JPH0815543B2 - Slow vent valve and control method thereof - Google Patents

Description

The present invention relates to an apparatus and a control method for controlling gas by flowing gas into a depressurized chamber in a depressurized state, and a method for controlling the same. A valve used for controlling the flow rate of gas flowing into the decompression chamber for the purpose of providing a slow vent valve and a control method therefor capable of shortening the time and preventing particles from floating in the decompression chamber. There is a pressure vessel for temporarily containing the inflowing gas, a valve body on the inflow side provided between the pressure vessel and the gas inflow side, and a valve on the outflow side provided between the pressure vessel and the decompression chamber. A body and a control device for independently controlling the opening and closing of the valve body on the inflow side and the opening and closing of the valve body on the outflow side.

[Industrial applications]

The present invention relates to an apparatus that utilizes a vacuum, and more particularly, to an apparatus and a control method thereof for injecting gas into a decompression chamber in a decompressed state to bring it to atmospheric pressure.

In recent years, in a device utilizing a vacuum, when a gas is introduced into a decompression chamber in a decompressed state to reach atmospheric pressure, the gas flowing into the decompression chamber causes particles in the decompression chamber to float inside the chamber, and the particles are processed in the decompression chamber. There is a failure that adheres to the surface of the produced product and deteriorates the quality of the product.

Under the circumstances as described above, there is a demand for an apparatus and a method capable of allowing gas to flow into the decompression chamber so that particles in the decompression chamber do not float inside the chamber due to the gas flowing into the decompression chamber.

[Conventional technology]

The conventional equipment and method used for introducing gas into the decompression chamber will be described with reference to FIGS. 6 to 8.

FIG. 6 is a block diagram of a conventional apparatus using a vacuum. In the figure, when the decompression chamber 16 in the decompressed state is set to the atmospheric pressure, the valve 18 on the exhaust side is closed and the valve 17 on the gas inflow side is opened, and the pressure difference between the room pressure of the decompression chamber 16 and the pressure of the outside air. Thereby, an air flow having a high flow velocity is generated, and the outside air flows into the decompression chamber 16.

When the gas flows into the decompression chamber 16 in this way, a large amount of particles in the decompression chamber 16 float and adhere to the surface of the processed product in the decompression chamber 16, reducing the product quality and reducing the product yield. Is decreasing.

As a method of preventing such a state, a throttle hole 19a as shown in FIG. 7 is provided in the pipe so as to throttle the gas flow passage in the pipe to limit the maximum flow rate of the inflowing gas. A restrictor 19 is provided, or a needle valve capable of minutely adjusting the flow rate is provided near the valve 17,
A method of reducing the flow rate of gas flowing into the decompression chamber 16 is adopted.

FIG. 8 shows a situation in which the internal pressure P ₁ of the decompression chamber 16 changes to the atmospheric pressure P ₀ with the passage of time when venting is performed by such a method.

In the figure, the fluid pressure refers to the kinetic energy that the molecules of the inflowing gas give to the particles when they collide with the particles.

The average velocity of molecules flying in a gas is considered to be constant when the type and temperature of the gas are specified, so when considering collisions between gas molecules or between gas molecules and particles, the problem is inflow. It is considered to be the probability of collision between gas molecules and particles.

In other words, the distance that a gas molecule can move under reduced pressure without colliding with other molecules (this distance is called the mean free path) is a few
The mean free path at m / sec and atmospheric pressure is several m / sec, and as the depressurized state approaches atmospheric pressure, the distance that molecules can move without colliding with other molecules becomes smaller.

In other words, when the room pressure is at the minimum decompression state, the probability that the inflowing gas collides with particles without being blocked by other molecules is as high as possible. The probability of colliding with particles is expected to be low.

[Problems to be Solved by the Invention]

In the conventional apparatus and method used for introducing gas into the decompression chamber described above, when the gas flow path in FIG. 8 is close to 0 when the gas flow path is not narrowed. However, there is a problem that particles in the decompression chamber float inside the decompression chamber due to the gas flowing into the decompression chamber, and adhere to the surface of the product processed in the decompression chamber. If the pressure is constantly reduced from beginning to end, it takes a very long time to bring the pressure inside the decompression chamber to atmospheric pressure, and there is a problem that it cannot be put to practical use.

The present invention shortens the time to reach atmospheric pressure by changing the flow rate of the gas flowing into the decompression chamber from the above situation,
An object of the present invention is to provide a slow vent valve capable of preventing particles from floating in a decompression chamber and a control method thereof.

[Means for solving the problem]

The slow vent valve of the present invention is a valve used for controlling the flow rate of gas flowing into a decompression chamber, and is provided between a pressure container that temporarily stores the inflow gas and between this pressure container and the gas inflow side. The inflow side valve body, the outflow side valve body provided between the pressure vessel and the decompression chamber, the opening and closing of the inflow side valve body and the opening and closing of the outflow side valve body are individually independent. The control method of the slow vent valve according to the present invention is configured such that the inflow side valve element and the opening and closing and the outflow side valve element are opened and closed by the control apparatus described above. By independently controlling and, the flow rate of the gas flowing into the decompression chamber is adjusted, and the dust is prevented from floating during the gas inflow.

[Action]

That is, in the present invention, the opening and closing of the valve body 2 on the gas inflow side and the valve body 3 on the outflow side shown in FIG. By changing the number of times per cycle of the operation of one cycle of the timing chart shown in FIG. 2 which is a combination of the four basic operation patterns, or changing the opening / closing timing of the valve body 2 and the valve body 3. By controlling the amount of gas flowing into the pressure vessel to limit the amount of gas flowing into the decompression chamber, it becomes possible to prevent particles from floating in the decompression chamber.

A. Close both valve body 2 and valve body 3.

B. Open the valve body 2 and let gas flow into the pressure vessel 4.

C. Close the valve body 2.

D. The valve body 3 is opened with the valve body 2 closed and the pressure vessel 4 completely blocked from the inflowing gas.

E. After the gas in the pressure vessel 4 has completely flowed into the decompression chamber 6,
The valve body 3 is closed.

In this way, by increasing the amount of gas flowing into the pressure vessel 4 with the lapse of time, it is possible to prevent the particles from floating in the decompression chamber while keeping the time required for the decompression chamber to reach the atmospheric pressure from beginning to end. It is possible to shorten the length as compared with the method using the diaphragm.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 3 to 5.

FIG. 3 is a diagram showing the configuration of an embodiment according to the present invention, in which the slow vent valve of the present invention is arranged between the valve 7 on the gas inflow side and the decompression chamber 6, and the vacuum gauge The recorder 10 and the recorder 11 are connected to the decompression chamber 6 via a valve 9 so that the situation inside the decompression chamber 6 can be indicated or recorded.

As the valve element 2 and the valve element 3 of this slow vent valve whose details are shown in FIG. 1, those driven by an electromagnetic method were used. The timing control of these valve elements is performed by the control device 5.

FIG. 4 shows a timing chart of the valve bodies 2 and 3 of the slow vent valve according to the embodiment of the present invention, and FIG. 5 shows a pressure change of the inflowing gas.

As shown in the timing chart of FIG. 4, the timing of the valve body can be roughly classified into three types.

Type 1: The opening and closing timings of the valve bodies 2 and 3 are separated by the isolation time of Δt _i , and the open state of each valve body is completely independent.

Type 2: Opening and closing timings of the valve bodies 2 and 3 are synchronized with the overlap time of Δt _o .

Type3: The valve body 2 and the valve body 3 are opened and closed at the same time.

These opening and closing patterns are controlled by time, and Type1 → Type2
→ You may move to Type3. Also, the isolation time of Δt _i of Type 1 may be changed to be gradually shortened, and the timing of the valve element 2 and the valve element 3 may be changed to asynchronous → semi-synchronous → synchronous.

In addition to the above-mentioned electromagnetic system, a pneumatic system can be used as a drive system for the valve element.

Further, the volume of the pressure vessel 4 in the slow vent valve can be changed by making a part of the valve seat 1 into a screwed structure so that the volume of the pressure vessel 4 can be changed and adapted to the volume of the decompression chamber 6. is there.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, by providing a slow vent valve having a plurality of valve bodies and a pressure vessel having a simple structure, the adhesion of particles to the surface of the product in the decompression chamber is prevented. However, if the conventional adhesion is set to 100, it can be reduced to 2, which has the advantage of being able to significantly improve the quality of the product. Is very useful for.

[Brief description of drawings]

1 is a detailed view of essential parts of a slow vent valve of the present invention, FIG. 2 is an operation timing chart of the slow vent valve of the present invention, FIG. 3 is a configuration diagram of an embodiment according to the present invention, and FIG. Is a timing chart of a slow vent valve according to an embodiment of the present invention, FIG. 5 is a diagram showing characteristics of the embodiment of the present invention, FIG. 6 is a configuration diagram of a conventional vacuum apparatus, and FIG. FIG. 8 is a view showing the restrictor, and FIG. 8 is a view showing the characteristics when venting is performed by the conventional method. In the figure, 1 is a valve seat, 2 is a valve body, 3 is a valve body, 4 is a pressure vessel, 5 is a control device, 6 is a decompression chamber, 7 is a valve, 8 is a valve, 9 is a valve, 10 is a vacuum gauge, 11 is a recorder.

Claims (2)

[Claims] 1. A valve used for controlling the flow rate of gas flowing into a decompression chamber, comprising: a pressure vessel for temporarily containing the inflow gas; and an inflow side provided between the pressure vessel and the gas inflow side. A valve element, an outflow-side valve element provided between the pressure vessel and the decompression chamber, and opening / closing of the inflow-side valve element and opening / closing of the outflow-side valve element are independently controlled. A slow vent valve, comprising: a control device. 2. The control device for a slow vent valve according to claim 1, wherein the opening / closing of the inflow side valve body and the opening / closing of the outflow side valve body are controlled independently of each other. A method for controlling a slow vent valve, which comprises controlling the flow rate of gas flowing into a decompression chamber to suppress the floating of dust when the gas flows in.