JPH10122144A - Cryotrap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cryotrap which improves exhaust performance for water molecule and hydrogen molecule, can be manufactured in a simple construction and comparatively small size, and is efficient, practical, and useful for industrial facilities in particular. SOLUTION: This cryotrap is provided with a helium refrigerator 12 having a cooling panel 14, the cooling panel is cooled by the helium refrigerator so as to exhaust water molecule, further an adsorption panel 15 made of hydrogen storage alloy is built in the interior, and hydrogen molecule is exhausted by the adsorption panel. The adsorption panel is provided on the inner face 11 of a cryotrap vessel. A heating mechanism 21 for reactivating the adsorption panel and heating the cooling panel by baking is provided. The cooling panel and the helium refrigerator are combined together through a mechanism 31 changing heat-conduction characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryotrap, and more particularly to a cryotrap, in which water molecules can be evacuated by utilizing the condensation of gas in a cooling panel connected to a helium refrigerator. It relates to a cryotrap that can also exhaust molecules.

[0002]

2. Description of the Related Art A cryotrap is usually a mechanical type.
A step-type helium refrigerator is used. The cooling panel connected to the helium refrigerator is cooled to about 55 to 120K,
Utilizing the condensation of the gas on the cooling surface, water molecules in the container to be exhausted are mainly exhausted. The temperature of the cooling surface of the cooling panel is 55 to 12 in order to efficiently exhaust only water molecules and to reach a target pressure or lower.
It is kept at about 0K. When the target ultimate pressure is relatively high, a temperature level of about 160K can be used.
The cooling panel is generally formed of copper or a copper alloy having good heat conduction characteristics, and is formed to have a smooth metal surface by applying nickel plating or the like to the surface. In a limited application range, aluminum alloy, stainless steel, etc. are also used as cooling panels.

[0003] A cryotrap is often used in combination with a turbo molecular pump which is a high vacuum pump. The cryotrap is used to supplementally exhaust water molecules, which are the main components of the residual gas in the container, by utilizing the high exhaust speed of the water molecules. When the container to be evacuated is evacuated from the atmospheric pressure to a medium vacuum to a high vacuum of 10 ^-1 Pa or less from the atmospheric pressure to a high vacuum, a large amount of the auxiliary evacuation by the cryoprap This is performed until the gas is released and the walls of the container and the like are sufficiently dried in vacuum by heating baking or the like.

[0004] Cryopumps and turbo-molecular pumps are generally used as vacuum pumps in vacuum evacuation devices that require an ultimate pressure of 10 ^-1 Pa or less. However, these pumps have advantages and disadvantages based on their respective evacuation principles. Cryopumps have the advantage of high pumping performance for water molecules and hydrogen molecules, but they are built-in pumps, so if they are used for a certain period of time, they must re-discharge and refresh the gas they have accumulated up to that time. (Hereinafter referred to as “reproduction”), and therefore cannot be used continuously for a long time, and has a disadvantage that it takes time for reproduction. On the other hand, the turbo-molecular pump is a discharge type pump, and thus has the advantage of not requiring a regeneration operation, but has the disadvantage that the exhaust performance for water molecules and hydrogen molecules is inferior to that of a cryopump.

[0005] In recent years, a method has been proposed for turbomolecular pumps in which the above-described cryotraps are used in combination to supplement the exhaust performance of water molecules.

[0006]

When the ultimate pressure of about 10 ^-1 to 10 ^-5 Pa is aimed at, the exhaustion of water molecules released from the walls of the container and various parts constituting the vacuum evacuation apparatus is required. It becomes a problem. When it is desired to further reduce the ultimate pressure of the vacuum exhaust device, for example, when it is necessary to reduce the ultimate pressure to 10 ⁻⁶ to 10 ⁻⁷ Pa or lower, a container wall constituting the vacuum exhaust device or A large amount of hydrogen molecules are released from the surface of various components, and become a main component of the residual gas in the vacuum exhaust device. Therefore, the ultimate pressure is 10 ^-6 ~
When the pressure is 10 ^-7 Pa or less, it is necessary to use a vacuum pump having improved exhaust performance for water molecules and high exhaust performance for hydrogen molecules.

As described above, according to the configuration in which the cryotrap is used in combination with the turbo molecular pump, the exhaust performance for water molecules can be improved. However, it is impossible to improve the exhaust performance for hydrogen molecules.

