JP2012160168A - Vacuum pressure control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum pressure control apparatus in which undershoot of pressure in a vacuum container is prevented without using a heater.SOLUTION: A vacuum pressure control apparatus 8 includes a pilot vacuum proportional open/close valve 18, a pressure sensor 17 and a controller 56. The vacuum proportional open/close valve 18 changes vacuum pressure in a vacuum container by changing an aperture on piping connecting the vacuum container and a vacuum pump and comprises a valve element including an O ring which is abutted with or separated from a valve seat and an air cylinder. The pressure sensor 17 measures the vacuum pressure in the vacuum container. The controller 56 changes an elastic deformation amount of the O ring on the basis of the pressure of the pressure sensor 17 and changes the amount of leakage from the O ring, thereby controlling the pressure in the vacuum container. In the vacuum pressure control apparatus 8, when the pressure in the vacuum container measured by the pressure sensor 17 becomes a fixed or more pressure drop rate, inner pressure of the air cylinder is exhausted.

Description

  The present invention relates to an elastic seal member which is on a pipe connecting a vacuum vessel and a vacuum pump and changes the vacuum pressure in the vacuum vessel by changing the opening, and abuts or separates the valve seat from the valve seat. The present invention relates to a vacuum pressure control device having a vacuum proportional on-off valve including a valve body including a pneumatic cylinder, a pressure sensor that measures a vacuum pressure in the vacuum container, and a controller that controls the pressure in the vacuum container.

Conventionally, as this type of technology, there is a vacuum proportional on-off valve described in the following Patent Document 1 filed by the present applicant. The vacuum proportional on-off valve is intended to prevent particles from rolling up in the reaction chamber. The vacuum proportional on-off valve throws the material gas from the reaction chamber so that particles do not roll up during the evacuation process that causes the vacuum pressure in the reaction chamber to reach the target vacuum pressure value from the atmospheric pressure or a low vacuum close to atmospheric pressure. Exhaust.
However, the vacuum proportional on-off valve 101 of Patent Document 1 shown in FIG. 21 has a problem that the O-ring 108 and the valve seat 106 are fixed when they are shut off. That is, the O-ring 108 and the valve seat 106 are in close contact with each other in the shut-off state, and the material gas discharged from the reaction chamber is precipitated at room temperature, so that it may be fixed due to the deposition of the material gas.
Therefore, in the vacuum proportional on-off valve 101 of Patent Document 1, the valve seat 106 is heated by the heater 110 so that the O-ring 108 and the valve seat 106 are not fixed. By heating the valve seat 106, the deposition of the material gas can be prevented and the O-ring 108 and the valve seat 106 can be prevented from sticking.

JP 2000-163136 A

However, the prior art has the following problems.
That is, the heater 110 is used as a measure for preventing the elastic O-ring 108 from adhering to the valve seat 106, but the heater 110 is expensive because it is a special heater that matches the vacuum proportional on-off valve 101. . Therefore, it becomes a problem because the cost increases.

In addition, if the heater 110 is disconnected, there is a problem that the O-ring 108 is fixed, and the pressure rapidly decreases when the slow exhaust control is started. The problem that the heater 110 is disconnected and there is no heater will be described with reference to FIGS. In FIG. 17, the horizontal axis represents time, and the vertical axis represents pressure and the like. Further, the pressure in the vacuum vessel, the stroke of the vacuum proportional on-off valve, and the internal pressure of the air cylinder are represented by line graphs.
In FIG. 17, the pressure X in the vacuum container, the stroke Y of the vacuum proportional on-off valve, and the internal pressure Z of the air cylinder show a line graph of the vacuum container and the vacuum proportional on-off valve 101 when the heater 110 is disconnected.
In addition, the pressure Q in the vacuum vessel, the stroke R of the vacuum proportional on-off valve, and the internal pressure S of the pneumatic cylinder in FIG. 17 are line graphs of the vacuum proportional on-off valve 101 when the heater 110 is normally operated. .

Specifically, first, as shown in FIG. 18, when the heater is disconnected, the O-ring 108 is fixed to the valve seat 106 due to a material gas or the like. As shown in FIG. 17, there is a time T <b> 1 until the O-ring 108 starts to partially separate from the valve seat 106. Since the heater is disconnected, it takes longer time T20 than time T10 when the O-ring 108 is partially separated from the valve seat 106 when the heater is activated.
During time T20, when the O-ring 108 is fixed to the valve seat 106 and no exhaust is generated, the control device attempts to exhaust by increasing the stroke, so the control device increases the internal pressure Z of the cylinder. to continue. Therefore, the O-ring 108 is elastically deformed and the extension stroke Y continues to rise.

Secondly, during the time T2, the pressure X starts to decrease due to the start of slow exhaust, and a command to lower the internal pressure Z of the cylinder is issued by the control device to match the set pressure Q. However, when “sticking and peeling” between the O-ring 108 and the valve seat 106 starts, the process proceeds to “complete peeling” in a short time. Therefore, the stroke Y is vigorously lifted by the internal pressure Z of the cylinder that has been raised so far, and the O-ring 108 and the valve seat 106 are separated, and the stroke Y rises until the stroke value becomes P2. Thereafter, the stroke Y is lowered, but the pressure X is greatly undershooted because the return of the stroke Y is slow.
Third, during the time T3, the pressure X that has decreased too much is returned to the pressure Q, so that the internal pressure Z of the cylinder is further decreased, the O-ring 108 and the valve seat 106 are brought into close contact, and the increase in the pressure X is waited. However, since the sticking occurs when the O-ring 108 and the valve seat 106 are brought into close contact with each other, the phenomenon of the times T20 and T2 is repeated. Since no sticking occurs when the heater is operating, there is no cylinder internal pressure value P3 for peeling, no stroke P2, and no pressure P1 drop. Therefore, the set pressure Q can be implemented by the cylinder internal pressure S and stroke R.

  Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide a vacuum pressure control device that prevents undershoot of the pressure of the vacuum pressure vessel without using a heater. And

In order to achieve the above object, a vacuum pressure control apparatus according to an aspect of the present invention has the following configuration.
(1) An elastic seal member which is on a pipe connecting the vacuum vessel and the vacuum pump and changes the vacuum pressure in the vacuum vessel by changing the opening, and makes contact with or separates the valve seat from the valve seat. In a vacuum pressure control device, comprising: a valve proportionally provided with a valve body and a pneumatic cylinder; a pressure sensor that measures a vacuum pressure in the vacuum vessel; and a controller that controls the pressure in the vacuum vessel. When the pressure in the vacuum vessel measured by the pressure sensor reaches a pressure drop rate of a certain level or higher, the internal pressure of the pneumatic cylinder is exhausted.
(2) In the vacuum pressure control device described in (1), an electro-pneumatic proportional on-off valve and a three-way valve are connected to the vacuum proportional on-off valve, and the three-way valve exhausts the internal pressure of the pneumatic cylinder. It is preferable to do.
(3) In the vacuum pressure control device described in (1), it is preferable that the pressure drop rate not less than a certain value is generated when a part of the elastic seal member is detached from the valve seat.
(4) In the vacuum pressure control apparatus described in (1), the apparatus has a cylinder internal pressure detector for detecting an internal pressure of the pneumatic cylinder, and the cylinder internal pressure detector has a constant internal pressure value of the pneumatic cylinder. It is preferable to stop exhausting the internal pressure of the pneumatic cylinder when detected.
(5) In the vacuum pressure control device described in (4), the pressure of the pneumatic cylinder is a value at which the pressure in the vacuum container starts to drop when the controller is provided with a heater in the vacuum proportional on-off valve. It is preferable that a reference value of the internal pressure is stored in advance, and the constant internal pressure value is a reference value of the internal pressure of the pneumatic cylinder.
(6) In the vacuum proportional on-off valve described in (1), when exhausting the internal pressure of the pneumatic cylinder, it is preferable to stop exhausting the internal pressure of the pneumatic cylinder when a certain time has elapsed. .

The operation and effect of the vacuum pressure control device will be described.
(1) An elastic seal member which is on a pipe connecting the vacuum vessel and the vacuum pump and changes the vacuum pressure in the vacuum vessel by changing the opening, and makes contact with or separates the valve seat from the valve seat. In a vacuum pressure control device, comprising: a valve proportionally provided with a valve body and a pneumatic cylinder; a pressure sensor that measures a vacuum pressure in the vacuum vessel; and a controller that controls the pressure in the vacuum vessel. When the pressure in the vacuum vessel measured by the pressure sensor reaches a pressure drop rate of a certain level or more, the internal pressure of the pneumatic cylinder can be reduced at a stroke by exhausting the internal pressure of the pneumatic cylinder. By reducing the internal pressure of the pneumatic cylinder at once, the valve body can be closed directly even when the stroke is large. Therefore, the time T2 described in the above problem can be shortened. Since the valve body can be closed immediately, the amount of pressure drop can be reduced, and undershoot can be reduced.
In addition, even if there is no heater, undershoot can be reduced, so there is no need to provide a heater. Therefore, it is not necessary to provide a heater, so that the cost can be reduced.
(2) An electro-pneumatic proportional on-off valve and a three-way valve are connected to the vacuum proportional on-off valve, and the internal pressure of the pneumatic cylinder can be lowered rapidly by exhausting the pressure in the vacuum vessel. it can. That is, it takes time to reduce the internal pressure of the pneumatic cylinder using the electro-pneumatic proportional on-off valve, but the internal pressure of the pneumatic cylinder can be rapidly reduced by using the three-way valve.

(3) A pressure drop rate of a certain level or more is generated when a part of the elastic seal member is detached from the valve seat, so that it is possible to recognize when the pressure decreases. By recognizing when the pressure decreases, the internal pressure of the pneumatic cylinder can be reduced at a stroke. Therefore, the valve body can be immediately closed, and the time for forming a gap between the O-ring and the valve seat can be shortened. Since the valve body can be closed directly, the amount of pressure drop can be reduced, and undershoot can be reduced.
In addition, even if there is no heater, undershoot can be reduced, so there is no need to provide a heater. Therefore, it is not necessary to provide a heater, so that the cost can be reduced.
(4) Having a cylinder internal pressure detector for detecting the internal pressure of the pneumatic cylinder, and stopping the exhaust of the internal pressure of the pneumatic cylinder when the cylinder internal pressure detector detects a constant internal pressure value of the pneumatic cylinder As a result, the internal pressure of the pneumatic cylinder can be prevented from excessively decreasing. This is because if the internal pressure of the pneumatic cylinder is excessively lowered, the subsequent slow exhaust control is adversely affected. That is, it takes time to increase the internal pressure of the pneumatic cylinder that has once decreased. As a result, it takes time for the subsequent evacuation, which is the purpose of the original vacuum proportional on-off valve, which is problematic.
However, in the present invention, it is possible to solve the problem, not to spend time to increase the internal pressure of the pneumatic cylinder, and to reduce undershoot.

