JPH0461229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a switching valve for a skeleton chromatograph suitable for use in high-speed process measurement.

[Prior art] A process gas chromatograph holds a sample gas, passes this sample gas and carrier gas through multiple columns, separates the gas components, and sends them to the detection section, where each separated gas component is detected. A series of operations such as measuring the concentration and flushing the pipes and columns with carrier gas to clean them for the next sampling are automatically repeated according to a sequence. In order to improve the response speed, it is necessary to send a small amount of sample gas at high speed, so it is desirable that the diameter of the flow path such as the metering tube or column is extremely small, and the switching valve is also small and has a small internal capacity. .

Therefore, pneumatically driven diaphragm valves are generally used as this type of switching valve.
An example is shown in FIG. This switching valve has diaphragms 11 and 12 respectively disposed on the front and back surfaces of a center plate 10 having a plurality of passages A1 to An formed through the front and back surfaces, and a plurality of pistons D1 to Dn and E1 to En. These piston groups D1 to Dn are arranged corresponding to each passage A1 to An,
E1 to En are air pressures P applied alternately behind the piston via another diaphragm 13, 14.
By alternately operating the passage A1~
The upper route and the lower route of An are alternately switched. In addition, in the figure,
Air pressure P is supplied to the upper air pressure receiving chamber 17 to push down the upper piston group D1 to Dn all at once to close the upper route of the passages A1 to An, while the air pressure P is removed from the lower air pressure receiving chamber 18. The lower piston group E1 to En is lowered all at once by the gas pressure, and the lower route of the passages A1 to An is opened by the sample gas (or carrier gas) gas pressure.

[Problems to be Solved by the Invention] However, in the conventional switching valve described above, the pistons D1 to Dn and E1 to En are connected to the diaphragm 11,
12, the opening edges of the ports A1 to An and the diaphragm portions corresponding to these opening edges are prone to wear and tear, resulting in a lack of durability. In particular, when the diaphragm wears out, its closing characteristics as a valve deteriorate, resulting in gas leakage, and when gas leakage occurs, the sample gas is diluted by the carrier gas, reducing analysis accuracy.

Therefore, the present invention was made to solve the above-mentioned problems, and its purpose is to provide a gas chroma that prevents wear and tear of the diaphragm and improves durability and passage closing characteristics. An object of the present invention is to provide a switching valve for a tograph.

[Means for solving the problem] The switching valve for gas chromatograph according to the present invention has the following features:
In order to achieve the above purpose, the passage is opened by elastically deforming the diaphragm using gas pressure,
In a gas chromatograph switching valve that closes the passage by pressing the diaphragm with a plunger, a recess is provided on the surface of the plunger that contacts the diaphragm, and an O-ring is inserted into the recess. It is attached by protruding from the recess.

[Function] In the present invention, the O-ring is pressed against the diaphragm by the operation of the plunger, thereby avoiding direct contact between the plunger and the diaphragm. Furthermore, the contact area between the O-ring and the diaphragm is small, and a large surface pressure can be obtained, increasing the sealing effect.

[Example] Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of a gas chromatograph switching valve according to the present invention, and FIG. 2 is an exploded perspective view of the same valve. In these figures, the sample gas or carrier gas flow path in this embodiment is divided into 10
An example is shown below. The switching valve 20 includes a center plate 21 whose front and back surfaces are finished with high precision, and this center plate 21 has ten small holes 22a to 22j that penetrate through the front and back surfaces, respectively, with the center of the plate 21 being the center. They are formed on the same circumference and at approximately equal intervals in the circumferential direction. Also,
A bolt insertion hole 2 is provided in the center of the center plate 21.
3 is formed, and a pair of positioning holes 24a and 24b are formed near the outer periphery, and furthermore, as shown in FIG.
10 side holes 25a each communicating with a to 22j
~25j are formed. Diaphragms 31 and 32 are provided on the front and back surfaces of the center plate 21.
via the first and second plunger plates 3
3 and 34 are arranged respectively, and these plates 2
1, 33, and 34 are integrally fastened by hexagonal hole tightening bolts 35. Each of the diaphragms 31, 32 preferably includes two elastic airtight sheets 31a, 31b, 32a arranged in a laminated manner.
and 32b, a through hole 36 for the tightening bolt 35 is formed in the center, and pin holes 37a, 37 are formed near the outer periphery corresponding to the respective positioning holes 24a, 24b of the center plate 21.
b, 38a, and 38b (38b is not shown) are formed, respectively.

