JPH0125903B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a vacuum valve equipped with a pressure relief function for exhausting to the outside a large amount of gas desorbed and released inside the cryopump during regeneration and heating of the cryopump. . (Prior Art) The typical structure and operation of a pressure relief valve conventionally used in cryopumps will be explained with reference to FIG. During operation of the cryopump, the inside of the cryopump 1 is a vacuum, and the inside 30 of the pressure relief valve 2 is at atmospheric pressure, so a downward force is applied to the valve plate 5 due to the pressure difference (as shown in FIG. 4). , the elastomer gasket 32 is pressed together with the force of the compression spring 31 against the sealing surface to create a vacuum seal. When the pump stops operating, the gas that was condensed and exhausted inside the cryopump 1 is released, and the pressure inside the cryopump 1 begins to rise. When this pressure exceeds atmospheric pressure, it eventually overcomes the force of the compression spring 31 and closes the valve. The plate 5 is pushed up and the gas is discharged to the atmosphere through the flow path 8, thereby preventing an excessive rise in pressure within the cryopump 1. As described above, the conventional pressure relief valve 2 has the following drawbacks because it uses the differential pressure between atmospheric pressure and vacuum and the pressing force of the compression spring 31 as a sealing force. When the force of the compression spring 31 is weak, sufficient sealing force cannot be obtained, and therefore vacuum leaks often occur due to dust and the like. When the force of the compression spring 31 is strong, the pressure inside the cryopump 1 is not sufficiently released, and the pressure inside the cryopump 1 increases, which is dangerous. Since the opening stroke of the valve plate 5 is not sufficient (because the pressing force of the compression spring 31 increases rapidly in proportion to the stroke), a large pressure loss occurs at the valve part when a large flow of gas is released, and the cryopump 1
It is dangerous because it increases the internal pressure. In order to solve these drawbacks, an electric means was devised that first detects that the internal pressure of the cryopump exceeds the atmospheric pressure and forcibly opens the relief valve to open to the atmosphere using an external force. (Problem to be Solved by the Invention) However, the electric means cannot operate during a power outage, and when a power outage occurs, the cryopump inevitably
Since the operation of the cryopump 1 is stopped, a large amount of gas is released and the pressure inside the cryopump 1 increases, which is dangerous. The present invention eliminates these drawbacks and prevents vacuum leaks by providing sufficient sealing force when the cryopump is in operation, and when the cryopump is stopped, the valve opens without any problem even during a power outage, allowing sufficient pressure release inside the cryopump. The purpose of the present invention is to provide a pressure relief valve device that prevents an excessive increase in the internal pressure of a cryopump. (Means for Solving the Problems) In order to achieve the above object, the present invention is configured as follows. That is, in the relief valve device attached to the cryopump container, the present invention allows the relief valve body to move backward in the order of the relief valve closing position, the relief valve opening start position, and the relief valve opening position, and advance in the reverse order. and a piston mechanism in which a piston connected to the relief valve body moves within a cylinder container, and the cylinder container of the piston mechanism is provided with a relief valve mechanism in which the relief valve mechanism of the piston is moved within a cylinder container. A valve forced opening operation opening for forcibly opening the relief valve is located at a location on the advance side of the position corresponding to the valve closing position, and a valve opening operation opening that assists the opening operation of the relief valve is provided near the position corresponding to the relief valve opening start position. An auxiliary operation port and a valve forced closing operation port for forcibly closing the relief valve are provided at a location on the backward side of the position corresponding to the relief valve open position, and these operation ports are operated at atmospheric pressure or This is a relief valve device that also includes a valve mechanism that communicates or disconnects from the compressed air supply device. (Operation) In the present invention having the above configuration, the sequence of opening and closing of each operation port is as follows. That is, while the cryopump is in operation, the relief valve body of the relief valve mechanism is attracted by the vacuum pressure inside the cryopump and is in the relief valve closed position, and the inside of the cryopump container is closed to the outside air. At this time, the piston in the cylinder container is in a position corresponding to closing the relief valve of the cylinder container. In this state, by opening the valve forced closing operation port and supplying compressed air, closing the valve opening auxiliary operation port, and opening the valve forced opening operation port to the atmosphere, the relief valve body is caused to close the valve hole by this air pressure. The closed state of the relief valve is maintained reliably and stably by being pressed to the side. Next, when stopping the operation of the cryopump and discharging the condensed gas inside the cryopump, keep the valve opening auxiliary operation port closed, and
The compressed air is supplied to the forced valve opening port, and the forced valve closing port is opened to the atmosphere to be in an open state.
