JP2631594B2 - Gate valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate valve mainly used in a high-purity gas system and an ultra-high vacuum system.

[0002]

2. Description of the Related Art Conventionally, in a gate valve used in a high-purity gas system or an ultra-high vacuum system, a valve body for opening and closing a through hole provided in a pair of flange portions at opposite positions in a valve box is usually used. Is movably supported at a valve-closing position facing the through-hole and a valve-opening position at which the space facing the through-hole is opened without facing the through-hole.

That is, when the valve is open, it is necessary that there is no valve body or the like that obstructs flow between the pair of flanges. Therefore, when the valve is opened, the valve is separated from the through hole. Position, and at the time of closing the valve, after a movement operation of moving the valve body to the valve closing position facing the through hole, a sealing operation of pressing the valve body against a seal portion around the through hole of the flange portion is started. Is necessary.

As a means for performing the sealing operation and the sealing releasing operation, there has been conventionally used a method in which a valve mechanism is pressed against a seal portion around a through hole using a link mechanism. A method in which high-pressure gas is applied to press the valve body against the seal around the hole, and a method in which mechanical driving force is transmitted from outside to the valve assembly through the bellows, and the valve body is pressed against the seal by the driving force. and so on.

However, these systems have the following problems. That is, in a gate valve, the flow path of a high-purity gas system or an ultra-high vacuum system that is opened and closed by the gate valve is usually in an atmosphere of a vacuum or low-pressure high-purity gas, and dislikes slight contamination by foreign substances. It is necessary to avoid the generation of dust due to abrasion or the like in the sliding portions of the valve member and the like.

[0006] Further, since the high-purity gas system or the ultra-high vacuum system described above is usually in a low pressure state, the bellows for supplying high-pressure fluid to the bellows for operating the valve element and the like is not used. The pressure difference between the inside and outside of the bellows is large, and it is necessary to take measures to damage the bellows. When the bellows breaks, the pressure fluid flows into the vacuum system, which diffuses into the system and significantly contaminates the entire system. In order to avoid such a problem, it is necessary to increase the pressure resistance of the bellows, but this increases the size of the valve opening / closing mechanism.

In addition, when the valve closing force is generated by the pressure of the fluid directly acting on the bellows, a pressure acting area corresponding to the magnitude of the valve closing force is required, and this also increases the size of the apparatus. . Further, in a system in which a mechanical driving force is transmitted from outside to the valve assembly through the bellows and the valve body is pressed against the sealing portion by the driving force, it is necessary to cause the valve body to perform the moving operation and the sealing operation. It is inevitable that the device becomes complicated or large.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to generate an operating force for sealing a gate valve on the outside of a valve box and, at the same time, construct a valve body with a simple valve plate. As a result, the drive part in the system is eliminated and the cause of dust generation is eliminated, and the structure is simplified and miniaturized.
Another object of the present invention is to make it possible to easily perform maintenance such as an operation force source outside the vacuum system.

[0009]

According to the present invention, there is provided a gate valve, comprising: a valve plate for opening and closing a through hole in a valve box; a valve closing position facing the through hole; A pressing member that movably supports a valve opening position that opens a portion facing the valve plate and that presses the valve plate against a seal around the through hole is provided on a peripheral portion behind the valve plate that is in the valve closing position. An operating force source for pressing and separating the valve plate to and from the seal portion is provided outside the valve box, and a pressing force transmission mechanism from the operating force source to the pressing member is provided within the valve box by the valve box and the pressing member. isolating Then bets from the valve chamber in the valve housing by bellows provided between the
In addition, a space defined by the bellows is opened to the outside .

In the above gate valve, the bellows for isolating the pressing force transmission mechanism from the operating force source to the pressing member from the valve chamber is provided between the valve box and the outer peripheral portion of the annular pressing member corresponding to the seal portion. Or the inner peripheral bellows provided between the valve box and the inner peripheral portion of the annular pressing member, or evenly from the operating force source to the annular pressing member corresponding to the seal portion. A bellows is provided between the valve box and the pressing member so as to individually cover each of the plurality of pressing force transmission mechanisms arranged, and the bellows is used to control the pressing force transmission mechanism by the valve in the valve box. Can be isolated from the room.

