is supplied to the pressure chamber 80 from a pressure fluid supply source (not shown). Then, the state in which the pressing piston 82, the pressing rod 84, and the pressing plate 74 are urged in the direction of separating from the disc portion 30 of the valve disc 22 against the spring force of the spring member 86 is set as the initial position. At the initial position, the disc portion 30 of the valve disc 22 is assumed to be in the position shown by the chain double-dashed line in FIG.

At the initial position, a pressure fluid is supplied from a pressure fluid supply source (not shown) to one of the cylinder chambers to urge the cylinder mechanism 36, whereby the piston and the piston rod 40 are displaced along the arrow X1 direction. .
The disc portion 3 of the valve disc 22 is inserted through the shaft portion 28 that engages with one end portion of the piston rod 40 through the pin member 46.
0 swings in a circular arc shape around the pivot 20 by a predetermined angle.

In this case, the pin member 46 that engages with the long groove 42 of the connecting portion 44 provided at one end of the shaft portion 28 is the long groove 4.
By displacing along the axis 2, the disk part 30 can be smoothly swung about the pivot 20 as the center of rotation.

When the disc portion 30 of the valve disc 22 swings by a predetermined angle and reaches a position facing the first opening 12 under the displacement action of the piston rod 40 constituting the cylinder mechanism 36, the disc portion 30 moves. Stop the swing motion. At that time, the first seal member 32 mounted on the disk portion 30 is not seated on the seat portion 34, and is in a state in which a predetermined gap is provided between the seat portion 34 and the seat portion 34 (see FIG. 4). .

When the disk portion 30 of the valve disk 22 faces the first opening 12 with a predetermined gap therebetween, the pressure fluid supplied to the pressure chamber 80 is stopped, and the pressure in the pressure chamber 80 is stopped. Discharge the fluid to the outside. The pressure in the pressure chamber 80 is reduced, and the spring force of the spring member 86 is changed to the pressure chamber 80.
By overcoming the internal pressure, the pressing piston 82, the pressing rod 84, the pressing plate 74, and the cylindrical member 92 are integrally displaced toward the disk portion 30 side, and the disk portion 30.
Press.

The pressing plate 74 presses the disk portion 30 toward the seating portion 34 under the action of the spring force of the spring member 86, whereby the pivot shaft 20 and the valve disc 22 are integrally tilted slightly, and The first mounted on the disc part 30
The seal member 32 is seated on the seat portion 34, and the first opening 12
Is blocked. The second seal member 76 of the pressing plate 74
A cushioning function is carried out when abuts on the side surface of the disk portion 30 (see FIG. 2).

When the pivot 20 tilts integrally with the valve disc 22, the spring member 60 attached to the one end 20a of the pivot 20 is pressed to cause the elongated hole 5 formed in the body 18.
Displace along 6.

Thus, in the state where the first opening 12 is closed by the disk portion 30 of the valve disc 22,
In order to open the first opening 12, a pressure fluid is supplied to the pressure chamber 80 by a pressure fluid supply source (not shown),
The pressing piston 82, the pressing rod 84, and the pressing plate 74 are displaced in the opposite direction to the spring force of the spring member 86, and the pressing plate 74 is separated from the disk portion 30 of the valve disc 22.

The pressing plate 74 is separated from the valve disc 2
When the pressing force applied to the disc portion 30 of the second disc is released, the disc portion 30 of the valve disc 22 has the one end portion 20a of the pivot shaft 20.
The spring force of the spring member 60 attached to the
The force that biases the shaft slightly upward acts, and the shaft 28
The valve disc 22 connected to the pivot shaft 20 via the seat is separated from the seat 34 by a predetermined distance.

When the valve disc 22 is separated from the seat portion 34 by a predetermined distance, a predetermined clearance is formed between the valve disc 22 and the pressing plate 74 so that the valve disc 22 does not contact the inner wall surface of the body 18. It is assumed to be in a state.

Therefore, the cylinder mechanism 36 is urged to swing the disc portion 30 of the valve disc 22 in an arcuate direction in the direction opposite to that described above, thereby returning to the initial position.