As a result, the electric pressure supplied from the valve forced opening operation causes the piston to move backward to a position corresponding to opening the relief valve. The relief valve body moves backward to the relief valve opening position of the relief valve mechanism in conjunction with the movement of the piston, so that the relief valve is fully opened and the condensed gas inside the cryopump is discharged to the outside. Next, if a power outage occurs while the cryopump is operating, open the forced valve closing operation port to the atmosphere, close the forced valve opening operation port, and open the valve opening auxiliary operation port. Supply compressed air. At this time, if the inside of the cryopump is below atmospheric pressure, the relief valve is closed due to pressure reduction of the relief valve element, and correspondingly, the piston is at a position corresponding to closing the relief valve of the cylinder container. Therefore, the compressed air supplied to the valve opening assist operation port moves the piston (moves the relief valve body).
not be involved in any way. However, as time passes after the power outage, the pressure inside the cryopump increases and when it exceeds atmospheric pressure, the relief valve body is pushed up by the internal pressure inside the cryopump. When the relief valve body is pushed up to the valve opening start position, the piston is pushed up and moved in the backward direction past the valve opening auxiliary operation port, and as a result, compressed air is supplied from the valve opening auxiliary operation port into the cylinder container. The piston is forcibly pushed up to a position corresponding to valve opening, and the relief valve is completely opened. Therefore,
The condensed gas inside the cryopump will be discharged to the outside through the relief valve, and the danger of overpressure inside the cryopump will be effectively prevented. (Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 shows an embodiment of the present invention, in which a relief valve device 20 according to the present invention is attached to a cryopump 1, and when the cryopump 1 is in operation, the relief valve hole 2a is closed, and when the cryopump is stopped, the internal pressure of the cryopump is When the pressure rises, the relief valve hole 2a is brought into communication with the flow path 8 to release the atmospheric pressure inside the cryopump 1. The relief valve device 20 is roughly divided into a relief valve mechanism 21, a piston mechanism 22, and a valve mechanism 23. Of these, the relief valve mechanism 21 consists of a valve container 3 and a valve plate 5 slidably inserted into the valve container 3, and the piston mechanism 22 includes a pneumatic cylinder 4 and a valve plate 5 slidably inserted into the valve container 3. It consists of a freely housed piston 6. The valve plate 5 in the valve container 3 constituting the relief valve mechanism 21 and the piston 6 of the piston mechanism 21 are connected by a shaft 7. The valve container 3 is provided with a flow passage 8 that communicates with the atmosphere at an upper part slightly away from the bottom of the valve container 3, while the pneumatic cylinder 4 has three air inlets 9 for supplying and discharging compressed air. 10 and 11 are provided. The air introduction port 9 opens at the lowest part of the pneumatic cylinder 4, that is, below the bottom dead center of the piston 6, and functions as a valve forced opening operation port. The air introduction port 10 opens slightly above the bottom dead center of the piston 6 (more specifically, relative to the sealing point 12 at the bottom dead center of the piston 6), and functions as a valve opening auxiliary operation port. Further, the air introduction port 11 opens above the top dead center of the piston 6 and functions as a valve forced closing operation port. The air inlet 11 is connected to the valve 14 on the one hand.
on the other hand to a compressed air supply 13 and on the other hand to the atmosphere via a valve 15. After the air inlets 9 and 10 are connected to individual valves 17 and 18,
Furthermore, the compressed air supply source 1 via a common valve 16
3 and to the atmosphere via a common valve 19. A sequence of a valve controller (not shown) is configured so that the operations of the above six valves are as shown in Table 1. The valve mechanism 23 is constituted by the piping system including these six valves, the compressed air supply source 13, and the sequence control section of the valve controller.

