JPS63667B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a seal structure for a metal valve of an ultra-high vacuum device. Conventionally, metal valves such as L-type valves, gate-type valves, and S-type valves have been used in ultra-high vacuum devices such as accelerators such as proton synchrotrons, storage rings, nuclear fusion devices, and space chambers. Since these metal valves must maintain an ultra-high vacuum, a high degree of precision is required in terms of relative positional accuracy between the valve seat and the valve body. However, the larger the metal valve, the more difficult it is to obtain a high degree of relative positional accuracy.Achieving high precision requires a great deal of effort and time, and costs increase significantly. There were flaws. Furthermore, although there are conventional bakeable all-metal valves for ultra-high vacuum use, there are almost no gate-type valves with highly reliable sealing performance. On the other hand, when large-sized ultra-high vacuum accelerators such as proton synchrotrons or nuclear fusion devices are required, the demand for highly reliable all-metal gate valves is increasing. Furthermore, conventional metal valves for ultra-high vacuum equipment have the disadvantage of poor reliability due to the difficulty in attaching a sealing valve body. An object of the present invention is to provide a sealing structure for a metal valve for an ultra-high vacuum device, particularly a metal valve for a large-sized ultra-high vacuum device. Another object of the present invention is to provide a large, highly reliable, and simple metal valve seal structure for large-scale ultra-high vacuum equipment. The sealing structure of a metal valve for an ultra-high vacuum apparatus of the present invention includes a valve body, a valve seat, and a gasket interposed between the two, and two knife edges are provided on the lower surface of the valve body spaced apart in the radial direction. 2 above on the bottom surface of the valve body.
A gasket fixing device is provided closer to the center than the knife edge, the gasket is provided on the lower surface of the valve body and extends radially outward, and the gasket fixing device fixes the radially inner end of the gasket to the valve seat. A smooth protrusion is provided so as to be located between the two knife edges of the valve body, so that the valve body can be pressed against the valve seat. Preferably, the valve body and seat are made from a hard valve metal such as stainless steel. The gasket is a flat ring-shaped gasket made of relatively soft metal such as pure aluminum or oxygen-free copper (OFHC). Alternatively, a gasket with copper plating on both sides of the elastic material is used. The means for pressing the valve body against the valve seat is similar to known metal valves. The invention will now be explained in more detail with reference to embodiments shown in the drawings. In the metal valve seal structure shown in Fig. 1, the valve body 1 and valve seat 2 are made of stainless steel.
Two knife edges 4 and 5 are provided on the lower side of the valve body 1 at a distance. The radially inner end of the gasket 3 made of oxygen-free copper is attached to a ring-shaped fitting 6 for gasket mounting, and the ring-shaped fitting 6 is attached to the radially inner end of the lower surface of the valve body 1 with a screw 8 through a spring washer 7. Attach to screw hole 9. When the gasket 3 is attached to the lower surface of the valve body 1 so that the upper surface of the gasket 3 is in direct contact with the tips of the two knife edges 4 and 5, the two knife edges 4 and 5 are attached to the part of the gasket 3 that is attached to the ring-shaped mounting bracket. No extra bending stress is applied to the part where the knife edge contacts, so
This is convenient (see Figure 1). A smooth protrusion 10 (with a radius of curvature of approximately 1
~2mm). When the valve body 1 is pressed downwardly toward the valve seat 2 by compressed air or a mechanical means such as a screw, the gasket 3 is pressed toward the valve seat 2 and is approximately midway between the two knife edges 4 and 5. It is curved upward by a smooth protrusion 10. Since gasket 3 is made of relatively soft metal,
This curvature is a slight elastic deformation. Therefore, valve body 1
Even if the relative vertical spacing between the valve seat 2 and the valve seat 2 is slightly different, the smooth protrusion 10 will tightly engage the gasket 3. Furthermore, since the gasket 3 closely engages with the smooth protrusion 10, strict accuracy is not required for horizontal positioning of the valve element 1 against the valve seat 2 at the beginning of pressing. When the pressing of the valve body 1 against the valve seat 2 is finished, the gasket 3 is sandwiched between the valve body 1 and the valve seat 2 like a sanderch, is pressed tightly against the valve seat 2, and the protrusion 10 of the valve seat 2 is pressed. Pressed closely together, as if crushed. At this time, since the knife edges 4 and 5 are made of a hard, wear-resistant metal such as stainless steel, the tips of the knife edges 4 and 5 