[0011]

When the gate valve is in the open state, the valve plate is held at the open position by the opening / closing actuator. In order to close the valve from this open state, the valve plate is moved to the valve closing position. In this movement, the valve plate can be easily prevented from contacting the valve box or the like. There is no sliding portion at. When the valve is closed from the above-mentioned open state, after the moving operation of moving the valve closing portion of the valve plate to the valve closing position facing the hole, the sealing operation of pressing the valve plate against the sealing portion around the through hole of the flange. Is performed.

That is, the state in which the pressing member presses the valve plate by the operating force source is released, and the valve closing portion of the valve plate is moved to a position facing the through hole by the operation of the opening / closing actuator. In the position, the valve plate is pressed against the seal portion of the flange via the pressing member by driving of the operating force source,
Close the valve. Also, the valve plate by the pressing member by the operating force source
When the pressure is released, the pressure contact with the seal of the valve plate is released.
Actuation of the opening / closing actuator causes the valve plate to shrink.
The valve moves to the valve open position without sliding with respect to the ruler portion.

According to the above configuration, when the operating force for sealing the valve plate is generated outside the valve box, the structure of the valve plate can be constituted by a simple plate material, and the driving portion in the system can be constituted by a simple plate. Eliminating the cause of dust generation and simplifying its structure,
It is possible to reduce the size and to easily perform maintenance of the operation force source and the like outside the vacuum system. Also, with bellows
For pressing the pressing member against the seal part in the partitioned space
Since there is no need to supply compressed air, etc.
Since the pressure difference of the fluid used is small, the strength of the bellows is low.
It can be cheaper.

[0014]

1 and 2 show the structure of an oscillating gate valve according to a first embodiment of the present invention. The gate valve includes flanges 2 and 3 provided at opposing positions in the valve box 1.
In this valve box 1, a valve plate 6 for opening and closing the through hole 4 of one of the flanges 2 is disposed. The valve plate 6 has a flat valve closing portion 6a facing the through hole 4 and closing the same, and a valve opening portion 6b holding the valve in an open state by an opening having substantially the same shape as the through hole 4. And a valve rod 7 attached thereto for opening and closing the through hole 4.
Is swingably supported outside of the valve box 1 by a swing support shaft 8. The valve plate 6 has a valve opening 6 in particular.
It is not necessary to provide b, and it is also possible to provide only the valve closing portion 6a which faces the through hole 4 and closes it.

The valve plate 6 has a valve closing position (a dotted line position) where the flat valve closing portion 6a faces the through hole 4 of the flange 2 and a position where the valve closing portion 6a is completely removed from the through hole 4. Go to
The valve-opening portion 6b having an opening is movable to a valve-opening position (a position indicated by a two-dot chain line) facing the through hole 4. In order to perform this movement, the valve rod 7 is provided outside the valve box 1 at the outside. An opening / closing actuator 9 is attached. The valve rod 7
And the valve box 1 are connected by a bent bellows 10, and the valve box 1
The internal valve chamber 11 is isolated from the outside. Although FIG. 1 schematically shows a case where a fluid pressure cylinder is used as the opening / closing actuator 9, a rotary actuator, a motor, or the like may be used.

The valve plate 6 closes the through hole 4 by pressing the valve closing portion 6a against a sealing material 13 in a sealing portion around the through hole 4, and closes the through hole 4. An annular pressing member 14 for pressing the valve plate 6 against the seal around the through hole 4 is provided opposite to the peripheral portion of the rear side. The pressing member 14 has a sealing member 15 which is in pressure contact with the back surface of the valve plate 6, but this sealing member 15 is not always necessary, and may have a function of preventing dusting due to metal contact. .

