JPS5937387A - Pressure control device of vacuum tank - Google Patents

Abstract

PURPOSE:To adjust the pressure in a vacuum tank automatically and finely to a desired value by providing a constant throttle at the intake side of the vacuum tank and adjusting the discharge side with a variable-conductance valve having a special shape. CONSTITUTION:A variable-leak valve 5 set to allow gas of a constant quantity to flow into a tank from a gas cylinder 4 is connected to the intake side pipe of a vacuum tank 1, and a variable-conductance valve 6 as a discharge valve and a vacuum pump 2 are connected to the discharge side pipe. When the piston valve 13 of the variable valve 6 retreats from a valve seat by means of a drive motor, the cross-sectional area of a key-type passage (a1, a2, a3) formed by the conical piston peripheral surface and the cone-shaped surface of the valve seat tends to increase gradually. It was found that the gas flow through such a fluid passage was nearly proportional to the piston displacement within a certain range of the piston stroke. Therefore, the degree of vacuum in the vacuum tank 1 can be automatically adjusted and maintained at a desired value by finaly adjusting the displacement quantity of the piston by means of the PID control of the drive motor.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a pressure control device that maintains the pressure in a vacuum chamber at a desired value by keeping the amount of air supplied to the chamber constant and adjusting the initial amount of air from the vacuum chamber. It is something.

To explain the conventional vacuum chamber pressure 1j1" axis device with reference to FIG. Connect the empty) Bonpco to exhaust the vacuum chamber l, control the variable leak valve 3,
The vacuum pressure in the vacuum chamber 1 was adjusted to a predetermined value by adjusting the amount of gas supplied from the gas cylinder through the pressure reducing valve q' into the negative chamber.

However, the conventionally known variable leak valve 3 has the drawback that it is difficult to make minute flow adjustments, particularly by remote control, because the variable leak valve 3 adjusts the flow rate of the gas amount in a relatively high-pressure state. there were. Therefore, it is possible to adjust the exhaust side of the vacuum chamber, but in this case, complicated control is difficult because it is controlled in a vacuum state, and it is usually 0.
Many of them use N-OFF control. Therefore, it has been difficult to finely control the pressure in the vacuum chamber.

The purpose of the present invention is to eliminate the drawbacks of the conventional ones described above,
To provide a control device that can easily finely adjust and control the pressure of a vacuum chamber with a simple configuration.

To achieve this objective, the present invention provides a variable leak valve on the supply side of the vacuum chamber, which is set to allow a constant small amount of gas to flow into the chamber, and on the exhaust side, a variable leak valve with a special shape. A piston-shaped variable conductance valve is provided, and a mechanical booster pump connected to an oil rotary pump is connected downstream of the variable conductance valve.

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 is an overall view of the vacuum chamber exhaust system according to the present invention.
In the conduit on the air supply side of the vacuum tank l, there is a variable leak valve S, which is set to allow a constant small amount of gas to flow into the gas cylinder through the gas cylinder peg and the pressure reducing valve q'. A variable conductance valve 6 is installed as an exhaust valve in the conduit on the exhaust side.
and a mechanical booster pump connected to the oil rotary valve ' are respectively connected, and the variable leak valve S has its aperture opening fixed at the value set during operation so as to keep the amount of inflow gas at a constant small amount. On the other hand, the variable conductance valve 6 serving as the exhaust valve is constructed as follows.

A valve Fl is formed, which is made up of a bowl-shaped inclined surface in contact with the outlet (exhaust port) g of the valve body 7 connected to the vacuum pump (iill) and an axis-perpendicular plane IO connected to its large diameter part. t
'1. , on the other hand, an intake port 1 connected to the vacuum chamber 1 side on the side.
A piston valve 1 inserted into a valve body 7 formed with a piston valve 2
3Vi, in a shape that comes into close contact with the valve seat when the valve is closed,
That is, a truncated conical inclined surface /S facing the mortar-like inclined surface W and a flat surface /S connected to the base thereof and facing the perpendicular plane /θ are formed, and the screw; The outer diameter of the cylindrical part of the valve 13 is made smaller than the inner diameter of the cylindrical part of the valve body so that a gas passage a1 with a certain gap is formed between them, and the back side of the piston part is roughly formed. A cylindrical cover 1g (lightweight instead of a piston) having the same outer diameter as the cylindrical surface of the piston part is fixed integrally with the piston valve n7 to ensure a gas passage a0, and a piston rod / 7 is installed. In addition, the piston plane part/S
A groove part /4' is formed in which an O-ring /6 is inserted.

The piston eye 17 is the lid (rod flange) of the valve body. It extends through the piston valve and is connected to the piston valve driving linear motor 2/ via the connecting portion 20. In addition, in order to display the displacement amount of the piston valve 13, the connecting portion 20
pinion 2 so that it meshes with the 2 racks attached to the
3 is attached to the drive motor side, and the rotation of the pinion 23 is transmitted to a piston valve displacement indicator (not shown).