(5) When the controller is equipped with a heater in the vacuum proportional on-off valve, the reference value of the internal pressure of the air cylinder, which is the value at which the pressure in the vacuum vessel starts to drop, is stored in advance, and the constant internal pressure value Is a reference value of the internal pressure of the pneumatic cylinder, so that it is possible to recognize when the internal pressure of the pneumatic cylinder has dropped too much. By recognizing that the internal pressure of the pneumatic cylinder is excessively reduced, it is possible to prevent the internal pressure of the pneumatic cylinder from excessively decreasing. This is because if the internal pressure of the pneumatic cylinder is excessively lowered, the subsequent slow exhaust control is adversely affected. That is, it takes time to increase the internal pressure of the pneumatic cylinder that has once decreased. As a result, it takes time for the subsequent evacuation, which is the purpose of the original vacuum proportional on-off valve, which is problematic.
(6) When exhausting the internal pressure of the air cylinder, the internal pressure of the air cylinder can be reduced without providing a cylinder internal pressure detector by stopping the exhaust of the internal pressure of the air cylinder when a certain time has elapsed. It can prevent falling too much.
That is, if the exhaust of the internal pressure of the air cylinder can be stopped before the internal pressure of the air cylinder decreases excessively, it is possible to prevent the internal pressure of the air cylinder from excessively decreasing.

It is a block diagram (1) of the vacuum pressure control device concerning the present invention. It is a block diagram (2) of the vacuum pressure control apparatus which concerns on this invention. It is a data figure showing the pressure which concerns on this invention, a stroke, and cylinder internal pressure. It is a conceptual diagram (1) showing the clearance gap between the O-ring which concerns on this invention, and a valve seat. It is a conceptual diagram (2) showing the clearance gap between the O-ring which concerns on this invention, and a valve seat. It is a conceptual diagram (3) showing the clearance gap between the O-ring which concerns on this invention, and a valve seat. It is a data figure of experiment (1) at the time of using the vacuum proportional on-off valve which concerns on this invention. It is a data figure of experiment (1) using the vacuum proportional on-off valve concerning the case where the heater is not provided and the case where the heater is disconnected. It is a data figure of experiment (2) at the time of using the vacuum proportional on-off valve which concerns on this invention. It is a data figure of experiment (2) using the vacuum proportional on-off valve concerning the case where the heater is not provided and the case where the heater is disconnected. It is a data figure of experiment (3) at the time of using the vacuum proportional on-off valve which concerns on this invention. It is a data figure of experiment (3) using the vacuum proportional on-off valve concerning the case where the heater is not provided and the case where the heater is disconnected. It is sectional drawing which shows the structure of the vacuum proportional on-off valve which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the valve seat vicinity of the vacuum proportional on-off valve which concerns on embodiment of this invention. It is a block diagram which shows the structure of the electropneumatic proportional on-off valve which concerns on embodiment of this invention. 1 is an overall view showing an overall configuration of a vacuum pressure control system in which a vacuum pressure control device according to an embodiment of the present invention is used. It is a data figure showing the pressure which concerns on a prior art, a stroke, and cylinder internal pressure. It is a conceptual diagram (1) showing the clearance gap between an O-ring and a valve seat which concerns on a prior art. It is a conceptual diagram (2) showing the clearance gap between an O-ring and a valve seat which concerns on a prior art. It is a conceptual diagram (3) showing the clearance gap between the O-ring which concerns on a prior art, and a valve seat. It is sectional drawing which shows the structure of the vacuum proportional on-off valve which concerns on a prior art.

An embodiment embodying the vacuum pressure control device of the present invention will be described in detail with reference to the drawings.
(Configuration of vacuum pressure control system)
FIG. 16 shows the overall configuration of an embodiment of a vacuum pressure control system in which the vacuum pressure control device 8 of the present embodiment is used.
As shown in FIG. 16, the wafers 15 are arranged in a step shape inside the vacuum vessel 11. An inlet 13 and an outlet 14 are formed in the vacuum vessel 11, and a process gas supply source and a nitrogen gas supply source for purging the inside of the vacuum vessel 11 are connected to the inlet 13. The outlet 14 is connected to an inlet port of a vacuum proportional on-off valve 18 that is a valve opening proportional valve. The outlet port of the vacuum proportional on-off valve 18 is connected to the vacuum pump 19. Further, a pressure sensor 17 is connected to the outlet 14 via a shutoff valve 16. In the present embodiment, a capacitance manometer is used as the pressure sensor 17.

(Configuration of vacuum proportional on-off valve)
Next, the structure of the vacuum proportional on-off valve 18 will be described in detail with reference to FIGS. FIG. 13 shows a state where the vacuum proportional on-off valve 18 is closed. The vacuum proportional on-off valve 18 is roughly divided into an upper air cylinder 32 and a lower bellows poppet valve 31. The pneumatic cylinder 32 has the following configuration. A piston 41 is slidably disposed with respect to the single acting pneumatic cylinder 43. The piston 41 is urged downward by a return spring 42.

  One end of a slide lever 48 is connected to the upper end of the piston 41. The slide lever 48 goes out of the single acting pneumatic cylinder 43 and is connected to a rod (not shown) of the potentiometer 50. The rod is connected to a variable resistor in the potentiometer 50, and the position of the piston 41 is accurately measured by the potentiometer 50. Further, the inner peripheral end portion of the bellophram 51 is fixed to the lower surface of the piston 41. The outer peripheral end of the belofram 51 is fixed to the chamber wall of the single acting pneumatic cylinder 43. The belofram 51 is designed to be extremely thin, and is structurally formed by coating rubber on a strong polyester, tetron cloth or the like. The bellophram 51 is a cylindrical diaphragm that has a large stroke and a deep turn-up portion, and whose effective pressure receiving area is kept constant during operation. In this embodiment, since the belofram 51 is used between the pneumatic cylinder 32 and the piston 41, there is no stick slip of the piston 41, and the piston 41 is moved with high responsiveness and accurate positional accuracy. It is possible.

