JPS58121387A - Gate valve used under vacuum - Google Patents

Abstract

PURPOSE:To obtain excellent sealing performance at all times by a method wherein an automatic controlling means for operating air pressure is provided so as not to apply excessive contact force by pressure during baking. CONSTITUTION:When a pressure instruction S is inputted, the opening of a pressure regulating valve is turned to be smaller so as to lower the operating air pressure. The operating air pressure is set at a value, in which a suitable contact force by pressure is obtained between a gate seal 13 and a seal ring 12 under the condition that an operating device 28 and the like are in the thermally enough elongated states with the rise of the temperature of their own. Accordingly, even during baking, no deterioration of sealing performance due to the yield of the knife edge of the gate seal 13 caused from excess contact force by pressure occurs, resulting in obtaining excellent sealing performance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gate pulp for vacuum use, and more particularly to a gate seal operating device for an all-metal gate pulp suitable for ultra-high vacuum use.

This type of all-metal gate pulp is often used in ultra-high vacuum equipment such as recent nuclear fusion equipment, where it is necessary to open and close the entire section of the boat for plasma observation, particle injection equipment, etc. However, the most important points that affect the sealing performance are maintaining elastic deformation on the sealing surface due to knife-like pressure contact between the metal gate seal and the metal seal ring, and the sealing surface being damaged by fine dust etc. The purpose is to prevent damage to the product.

Of these, the former poses a particular problem when baking a vacuum device at high temperatures.

Figure 1 is a system diagram showing the driving method of a conventional all-metal gate valve. The all-metal gate valve l is installed between the vacuum vessel 8 and the external equipment of the plasma observation device via the boat 2, and a heater (not shown) and a paving made of heat insulating material are installed outside of these. The device 5 is coated. 6 is a gate valve driving cylinder 1. 7 is an electromagnetic switching valve, 8 is an air pipe, 9 is an air tank,
10 is a compressor, which constitutes a drive system for the gate valve.

Moreover, FIG. 2 is a sectional view showing the structure of an all-metal gate valve. The gate valve l includes a valve body 11 having a supply/discharge port and a hollow chamber, a metal seal ring 12 attached to this valve body 11, and a valve body 1.
It moves inside the hollow chamber of 1 and opens and closes the valve by interaction with the seal ring 12.
□8. Ka, uhue bubble 11, ru. And its closing action,
That is, the boat 2 is sealed by an operating device using a link mechanism, and this operating device 28 is connected to the rod 14 of the driving cylinder 6, a bracket 15 connected to the rod 14, and a pin 16 connected to the bracket 15. Rollers 17 and 18 are rotatably supported by a bracket and roll along the earthen wall of the hollow chamber of the valve body 2; It is composed of links 19 and 20 rotatably supported by a pin 16, and a roller 22 rotatably supported by a pin 16 on a support arm 21 protruding from the side opposite to the rod 14 of the seal ring 12.

That is, when pressurized air is supplied from the air tank 9 to the driving cylinder 6 via the air piping 8 and the electromagnetic switching valve 7,
The rod 14 extends to the left, and accordingly the operating device 28 also moves its roller l? , 18 moves to the left while rolling along the earthen wall of the hollow chamber. Then, that roller 22
is the piece on the side opposite to rod 14 of the hollow chamber.

When the gate seal 18 reaches the position indicated by the dashed line where it contacts the wall, further movement of the gate seal 18 is prevented, but the bracket 15 still continues to move to the left, so the gate seal 18 is guided by the p-ra 22. While being pushed downwards by the links 19 and 20, the seat ring 12 is brought into close contact with the seat ring 12 with a sharp pressing force.

By the way, in order to obtain an ultra-high vacuum, the vacuum equipment is heated to a high temperature of T!
(approximately 200℃)
At this time, the valve l is closed), and in this case, as shown in FIG. Previous n temperature Tt (approximately 20℃
) Valve leakage amount Q+ (approximately 1 x 10
Torrl/s) at the end of paking 1
Valve leak t'4 at temperature T1 after that is approximately 2
X IQ 'Torrl/s and one 1ti [100
~200 times increase in stiffness and loss of sealing performance.