Since the present invention is structured as described above,
When the piston valve 13 is closed, the piston valve 13 and the valve seat are in close contact with each other, and their respective conical inclined surfaces (9 and /<j) and axis-perpendicular planes (10 and tS) are in close contact with each other. In addition, the presence of the O-ring 16 allows the piston valve F to seal the valve seat.

Next, when the piston valve 13 is retracted from the valve seat via the piston rod 17 by the driving linear motor l,
The piston circumferential surface, the inner surface of the valve body cylindrical portion l/, the axis-perpendicular flesh planes IO and /S, the conical surface of the valve seat, and the piston valve 13
The conical surface of /Q (-tl.

A hook-shaped passage formed by the faces of it (al.

The cross-sectional area of atta5) is about to gradually increase.

However, since the passage is formed in a hook shape as described above, the cross-sectional area of the passage changes partially, for example, in the passage a2 between the planes 10 and 15 perpendicular to the axis, in proportion to the displacement of the piston valve. However, the passage a in the inclined surface section is affected by the inclination angle θ, and the cross-sectional area in the passage a1 in the rounded cylindrical surface section is not changed, but only the passage length is reduced.

By the way, in general, the flow rate of fluid passing through a valve section provided in the middle of a pipe line changes depending on the degree of opening of the valve body, and is normally proportional to the passage cross-sectional area of the valve body. However, in the case of a vacuum where the gas flow n- becomes a molecular flow (or an intermediate region between a molecular flow and a viscous flow), the flow rate passing through the valve body is 011 degrees, as described above, It is not a pure thing that is proportional to the cross-sectional area of the road. In the case of a vacuum, the phenomenon of gas flow n must be viewed from the kinetic theory of gas molecules, and the conductance (reciprocal of resistance) of the flow becomes an issue.

For the reasons described above, in the present invention, by forming the fluid passages as described above, the flow force of the gas (flow f
i: ) tffl: %According to the experimental results, within the range of 4 degrees consisting of the piston stroke, the displacement of the piston is t.
It was found that there is a proportional relationship. ko;i, l'i stylen
The passage a1. a2. It is considered that the change in the conductance of the diameter n of a is a value that is proportional to the piston displacement by #1 as a whole.

Therefore, the amount of displacement of the piston valve indicated by the indicator can be controlled, for example, by PID control of the linear motor 2/
By adjusting the proportional (P), integral (1), and differential (D) operations to 1, the degree of vacuum in the vacuum chamber can be adjusted to 1. It can be maintained automatically adjusted to the desired value. As in the present invention, the amount of air supplied to the vacuum chamber is kept constant by a leak valve that is installed on the air supply side, which has a relatively high pressure, and allows a large amount of gas to pass through, thereby maintaining a low pressure (vacuum) state. By automatically adjusting and controlling the exhaust side using the variable conductance nozzle as described above, pressure control full operation is easier than with conventional systems that control the air supply side. It can be done reliably.

As described above, the present invention automatically adjusts the pressure inside the vacuum chamber to a desired value by setting a constant restriction on the air supply side of the vacuum chamber and adjusting the exhaust side with a specially shaped variable conductance valve. And it can be finely divided into 6 circles.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional vacuum chamber pressure control device;
Schematic diagram of a Makabe tank pressure control device according to the present invention,
FIG. 3 is a sectional view of a variable reactance valve provided on the exhaust side of the vacuum chamber according to the present invention, and FIG. 9 is an enlarged sectional view of the main part of FIG. 3. /19. Vacuum chamber, S, variable leak valve set to allow metered gas to pass through;
B...Variable conductance ζ rub, 701. Valve body, 62. Mortar-shaped slope direction, /θ, , , q'+I
I in angle plane, l da19. frustoconical tilt elr
n4i, t s , , eh surface angle plane, /7
．． ,, piston rod, 21. ,,Linear motor for piston valve drive. Figure 1 for Kindergarteners 2

Claims (1)

[Claims] i. A leak l set to allow a fixed amount of gas to pass through the supply side of the vacuum chamber: A shib is provided and a variable conductance valve is provided on the exhaust side, and the variable conductance valve is connected to a vacuum pump. A cylindrical valve body with a valve seat at one end connected to the side and an intake port connected to the vacuum chamber side on the side, a mortar-shaped slope formed around the exhaust port, and the A valve seat formed by a plane perpendicular to the axis connected to the large diameter part, a truncated conical inclined surface formed to come into close contact with the valve seat when the valve is closed, and an angle perpendicular to the axis connected to the base thereof. A pressure control device for a Makabe tank, characterized by comprising a piston valve consisting of a flat surface and a cylindrical surface forming a passage with a constant gap between the inner surface of the cylindrical portion of the valve body, and a drive device for displacing the piston valve. . The pressure control device for a vacuum chamber according to claim 1, characterized in that a cylindrical cover having the same outer diameter as the cylindrical surface of the pinuton portion is attached to the back side of the piston valve.