The first plunger plate 33 has a smaller outer diameter than the center plate 21, and as shown in FIGS. 4 and 5, has bolt mounting holes 39 penetrating the front and back surfaces, a pair of pin insertion holes 41a, 4
1b and five diaphragm chambers 42a to 42e, and five long grooves 43a to 43a on the surface that contacts the center plate 21 via the diaphragm 31.
43e is formed, and spring storage holes 44a to 44d consisting of four non-through holes are formed on the opposite surface. The bolt attachment hole 39 is provided at the center of the first plunger plate 33, and the pair of pin insertion holes 41a, 41b are provided at the center of the center plate 21.
are formed corresponding to the respective positioning holes 24a, 24b. Five plunger chambers 42a to 42e
Out of the ten pores 22a to 22j formed in the center plate 21, every other pore, for example, the pore 22b, as shown in FIG. 1 and FIG.
They are formed on the same circumference corresponding to 22d, 22f, 22h, and 22j. Plungers 46 (4) are provided in these plunger chambers 42a to 42e.
6a to 46e, however, 46b to 46e are not shown)
are slidably inserted into each other to form a first plunger group. A recess 47 is formed in the center of the surface of each plunger 46 in contact with the diaphragm 31, as shown in FIG.
A ring 48 is fitted and fixed with a portion thereof protruding outward, and this protrusion presses the diaphragm 31.

The five long grooves 43a to 43e are two pores adjacent to each other among the ten pores 22a to 22j, for example, 22b and 22c, 22d and 22e,
22f and 22g, 22h and 22i, and 22j and 22a communicate with each other when the diaphragm 31 is deformed, and are formed in an arc shape on the same circumference centered on the center of the first plunger plate 33, and each of the above-mentioned Plunger chambers 42a to 42e are in communication. The four spring storage holes 44a~
44da accommodates springs 51 that give the first piston 50 (described later) a tendency to return upward, that is, in a direction away from the center plate 21.

Note that the central portion of the first plunger 33 in contact with the diaphragm 31, where the long grooves 43a to 43e are formed, preferably has a peripheral edge as shown in FIG. 5 in order to increase the tightening effect and maintain airtightness. The convex portion 64 is formed thicker than the convex portion 64.
It consists of

The second plunger plate 34 has exactly the same structure as the first plunger plate 33 described above, so a detailed explanation thereof will be omitted. However, the second plunger plate 34 is upside down from the first plunger plate 33, and a diaphragm is installed on the back side of the center plate 21. Five long grooves 56a to 56e (second
Among the ten pores 22a to 22j, two pores 22a and 22b, 22c and 22d, which are adjacent to each other but not communicated with each other by the long grooves 43a to 43e of the first plunger plate 33 (see figure) are
2e and 22f, 22g and 22h, 22i and 22j
In order to communicate with each other when the diaphragm 32 is deformed, the first plunger plate 33 and the small holes 22a to 22j are arranged so as to be shifted by one pitch, and a threaded hole 57 into which the tightening bolt 35 is screwed is formed. They are different in that they are
Such long grooves 43a to 43e, 56a to 56e
For positioning with respect to the small holes 22a to 22j, a pair of positioning pins 60 are inserted into the pin insertion holes 41a, 41b of the first plunger plate 33, the positioning holes 24a, 24b of the center plate 21, and the pin insertion holes of the second plunger plate 34. 61a,
61b, and then the plates 21, 33, 34 are integrally connected with the tightening bolts 35.
It goes without saying that the diaphragms 31 and 32 are interposed between the plates in advance when positioning and connecting the plates.

Five plungers 63 (63
a to 63e) constitute the second plunger group, and a recess is formed in the upper surface thereof, that is, a surface in contact with the diaphragm 32, as explained in FIG. 6, and an O-ring 64 is fitted and fixed in this recess. ing.