On the other hand, since a hydrogen storage alloy has a hydrogen storage ability even at normal temperature, a normal temperature type adsorption trap using the hydrogen storage alloy is already known. Therefore, in order to improve the exhaust performance with respect to hydrogen molecules, it is conceivable to adopt a structure in which a turbo-molecular pump and a cryotrap are used in combination, and a hydrogen storage alloy is further attached to and integrated with the cryotrap. However, when a certain amount of hydrogen is stored in a hydrogen storage alloy, its storage capacity decreases.Therefore, it is necessary to re-release the stored hydrogen by heating and reactivating it at regular intervals. . In heating the hydrogen storage alloy, it is necessary to heat the hydrogen storage alloy to a temperature of at least 250 ° C. or more, practically 300 ° C. or more, even if the material is appropriately selected. Accordingly, since the helium refrigerator used can generally only heat up to a temperature of about 70 ° C., it has not been possible to integrate the cryotrap and the hydrogen storage alloy.

Further, considering only the adsorption trap of the hydrogen storage alloy, only the adsorption trap of the hydrogen storage alloy can improve the exhaust performance for hydrogen molecules, but cannot simultaneously enhance the exhaust performance for water molecules. Therefore, it is conceivable to incorporate the cryotrap and the adsorption trap of the hydrogen storage alloy as separate units into a vacuum exhaust device. However, according to this configuration, the device configuration is complicated and large in size,
A compact device cannot be realized. Although this is not a major problem in research applications, it is not practical as a device intended for industrial equipment for production where there are great restrictions on the shape of the vacuum pump. In addition, there is a problem that the cost is increased by separately configuring the devices.

[0010] An object of the present invention is to solve the above-mentioned problems, and can simultaneously improve the exhaust performance for water molecules and the exhaust performance for hydrogen molecules, and have a simple structure and can be manufactured in a relatively small size. An object of the present invention is to provide a cryotrap that is efficient and practical, and is particularly useful as industrial equipment.

[0011]

A cryotrap according to the present invention has the following configuration to achieve the above object.

A cryotrap according to a first aspect of the present invention (corresponding to claim 1) has a helium refrigerator having a cooling panel as a basic configuration, cools the cooling panel with the helium refrigerator, and condenses gas. Water molecules in the vacuum vessel to be evacuated are evacuated by utilizing the action, and an adsorption panel made of a hydrogen storage alloy is incorporated therein, so that the adsorption panel exhausts the hydrogen molecules.

In the first aspect of the present invention, in a cryotrap used mainly in combination with a turbo molecular pump or the like, a cooling panel suitable for exhausting water molecules and an adsorption panel made of a hydrogen storage alloy are provided together. I made it. Therefore, hydrogen molecules can be exhausted by the adsorption panel.

According to a second aspect of the present invention (corresponding to claim 2), in the first aspect, preferably, the suction panel is provided on an inner surface of the cryotrap container.

According to a third aspect of the present invention (corresponding to claim 3), the cryotrap according to the first aspect,
The suction panel is provided in good thermal contact with the cooling panel and makes the temperature of the suction panel substantially equal to the temperature of the cooling panel.

Since the hydrogen storage alloy has a practical hydrogen exhausting ability even at room temperature if the reactivation is sufficient, it is possible to arrange an adsorption panel made of the hydrogen storage alloy in a cryotrap container or the like and use it at room temperature. Further, even when the cooling panel is placed on the cooling panel surface or in thermal contact with the cooling panel and the temperature of the suction panel is made equal to that of the cooling panel, the same effect of improving the exhaust performance can be obtained. Note that cooling the adsorption panel significantly lowers the saturated vapor pressure with respect to hydrogen and improves the ultimate pressure. Therefore, cooling the adsorption panel has a greater effect of improving the pump performance.

In a fourth aspect of the present invention (corresponding to claim 4), in each of the above-mentioned inventions, preferably, the cooling panel is located in front of the suction panel. The adsorption panel has an adsorption performance for other active gases such as water molecules other than hydrogen molecules and nitrogen,
In a cryotrap mainly used in combination with a turbo-molecular pump or the like, a configuration in which a cooling trap is arranged on the front surface of the adsorption panel is preferable because it is desired to mainly use the exhaust capability for hydrogen.

According to a fifth aspect of the present invention (corresponding to claim 5), in the cryotrap according to the fourth aspect, the cooling panel located in front of the suction panel is provided with a high probability that the gas to be exhausted passes through the suction panel. It was formed in a shape. The shape is, for example, the shape of a chevron baffle or a louver.