The pressing member 14 is provided with an operating force source 16 for pressing the valve plate 6 against the sealing portion of the flange 2. The operating force source 16 presses the pressing member 14 against the valve plate 6 for closing the valve via a plurality of pressing force transmission mechanisms 17 uniformly arranged on the annular pressing member 14. As the pressing force transmitting mechanism 17, a link mechanism or the like as schematically illustrated can be used. In this case, as the operating force source 16, an arbitrary actuator that presses the link connecting portion 18 is used. Can be used.

The operating force source 16 is provided outside the valve box 1. The pressing force transmitting mechanism 17 for transmitting the operating force from the operating force source 16 to the pressing member 14 is provided with a valve box. A large-diameter outer bellows 20 and a small-diameter inner peripheral bellows 21 provided between the valve member 1 and the pressing member 14 are isolated from the valve chamber 11 in the valve box 1. The outer peripheral bellows 20
Is a valve box 1 and an annular pressing member 14 corresponding to a seal portion.
The inner peripheral bellows 21 is provided between the valve box 1 and the inner peripheral portion of the pressing member 14, and these bellows are: Valve box 1
It is attached to the pressure member 14 by welding or the like so as to maintain airtightness, and maintains the vacuum in the valve box 1. Therefore, the operating force source 16 and the pressing force transmission mechanism 17 are disposed outside the valve box 1 at atmospheric pressure.

The swing type gate valve having the above structure is
When it is in the valve-open state, the valve plate 6 is opened by the opening / closing actuator 9 (in FIG.
(A two-dot chain line inclined only to the left). In this open state, the valve opening portion 6b of the valve plate 6
The through hole 4 of the flange 2 and the through hole 5 of the flange 3 are in a conductive state. In this case, the valve plate 6 is connected to the sealing material 13 of the flange 2 via the pressing member 14 by driving the operating force source 16.
Although it may be held in a state of being pressed against, it is not particularly necessary.

When the valve is closed from the above-mentioned open state, after the valve plate 6 is moved to the valve closing position facing the through hole 4, the valve plate 6 is moved around the through hole of the flange 2. It is necessary to carry out a step of starting a sealing operation of pressing against the sealing material 13 of FIG.

Specifically, the valve plate 6 is held released from the pressing member 14 by the operating force source 16, and the valve plate 6 integrated with the valve rod 7 is swingably supported by the operation of the opening / closing actuator 9. By swinging about the shaft 8 by 2θ, the valve closing portion 6a of the valve plate 6 is moved to a position facing the through hole 4 (a position indicated by a dotted line in FIG. 1). The surface of the seal member 13 provided on the flange 2 of the valve box 1 is opposed. After the movement of the valve plate 6, the valve plate 6 is pressed against the sealing member 13 of the flange 2 via the pressing member 14 by driving the operating force source 16, and the valve closing is completed.

When the valve plate 6 is moved, the pressing member 1
When the valve 4 is retracted, a predetermined clearance is maintained so that the seat surface of the valve plate 6 does not come into contact with the sealing material 13 and the valve plate 6 does not come into contact with the sealing material 15 of the pressing member 14. There are no mechanical sliding parts inside.

FIGS. 3 and 4 show a swing type gate valve similar to that of the first embodiment, in which a plurality of pressing force transmission mechanisms from an operating force source to a pressing member are individually covered with bellows. An example is shown. That is, in the second embodiment, a valve plate 26 is provided which opens and closes a through-hole by being pressed against a seal member 33 of a valve box 30, and a push-up member from an operating force source 36 constituted by an appropriate actuator to an annular pressing member 34. As shown in FIG. 4, the pressure transmitting mechanism 37 is evenly arranged around the pressing member 34, and when the pressing force transmitting mechanism 37 is isolated from the valve chamber 31, a plurality of pressing force transmitting mechanisms 3 are provided.
7 are individually encapsulated by bellows 40 hermetically attached by welding or the like between valve box 30 and pressing member 34, and pressing force transmitting mechanism 37 is provided by these bellows 40.
Is isolated from the valve chamber 31 in the valve box. The operation of this embodiment is substantially the same as that of the first embodiment.