After investigating the cause through various disaster experiences, we found the following. That is, at the time of paking, in the gate valve I, the valve body ■ and the seal ring 12 are first heated and reach a high temperature, but the gate seal 18 disposed in the hollow chamber of the gate seal 1 and its operating device 28 are heated to a high temperature. Since there are few parts in contact with 11 etc. and it is in a vacuum, it takes time for it to heat up to a high temperature. On the other hand, as mentioned above, gate seal 1B
sealing ring II by means of a suitable pressing blade of the operating device 28 with pressurized air (pressure P, constant) from the air tank 9.
However, in the initial stage of paking, there is a temperature difference between the pulp body 11, etc. and the operating device 28, etc., as described above, and the former expands due to heat. On the other hand, the latter undergoes almost no thermal expansion and maintains the same dimensions, so when a constant operating air pressure P is applied, the rod 14 and bracket are 15 moves to the left, the links 19 and 20 become nearly upright, and the gate seal 18 is pressed into contact with the seal ring 12 using the same appropriate pressing blade as at room temperature. However, as the paking progresses, the temperature of the operating device 28 etc. gradually rises, causing thermal expansion of the operating device 28 etc., and the vertical dimension of the operating device 28 etc. becomes thicker. Since it is in the fully extended state and the vertical distance in the hollow chamber is maintained at approximately the same level, the pressing contact force between the pushing blade by the operating device 28, that is, the gate seal 18 and the seal ring 12, is at an appropriate value. Moreover, the gate seal 18 is heated to a high temperature during paking, and the knife 1
8a is easily deformed, so when an excessive pressing contact force as described above is applied, the contact area with the seal ring 12 increases by 1" as shown by the broken line 18a' in FIG. It was found that elastic deformation could not be maintained on the sealing surface due to knife-like suppressive contact, and sealing performance was impaired.

Incidentally, such a problem also occurs in cases other than the case where the link mechanism as described above is used as the operating device.

The present invention has been made in view of this point, and its purpose is to
The purpose of this invention is to provide a vacuum gate pulp that has good sealing performance and is one of the drawbacks of the gate seal knife during paking.

To achieve this objective, the present invention provides an operating pressure port IAi
ti control means is provided to automatically lower the operating pressure of the gate seal operating device to press the metal gate seal into contact with the metal seal ring at the time of pecking1, thereby preventing excessive suppressing contact force from being applied during pecking. It is characterized by what it did.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. In FIG. 5, the same reference numerals as in FIG. 1 indicate the same or equivalent components.

This embodiment differs from the conventional example shown in FIG.
An automatic operating pressure control system is provided, which is comprised of a pressure command generator t25 consisting of a converter, micro combinator, D-A converter, etc., and an air pressure regulator z6 consisting of a pressure regulating valve, etc. .

During baking, the temperature of gate pulp 1 is room temperature T.

As the temperature rises more gradually, the temperature sensor
The analog detection signal S from □24 also increases and is input to the pressure command generator 25. Pressure command generator 2
5, the analog detection signal Sl is converted into a digital detection signal by the A-D converter, and then the value of this digital detection signal is converted to a predetermined gate pulp temperature Tax (Tt<T- + (Tt).When it is determined that the detection signal exceeds the set value (time ts), a digital pressure command is output, and this is converted into an analog signal using a D-A converter. It is converted into a pressure command S! and added to the desired pressure adjustment device 2.The air pressure adjustment device 26 always uses operating air similar to the conventional example shown in Fig. 81 at room temperature T when the pressure command S is not output. The opening degree of the pressure regulating valve is set so that the pressure becomes P1, but when the pressure command S is input, the opening degree of the pressure regulating valve is set to zero and the operating air pressure is changed as shown in Fig. 6. This operating air pressure P is lowered to P2.

The value is set to such a value that an appropriate pressing contact force can be obtained between the 1-gate seal 18 and the seal ring 12 when the operating device 28, etc. is in a state of light thermal expansion due to a rise in temperature. do. Therefore, when paying? Even if
If the suppressing contact force is excessive, the sealing performance will not deteriorate even if the contact force is excessive and the knife blade 18a of the gate seal 18 is damaged.

Further, in the final stage of pacing, when the heating by the pacing device 5 is finished, the temperature of the pulp body 11 and the like first decreases, and after a while, the temperature of the operating device 28 and the like decreases. That is, since there is a delay in the timing of thermal contraction of both, if the operating air pressure is immediately returned to the original Pl, there is a risk that the suppressing contact force will become excessive. Therefore, in this embodiment, the temperature of the operating device 28 and the like is sufficiently lowered after the paking is completed, and is returned to the operating air pressure Pl only after waiting until it approaches the room temperature T1.

That is, at the end of pacing, the micro combinator of the pressure command generator 25 changes the value of the digital detection signal to a predetermined gate pulp temperature T, as shown in FIG.
After a predetermined time τ (this time τ is set by a counter, etc.) has elapsed from the time when it is determined that the value is less than or equal to this set value (time point 14) after comparing it with the set value corresponding to I2 (Tt (Tax (T, )). The output of the digital pressure command is stopped at time t.Therefore, the analog pressure command S is input to the air pressure regulator 26, and the operating air pressure returns to the original PIK.