In particular, when the temperature of the adsorption panel is cooled to a temperature equivalent to that of the cooling panel, the surface of the adsorption panel is covered with water molecules in a short time, and the exhaust performance for hydrogen molecules is reduced. Place a cooling panel on the
Further, by making the shape of the cooling panel into a chevron baffle or a louver shape, the passage probability (conductance) of hydrogen molecules to the adsorption panel is kept good, and the whole cryotrap is configured to easily capture water molecules.

According to a sixth aspect of the present invention (corresponding to claim 6), in each of the above-mentioned inventions, the cryotrap is provided with a heating mechanism for activating heating of the suction panel and baking the cooling panel. Is done. It is necessary to reactivate an adsorption panel made of a hydrogen storage alloy. Therefore, a heating mechanism for reactivation is provided.

According to a seventh aspect of the present invention (corresponding to claim 7), in the cryotrap according to the sixth aspect, the helium refrigerator and the cooling panel are provided with a mechanism for changing a heat conduction characteristic (hereinafter, for simplification of description). The variable heat transfer characteristic mechanism is configured so that when the heating mechanism heats the suction panel and the cooling panel, the heat transfer characteristic is reduced. When the heating mechanism is provided in the cryotrap container and provided close to the cooling panel, in order to efficiently heat the adsorption panel and the cooling panel during reactivation and not to apply heat to the helium refrigerator, It is preferable that a heat transfer characteristic variable mechanism is interposed between the helium refrigerator and the cooling panel, and the helium refrigerator and the cooling panel are connected by the heat transfer characteristic variable mechanism.

Since a hydrogen storage alloy loses its storage capacity when it stores a certain amount of hydrogen, it is necessary to re-activate it by heating at regular intervals and re-release the stored hydrogen. This reactivation reduces the hydrogen storage alloy by at least 25
It is necessary to heat to 0 ° C. or more, practically 300 ° C. or more. On the other hand, helium refrigerators can generally only be heated up to about 70 ° C due to the problem of the heat resistance of the internal components of the refrigerator itself. As such, the adsorption panel installed in the cryotrap is particularly cooled. It is not possible to heat the suction panel to such a high temperature when it is in thermal good contact with the panel. for that reason,
A variable heat transfer characteristic mechanism is installed between the helium refrigerator and the cooling panel to protect the helium refrigerator from rising above the heat resistant temperature during heating.

According to an eighth aspect of the present invention (corresponding to claim 8), in the cryoprap according to the seventh aspect, the heat transfer characteristic variable mechanism includes a heat-conducting expansion and contraction portion which is expandable and contractable by gas pressure. When the gas is supplied by an external gas supply / discharge mechanism, the expansion / contraction portion extends and the heat conduction member connects the helium refrigerator and the cooling panel in terms of heat conduction,
When the gas is discharged by the gas supply / discharge mechanism, the expansion and contraction portion is contracted, and the heat conduction member is configured to block the helium refrigerator and the cooling panel in terms of heat conduction. In this way, good thermal contact is maintained when the cryotrap operates normally and the cooling panel is cooled to a low temperature range where water molecules are efficiently condensed, while, for example, heat conduction is performed when heating and baking the cooling panel. The characteristics are kept low so that heat is hardly transmitted from the cooling panel side heated by the heating mechanism to the helium refrigerator side.

According to a ninth aspect (corresponding to claim 9) of the cryotrap according to the eighth aspect, preferably,
The elastic part is composed of at least one bellows.

According to a tenth aspect of the present invention (corresponding to claim 10), in the cryotrap according to the seventh aspect, the heat transfer characteristic variable mechanism includes a heat-conducting expansion / contraction part which is expandable and contractable depending on the ambient temperature. When the heating mechanism is in a non-heating state, the expansion and contraction portion extends and the heat conduction member connects the helium refrigerator and the cooling panel through a heat conducting surface, and when the heating mechanism is in the heating state, the expansion and contraction portion shrinks. The heat conducting member is configured to shut off the helium refrigerator and the cooling panel in terms of heat conduction. In this case as well, when the cryotrap operates normally and the cooling panel is cooled to a low temperature range where water molecules are efficiently condensed, good thermal contact is maintained, while the cooling panel is kept During the heat baking, the heat conduction characteristics are kept low so that heat is not easily transmitted from the cooling panel side heated by the heating mechanism to the helium refrigerator side.

An eleventh aspect of the present invention (corresponding to claim 11) is the cryotrap according to the tenth aspect, wherein the expansion and contraction portion is a shape memory alloy support.

According to a twelfth aspect of the present invention (corresponding to claim 12), in the eleventh aspect of the present invention, preferably, the expansion and contraction portion is formed of a combination of a shape memory alloy support and a bellows.

According to a thirteenth aspect of the present invention (corresponding to claim 13), a cryotrap is provided with a gas supply / discharge mechanism externally, and the gas supply / discharge mechanism supplies gas to the space inside the bellows or the space. The bellows is expanded and contracted by a combination of the discharge of the gas from the substrate and the expansion and contraction of the shape memory alloy support, so that the heat conduction characteristic is changed.

According to a fourteenth aspect of the present invention (corresponding to claim 14), in the ninth or twelfth aspect, the bellows is preferably a good heat conduction bellows.

In the cryotrap according to the fifteenth aspect of the present invention (corresponding to claim 15), the cooling temperature of the cooling panel is preferably set in a range of about 55 to 160K. The temperature of the cooling panel should be a temperature at which water molecules are mainly condensed efficiently and other gases such as nitrogen and argon are not condensed, and therefore a temperature range of 55 to 160K is appropriate.

As described above, the combination of the cooling panel cooled to the optimum temperature for exhausting water molecules and the adsorption panel made of a hydrogen storage alloy makes it possible to reduce the performance of the turbo molecular pump and the like used in combination. It has become possible to simultaneously improve the exhaust performance for water molecules and the exhaust performance for hydrogen molecules. In addition, by incorporating a mechanism to change the heat transfer characteristics between the helium refrigerator and the cooling panel, the adsorption panel and cooling panel are kept at a sufficiently high temperature while protecting the helium refrigerator from overheating beyond the allowable temperature limit. Up to the maximum temperature, so that efficient reactivation can be performed to fully demonstrate the performance of the hydrogen storage alloy, and heating and baking of the cryotrap container and the cooling panel itself can be performed at the same time. Outgassing from the cryotrap itself, which was one of the obstacles in reducing the ultimate pressure of the exhaust device to 10 ^-6 to 10 ^-7 Pa or lower, can be greatly reduced.

Further, by providing a heating mechanism, it is possible to reduce the time required for raising the temperature from a cooled state in regenerating the cryotrap, and to produce equipment such as a production cryotrap in comparison with a conventional cryotrap having no heating mechanism. Improve the operating rate of As described above, it is possible to improve the exhaust performance and the usability as a vacuum pump more than simply adding the conventional cryotrap and the normal temperature type hydrogen storage alloy adsorption trap. In addition, since the outer shape of the cryotrap is almost not larger than that of a conventional cryotrap including only cooling panels, the shape of the cryotrap does not increase the shape of the evacuation device.

Since the cooling panel and the adsorption panel are actually built-in pumps similar to a cryopump, they need to be regenerated or reactivated someday. Except when molecules are introduced into the evacuation system, the absolute amount of water and hydrogen molecules released from the walls of each part of the vacuum vessel is extremely small. is not. Accordingly, the turbo molecular pump or the like which is used in combination can be used substantially with the convenience close to the case where the turbo molecular pump is used alone.

[0034]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

Various embodiments of the cryotrap according to the present invention will be described with reference to FIGS. The cryotrap shown in FIGS. 1 to 9 is used in combination with a general discharge type vacuum pump such as a turbo molecular pump. Therefore, flanges for vacuum connection are formed at both ends of each cryotrap. One of the flanges is connected to a vacuum evacuation device which is a system to be evacuated, and the other flange is connected to the vacuum pump.

The cryotrap of the embodiment shown in FIGS. 1 to 3 uses a one-stage helium refrigerator, and arranges an adsorption panel made of a hydrogen storage alloy on the inner surface of the cryotrap container. The example of a structure which installed the cooling panel in the front is shown.

FIG. 1 shows a first embodiment. In the first embodiment, 11 has flanges 11a,
11b is a cylindrical cryotrap container on which is formed. The cryotrap container 11 includes a one-stage helium refrigerator 12 provided on the wall in the radial direction, a cylindrical cooling panel 14 connected to a cooling stage 13 of the helium refrigerator 12, and a cryotrap. A suction panel 15 is provided on the inner surface of the container 11. Suction panel 15
Is formed of a hydrogen storage alloy and faces the cooling panel 14. As a heating mechanism for reactivating the suction panel 15, a panel-shaped or sheath-shaped external heater unit 16 is provided on the outer surface of the cryotrap container 11.