slightly bite into the upper surface of the gasket 3 made of a relatively soft metal such as oxygen-free copper. Therefore, the valve body 1 and the valve seat 2 are easily and sufficiently sealed by the gasket 3, the knife edges 4, 5, and the protrusion 10. Since it is easy to seal, the mechanical energy required for sealing is relatively small. The spring washer 7 functions to prevent the knife edges 4, 5 of the valve body 1 from digging into the gasket 3 excessively and causing play. In addition, through holes 11 with a diameter of approximately 2 mm are provided at one or two locations in the radial direction of the valve body 1 between the two knife edges 4 and 5, and between the gasket 3 and the knife edges 4 and 5. If the gas in the space is evacuated, sealing to an ultra-high vacuum can be more easily achieved. The seal structure of the metal valve of the present invention has a valve body 1
Since the mutual positional relationship between the valve seat 2 and the valve seat 2 in the vertical and horizontal directions does not require strict high precision, even large valves can be manufactured extremely easily. In addition, even if the axis of the valve body is slightly misaligned with the axis of the valve seat due to processing accuracy or the tightening condition of the flange of the valve body during assembly, the valve body can be tightly sealed to the valve seat. The energy required for sealing remains almost the same. Therefore, it is possible to manufacture a highly reliable large-scale ultra-high vacuum valve, which has been considered difficult in the past, and a highly reliable large-scale ultra-high vacuum apparatus can be realized. Although this example has been described assuming that the valve body 1 moves relative to the valve seat 2, the same effect can be obtained even if the valve seat 2 moves relative to the valve body 1. The same effect can also be obtained by providing the valve body 1 with a smooth protrusion and the valve seat 2 with two knife edges. In one embodiment of the invention, the height of the knife edge is 1 to 1.5 mm, and the tip angle is 30 degrees. The knife edge is a concentric double knife edge. The spacing between the knife edges and the thickness of the gasket are determined as appropriate depending on the diameter of the valve. For example, the caliber
For 100-200mm valves, the spacing between both knife edges is approximately 4-6mm, and the gasket thickness is approximately 1.5mm.
mm is appropriate. The height and width of the smooth protrusion are approximately 2.5 mm each, and the tip of the protrusion is semispherical with a radius of curvature of approximately 1.25 mm. Next, an example in which the seal structure of the present invention is used for an L-type valve and a gate-type valve will be explained. FIG. 2 is a partially cutaway side view of the 4-inch L-shaped valve. In the case of an L-type valve, the valve body and drive shaft are generally directly connected, but the structure of the valve body and shaft of the valve of the present invention as shown in FIG. 3 is optimal. In FIG. 3, the tip 16 of the drive shaft 15 has a hemispherical shape, and the valve body 17 has a hemispherical shape to receive it. A gap 19 is provided between the drive shaft 15 and the drive shaft mounting fitting 18. The hemispherical surface is coated with alcohol or other lubricant that can withstand ultra-high vacuum (for example, flaky graphite or boron nitride powder) to reduce frictional force. Due to the gap 19 between the drive shaft 15 and the shaft mounting bracket 18, the valve body 17 is at any position relative to the drive shaft shaft 15 within this gap 19, and the valve is always in the position when the valve body 17 is tightened to the valve seat. The body 17 is parallel to the valve seat and always exerts a uniform force on the gasket surface. FIG. 4 is a longitudinal sectional view of a gate type valve using the seal structure of the present invention, and FIG. 5 is a plan view thereof. Gate type valves include types in which the valve body is driven up and down, types in which the valve body is driven in a pendulum manner, and the like. For any type, the sealing force against the gasket is
For example, applying internal pressure to a bellows. The vertical drive type of the valve body is shown in FIG. 6, and the pendulum drive type is shown in FIG. In FIG. 6, this double bellows 21 expands and contracts as compressed air enters and exits from the compressed air inlet and outlet holes 23. When the valve body 1 is closed, the valve body 1 is attached to the flange 2
Push out on the 7th side. The exhaust groove 31 is normally closed and opens when exhausting air. In FIG. 7, the drive pipe 33 also serves as an inlet and outlet for compressed air. The disc 35 extends against the flange 39 when the valve body 1 is closed. 41 is a stopper. Comparing the seal structure of the metal valve of the present invention with the seal structure of conventional metal valves, the relative positional accuracy of the valve seat and valve body for sealing with a probability of 95% is as follows for a valve with a diameter of 100 to 150 mm. The value is as expected.