Reference numeral 70 designates a first lid, which is fitted onto the outer peripheral surface of the first plunger plate 33 and fixed to the plate 33 by a plurality of setscrews 71. A first air receiving chamber 72 is formed. Air intake chamber 7
The first piston 50, which is formed into a flat plate shape, is slidably disposed inside the piston 2 via an O-ring 73. The first piston 50 is urged upward by the spring 51, and the air pressure P supplied to the first air receiving chamber 72 through the air supply port 75 provided in the first lid 70 is applied to the upper surface side of the first piston 50. When applied, it descends against the spring 51,
It is configured to push down the first plunger group 46.

A second lid 78 is fitted onto the outer peripheral surface of the second plunger plate 34 and fixed to the plate 34 by a plurality of setscrews 79, and the lid 78 and the second plunger plate 34 are And the second
An air receiving chamber 80 is formed. Second air intake chamber 8
Similarly to the first piston 50, a second piston 81 formed in a flat plate shape is slidably inserted into the second piston 81 through an O-ring 82, and each plunger constituting the second plunger group is attached to the upper surface of the second piston 81. 63a-63e
The lower end surfaces of the four spring housing holes 83a to 83d (83b, 8
3d (not shown) are respectively in contact with the lower ends of four springs 84 housed in the springs 84, respectively. The second piston 81 is connected to the spring 84.
The second air receiving chamber 80 is forced downward by the air pressure supply port 86 provided in the second lid body 78.
When the air pressure P supplied to is applied to the lower surface side,
It is configured to be pushed up against the spring 84 and push up the second plunger group 63.

Next, the operation of the switching valve 20 having the above configuration and the flow of gas will be explained mainly in FIGS. 1, 7, and 8.
This will be explained based on the diagram. In Fig. 8, side hole 2
5a is a sample gas supply hole, side hole 25c is a carrier gas supply hole, 90 is a metering tube connecting between side holes 25b and 25i, side hole 25j is a sample gas discharge hole, and 91 is a column connected to side hole 25h. .

In such a configuration, the first air receiving chamber 72
When the first piston 50 is pushed down against the spring 51 by supplying air pressure P to
AIR ON) removes the air pressure P in the second air receiving chamber 80 (hereinafter referred to as BOTTOM AIR OFF). Similarly, when air pressure P is supplied to the second air receiving chamber 80 and the second piston 81 is pushed up against the spring 84 (hereinafter referred to as BOTTOM AIR ON
) discharges the air pressure P in the first air receiving chamber 72 (hereinafter referred to as TOP AIR OFF). In this way, the first and second pistons 50, 81 are driven alternately by the supply of air pressure P.
In the case of TOP AIR ON, the first piston 50 descends and pushes down the first plunger group 46, so
As shown in FIG.
1, the diaphragm 31 is brought into close contact with the surface of the center plate 21. Therefore, the pores 22b, 22c, 22 formed by the long grooves 43a to 43e
Communication between d and 22e, 22f and 22g, 22h and 22i, and 22j and 22a is cut off. On the other hand, the second piston 81 is lowered by the force of the spring 84 because of BOTTOM AIR OFF, and does not act on the diaphragm 32 at all. Therefore, in this state, when sample gas is supplied to the pores 22a from the sample gas supply port 25a, the long grooves 56a to 5 of the diaphragm 32 are caused by the gas pressure.
The portions corresponding to 6e are sequentially elastically deformed downward to form pores 22a and 22b, 22c and 22d, and 22e and 2.
2f, 22g and 22h, and 22i and 22j are connected to each other. In this state, the sample gas is 25a → 22a → 22b → 25b → 90 → 25
Measuring tube 9 along the route i → 22i → 22j → 25j
It will lead you to 0.