[Table] The operation of the relief valve device 20 with the above configuration will be explained based on FIG. 1 and Table 1. During operation of the cryopump 1, the valve operation mode is
Set it to force table close mode. In this state, the valve mechanism 23 performs the same operation as when closing a normal pneumatic valve. That is, compressed air sent from the compressed air supply source 13 passes through the open valve 14 and is led to the upper chamber of the pneumatic cylinder 4 through the air inlet 11. On the other hand, air in the lower chamber of the pneumatic cylinder 4 is discharged to the atmosphere from the air inlet 9 through the open valves 17 and 19. Therefore, the piston 6 is pushed downward, and the valve plate 5 connected by the shaft 7 is also pushed down, thereby sealing off the inside of the cryopump 1 from the atmosphere. When the cryopump 1 is stopped, all valves are placed in a non-energized mode. At this time, valves 15, 16, and 18 are normally open valves, and valves 14, 17, and 18 are normally open valves.
Since 9 is constituted by a normally closed valve, the upper chamber of the pneumatic cylinder 4 is open to atmospheric pressure. Then, the piston 6 and the valve plate 5
is under pressure due to the differential pressure while the inside of the pump 1 is a vacuum (below atmospheric pressure), but when the temperature inside the cryopump 1 rises and the pressure inside the cryopump 1 rises and exceeds atmospheric pressure, An opposite force is applied to the valve plate 5 from below to above. At this time, the valve 17 is in a closed state, but the pneumatic cylinder 4 is structured to ensure a sufficiently large space A below the piston 6 even at the bottom dead center of the piston 6, as shown in FIG. Therefore, the piston 6 forcibly expands the air in this space,
Even if the piston 6 rises by several millimeters, a pressure difference large enough to prevent the rise will not be generated between the upper and lower sides of the piston 6. As the valve plate 5 and the piston 6 move upward by a few mm, the sealing point 12 of the piston 6 connects to the air inlet 1.
reaches above 0 and its opening switches below the piston. This allows valves 16 and 18 to
(both are open), compressed air flows into the lower chamber of the pneumatic cylinder 4 from the air inlet 10, while the upper chamber side is open to atmospheric pressure from the air inlet 11 through the valve 15, so the piston 6 It is pushed up to the top dead center, the valve plate 5 also moves to the top dead center, and the valve of the relief valve mechanism 21 becomes fully open. At this time, the gas flow path 8 is sufficiently opened and pressure loss due to flow path resistance is minute. Note that the valve operation in the de-energized mode corresponds to the valve operation state during a power outage. Therefore, the present relief valve device 20 performs exactly the same operation even during a power outage, and opens the inside of the cryopump 1 to the atmosphere. It is also possible to open the relief valve device 20 in the forced open mode shown in Table 1. If this mode is used, the relief valve can be used as the roughing valve of the cryopump 1 as shown in FIG. It is also possible to use it for both. That is, as shown in Figure 2,
During roughing, the air release valve 24 is closed and the roughing pipe 25 connected to the flow path 8 and the rotary pump 2
6 to perform rough evacuation inside the cryopump 1. At this time, the relief valve device 20 is in forced open mode. Furthermore, when the cryopump 1 is stopped, the relief valve device 20 is set to the non-energized mode, the rotary pump 26 is stopped, and the atmosphere release valve 24 is opened.As the pressure inside the cryopump 1 increases, the relief valve device 20 The cryopump 1 operates in the non-energized mode as described above, and the gas discharged from the inside of the cryopump 1 is discharged into the roughing pipe 25, and further this gas is discharged to the atmosphere through the atmosphere discharge valve 24. FIG. 3 shows a further improved embodiment of the invention. In the embodiment shown in FIG. 1, when the piston 6 is at the bottom dead center in the non-energized mode, compressed air supplied from the air pressure inlet 10 continues to be released from the air pressure inlet 11 through the valve 15 to atmospheric pressure. For,