FIG. 2 shows a second embodiment. In FIG. 2, substantially the same elements as those shown in FIG. 1 are denoted by the same reference numerals. In the second embodiment, instead of providing the external heater unit 16, the cooling panel 1 inside the cryotrap container 11 via the input terminal 20.
4, a sheath-shaped or lamp-shaped internal heater unit 21 is provided. Other configurations are the same as those of the first embodiment.

FIG. 3 shows a third embodiment. In FIG. 3, elements that are substantially the same as the elements shown in FIG. 1 are given the same reference numerals. In the third embodiment, the suction panel 15
Is formed so as to have a chevron baffle or louver shape. Other configurations are the same as those of the first embodiment. With this structure, the passage probability of hydrogen in the adsorption panel 15 is increased.

According to the cryotrap according to the first to third embodiments, in addition to the helium refrigerator 12 and the cooling panel 14 (or 14A), the inner surface of the cryotrap container 11 is made of a hydrogen storage alloy. Panel 1
5 is provided, the water molecules can be exhausted by the condensation action in the cooling panels 14 and 14A, and the hydrogen molecules can be exhausted together by the adsorption action by the adsorption panel 15. Also, for the suction panel 15,
Since the external heater unit 16 is provided with good thermal contact or the internal heater unit 21 is provided near the external heater unit 16, the suction panel 15 can be reactivated by heating. In this case, in the configuration of the first or third embodiment shown in FIG. 1 and FIG. 3, a sufficient distance for blocking heat conduction is secured between the external heater unit 16 and the cooling panels 14 and 14A. Since the adsorbing panel 15 and the cryotrap container 11 exist between them, the cooling panels 14 and 14A are hardly affected by heat, and there is no problem. On the other hand, in the second embodiment shown in FIG.
Is placed at a relatively close distance to and heated. However, by setting the heating temperature conditions appropriately, practical use becomes possible.

FIG. 4 shows a fourth embodiment of a cryotrap according to the present invention, which is a modification of the second embodiment described with reference to FIG. In FIG. 4, substantially the same elements as those described in FIG. 2 are denoted by the same reference numerals. In the fourth embodiment, a mechanism 31 is provided between the cooling stage 13 and the cooling panel 14 of the helium refrigerator 12 to change the heat conduction characteristic thereof, and the mechanism 31 for changing the heat conduction characteristic is provided in the mechanism 32. A gas introduction mechanism 32 for supplying a gas such as helium (He) for expanding and contracting the provided expansion and contraction section is provided. Other configurations are
This is substantially the same as the case of the second embodiment shown in FIG. As described in (Means for Solving the Problems and Action), the mechanism 31 for changing the heat conduction characteristics is referred to as a “heat transfer characteristic variable mechanism” for convenience of explanation.

The heat transfer characteristic variable mechanism 31 in this embodiment
As will be described later, a bellows mechanism is built in as a telescopic part, gas is supplied to the internal space of the bellows mechanism, and the bellows mechanism is extended to enhance the heat conduction characteristics. On the contrary, the gas is discharged from the internal space of the bellows mechanism. The bellows mechanism is contracted to reduce heat conduction characteristics. Thus, the heat transfer characteristic variable mechanism 31 changes the heat transfer characteristics between the cooling panel 14 and the helium refrigerator 12.

The gas introducing mechanism 32 has a function of supplying gas to the internal space of the bellows mechanism of the heat transfer characteristic varying mechanism 31 and discharging the gas from the internal space. The gas introduction mechanism 32 includes a gas introduction pipe 33
And a gas supply valve 34 and a gas discharge valve 35 for switching between supply and discharge of gas. The gas supply valve 34 is connected to a gas supply source (not shown) through the gas supply valve 34, and is connected through the gas discharge valve 35. Connected to a vacuum pump (not shown). The gas supply valve 34 and the gas discharge valve 35 are generally installed outside the cryotrap container 11.

As the vacuum pump, an auxiliary pump such as a turbo molecular pump used in combination with a cryotrap can be used as it is, and a new vacuum pump is not required. Helium (He) gas is appropriate as a gas to be introduced in consideration of safety and the like. However, other gases that do not condense at 55K can be used.