Then TOP AIR OFF, BOTTOM AIR ON
When the first plunger group 46 is released and the second plunger group 63 is moved upward, the diaphragm 32 comes into close contact with the lower surface of the center plate 21 and the pores 22a and 22b, 22c and 22d,
The communication between 22e and 22f, 22g and 22h, and 22i and 22j is cut off, and the portions of the diaphragm 31 corresponding to the long grooves 43a to 43e are elastically deformed upward against the first plungers 46a to 46e using the gas pressure of the carrier gas. Pores 22b and 22c, 22
d and 22e, 22f and 22g, 22h and 22i, and 22j to 22a are made to communicate with each other. As a result, the sample gas held in the measuring tube 90 changes from 25c→22c→22b→25b→9
The carrier gas supplied through the route 0→25i→22i→22h is sent to the column 91, and each gas component is separated and measured.

Here, in FIG. 8, no explanation was given on how to use the side holes 25d, 25e, 25f, and 25g, which similarly switch communication paths, but for example, they can be used to connect another column or to back flush. It can also be used to switch carrier gases for various applications, and by increasing the number of ports, it is possible to add more advanced functions to gas chromatographs than in the past.

In addition, in the description of this embodiment, an example was shown in which the diaphragms 31 and 32 were constructed of two elastic airtight sheets 31a, 31b and 32a, 32b arranged in a laminated manner. Although the two elastic airtight sheets may be made of the same material, they have a diaphragm made of a softer material to maintain sealing properties, and long grooves 43a to 43e, 56a.
In order to improve the communication along the lines 56e to 56e, a diaphragm made of a harder material that can be retro-deformed into a long groove shape may be combined. Of course,
It goes without saying that the present invention is not limited to a configuration in which diaphragms are stacked and arranged, but can be constructed using only one diaphragm as long as it is made of a suitable material.

Furthermore, the first plunger plate 33 and the second
The convex portion 54 of the plunger plate 34 is provided to increase the tightening effect, and is not necessarily necessary in the present invention. Furthermore, although this embodiment has been described with reference to the case in which ten pores 22a to 22j are provided in the center plate 21, the present invention is not limited to the number of holes 22a to 22j, and the number can be increased or decreased as necessary. It is.

[Effects of the Invention] As described above, the switching valve for a gas chromatograph according to the present invention has a recessed portion on the surface of the plunger that contacts the diaphragm, and an O-ring is fitted into this recessed portion, so that the plunger itself and the diaphragm are directly connected. Since the structure is configured to avoid contact, damage to the diaphragm is significantly reduced, and since a large surface pressure is obtained, the passage can be more reliably closed and gas leakage can be prevented. Incidentally, when we conducted wear tests on the diaphragm when the plunger was pressed directly against the diaphragm and when the O-ring was pressed against it, we found that in the former case, at most,
Whereas the limit was 500,000 aisle changes,
In the latter case, it was possible to repeat up to 5 million times. As a result, stable analytical accuracy can be maintained over a long period of time, improving the durability and reliability of the switching valve.
Furthermore, the plunger does not require strict machining accuracy, and can be manufactured and provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the switching valve for gas chromatograph according to the present invention, FIG. 2 is an exploded perspective view of the valve, and FIG. 3 is a sectional view of the center plate.
Figure 4 is a bottom view of the first plunger plate,
Figures a and b are sectional views taken along lines A-A and B-B in Figure 4, Figure 6 is a partially cutaway front view of the plunger, and Figure 7 is a partially cutaway front view of the plunger.
The figure is a cross-sectional view of main parts showing the state when TOP AIR is ON.
FIG. 8 is a schematic configuration diagram of a gas chromatograph equipped with a switching valve, and FIG. 9 is a sectional view showing a conventional example of a switching valve. 20...Switching valve, 21...Center plate, 3
1, 32...Diaphragm, 33...First plunger plate, 34...Second plunger plate, 47
... recess, 48... O-ring, 50... first piston, 64... O-ring, 81... second piston.

Claims (1)

[Claims] 1. In a gas chromatograph switching valve in which a passage is opened by elastically deforming a diaphragm by gas pressure, and the passage is closed by pressing the diaphragm with a plunger, the surface of the plunger in contact with the diaphragm A switching valve for a skeleton chromatograph, characterized in that a recess is provided in the recess, and an O-ring is mounted in the recess with a part of the O-ring protruding from the recess.