At the initial position, the pressure fluid in the pressure chamber 80 is discharged to the outside. The pressure in the pressure chamber 80 is reduced and the spring force of the spring member 86 overcomes the pressure in the pressure chamber 80, whereby the pressing piston 82 and the pressing rod 8 are pressed.
4, the pressing plate 74 and the cylindrical member 92 are integrally displaced toward the first opening 12 side, and the second seal member 76 of the pressing plate 74 directly abuts on the seating portion 34 of the first opening 12. It is sealed (see FIG. 5).

The pressing plate 74 is displaced under the urging action of the pressing mechanism 64 and is seated on the seating portion 34 of the first opening 12, so that the first opening 12 on the chamber side and the second opening 12 on the vacuum pump side. A communication chamber 24 that communicates with the opening 14 is formed, and the communication chamber 24 is closed airtightly with the gate chamber 26, which is another space in the body 18, by being closed by the bellows 90a and 90b having a sealing function. Separately formed. Therefore, it is possible to prevent the gas or the like flowing through the communication chamber 24 from leaking from the communication chamber 24 to the outside.

As a result, even when the valve disc 22 swings and is separated from the first opening 12 by a predetermined angle, in other words, the valve disc 22 does not face the first opening 12, the pressing plate is pressed. By displacing 74 and directly seating it in the first opening 12, the communication chamber 24
The airtightness of can be maintained.

In the first embodiment of the present invention, a cylindrical member 92 is provided on the inner peripheral side of the bellows 90b and the bellows 90b is provided.
The bellows 90b is protected so that the fluid flowing through the fluid passage does not enter the b side. Therefore, in the first embodiment, it is possible to prevent the by-product contained in the fluid flowing through the fluid passage from adhering to the folds of the bellows 90b and deteriorating the durability of the bellows 90b. As a result, the durability of the bellows 90b is improved, and the bellows 9b
The maintenance cycle for 0b can be extended.

Also, in the first embodiment, the communication chamber 24
Corrosion can be reduced because the gas flowing through the chamber does not always enter the gate chamber 26 side.

Further, in the first embodiment, when the gas is flowed to the chamber side and the vacuum pump side is evacuated to exhaust the gas, the valve disc 22 is moved to the first opening portion 1 on the chamber side.
Since it is not opposed to No. 2, it is possible to prevent a seal defect due to adhesion of by-products, and it is not necessary to attach a heater for preventing adhesion of by-products in the vicinity of the gate. Therefore, by preventing the by-products from adhering to the first seal member 32, it is possible to prevent the generation of dust due to the separated by-products and maintain a clean environment.

Furthermore, in the first embodiment, the pressing mechanism 64 for pressing the valve disc 22 is constructed with a simple structure, so that it can be manufactured at low cost.

Next, FIG. 6 shows a gate valve 100 according to a second embodiment of the present invention. In the following embodiments, the same constituent elements will be denoted by the same reference symbols, and detailed description thereof will be omitted.

The gate valve 100 according to the second embodiment is provided with a portion near the inner wall surface of the first opening 12.
A pair of protrusions 105a, each of which includes a sealing plate 104 on which a sealing member 102 surrounding the first opening 12 is mounted,
105b for holding the sealing plate 104
The inner wall surface of the first opening 12 and the disc portion 3 of the valve disc 22.
It is characterized in that it is detachably interposed between 0 and 0. A circular hole is formed in the sealing plate 104, and the groove portion of the seal member 102 is attached to the thin seal holding portion 106 formed in the peripheral portion of the hole.

By detachably providing the sealing plate 104 on which the sealing member 102 is mounted, the sealing plate 104 can be easily replaced in a short time, and the maintenance work time can be shortened. You can

In addition, the valve disk 22 has a first seal member 3
The thickness of the valve disc 22 can be reduced since it is not necessary to mount the valve 2 directly. Further, by reducing the expansion amount of the bellows 90a, 90b as compared with the conventional technique, the durability of the bellows 90a, 90b can be improved.

Next, FIG. 7 shows a gate valve 110 according to a third embodiment of the present invention.

