JPH0343496Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum gate valve used in a vacuum device such as an electron microscope.

[Prior Art] An example of a gate valve that has been commonly used in the past is shown in FIG. In the figure, 1 is a vacuum casing, and 2a and 2b are vacuum paths communicating with a vacuum chamber, respectively. This vacuum path is set at a certain angle (usually right angle)
A valve guide groove 3 is formed in the transverse direction, and a valve holder 4 is movably placed in the groove. An inclined surface 5 is provided in the middle of the upper surface of the valve holder,
A valve 7 having an inclined surface 6 similar to this inclined surface on its lower surface is integrated onto the valve holder. A tension spring 8 is provided between the valve holder 4 and the valve 7.
is strung up, strongly drawing the two together. A valve seat 9 is provided around the vacuum path 2a on the upper surface of the guide groove 3.
is provided, and by pressing the valve 7 against this valve seat, both vacuum paths 2a and 2b are cut off. The valve holder 4 is fixed to a connecting rod 10 and is attached to the housing 1.
It is engaged with a valve drive mechanism 11 installed outside of the valve drive mechanism 11 . A stopper 12 is provided at the end of the guide groove.
is provided so that when the valve 7 moves, it comes into contact with this stopper.

In the illustrated state, the valve is closed, and the valve 7 rides on the upper surface of the valve holder 4 and is strongly pressed against the valve seat 9. From this state, the drive mechanism 11
When the valve holder 4 is moved to the right, first only the valve holder 4 moves, and when the inclined surface 5 coincides with the inclined surface 6 of the valve 7, the valve 7 slides downward, and then the valve 7 It will now move together with the holding body 4, and the valve will be in the open state. When the vacuum path is closed, by pushing the valve holder 4 to the left, first, only the valve 7 hits the stopper 12 and stops. Further, when the valve holder is moved, the inclined surface 6 of the valve 7 rides on the inclined surface 5 of the valve holder, and the valve 7 is pushed upward and pressed against the valve seat 9.

[Problems to be solved by the invention] With such conventional gate valves, it is possible to open and close the vacuum path relatively easily, but when the valve is opened and closed, the valve holder and the inclined surface of the valve rub against each other, so the metal Shavings are generated from the valve and its holder, which fall into the vacuum path and the vacuum chamber, causing trouble to various parts, and the guide groove 3 and valve 7.
and the dimensions of the valve holder 4 require accuracy;
High precision processing is required.

Therefore, in view of the above points, the present invention aims to provide a gate valve in which metals do not rub against each other.

[Means for Solving the Problems] In order to achieve the above object, the gate valve of the present invention includes a valve body that is movable in a direction across a vacuum path, and a valve body that is provided at a constant angle with the vacuum path. a valve seat supported by the valve body through a bellows so as to be movable in a direction toward the valve seat; a piston and a cylinder for moving the valve body in a direction across a vacuum path; a connecting body for connecting the valve body; and pressurized fluid supply means for moving the piston so that the valve body moves in a direction to block the vacuum path by introducing pressurized fluid into the cylinder. and an introduction passage for introducing the pressurized fluid introduced into the cylinder into the bellows;
An on-off valve is provided at the inlet portion of the introduction passage on the cylinder side and opens and closes based on the movement of the valve body toward and away from the cutoff position, and the valve body controls the flow rate of the pressurized fluid flowing through the introduction passage. The present invention is characterized in that it is equipped with a valve for reducing the amount in the stroke of shutting off the vacuum path and increasing the amount in the stroke of the valve body leaving the vacuum path.

Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

[Embodiment] FIG. 1 is a sectional view showing an embodiment of the present invention, and the same reference numerals as in FIG. 4 indicate the same constituent members.

In this embodiment, the valve 7 is made of a metal member, such as stainless steel, processed into a thin plate shape, and is attached to the valve holder 4 via an expandable metal bellows 13. Further, this valve 7 is housed in a recess 14 provided in the valve holder 4. As the valve drive mechanism 11,
A mechanism consisting of a cylinder 15 and a piston 16 is used, and the piston 16 is connected to the valve holder 4 via a connecting rod 10. In addition, a pipe 1 is installed in the cylinder formed on both sides of this piston.
7a and 17b are connected, and each pipe is connected to a compressed air source 19 via a switching valve 18. 20 is a bellows for vacuum sealing between the valve drive mechanism 11 and the connecting rod 10.

Reference numeral 21 denotes a passage for introducing compressed air supplied into the cylinder 15 on the right side of the piston 16, that is, compressed air introduced to move the valve holder 4 in the direction of blocking the vacuum path, into the metal bellows 13. be. 22 is an on-off valve provided at the entrance of this passage 21, and this on-off valve is connected to the piston 1.
6 is fixed to one end of a shaft 23 that movably passes through the shaft 23. The other end of the shaft 23 protrudes slightly from the left side surface of the piston 16, and this shaft is constantly pressed by a spring 24 in a direction to close the on-off valve 22.

Reference numeral 25 denotes a relief valve for changing the flow rate of compressed air supplied into the metal bellows 13 according to the moving direction of the valve holder 4, and this valve is connected to the shaft as shown in an enlarged sectional view in FIG. 2
It is composed of a sliding piece 26 and a spring 27 which are movably held on the outer periphery of 3. As shown in the figure, this sliding piece is always pressed by a spring so as to close the passage 21, and this sliding piece is provided with a minute hole 28 and a long groove 29, respectively. 30 is the spring 2
This is a nut that adjusts the pressing force of the sliding piece by 7.