FIG. 5 shows a fifth embodiment of a cryotrap according to the present invention, which is a modification of the second embodiment described with reference to FIG. 2 as in the fourth embodiment. In FIG. 5, elements substantially the same as the elements described in FIG. 2 are denoted by the same reference numerals. In the fifth embodiment, between the cooling stage 13 and the cooling panel 14 of the helium refrigerator 12, a variable heat transfer characteristic mechanism 36 having a structure different from that of the variable heat transfer characteristic mechanism 31 is provided. The heat transfer characteristic variable mechanism 36 does not require the gas supply / discharge by the gas introduction mechanism 32, and has a built-in bellows mechanism and a shape memory alloy support, as will be described later. The bellows structure is expanded and contracted by changing the temperature condition, and the heat conduction characteristics between the cooling panel 14 and the helium refrigerator 12 are changed. Other configurations are the same as those of the second embodiment shown in FIG.

According to the fourth and fifth embodiments, the suction panel 1 provided in the cryotrap container 11
Internal heater unit 2 provided for reactivating the cooling unit 5 and for heating and baking the cooling panel 15 and the like.
1 is connected to the helium refrigerator 12 via the cooling panel 14.
In the case where heat causing a sufficiently high temperature, which is not desirable to the helium refrigerator 12, is applied, the heat transfer characteristics of the heat transfer characteristic variable mechanisms 31 and 36 are reduced to prevent heat from being transferred to the helium refrigerator 12. In the exhaust operation, the heat transfer characteristics of the heat transfer characteristic changing mechanisms 31 and 36 are enhanced so that the cooling panel 14 is effectively cooled by the helium refrigerator 12.

FIG. 6 shows a sixth embodiment of the cryotrap according to the present invention, which is a modification of the fourth embodiment described with reference to FIG. In FIG. 6, elements substantially the same as the elements described in FIG. 4 are denoted by the same reference numerals. In the sixth embodiment, the adsorption panel 15 made of a hydrogen storage alloy is installed on the outer surface of the cooling panel 14, or is installed in another structure in good thermal contact with the cooling panel 14 outside. The cooling panel 14 is cooled so that the temperature of the suction panel 15 becomes equal to the temperature of the cooling panel 14. Other configurations are substantially the same as the fourth embodiment described with reference to FIG.

In the sixth embodiment, when the hydrogen storage alloy forming the adsorption panel 15 is heated by the internal heater unit 21 and reactivated, the cooling panel 14 is also heated and baked at a high temperature by the internal heater unit 21 at the same time. It is configured as follows. Thus, when the cooling panel 14 is heated and baked, the heat conduction characteristics of the above-described variable heat transfer characteristic mechanism 31 are reduced, so that the heat of the cooling panel 14 is less likely to be transmitted to the helium refrigerator 12.

FIG. 7 shows a seventh embodiment of the cryotrap according to the present invention, which is a modification of the sixth embodiment described with reference to FIG. In FIG. 7, elements substantially the same as the elements described in FIG. 6 are denoted by the same reference numerals. In the seventh embodiment, an adsorption panel 1 made of a hydrogen storage alloy
5 is placed on the inner surface of the cooling panel 14 or placed inside in good thermal contact with the cooling panel 14 so that the temperature of the suction panel 15 becomes equal to the temperature of the cooling panel 14. Cooling. Further, in the present embodiment, a through-type cooling panel 37 is provided inside the cooling panel 14 so as to face the suction panel 15. This cooling panel 37
This is for preventing the surface of the adsorption panel 15 from being covered with water molecules in a short time, preventing the exhaust performance for hydrogen molecules from being lowered, and keeping the probability of passing hydrogen molecules to the adsorption panel 15 good. It has a chevron baffle or louver shape. Other configurations are similar to those of the fourth embodiment described with reference to FIG.
It is substantially the same as the embodiment.

FIG. 8 shows an eighth embodiment of a cryotrap according to the present invention, which is a modification of the sixth embodiment described with reference to FIG. In FIG. 8, substantially the same elements as those described in FIG. 6 are denoted by the same reference numerals. In the eighth embodiment, instead of the heat transfer characteristic variable mechanism 31 using the gas introduction mechanism 32, the heat transfer characteristic variable mechanism 36 used in the fifth embodiment (FIG. 5) is used. I have. Other configurations are substantially the same as the sixth embodiment described with reference to FIG.

FIG. 9 shows a ninth embodiment of a cryotrap according to the present invention, which is a modification of the seventh embodiment described with reference to FIG. In FIG. 9, elements substantially the same as the elements described in FIG. 7 are denoted by the same reference numerals. In the ninth embodiment, a variable heat transfer characteristic mechanism 36 used in the fifth embodiment (FIG. 5) is used instead of the variable heat transfer characteristic mechanism 31 using the gas introduction mechanism 32. ing. Other configurations are substantially the same as those of the seventh embodiment described with reference to FIG.