A piston rod 37 is fixed at the center of the piston 41 and slides up and down according to the movement of the piston 41. A valve element 33 is attached to the lower end of the piston rod 37. Further, one end of a bellows 38 is attached to the upper surface of the valve body 33 by circular welding.
The detailed structure of the valve body 33 is shown in FIG. FIG. 14 shows a state where the vacuum proportional on-off valve 18 is closed. The valve body 33 includes a valve main body 33a connected to the piston rod 37, an O-ring attachment portion 33b for fixing an O-ring 35, which is an elastic seal member, and a stainless valve body attachment portion 33c for attaching a stainless valve body portion 34. And a stainless valve body 34. In the present embodiment, SUS316L (JIS standard) is used as the material of the stainless valve body 34 (the “valve body” in the claims includes the valve body 33 and the stainless valve body 34). ). The O-ring 35 is held by the O-ring mounting portion 33 b of the valve body 33 and the O-ring mounting portion 34 b of the stainless steel valve body portion 34. The O-ring 35 serves to eliminate fluid leakage when pressed against the horizontal valve seat 36a, and at the same time is an elastic seal member that is a main part of the present invention.

  In this embodiment, a heater is not provided on the outer periphery of the vacuum proportional on-off valve 18, but a heater can be provided to heat the valve seat 36 and the O-ring 35 to prevent sticking.

(Configuration of vacuum pressure control device)
Next, the vacuum pressure control device 8 of the present embodiment will be described. FIG. 1 shows the configuration of the vacuum pressure control device 8 when pressure undershoot occurs in the vacuum vessel, and FIG. 2 shows the configuration of the normal vacuum pressure control device 8. FIG. 15 shows a detailed configuration of the electropneumatic proportional on-off valve 62.
First, the configuration of the air system will be described. As shown in FIG. 2, the vacuum proportional on-off valve 18 is connected to the output port of the first electromagnetic valve 60. An electropneumatic proportional on-off valve 62 is connected to the first input port 601 of the first electromagnetic valve 60. A second electromagnetic valve 61 is connected to the second input port 602 of the first electromagnetic valve 60.
As shown in FIG. 15, the electropneumatic proportional on-off valve 62 includes an air supply side proportional valve 74 and an exhaust side proportional valve 75. The input port 74a of the supply side proportional valve 74 is connected to supply air. The output port 75a of the exhaust side proportional valve 75 is connected to the exhaust pipe. The output port 74 b of the supply side proportional valve 74 and the input port 75 b of the exhaust side proportional valve 75 are both connected to the first input port 601 of the first electromagnetic valve 60.
As shown in FIGS. 1 and 2, a cylinder internal pressure detector 55 for measuring the internal pressure of the pneumatic cylinder is connected to the vacuum proportional on-off valve 18.

Next, the configuration of the electric system will be described. A pulse drive circuit 68 is connected to the electropneumatic proportional on-off valve 62. A position control circuit 64 is connected to the pulse drive circuit 68. Further, the position signal of the potentiometer 50 is connected to the position control circuit 64 via an amplifier 63. A vacuum pressure control circuit 67 is connected to the position control circuit 64. An interface circuit 66 is connected to the vacuum pressure control circuit 67. The pressure sensor 17 is connected to the vacuum pressure control circuit 67. A sequence control circuit 65 is connected to the interface circuit 66. The sequence control circuit 65 is connected to the drive coil SV 1 of the first electromagnetic valve 60 and the drive coil SV 2 of the second electromagnetic valve 61.
The controller 56 includes a sequence control circuit 65, an interface circuit 66, and a vacuum pressure control circuit 67.
The vacuum pressure control circuit 67 includes a storage unit, and stores in advance a diagram S of cylinder internal pressure value data when the vacuum proportional on-off valve 18 is provided with a heater, as shown in FIG.

(Operation of vacuum pressure control device)
The operation of the vacuum pressure control device 8 having the above configuration will be described.
(Fully open / closed operation of vacuum proportional on-off valve)
First, the rapid air supply / exhaust operation will be described. When the vacuum proportional on-off valve 18 is fully opened, the first electromagnetic valve 60 is turned off and the second electromagnetic valve 61 is turned on. As a result, the first input port 601 of the first electromagnetic valve 60 is connected to the output port 603, and driving air is supplied to the vacuum proportional on-off valve 18. The valve body 33 is far away from the valve seat 36, and the vacuum pump 19 can suck a large amount of gas in the vacuum vessel 11 and exhaust it rapidly.
Next, the fully closed state of the vacuum proportional on-off valve 18 will be described. As shown in FIG. 1, the first electromagnetic valve 60 is turned off, and the second electromagnetic valve 61 is also turned off. Thereby, the second input port 612 of the second electromagnetic valve 61 is connected to the output port 613, the second input port 602 of the first electromagnetic valve 60 is connected to the output port 603, and the vacuum proportional on-off valve 18 is connected to the exhaust pipe. Connected.
Then, the drive air is not supplied to the vacuum proportional on-off valve 18, the air inside the cylinder is exhausted, the piston 41 is urged downward by the return spring 42, and the valve body 33 is brought into contact with the upper surface of the valve seat 36. The At this time, since the O-ring 35 is pressed and deformed by the valve body 33 and the horizontal valve seat portion 36a of the valve seat 36, there is no fluid leakage and the vacuum proportional on-off valve 18 is completely shut off.
On the other hand, even when a power failure occurs, the output spring 603 and the second input port 602 of the first solenoid valve 60 communicate with each other by the return spring, and the output port 613 and the second input port 612 of the second solenoid valve 61 communicate. Similarly, the vacuum proportional on-off valve 18 is blocked by the return spring 42. As a result, an emergency shut-off function is realized.

(Valve stroke during slow exhaust control)
The pressure in the vacuum vessel 11, the stroke of the valve element 33, and the internal pressure of the pneumatic cylinder 32 during the slow exhaust control are shown in FIG. 3 as line graphs. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates height, magnitude, and the like. 4 to 6 show conceptual diagrams of the relationship between the O-ring 35 and the valve seat 36. FIG.
In FIG. 3, the pressure A in the vacuum vessel 11, the stroke B of the valve body 33, and the internal pressure C of the air cylinder 32 are line graphs of the vacuum proportional on-off valve 18 when the vacuum proportional on-off valve in this embodiment does not have a heater. Indicates.
Further, the pressure Q in the vacuum vessel, the valve body stroke R, and the internal pressure S of the pneumatic cylinder in FIG. 3 are line graphs of the vacuum proportional on-off valve of the embodiment when the heater is provided and the normal operation is performed.

In the slow exhaust control, the elastic deformation amount of the O-ring 35 that is completely shut off is adjusted by gradually increasing the air pressure applied to the pneumatic cylinder 32. That is, by increasing the air pressure, a flow of the supply gas is generated between the circumferential O-ring 35 and the valve seat 36, and the vacuum pressure control in the vacuum vessel 11 is realized by the flow.
The vacuum proportional on-off valve 8 in this embodiment does not have a heater. Therefore, if the O-ring 35 and the valve seat 36 are brought into close contact with each other, they are fixed.

A state when the slow exhaust control starts from the state where the O-ring 35 and the valve seat 36 are fixed will be described. First, the position control operation at time U1 shown in FIG. 3 will be described. Time U1 is a time until the O-ring 35 starts to separate from the valve seat 36.
In this embodiment, since there is no heater, as shown in FIG. 4, the O-ring 35 is fixed to the valve seat 36, and the fixed O-ring 35 starts to separate and the exhaust time starts until time U20. It takes.
That is, when the O-ring 35 is elastically deformed, the stroke B increases, but since the O-ring 35 is fixed, it takes an extra time U20 until the exhaust starts.
The time U20 shown in FIG. 3 and the time T20 shown in FIG. 17 have the same length of time. Since FIGS. 3 and 17 both assume a case where there is no heater, the time until the O-ring 35 is separated from the valve seat 36 is the same.

As shown in FIG. 3, the pressure A hardly changes at time U1. This is because the O-ring 35 is fixed to the valve seat 36 and elastically deformed, and the pressure in the vacuum vessel 11 hardly changes until the O-ring 35 starts to separate from the valve seat 36.
Further, when the pressure is A, the O-ring 35 and the valve seat 36 are in contact with each other for a longer time U20 than when the pressure Q starts to descend at the time U10 when the O-ring 35 and the valve seat 36 start to separate with a heater. Yes.
The vacuum pressure control device 8 measures the pressure in the vacuum vessel 11 measured by the pressure sensor 17 at time U1.

Further, as shown in FIG. 3, the stroke B continues to rise as compared with the stroke R when the heater is provided. Because the O-ring 35 is fixed to the valve seat 36 and is elastically deformed, even if the stroke R is exceeded, the O-ring 35 is not separated from the valve seat 36 by the time U20, and the vacuum pressure control circuit 67 raises the stroke B and exhausts. This is to make it happen.
Further, the internal pressure C of the cylinder continues to rise as compared with the internal pressure S of the cylinder having the heater. This is because the O-ring 35 is fixed to the valve seat 36 and is elastically deformed, so that it is not separated from the valve seat 36 by time U20. For this reason, the vacuum pressure control circuit 67 increases the stroke B and tries to exhaust, so that the control is performed to increase the internal pressure of the cylinder during the time U20.
The vacuum pressure control device 8 measures the internal pressure of the cylinder measured by the cylinder internal pressure detector 55 at time U1.

Next, the position control operation at time U2 shown in FIG. 3 will be described.
The time U2 is the time from when the O-ring 35 is partly separated from the valve seat 36 to when the gap V that allows slow exhaust shown in FIG. 6 is formed between the O-ring 35 and the valve seat 36.
As shown in FIG. 5, the stroke B rises and a part of the O-ring 35 is detached from the state where it is fixed to the valve seat 36.

In the present embodiment, when the O-ring 35 is partly separated from the valve seat 36, the pressure A starts to decrease with the set decrease rate as a target value as shown in FIG. When the pressure A starts to decrease, the pressure sensor 17 of the vacuum pressure control device 8 can recognize and grasp that a certain rate of decrease has occurred. Here, the constant descending rate is when the O-ring 35 is partially separated from the valve seat 36 and the pressure A in the vacuum vessel 11 starts to descend from a constant state as shown in FIG. It is. Since part of the O-ring 35 and the valve seat 36 start to separate from the contact state, the pressure A starts to decrease from a constant state (time U1) as shown in FIG. 3 (time U2). Therefore, it is objectively possible for the pressure sensor 17 to grasp that the O-ring 35 and the valve seat 36 are partly separated and a constant lowering rate occurs.
When the descending rate of the pressure A is larger than the set descending rate target value by a certain level or more, it is determined that the O-ring 35 is stuck, the first solenoid valve 60 is turned off, and the second solenoid valve 61 is turned off. Is also turned off. Thereby, the second input port 612 of the second electromagnetic valve 61 is connected to the output port 613, the second input port 602 of the first electromagnetic valve 60 is connected to the output port 603, and the vacuum proportional on-off valve 18 is connected to the exhaust pipe. Connected. Then, the drive air is not supplied to the vacuum proportional on-off valve 18, the air inside the pneumatic cylinder 32 is exhausted rapidly, and the internal pressure of the cylinder is lowered at a stroke as shown in FIG. The piston 41 whose stroke rise is smaller than that of the piston 41 is urged downward by the return spring 42 and, as shown in FIG. V can be formed.

The internal pressure in the pneumatic cylinder 32 can be exhausted rapidly by the first electromagnetic valve 60. As a result, as shown in FIG. 3, the internal pressure C of the cylinder, which is the internal pressure of the pneumatic cylinder 32, can be reduced at a stretch. Therefore, when the internal pressure C of the cylinder suddenly drops, the valve element 33 can be lowered by the urging force of the return spring 42, and the stroke B can be lowered all at once.
Since the valve body 33 can be closed without using the electropneumatic proportional on-off valve 62, the O-ring 35 and the valve seat 36 can be prevented from moving away due to the internal pressure C of the cylinder. It is possible to shorten the time U2 that is the time until the gap V that can be slowly exhausted is formed between the valve seat 36 and the valve seat 36. Therefore, it is possible to perform slow exhaust in an early time, and the amount of decrease in the pressure A shown in FIG. 3 can be reduced. As a result, the pressure undershoot in the vacuum vessel can be reduced.
Moreover, even if there is no heater as in this embodiment, the undershoot of the pressure in the vacuum vessel can be reduced. Since it is not necessary to provide a heater, cost can be reduced.

Further, as shown in FIG. 3, since the internal pressure in the pneumatic cylinder 32 is exhausted rapidly, it hardly takes time until the internal pressure C of the cylinder intersects the internal pressure S of the cylinder. The internal pressure C of the cylinder in the air cylinder 32 drops rapidly due to sudden exhaust, and it takes almost no time U2 for the O-ring 35 and the valve seat 36 to form a gap V that allows slow exhaust.
Therefore, the stroke Y shown in FIG. 17 which is a comparison with the stroke R with the heater is the stroke amount P2, whereas in this embodiment, the stroke B is the stroke amount with respect to the stroke R as shown in FIG. D2 is enough. That is, the time T2 until the stroke Y according to the prior art in FIG. 17 reaches the position of the stroke R is the time U2 in this embodiment, and the time is short.
Therefore, since the stroke amount starts to decrease at a stage where the stroke amount D2 is subtracted from the stroke amount P2 as compared with the prior art, the stroke amount can be reduced as compared with the prior art. Therefore, according to the present embodiment, it is possible to quickly form the gap V that can be slowly exhausted between the O-ring 35 and the valve seat 36.

Further, as shown in FIG. 3, since the internal pressure C of the cylinder can be rapidly lowered, the stroke B is only the stroke amount D2 as compared with the stroke R when the heater is provided. That is, the stroke amount D2 may be smaller than the stroke amount P2 according to the prior art of FIG. Therefore, the O-ring 35 and the valve seat 36 can form the gap V earlier by the amount obtained by subtracting the stroke amount D2 from the stroke amount P2 as compared with the prior art.
Further, as shown in FIG. 3, the pressure Q when the heater is provided is compared with the pressure A when the heater is not provided, and the undershoot in the vacuum vessel is only the pressure amount D1. That is, the pressure amount D1 may be smaller than the pressure amount P1 according to the prior art of FIG. Therefore, as compared with the prior art, the pressure amount D1 can be subtracted from the pressure amount P1, and the undershoot of the pressure in the vacuum vessel can be reduced.

Further, the internal pressure in the air cylinder 32 is detected by a cylinder internal pressure detector 55. When the cylinder internal pressure detector 55 detects a constant internal pressure value, the exhaust of the internal pressure in the pneumatic cylinder 32 by the first electromagnetic valve 60 and the second electromagnetic valve 61 is stopped. Here, the constant internal pressure value is a reference value S1 which is a value at which the pressure of the vacuum vessel 11 starts to drop at the internal pressure S of the cylinder when there is a heater shown in FIG. If the internal pressure of the cylinder is further exhausted from the reference value S1, the internal pressure of the pneumatic cylinder 32 will be excessively lowered. If the internal pressure of the pneumatic cylinder 32 decreases excessively, the subsequent slow exhaust control will be adversely affected. In other words, it takes time to increase the internal pressure of the cylinder once lowered, and it takes time to evacuate, which is the purpose of the original vacuum proportional on-off valve 18 thereafter. Therefore, the exhaust of the internal pressure in the pneumatic cylinder 32 is stopped based on the reference value S1.
The reference value S1 is stored in advance in the vacuum pressure control circuit 67 of the controller 56, and the internal pressure in the pneumatic cylinder 32 is controlled by the vacuum pressure control circuit 67 when the value of the cylinder internal pressure C falls below the reference value S1. Stop exhausting. Thereafter, the first electromagnetic valve 60 is turned on, and the control is switched to the control by the electropneumatic proportional on-off valve.

In the present embodiment, the cylinder internal pressure detector 55 is used to detect the internal pressure of the cylinder. However, when a certain period of time has elapsed since the start of exhaust of the internal pressure in the air cylinder 32, the exhaust is stopped. Can do. This fixed time can be obtained by calculating an average time until the internal pressure S of the pneumatic cylinder 32 reaches the reference value S1. By stopping the exhaust when the average time has elapsed after starting the exhaust of the internal pressure of the cylinder, the internal pressure of the cylinder can be prevented from excessively decreasing.
By calculating and using the average time, it is possible to prevent the internal pressure of the cylinder from excessively decreasing without using the cylinder internal pressure detector 55. Therefore, it is possible to provide the vacuum pressure control device 8 with reduced costs.

Experimental results in the present embodiment will be described with reference to FIGS. FIG. 7 shows a data diagram of the experiment (1) when the vacuum proportional on-off valve according to the present invention is used. FIG. 8 shows a data diagram of the experiment (1) using the vacuum proportional on-off valve when the heater is not provided and when the heater is disconnected. FIG. 9 shows a data diagram of the experiment (2) when the vacuum proportional on-off valve according to the present invention is used. FIG. 10 shows a data diagram of the experiment (2) using the vacuum proportional on-off valve when the heater is not provided and when the heater is disconnected. FIG. 11 shows a data diagram of the experiment (3) when the vacuum proportional on-off valve according to the present invention is used. FIG. 12 shows a data diagram of the experiment (3) using the vacuum proportional on-off valve when the heater is not provided and when the heater is disconnected.
7 to 12, the horizontal axis represents time (sec), and the vertical axis represents pressure (× 133 Pa), stroke (mm), and the like. A thick line graph indicates the pressure F in the vacuum vessel, and a thin line graph indicates the stroke G of the valve body.

In the experiment (1) of FIGS. 7 and 8, the experiment was performed at a slow exhaust rate of 2.5 × 133 Pa / sec and the valve CLOSE standing time as 18 hours.
FIG. 8 is a data diagram in which an experiment was performed in the state before the countermeasure according to the present embodiment in the case where the vacuum proportional on-off valve is not equipped with a heater and the heater is disconnected. As shown in FIG. 8, the stroke G <b> 2 is about 1.4 mm for the O-ring 35 to rise completely away from the valve seat 36. Since the peak value of the stroke G2 is about 1.4 mm, the pressure F2 in the vacuum vessel rapidly drops (undershoot) by 228 × 133 Pa. Since undershoot occurs, when the stroke G2 is lowered to return the pressure F2 to the target value and the O-ring 35 and the valve seat 36 are brought into close contact with each other, the pressure F2 starts to increase and reaches the target value. At that time, the stroke G2 is increased and the pressure F2 is decreased. At this time, since the O-ring 35 and the valve seat 36 are fixed, an undershoot occurs by repeating the same steps. By repeating this several times, it is possible to finally form a stable gap V.
On the other hand, as shown in FIG. 7, in this embodiment, the O-ring 35 starts to be partially separated from the valve seat 36, and the internal pressure of the cylinder is rapidly increased when the pressure becomes larger than a certain value with respect to the set lowering rate target value. Exhaust. For this reason, the stroke G1 begins to drop at about 0.6 mm earlier than when the O-ring 35 is completely separated from the valve seat 36. Further, the exhaust of the internal pressure of the cylinder through the first electromagnetic valve 60 is stopped when the internal pressure of the cylinder reaches the reference value S1. For this reason, the O-ring 35 and the valve seat 36 are not in contact with each other, or even if they come into contact with each other, the O-ring 35 and the valve seat 36 are not easily fixed due to a low load. .

In the experiment (2) of FIGS. 9 and 10, the experiment was performed at a slow exhaust rate of 2.5 × 133 Pa / sec and the valve CLOSE standing time was 0.25 hours.
FIG. 10 is a data diagram in which an experiment was performed in a state before the countermeasure according to the present embodiment when the vacuum proportional on-off valve was not equipped with a heater and when the heater was disconnected. As shown in FIG. 10, the stroke G <b> 4 is about 0.9 mm for the O-ring 35 to rise completely from the valve seat 36. Since the peak value of the stroke G4 is about 0.9 mm, the pressure F4 in the vacuum vessel suddenly drops (undershoot) by 106 × 133 Pa. Since undershoot occurs, when the stroke G4 is lowered to return the pressure F4 to the target value and the O-ring 35 and the valve seat 36 are brought into close contact with each other, the pressure F4 starts to increase and reaches the target value. At that time, the stroke G4 is increased to decrease the pressure F4. At this time, since the O-ring 35 and the valve seat 36 are fixed, the same step is repeated to cause undershoot. By repeating this several times, it is possible to finally form a stable gap V.
As shown in FIG. 9, in this embodiment, when the O-ring 35 begins to be partially separated from the valve seat 36 and the pressure in the vacuum vessel becomes larger than a predetermined lowering rate target value, the internal pressure of the cylinder is reduced. Exhaust rapidly. For this reason, the stroke G3 starts to drop at a position about 0.55 mm earlier than when the O-ring 35 is completely separated from the valve seat 36. Further, the exhaust of the internal pressure of the cylinder through the first electromagnetic valve 60 is stopped when the internal pressure of the cylinder reaches the reference value S1. For this reason, the O-ring 35 and the valve seat 36 are not in contact with each other, or even if they come into contact with each other, the O-ring 35 and the valve seat 36 are not easily fixed because of a low load, and the gap V can be quickly formed. I was able to suppress it.