In the above two embodiments, the pressing members 14,
Reference numeral 34 designates the valve plates 6 and 26 as sealing materials 13 and 3 for the valve boxes 1 and 30.
The pressure plate 3 is pressed against the pressure plate 3, but a pressing member, its operating force source, a pressing force transmission mechanism, and the like are provided on both sides of the valve plates 6 and 26, and the valve plate is sandwiched from both sides by a pressing member having a seal portion. You can also Further, here, the swing type gate valve has been described as an example, but the present invention is not limited to the swing type gate valve, but may be applied to various types of gate valves that move a valve plate between an open position and a closed position. Can be applied.

[0025]

As described in detail above, according to the present invention, in a gate valve mainly used in a high-purity gas system or an ultra-high vacuum system, the operating force for sealing the valve plate is controlled by the valve box. Since it is generated on the outside, the structure of the valve plate can be composed of a simple plate material, eliminating the need for driving parts in the system to eliminate the cause of dust generation, and making the structure simple and compact. This makes it possible to easily perform maintenance of the operating force source and the like outside the vacuum system.

Since the operating force for sealing the valve plate is generated outside the valve box, the following effects can be expected. a. By reducing the surface area of the valve chamber, the amount of gas released when the valve chamber is evacuated can be reduced. b. Any actuator can be used as the operating force source for generating the above operating force, and the present invention can be applied to a metal seal requiring a strong sealing force. c. Unlike the conventional example in which the sealing force is obtained by applying a high pressure to the bellows, the bellows is only subjected to the differential pressure between the atmospheric pressure and the vacuum, so that its strength does not need to be increased and its manufacture is easy. d. Since the valve plate can be formed by a simple plate material, the valve plate is light in weight, has no failure, and can be downsized in a valve plate moving mechanism such as swinging.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of the present invention.

FIG. 2 is a side sectional view of the embodiment.

FIG. 3 is a side sectional view of a main part of a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional front view of a valve box according to the second embodiment.

[Explanation of symbols]

1,30 valve box, 4,5,24
Through hole, 6,26 Valve plate, 11,3
1 valve chamber, 14, 34 pressing member, 16,
36 operating force source, 17, 37 pressing force transmission mechanism,
20 outer bellows, 21 inner bellows,
40 Bellows.

Claims (3)

(57) [Claims] A valve plate for opening and closing a through hole in a valve box is movably supported between a valve closing position facing the through hole and a valve opening position opening a portion facing the through hole. A pressure member for pressing the valve plate against the seal portion around the through hole is provided opposite to the peripheral portion behind the valve plate at the valve closed position, and an operating force source for pressing and separating the valve plate from the seal portion. Is provided outside the valve box, and the pressing force transmission mechanism from the operating force source to the pressing member is isolated from the valve chamber in the valve box by a bellows provided between the valve box and the pressing member in the valve box . Vero above
A gate valve, wherein a space defined by a nozzle is opened to the outside . 2. A bellows for isolating a pressing force transmission mechanism from an operating force source to a pressing member from a valve chamber, comprising: a valve box;
An outer peripheral bellows provided between the outer peripheral portion of the annular pressing member corresponding to the seal portion, and an inner peripheral bellows provided between the valve box and the inner peripheral portion of the annular pressing member. The gate valve according to claim 1, wherein a pressing force transmission mechanism between the bellows is isolated from a valve chamber in the valve box. 3. A bellows for isolating a pressing force transmission mechanism from an operating force source to a pressing member from a valve chamber is provided with a plurality of pressing members arranged uniformly from the operating force source to an annular pressing member corresponding to a seal portion. The bellows provided between the valve box and the pressing member so as to individually enclose each of the pressure transmitting mechanisms, and the pressing force transmitting mechanism is isolated from the valve chamber in the valve box by these bellows. The gate valve according to claim 1, wherein: