JP2812658B2 - Gas inlet valve for mass spectrometry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas inlet valve for mass spectrometry, particularly a mass spectrometer for analyzing a gas sample, and a mass spectrometer connected to a sample gas generating chamber to be analyzed. The present invention relates to an improvement of a gas inlet valve for mass spectrometry for introducing a sample gas into an ionization chamber of a spectrometer at a desired pressure.

[0002]

2. Description of the Related Art FIG. 6 shows a schematic configuration of a gas sample mass spectrometer. In particular, a sample gas generating chamber 10 and a mass spectrometer 1 are shown.
2 is connected by a gas introduction valve 14 and the internal structure of the mass spectrometer 12 is shown in a broken state. The sample gas generation chamber 10 is provided with an outlet flange 10a, and the mass spectrometer 12 is provided with an inlet flange 12a. The inlet flange 14a at the gas inlet end of the gas inlet valve 14 and the outlet flange 14b at the gas outlet end of the gas inlet valve 14 are connected to the two flanges 10a and 12a in an airtight manner, respectively. It is led to the mass spectrometer 12 through the introduction valve 14.

A well-known ion source 16 is provided in the mass spectrometer 12. In an ionization chamber 18 in the ion source 16, a sample gas is ionized by being subjected to electron impact by an ionized electron beam. The path of the sample gas in the mass spectrometer 12 is performed through an introduction pipe 20 and a connection pipe 22 extending from the inlet flange 12a, and ions generated in the ionization chamber 18 are connected to the ionization chamber 18 and the main body. The ion beam accelerated by the acceleration voltage applied to the slit 24 and passed through the main slit 24 is sent to the ion separation unit 26. As is well known, the ions separated by the ion separation unit 26 are detected by the ion detection unit 28, and mass analysis of the sample gas is performed.

What is important in such mass spectrometry is to guide the sample gas in the sample gas generation chamber 10 to the mass spectrometer 12 at a desired pressure.
It is necessary not only to control the introduction and shielding of the sample gas, but also to perform the pressure adjustment. In addition, it is desirable that the sample gas moves from the sample gas generation chamber 10 to the mass spectrometer 12 through a linearly visible conduit.
This is because, when the sample gas generated in the generation chamber 10 collides with the container wall before being guided to the ionization chamber 18 of the mass spectrometer 12, a phenomenon occurs in which a chemical reaction occurs on the container wall or is adsorbed on the container wall. . In particular, strongly adsorbable gas such as moisture, highly reactive active gas such as halogen, or condensable gas components with low vapor pressure will react sensitively if they collide with the vessel wall before measurement. As a result, the sample gas component changes.

For this reason, the conventional gas introduction valve 14 includes a valve body 36, and a linear gas introduction line which can be seen straight from the gas introduction end 36a of the inlet flange 14a to the gas outlet end 36b of the outlet flange 14b. A path 38 is provided. A switching valve for switching the flow rate of the gas conduit 38 between the open state and the throttle state is provided in the middle of the gas conduit 38. That is, a tapered switching valve seat 40 is provided in the gas conduit 38 in the direction perpendicular to the axis of the gas conduit 38 in the middle of the first diameter 38a having a large diameter.
A switching valve 42 is mounted inside 0 to be able to move forward and backward. The switching valve 42 has an orifice 44 therein. For example, when the pressure of the sample gas is higher than 0.1 Pascal, as shown in FIG. 6, the switching valve 42 enters the switching valve seat 40 by the opening / closing mechanism 46, and the flow rate of the sample gas is reduced by the orifice 44. To reduce pressure. When the pressure of the sample gas is lower than a predetermined value, for example, 0.1 Pascal, the switching valve 42 is switched by the opening / closing mechanism 46 to the switching valve seat 4.
The sample gas can be guided to the mass spectrometer 12 without evacuation by retracting from zero and leaving the gas conduit 38 open. Of course, the diameter of the passage of the orifice 44 is previously selected to an appropriate value in order to perform a desired pressure reduction according to the sample gas. Also, of the gas conduit 38, the second conduit 3 having a smaller diameter is used.
An opening / closing valve seat 64 is provided in the middle of 8b, and an opening / closing valve 66 is mounted inside the opening / closing valve seat 64 so as to be able to advance and retreat by an opening / closing mechanism 68, and controls opening and closing of the gas conduit 38.

However, even when the gas conduit 38 is provided so as to be able to be seen straight, even if the gas has a high adsorptivity such as moisture, an active gas such as halogen or a reactive gas having a low vapor pressure as described above. Condensable gas components, etc. often remain on the vessel wall after measurement, causing a so-called memory effect, which may result in the mixing of residual gas during subsequent measurement of different sample gases, reducing the reliability of the measurement. there were.
For this reason, the gas introduction valve for mass spectrometry incorporated in the gas sample mass spectrometer performs so-called vacuum baking, where necessary, heating to a high temperature while evacuating to vacuum to clean the valve wall. The remaining sample gas was forcibly discharged to improve the reliability of the measurement.

[0007]

However, the metal surfaces of the switching valve and the switching valve seat, which have been cleaned by vacuum baking, are brought into contact with each other when they are brought into contact with each other while being pressurized for adjusting the pressure of the sample gas. A phenomenon that becomes difficult occurs. In particular, when the switching valve is inserted into the tapered switching valve seat, the two are brought into a fitted state, and as a result, the above-mentioned adhesive state is established, and an excessive force is required to retract the switching valve from the switching valve seat. However, there is a problem that the opening / closing mechanism 46 is broken or the contact surfaces of the switching valve and the switching valve seat are damaged even when the two can be separated.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to easily insert and retract a switching valve into and from a switching valve seat even when vacuum baking is performed. It is an object of the present invention to provide an improved gas inlet valve for mass spectrometry which can be easily used.

[0009]

In order to achieve the above object, the present invention provides a gas inlet valve for mass spectrometry having a gas inlet connected to a sample gas generating chamber and a gas outlet connected to a mass spectrometer. In the valve body, a straight gas passage that can be seen straight from the gas introduction end to the gas outlet end, and a switching valve seat provided in the middle of the gas passage, wherein the gas passage A switching valve seat provided with a right-angled or acute-angled edge-shaped ridge inclined at a predetermined angle with respect to the gas conduit, and a tapered surface mounted on the switching valve seat and in contact with the ridge. And a switching valve for switching the gas conduit to an open state or a throttled state.

Further, according to the present invention, there is provided a gas inlet valve for mass spectrometry having a gas inlet connected to a sample gas generating chamber and a gas outlet connected to a mass spectrometer. A straight gas passage that can be seen straight to the gas outlet end, and a switching valve seat provided in the middle of the gas passage, wherein a right angle or an acute angle edge shape inclined at a predetermined angle with respect to the gas passage. A switching valve seat provided so that the ridge portion surrounds the gas conduit, and a switching valve mounted on the switching valve seat and having a tapered surface that abuts on the ridge portion, wherein the gas conduit is A switching valve for switching between an open state and a throttled state, wherein an on-off valve seat is further provided in the middle of the gas conduit, and an on-off valve for switching the gas conduit between open and closed is mounted on the on-off valve seat. It is characterized by having been done.

[0011]

As described above, according to the present invention, the switching valve seat is provided on the ridge of the switching valve seat, that is, the ridge having a right-angled or acute-edge shape provided at a predetermined angle to the gas conduit. The tapered surfaces come into contact with each other, and both are in line contact. Therefore, it becomes possible to insert the switching valve into the switching valve seat without performing surface contact as in the conventional case, and even if the switching valve is inserted into the switching valve seat after performing vacuum baking, adhesion occurs. There is no. Even when vacuum baking is performed with the switching valve inserted in the switching valve seat, the two do not adhere to each other.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view showing a preferred first embodiment of a gas inlet valve for mass spectrometry according to the present invention.

In FIG. 1, the gas introduction valve 14 includes a valve body 76, and the aforementioned flanges 14a and 14b are fixed to both ends of the body 76 in an airtight state. The valve body 76 has two flanges 14a, 14
A straight gas passage 38 is provided between the gas inlet end 76a and the gas outlet end 76b. In the embodiment, a switching valve seat 70 is provided on the entrance flange 14a side of the gas conduit 38 so as to obliquely cross the gas conduit 38, and an opening / closing mechanism 46 is provided inside the switching valve seat 70. The switching valve 72 which can move forward and backward is mounted.
In this embodiment, the axis of the gas conduit 38 and the axis of the switching valve seat intersect at an angle of 60 °.

As shown in the enlarged sectional view of FIG. 2, the switching valve 72 has a tapered tip portion 72a, and the switching valve 72 is inserted into the switching valve seat 70 therein. An orifice 74 is sometimes provided so that it is on the same track as the gas conduit 38.