[Table] As is clear from Table 1 above, the seal structure of the metal valve of the present invention is different from the conventional type of the applicant, which allowed the greatest relative positional accuracy between the valve seat and the valve body. This enables relative positional accuracy between the valve seat and the valve body to be approximately 2.5 to 5 times greater than that of the conventional valve. That is, the high degree of precision that was conventionally required regarding the relative positional precision between the valve seat and the valve body is not required. As a result, highly reliable large metal valves can be manufactured easily, quickly, and at low cost. Therefore, the present invention can significantly contribute to the production of ultra-high vacuum devices, particularly large-sized ultra-high vacuum devices, and is extremely useful industrially. Although the invention has been described with reference to specific examples and numerical values,
Of course, various changes and modifications may be made without departing from the broad spirit and scope of the invention.

[Brief explanation of the drawing]

Fig. 1 is a diagrammatic explanatory diagram showing the principle of the seal structure of the metal valve of the present invention, Fig. 2 is a partially cutaway side view showing the seal structure of the L-type valve according to the present invention, and Fig. 3 is the 4 is a longitudinal sectional view of a gate type valve using the seal structure of the present invention, FIG. 5 is a plan view thereof, and FIG. Figures 6 and 7 show how to apply internal pressure to the bellows used in gate-type valves.
FIG. 4 is a diagrammatic side view showing each type of model. 1... Valve body, 2... Valve seat, 3... Gasket,
4, 5... Knife edge, 6... Gasket mounting bracket, 7... Spring washer, 8... Screw, 9...
...Screw hole of valve body 1, 10...Smooth protrusion of valve seat 2, 11...Through hole provided in valve body 1, 15...Drive shaft, 16...Semispherical tip of drive shaft 15, 17... Valve body, 18... Drive shaft mounting bracket, 19... Gap between drive shaft 15 and drive shaft mounting bracket, 21... Bellows, 2
3... Compressed air inlet/outlet, 25... Exhaust groove, 27...
...Flange, 29... Valve stopper, 31... Bellows, 33... Intermediate disc, 35... Valve drive pipe that also serves as an inlet and outlet for compressed air, 37... Disc, 3
9...Flange, 41...Valve stopper.

Claims (1)

[Claims] 1. A sealing structure for a metal valve for an ultra-high vacuum device, which comprises a valve body, a valve seat, and a ring-shaped gasket interposed between the two, and which is spaced apart in the radial direction on the lower surface of the valve body. Two knife edges are provided as concentric double knife edges, a gasket fixing device is provided on the lower surface of the valve closer to the center than both of the knife edges, and the gasket is extended radially on the lower surface of the valve so that the upper surface of the gasket is two. The inner end of the gasket in the radial direction is fixed by the gasket fixing device, and a smooth hemispherical protrusion with a small radius of curvature is attached to the valve seat so as to be in contact with the tip of the knife edge of the valve body. The valve body is provided with at least one through hole located between the knife edges, and at least one through hole is provided between the knife edges to exhaust gas from the space between the gasket and the knife edges.
A sealing structure for a metal valve of an ultra-high vacuum device, characterized in that the valve body can be pressed against a valve seat. 2. In the metal valve sealing structure according to claim 1, the gasket fixing device passes through the gasket fixing member, the spring washer that abuts the lower surface of the gasket fixing member, and both the gasket fixing member and the spring washer to secure the lower part of the valve body. Consisting of a screw that threads into a screw hole.