In the experiment (3) of FIG. 11 and FIG. 12, the experiment was performed at a slow exhaust rate of 0.5 × 133 Pa / sec and the valve CLOSE standing time was 0.25 hours.
FIG. 12 is a data diagram in which an experiment was performed in the state before the countermeasure according to the present embodiment when the vacuum proportional on-off valve is not equipped with a heater and when the heater is disconnected. As shown in FIG. 12, the stroke G <b> 6 is about 0.6 mm for the O-ring 35 to rise completely from the valve seat 36. Since the peak value of the stroke G6 is about 0.6 mm, the pressure F6 in the vacuum vessel suddenly drops (undershoot) by 33 × 133 Pa. Since undershoot occurs, the stroke G6 is lowered to return the pressure F6 to the target value, and when the O-ring 35 and the valve seat 36 are brought into close contact with each other, the pressure F6 starts to increase and reaches the target value. At that time, the stroke G6 is increased to lower the pressure F6. At this time, since the O-ring 35 and the valve seat 36 are fixed, this is repeated. That is, the pressure undershoot in the vacuum vessel is repeated.
On the other hand, as shown in FIG. 11, in this embodiment, the O-ring 35 starts to be partly separated from the valve seat 36, and the internal pressure of the cylinder is increased when the pressure becomes larger than a certain value relative to the set lowering rate target value. Exhaust rapidly. For this reason, the stroke G5 starts to drop at a position about 0.52 mm earlier than when the O-ring 35 is completely separated from the valve seat 36. Further, the exhaust of the internal pressure of the cylinder through the first electromagnetic valve 60 is stopped when the internal pressure of the cylinder reaches the reference value S1. For this reason, the O-ring 35 and the valve seat 36 are not in contact with each other, or even if they come into contact with each other, the O-ring 35 and the valve seat 36 are not easily fixed due to a low load, and the gap V can be formed quickly. It was.

Note that the present invention is not limited to the above-described embodiment, and various applications are possible without departing from the spirit of the invention.
For example, in the present embodiment, the effect that the undershoot can be reduced without mounting a heater on the vacuum proportional on-off valve 18 is described, but a heater can also be mounted. When the heater is mounted, the problem of the O-ring 35 and the valve seat 36 sticking can be solved. However, even when the heater is disconnected or when the heater fails and cannot be used, the undershoot of the pressure in the vacuum vessel is lost. This is advantageous because it can be reduced.
For example, the first solenoid valve and the second solenoid valve may be air operation valves, and are not limited to three-way valves as shown in the figure, but if four-way valves and five-way valves are used as three-way valves, The same can be done.
Moreover, the same effect can be obtained even in a circuit without the second electromagnetic valve.
Further, in the present embodiment, when the rate of decrease of the pressure A is larger than a predetermined decrease target value by a certain amount or more, it is determined that sticking has occurred. For example, a sensor that measures the internal pressure C of the cylinder If the internal pressure of the cylinder measured by the above is higher than a certain value with respect to the pressure target value, it can be determined that the sticking has occurred.

8 Vacuum Pressure Control Device 11 Vacuum Container 17 Pressure Sensor 18 Vacuum Proportional Open / Close Valve 19 Vacuum Pump 32 Pneumatic Cylinder 33 Valve Element 35 O-ring (“Elastic Seal Member” in Claims)
36 Valve seat 55 Cylinder internal pressure detection device 56 Controller 60 First electromagnetic valve 60 ("3-way valve" in claims)
62 Electropneumatic proportional on-off valve

Claims (6)

A valve body including an elastic seal member which is on a pipe connecting a vacuum vessel and a vacuum pump and changes a vacuum pressure in the vacuum vessel by changing an opening degree, and contacts or separates the valve seat and the valve seat. And a vacuum proportional on-off valve comprising a pneumatic cylinder, a pressure sensor for measuring the vacuum pressure in the vacuum vessel, and a controller for controlling the pressure in the vacuum vessel,
Exhausting the internal pressure of the pneumatic cylinder when the pressure in the vacuum vessel measured by the pressure sensor drops at a pressure drop rate of a certain level or more;
A vacuum pressure control device characterized by. In the vacuum pressure control device according to claim 1,
An electropneumatic proportional on / off valve and a three-way valve are connected to the vacuum proportional on / off valve;
The three-way valve exhausts the internal pressure of the pneumatic cylinder;
A vacuum pressure control device characterized by. In the vacuum pressure control device according to claim 1,
The rate of pressure drop above a certain level is generated when a part of the elastic seal member is detached from the valve seat;
A vacuum pressure control device characterized by. In the vacuum pressure control device according to claim 1,
A cylinder internal pressure detector for detecting an internal pressure of the pneumatic cylinder;
Stopping the exhaust of the internal pressure of the pneumatic cylinder when the cylinder internal pressure detector detects a constant internal pressure value of the internal pressure of the pneumatic cylinder;
A vacuum pressure control device characterized by. In the vacuum pressure control device according to claim 4,
The controller stores in advance a reference value of the internal pressure of the pneumatic cylinder, which is a value at which the pressure in the vacuum vessel starts to drop when the vacuum proportional on-off valve is equipped with a heater,
The constant internal pressure value is a reference value of the internal pressure of the pneumatic cylinder;
A vacuum pressure control device characterized by. In the vacuum pressure control device according to claim 1,
When exhausting the internal pressure of the pneumatic cylinder, stopping the exhaust of the internal pressure of the pneumatic cylinder when a certain time has elapsed;
A vacuum pressure control device characterized by.

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