On the other hand, the switching valve seat 70 has a substantially cylindrical shape, and a right-angled edge-shaped ridge 70a is provided around the inner wall surface of the switching valve seat 70 as shown in FIG. In this embodiment, the switching valve seat 70 includes two types having different inner diameters, that is, a first valve seat 70b having a larger inner diameter and a second valve seat 70c having a smaller inner diameter, and the first valve seat 70b and the second valve seat 70c. And the junction with the ridge 70a functions as the ridge 70a. The gas conduit 38c on the inflow side of the switching valve is connected to the second valve seat 70c, and the ridge 70a obliquely surrounds the gas conduit 38c. The first valve seat 70b is connected to a gas conduit 38d on the outflow side of the switching valve. Therefore, as shown in FIG. 2, the switching valve 72 enters the switching valve seat 70,
When the distal end portion 72a of the switching valve 72 is pressed against the ridge 70a, the sealing on the inflow side of the switching valve 72 is completely performed, and the throttle of the gas conduit 38 is controlled dominantly by the orifice 74. Can be provided, and an aperture state can be provided. It should be noted that the gas conduit 38d on the outflow side of the switching valve is sealed by a gasket 78.

Further, since the gas conduit 38 is opened, the switching valve 72 can be retracted from the switching valve seat 70, and as shown in FIG.
Is provided on the outer wall. The opening / closing mechanism 46 is a casing 4
8, a support shaft 50 for moving the switching valve 72 in the axial direction is built in the casing 48, and between the casing 48 and the support shaft 50 in order to keep the support shaft 50 airtight within the casing 48. Is provided with a bellows 52. The axial movement of the support shaft 50 is performed by a nut 54 fixed to the casing 48 and a push screw 56, and an engaging element 58 provided at an upper end of the push screw 56 is provided at a lower end of the support shaft 50. When the push screw 56 is rotated by engaging with the stop seat 60, the support shaft 50, that is, the switching valve 7
2 can be moved only in the axial direction without rotating. A switching handle 62 is provided at the lower end of the push screw 56, and a user can rotate the switching handle 62 to adjust the position of the switching valve 72 when adjusting the aperture of the passage.

Further, in the first embodiment, an opening / closing valve seat 64 is provided on the outlet flange 14b side of the gas conduit 38, and an opening / closing valve 66 is mounted on the opening / closing valve seat 64.
The opening and closing of the gas conduit 38 is controlled by the axial movement 6.

At the upper end of the valve body 76, the on-off valve 6
An opening / closing mechanism 68 for moving the shaft 6 in the axial direction is provided,
Since the opening / closing mechanism 68 has the same configuration as that of the opening / closing mechanism 46, detailed description of each part is omitted.

As described above, according to the first embodiment of the present invention, the switching valve for switching between the open state and the throttle state of the straight gas passage 38 which is provided in the valve body 76 and can be seen in a straight line. The distal end 72a of the 72 has a tapered shape, and the distal end 72a is pressed against a ridge 70a having a right-angle edge provided on the switching valve seat 70. At this time,
Since the ridge 70a obliquely surrounds the gas conduit 38c, the inflow side seal of the switching valve 72 is performed by the line contact between the ridge 70a and the tip 72a, and the sealing is completely performed. After the inner surface of the gas inlet valve for mass spectrometry has been cleaned by vacuum baking, the switching valve 7
There is an advantage that even if the two are brought into contact with the switching valve seat 70, they do not adhere to each other.

The operation of the first embodiment will be described with reference to FIGS.

FIG. 3 shows a switching valve 72 similar to FIGS.
Is shown in close contact with the switching valve seat 70. In this state, the orifice 74 is located at the central axis of the gas conduit 38, whereby the throttle of the introduced gas is controlled dominantly by the orifice 74, and the pressure of the sample gas is controlled. When the pressure is high, the pressure can be reduced.

In the state shown in FIG. 3, the opening / closing valve 66 is retracted from the opening / closing valve seat 64 by the opening / closing mechanism, and is open in this state.

FIG. 4 shows a state in which the gas conduit 38 is opened by the switching valve 72. As described above, the opening / closing mechanism 46 moves the switching valve 72 downward in FIG. As described above, the switching valve 72 is completely retracted from the switching valve seat 70 and the gas conduit 38, and in this state, the flow rate of the sample gas is mainly controlled only by the pipe diameter and length of the gas conduit 38, and when the gas pressure is low. The sample gas can be efficiently guided to the mass spectrometer 12.