Next, a specific configuration example of the heat transfer characteristic variable mechanism 31 used in the fourth, sixth, and seventh embodiments will be described with reference to FIGS.

FIG. 10 shows a first example of the structure of the heat transfer characteristic variable mechanism 31 provided on the cooling stage 13 of the helium refrigerator 12. FIG. 10A shows a case where the heat transfer characteristic is high (good). (In the case of maintaining a good thermal contact state), (B)
Indicates a configuration in the case of having a low thermal conductivity.
In this configuration example, a bellows structure is used as a telescopic part that expands and contracts in conjunction with gas supply from the gas introduction mechanism 32 to the heat transfer characteristic variable mechanism 31 and gas discharge from the heat transfer characteristic variable mechanism 31. This bellows structure has a plurality of bellows portions. In the illustrated example, the suction panel 15 is provided on the inner surface of the cooling panel 14 and corresponds to the structure of the seventh embodiment shown in FIG. In FIG. 10, illustration of the internal heater unit 21 and the like is omitted.

The variable heat transfer characteristic mechanism 31 is provided between the cooling stage 13 of the helium refrigerator 12 and the cooling panel 14. This heat transfer characteristic variable mechanism 31 is
3. The good heat conductive support 41 fixed to 3 is used as a base member,
It is mechanically connected to the cooling panel 14 via a low heat conduction connector 42 formed of a thin stainless steel pipe or the like with mechanically sufficiently strong strength. Inside the low heat conductive connector 42, a good heat conductive contact 43 and a good heat conductive bellows 44 are provided based on the above-mentioned good heat conductive support 41. The good heat conductive support 41, the good heat conductive contact 43, and the good heat conductive bellows 44 are joined by welding or brazing so as not to cause a leak, and an airtight space is formed inside. The above-mentioned gas introduction pipe 33 is connected to the good heat conducting support 41, and helium gas or the like is supplied to the space in the heat transfer characteristic variable mechanism 31 via the gas introduction pipe 32, and helium gas is supplied from the space. Etc. are discharged.

In the heat transfer characteristic varying mechanism 31, the mechanism itself for changing the heat transfer characteristic is the same as the good heat transfer support 4.
1, a good heat conductive contact 43, and a good heat conductive bellows 44
And the gas introduction pipe 33. Even if helium gas is introduced into the internal space formed by these components by the gas introduction mechanism 32 and the gas introduction pipe 33, there is no effect on the vacuum side. Gas inlet pipe 33
Is connected to the helium gas supply source via the gas introduction valve 34 as described above, and the gas discharge valve 3
5 is connected to a vacuum pump.

The good heat conductive bellows 44 is designed to expand and contract in accordance with the pressure difference between the inside and the outside. The cooling panel 43 is not in contact with the cooling panel 14, that is, the cooling panel 14 is shut off at a heat conduction surface. Conversely, when helium gas is supplied to the inside and the internal pressure is higher than the external pressure, the length of the good heat conductive bellows 44 is elongated, and the good heat conductive contact body 43 and the cooling panel 14 are in close contact with each other, It is configured to be connected in the plane of. Further, the good heat conduction bellows 44 itself is formed of a material having good heat conduction characteristics such as copper or a copper alloy, and when the helium refrigerator 12 performs a cooling operation, the cooling panel 14 reaches a required low temperature. It is designed to have sufficient heat transfer properties to be cooled.

FIG. 10A shows the mutual positional relationship between the components when the cryotrap operates normally and cooling is performed by the helium refrigerator 12. When starting operation of the cryotrap, the inside of the cryotrap is first evacuated to a vacuum. In this state, the gas supply valve 34 is opened, and helium gas is introduced into the internal space of the good heat conduction bellows 44 to about 1 atm. Then, FIG. 10 (A)
As shown in FIG. 5, the good heat conductive contact body 43 and the cooling panel 14 are in close contact with each other, and the cooling panel 14 is cooled by the heat conduction characteristics of the good heat conductive bellows 44 and the convection of the helium gas introduced therein. This state is maintained while the cryotrap is operating.