In the gate valve 110 according to the third embodiment, the pivot 114 is rotatably supported by the body 18 via a pair of bearing members 112a and 112b, and
A spring portion 11 in which a part of the shaft portion 28 of the valve disc 22 is made thin and is swingably formed of a material having a spring property.
6 is provided. Therefore, the spring portion 116 of the shaft portion 28 is
The feature is that the disk portion 30 is tilted under the action of.

As described above, by providing the spring portion 116 having the spring property on a part of the shaft portion 28 of the valve disc 22, the spring member 60 and the convex portion 62 are not required, the number of parts is reduced and the manufacturing cost is reduced. It can be reduced.

[0060]

According to the present invention, the following effects can be obtained.

That is, when the communication between the communication chamber and another space is blocked by the blocking member, the fluid flowing into the communication chamber is prevented from entering the blocking member side by the protective member, so It is possible to prevent the contained by-products and the like from adhering to the blocking member and improve the durability of the blocking member.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view of a gate valve according to a first embodiment of the present invention.

2 is a vertical cross-sectional side view of the gate valve shown in FIG.

3 is a partially omitted enlarged vertical cross-sectional view of the gate valve shown in FIG. 2. FIG.

FIG. 4 is an operation explanatory view of the gate valve shown in FIG.

5 is an operation explanatory view of the gate valve shown in FIG. 1. FIG.

FIG. 6 is a vertical sectional side view of a gate valve according to a second embodiment of the present invention.

FIG. 7 is a vertical sectional side view of a gate valve according to a third embodiment of the present invention.

[Explanation of symbols]

10, 100, 110 ... Gate valves 12, 14 ... Openings 18 ... Body 20, 114 ...
Axis 22 ... Valve disk 24 ... Communication chamber 26 ... Gate chamber 28 ... Shaft 30 ... Discs 32,76,1
02 ... Seal member 34 ... Seating portion 36 ... Cylinder mechanism 44 ... Connecting portion 46 ... Pin members 52, 90a, 90b ... Bellows 56 ... Long hole 58 ... Spherical portion 60, 86 ... Spring member 64 ... Pressing mechanism 70 ... Actuator 74 ... Pressing plate 80 ... Pressure chamber 82 ... Pressing piston 84 ... Pressing rod 92 ... Cylindrical member 104 ... Sealing plate 116 ... Spring part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuhiro Someya             4-2-2 Kinnodai, Taniwahara Village, Tsukuba-gun, Ibaraki Prefecture             SMC Corporation Tsukuba Technology Center (72) Inventor Shogo Miyazaki             4-2-2 Kinnodai, Taniwahara Village, Tsukuba-gun, Ibaraki Prefecture             SMC Corporation Tsukuba Technology Center F-term (reference) 3H053 AA02 AA21 AA31 BD05 DA08                       DA09                 3H066 AA03 BA11 BA38

Claims (4)

[Claims] 1. A main body portion in which a fluid passage that connects one first port and the other second port is formed, and is provided so as to be swingable in an arc shape under the biasing action of a drive mechanism,
A valve disc that opens and closes the fluid passage, a communication chamber formed between the first port and the second port, which is connected to a pressing member that presses the valve disc or seats on a seat, and another space. A pressing mechanism provided with a blocking member for blocking communication between the blocking member, and a protection member provided on the inner peripheral side of the blocking member for blocking the fluid flowing through the communication chamber from entering the blocking member side. A gate valve characterized in that. 2. The gate valve according to claim 1, wherein the blocking member is formed of a ring-shaped metal bellows, and the protection member is formed of a cylindrical member arranged on an inner peripheral side of the bellows. A gate valve that is characterized by 3. The gate valve according to claim 2, wherein one end portion of the cylindrical member along the axial direction is fixed to the pressing member, and the other end portion is a free end extending along the fluid passage, The gate valve, wherein the cylindrical member is provided so as to be displaceable integrally with the pressing member. 4. The gate valve according to claim 1, wherein a seal member surrounding the first port or the second port is attached to an inner wall surface of the main body portion adjacent to the first port or the second port. A gate valve characterized in that the plate is detachably held.