In the gate pulp to which this example is applied, the sixth
As shown in the figure, it was confirmed through experiments that the leakage amount Qx' after pacing was significantly reduced compared to the conventional example.

As mentioned above, at times t and t in the initial and final stages of paking, the operating air pressure is changed from Pl to P.
Lowering tK and increasing Pl to P [initially, time 1. to time t6 when the temperature of the operating device, etc. reaches T2 and is sufficiently thermally expanded, and in the final stage from time t to time tll when the temperature of the operating device, etc. decreases to T and sufficiently thermally shrinks. that is, the delay time τ
In this case, there is a concern that the operating air pressure is too low, the pressing force' contact force is less than an appropriate value, and the amount of leakage increases. However, as is generally known, in a vacuum, the J1ml coefficient between each related member such as a link mechanism is larger than in the atmosphere, and each related member is in a stiff state, so the suppressing contact force If the seal state is maintained as it is even if the pressure drops below an appropriate value for a while, and if the amount of leakage requires adjustment of the contact force, the pressure command The air pressure adjusting device 25 may be configured so that the operating air pressure is sequentially lowered or increased by turning on and off.

Further, as the operating pressure automatic control means, the gate pulp temperature detection 'a 24 as in the above embodiment, the pressure command generation device 25, and the air pressure v! It is not limited to the one consisting of the four adjustment device 26, but other means can also be used.

That is, for example, a pressure command generation switch and a timer are provided in place of the gate pulp temperature detector 24 and pressure command generation device 25 of the embodiment described above, and a pressure command is generated in conjunction with turning on the heater power switch of the pacing device 5. Pressure command S is generated by automatically turning on the heater power switch, and when the heater power switch is turned off, K is the timer. After a predetermined time has passed, the pressure command generation switch is activated. It is also possible to stop the generation of the pressure command S by automatically turning off the pressure command S.

As explained above, according to the present invention, the operating pressure automatic control means is provided, and by automatically lowering the operating pressure for bringing the metal gate seal into pressure contact with the metal seal ring by the gate seal operating device at the time of paking, Since an excessive suppressing contact force is not applied during pacing, it is possible to eliminate the fatigue of the gate seal knife during pacing, and always obtain good sealing performance.

[Brief explanation of drawings]

Figure 1 is a system diagram showing the conventional gate pulp driving system.
2nd rI! J is a cross-sectional view of gate pulp, FIG. 8(a),
(b) is a characteristic diagram showing the relationship between operating air pressure, pulp temperature, and leakage amount in conventional gate pulp.
The figure is an enlarged cross-sectional view showing the state of the knife of the gate seal in the 1' set state, FIG. 5 is a system diagram showing the driving method of the gate pulp according to an embodiment of the present invention, and FIGS. 6 (a) and (b).
FIG. 2 is a characteristic diagram showing the relationship between operating air pressure, pulp temperature, and leakage amount of gate pulp according to an embodiment of the present invention. l...Gate pulp, 8. Song, Vacuum container, 5.
Curving/paking device, 6... Cylinder for bending section movement, 9...
・・・・Air tank, 11・Song・Pulp body, 12・
・Curved seal ring, 1B... Kate seal, 28... Operating device, 24... Gate pulp temperature detector, 25... Pressure command generator, 26...Air pressure adjustment device? 1 figure t 2 lower 3 stroke ttl) 74 figure

Claims (1)

[Claims] 1. A pulp body having a supply/discharge port, a metal seal ring, and a hollow chamber, a metal gate seal, and the metal gate seal pressed into contact with the metal seal ring in the hollow chamber of the pod. and a gate seal operating device that closes the discharge port, automatic operating pressure control that automatically lowers the operating pressure of the gate seal operating device for bringing the metal gate seal into pressure contact with the metal seal ring at the time of paking. Vacuum gate pulp with facing ridges provided with means. 2. In claim 1, the operating pressure is air pressure, and the operating pressure automatic control means includes a temperature detection means for detecting the temperature of the gate pulp, and a temperature detection means for detecting the temperature of the gate pulp detected by the temperature detection means. The apparatus is characterized by comprising: an output command generation means for generating a pressure command when the temperature of the pressure command exceeds a predetermined value; and an adjustment means for adjusting the operating air pressure in accordance with the pressure command from the pressure command generation means. Gate pulp for vacuum. 8. The vacuum gate pulp according to Item 1, wherein the operating pressure automatic control means sequentially lowers the operating pressure as the temperature of the gate pulp increases during paking.