In such a configuration, first, in the state shown in FIG.
The piston is introduced into the cylinder 15 on the left side and moves to the right, thereby setting the valve holder 4 in a position out of the vacuum path. In this state, compressed air is not supplied into the metal bellows 13, and the valve 7 is lowered and housed in the recess 14 by the contraction force of the bellows itself. Further, the on-off valve 22 is closed by the tension of a spring 24.

In this state, when the switching valve 18 is operated to supply compressed air to the right side of the piston 16 through the pipe 17a, the piston 16 moves to the left as shown in FIG.
In other words, the valve holder 4 is set in the blocking position. Here, just before the piston 16 comes into contact with the left side wall of the cylinder 15, the tip of the shaft 23 provided on the piston engages with the side wall of this cylinder, so the on-off valve 22 is opened, thereby allowing compressed air to pass through the passage. 21 into the metal bellows 13. However, in this moving process, passage 21
As shown in FIG. 2, it is closed by a slide piece 26 of a relief valve 25, and compressed air is introduced through a microhole 28. The compressed air passing through this microhole has a large resistance, so gradually the metal bellows 13
Since the metal bellows is introduced into the metal bellows, the metal bellows does not swell immediately even when the on-off valve 22 is opened. Therefore, when the valve 7 moves the valve holder 4, the housing 1
It can prevent contact with. After the valve holder has completely reached the shutoff position, the pressure inside the metal bellows 13 becomes higher than the outer circumference of the valve 7, so the valve is pushed upward, and this valve is strongly pressed against the valve seat 9. . Here, since the valve is formed in a thin plate shape, this thin plate deforms as the pressure inside the metal bellows increases, allowing the valve 7 to be brought into close contact with the valve seat 9. As a result, vacuum paths 2a and 2b are cut off.

Next, in the state shown in FIG. 3, when the switching valve 18 is switched, the pipe 17a side is opened to the atmosphere, and the compressed air introduced into the cylinder 15 on the right side of the piston 16 is instantly discharged. Due to the discharge of this compressed air, the pressure on the metal bellows 13 side becomes higher, so the sliding piece 26 of the relief valve 25 is pressed against the spring 27.
It moves to the right in FIG. 2 against the pressing force of. As a result, the compressed air inside the metal bellows suddenly flows out through the long groove 29 having a resistance smaller than that of the microhole 28, so that the compressed air introduced into the cylinder is discharged at the same time. The compressed air in the metal bellows is also exhausted, the metal bellows contracts and the valve 7 is lowered. After that, compressed air is introduced into the cylinder 15 on the left side of the piston 16 through the pipe 17b, so the piston is moved to the right, and the valve 7 is moved to a position where it is out of the vacuum path, as shown in FIG. Move to. As a result, the vacuum paths 2a and 2b are brought into communication. At this time, as the piston 16 moves, the shaft 23
4, the on-off valve 22 closes.

It should be noted that the above description is an example of the present invention, and many modifications may be made in its implementation. For example, in the above embodiment, when reciprocating the piston, compressed air is introduced into the cylinders on both sides of the piston, but the invention is not limited to this. The opening process may utilize the elastic force of a spring or the like.

Further, the valve may have an appropriate thickness so as not to be deformed, and may be vacuum-sealed using O-ring packing. However, if a metal member is used as the valve, baking out becomes possible and it becomes possible to implement the method in an apparatus that requires an ultra-high vacuum.

Furthermore, although compressed air was introduced into the cylinder in the above embodiment, a liquid such as oil may also be introduced.

[Effects] As detailed above, according to the present invention, the valve can be automatically pressed against and separated from the valve seat when the valve holder reaches the shut-off position or leaves the shut-off position. The valve can be opened and closed without friction. Therefore, metal powder is not generated, and it can be used in high-performance vacuum equipment without causing any problems. In addition, the handling operation becomes very easy.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figures are an enlarged sectional view of the main part of FIG. 1, FIG. 3 is a diagram for explaining the operation, and FIG. 4 is a diagram for explaining the conventional example. 1: Vacuum housing, 2a, 2b: Vacuum path, 3: Valve guide, 4: Valve holder, 10: Connecting rod, 1
1: Valve drive mechanism, 14: Recess, 13: Metal bellows, 15: Cylinder, 16: Piston, 17
a, 17b: pipe, 18: switching valve, 19:
Compressed air source, 21: passage, 22: on-off valve, 13:
Shaft, 24, 27: Spring, 25: Relief valve,
26: Smooth piece, 28: Microhole, 29: Long groove.

Claims (1)

[Scope of utility model registration request] A valve body placed so as to be movable in a direction across a vacuum path, a valve seat provided at a constant angle with the vacuum path, and supported by the valve body so as to be movable in a direction toward the valve seat via a bellows. a piston and a cylinder for moving the valve body in a direction across the vacuum path; a connecting body for connecting the piston and the valve body; and introducing pressurized fluid into the cylinder. pressurized fluid supply means for moving a piston so that the valve body moves in a direction that blocks a vacuum path; and an introduction passage for introducing pressurized fluid introduced into the cylinder into the bellows. and,
An on-off valve is provided at the inlet portion of the introduction passage on the cylinder side and opens and closes based on the movement of the valve body toward and away from the cutoff position, and the valve body controls the flow rate of the pressurized fluid flowing through the introduction passage. 1. A vacuum gate valve characterized by comprising a valve for reducing the amount in a stroke of shutting off a vacuum path and increasing the amount in a stroke of the valve body leaving the vacuum path.