For example, if the compressed air supply source 13 is an electric compressor or the like, there is a drawback that the air pressure gradually decreases during a power outage, making it impossible for the relief valve device 20 to operate. In the embodiment shown in FIG. 3, another sealing point 12' is provided above the sealing point 12 at bottom dead center,
When the piston 6 is at the bottom dead center, the air pressure inlet 1
0 is arranged between sealing points 12 and 12'. The other configurations and the operations of the valves 14 to 19 are completely the same as in the embodiment shown in FIG. According to this structure, even in the non-energized operation mode, the compressed air flowing in from the air pressure inlet 10 is confined inside the seal points 12 and 12' on both sides, so that the compressed air is not allowed to flow. Therefore, even during a power outage, the pressure of the compressed air supply source 13 does not drop, and the relief valve device 20 operates reliably. In the above description of the embodiment shown in FIGS. 1 to 3, two-way valves were used for valves 14 to 19 for convenience of explanation, but three-way or four-way valves could be used to reduce the number of valves. It is easy to reduce
It is clear that such a configuration does not depart from the scope of the claims of the present invention. (Effects of the Invention) As explained above, according to the present invention, reliable vacuum sealing is performed during operation of the cryopump, and when the internal pressure increases due to stoppage of the cryopump, the released gas inside the cryopump is released to the atmosphere. As a pressure release valve, it is possible to quickly secure a gas flow passage with a sufficient cross-sectional area. Furthermore, this relief valve can be used for unmanned operation as it simultaneously opens even during a power outage.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of a state in which the relief valve device of the present invention is combined with a rotary pump for roughing, and Fig. 3 is an illustration of another improved embodiment of the present invention. Main part configuration diagram of the embodiment, No. 4
The figure is a configuration diagram of a conventional device. 1... Cryopump, 2... Pressure relief valve, 2a... Relief valve hole, 3... Valve container, 4...
...Pneumatic cylinder, 5...Valve plate, 6...Piston, 7...Shaft, 8...Flow path, 9, 10,
11... Air inlet, 12, 12'... Seal point,
13... Compressed air supply source, 14, 15, 16, 1
7, 18, 19... Valve, 20... Relief valve device, 21... Relief valve mechanism, 22... Piston mechanism, 23... Valve mechanism, 24... Atmospheric release valve, 30... Inside of relief valve, 31... Compression spring, 32... Elastomer gasket, 25...
Roughing pipe, 26... rotary pump.

Claims (1)

[Claims] 1. In a relief valve device attached to a cryopump container, the relief valve body can move backward in the order of the relief valve closed position, the relief valve opening start position, and the relief valve open position, and advance in the reverse order. Two mechanisms are provided: a valve mechanism and a piston mechanism in which a piston connected to the relief valve body moves within a cylinder container, and the cylinder container of the piston mechanism corresponds to the relief valve closed position of the piston. a valve forced opening operation port for forcibly opening the relief valve at a location on the advancing side of the relief valve; a valve opening auxiliary operation port for assisting the opening operation of the relief valve near the position corresponding to the relief valve opening start position; A valve forced closing operation port for forcibly closing the relief valve is provided at a location on the retreat side of the position corresponding to the relief valve open position, and these operation ports are connected to atmospheric pressure or a compressed air supply device according to a predetermined sequence. A relief valve device characterized by having a valve mechanism for communicating or not communicating.