Embodiment 2 FIG. 5 shows a preferred second embodiment according to the present invention. In this second embodiment, only the switching valve is mounted on the gas conduit 38, and the second embodiment is different from the first embodiment. The on-off valve has been removed.

As described above, according to the second embodiment, the gas conduit 38 cannot be shut off, but the throttle amount or the pressure can be adjusted according to the pressure of the sample gas. Switching valve 7
2 and the structure of the switching valve seat 72 are the same as those of the first embodiment. Even if the switching valve 72 enters and comes into contact with the switching valve seat 70 after the inner surface of the valve is cleaned by vacuum baking, it can be adhered to each other. There is no advantage, and the present invention is also useful for a mass spectrometer used for this kind of application or a mass spectrometer provided with an existing gate valve or straight valve corresponding to the on-off valve in the first embodiment.

In the above-described first and second embodiments, the shape of the ridge provided on the switching valve seat has been described as a right angle.
For example, the same effect as described above can be obtained with an acute edge shape. Also, the intersection angle between the gas conduit and the switching valve seat has been described as 60 °. However, the convex angle is disposed so as to cross the gas conduit obliquely, and the sealing at the switching valve inflow side can be performed. The same effect can be obtained even if is arbitrary.

[0028]

As described above, according to the gas inlet valve for mass spectrometry according to the present invention, after cleaning the inner surface of the valve by vacuum baking necessary for performing highly reliable measurement. Even if the switching valve is inserted into and brought into contact with the switching valve seat, the two are in line contact with each other, so they do not adhere to each other and cannot be separated from each other. Damage to the contact surface of the valve and damage to the opening / closing mechanism for inserting and retracting the switching valve can be prevented, and usability of the gas inlet valve for mass spectrometry can be improved.

[Brief description of the drawings]

FIG. 1 is a first diagram of a gas inlet valve for mass spectrometry according to the present invention.
It is a partial sectional view showing an example.

FIG. 2 is a partially enlarged cross-sectional view of a gas inlet valve for mass spectrometry according to the present invention.

FIG. 3 is a partial cross-sectional view showing a gas introducing action in a throttle state according to the first embodiment of the present invention.

FIG. 4 is a partial sectional view showing an open state according to the first embodiment of the present invention.

FIG. 5 is a partial sectional view showing a second preferred embodiment of the gas inlet valve for mass spectrometry according to the present invention.

FIG. 6 is a partially broken view showing a state in which a conventional gas introduction valve is mounted between a sample gas generation chamber and a mass spectrometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sample gas generation chamber 12 Mass spectrometer 14 Gas introduction valve 36, 76 Valve main body 36a, 76a Gas introduction end 36b, 76b Gas outlet end 38 Gas conduit 40, 70 Switching valve seat 42, 72 Switching valve 44, 74 Orifice 46 , 68 opening / closing mechanism 64 opening / closing valve seat 66 opening / closing valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01J 49/00-49/48 F16K 1/00-1/54 G01N 27/62

Claims (2)

(57) [Claims] 1. A gas introduction valve for mass spectrometry, wherein a gas introduction end is connected to a sample gas generation chamber, and a gas discharge end is connected to a mass spectrometer. A straight gas passage that can be seen in a straight line, and a switching valve seat provided in the middle of the gas passage, wherein a convex portion having a right angle or an acute angle that is inclined at a predetermined angle with respect to the gas passage. A switching valve seat provided so as to surround the gas conduit, and a switching valve mounted on the switching valve seat and having a tapered surface that abuts on the ridge portion, wherein the gas conduit is open or throttled. A gas introduction valve for mass spectrometry, comprising: a switching valve for switching to a state. 2. A gas introduction valve for mass spectrometry, wherein a gas introduction end is connected to a sample gas generation chamber, and a gas discharge end is connected to a mass spectrometer. A straight gas passage that can be seen in a straight line, and a switching valve seat provided in the middle of the gas passage, wherein a convex portion having a right angle or an acute angle that is inclined at a predetermined angle with respect to the gas passage. A switching valve seat provided so as to surround the gas conduit, and a switching valve mounted on the switching valve seat and having a tapered surface that abuts on the ridge portion, wherein the gas conduit is open or throttled. A switching valve for switching to a state, wherein an on-off valve seat is further provided in the middle of the gas conduit, and an on-off valve for switching the gas conduit to open or closed is mounted on the on-off valve seat. Gas inlet valve for mass spectrometry characterized by Bu.