FIG. 10B shows the mutual positional relationship of the components when the suction panel 15 is reactivated and the cooling panel 14 is heated and baked. When heating the cooling panel 14 and the adsorption panel 15, the gas exhaust valve 35 is opened, and the helium gas in the internal space of the good heat conduction bellows 44 is exhausted using a vacuum pump. Then, the pressure difference between the inside and the outside of the good heat conduction bellows 44 disappears, and the bellows shrinks. As shown in FIG. 10B, the good heat conduction contact body 43 and the cooling panel 14 are separated, and the heat conduction is almost negligible. Is held. In some cases, the pressure outside the good heat conduction bellows 44 may be temporarily increased due to the gas released during the process of regeneration or baking of the cryotrap, but this does not affect the expansion and contraction of the bellows and is not a problem. . In particular, when the cryotrap is regenerated after exhausting a large amount of gas, the inside of the bellows may be in a vacuum state and the pressure inside the pump, that is, the outside of the bellows, may temporarily rise to the atmospheric pressure or to a greater pressure exceeding the atmospheric pressure. However, only the bellows is kept in a contracted state,
The original operation of the heat transfer characteristic varying mechanism 31 is not affected, and no measures such as performing a gas introduction operation are required.

Gas supply valve 34 and gas discharge valve 35
Supply and discharge operations can be performed freely. The operation of these valves is controlled by the helium refrigerator 1
The compressor 2 is configured to be controlled in conjunction with the operation of a separate compressor unit for operating the compressor 2.

FIG. 11 shows a second example of the structure of the above-described variable heat transfer characteristic mechanism 31 and is similar to FIG. FIG.
(A) shows the configuration in the case of having a high thermal conductivity (in the case of maintaining a good thermal contact state), and (B) shows the configuration in the case of having a low thermal conductivity. 11 (A),
In FIG. 10B, the same reference numerals are given to substantially the same elements as those described with reference to FIG. Also in this configuration example, a bellows structure that expands and contracts in conjunction with gas supply from the gas introduction mechanism 32 to the heat transfer characteristic variable mechanism 31 and gas discharge from the heat transfer characteristic variable mechanism 31 is used. The difference from the configuration of FIG. 10 is that a good heat conduction bellows 45 having one bellows portion is used. The basic operation principle is the same as that described in FIG. 10, and a detailed description will be omitted.

FIG. 12 shows a third configuration example of the heat transfer characteristic varying mechanism 31, which is an example in which the structure utilizing gas introduction is further simplified. In this configuration example, a configuration in which the heat conduction is changed by expansion and contraction of the bellows portion is not adopted, and the heat conduction characteristics required at the time of cooling are secured only by the heat conduction by the convection of the introduced helium gas. Therefore, in the heat transfer characteristic varying mechanism 31 shown in FIG.
And a low thermal conductive connector 42 and a good thermal conductive contact 43 are provided, and there is no portion of the good thermal conductive bellows. The heat transfer characteristic variable mechanism 31 formed by only the good heat conductive support 41, the low heat conductive connector 42, and the good heat conductive contact 43 does not cause a change such as expansion and contraction. According to the heat transfer characteristic varying mechanism 31 according to the third configuration example, the helium gas introduced through the gas introduction pipe 33 based on the conditions such as the required heat conduction amount and the cross-sectional area of the gas introduction portion that can be secured. The cooling panel 14 can be cooled to a required temperature range only by the contribution of heat conduction due to the convection.

FIG. 13 shows a fourth configuration example obtained by modifying the third configuration example of the heat transfer characteristic varying mechanism 31 shown in FIG. In order to reduce the distance between the cooling stage 13 and the cooling panel 14 of the helium refrigerator 12 due to dimensional restrictions, the heat transfer characteristic variable mechanism 31 according to the fourth configuration example has a shape of the low heat conduction coupling body. An example of a change is shown. In the low heat conduction connector 46 of the present configuration example, the folded portion 46 a is formed, so that the axial length of the low heat conduction connector 46, that is, the distance of the heat conduction path between the cooling stage 13 and the cooling panel 14. Is increasing.

Next, referring to FIG. 14, the heat transfer characteristic varying mechanism 36 used in the fifth, eighth, and ninth embodiments will be described.
A specific configuration example will be described.

FIG. 14 shows the internal structure of the heat transfer characteristic varying mechanism 36 provided between the cooling stage 13 and the cooling panel 14. In the fifth, eighth, and ninth embodiments, as described above, the gas introduction mechanism is not used, and instead, a shape memory alloy support capable of changing its shape depending on the ambient temperature and an expandable bellows structure are used. The combination forms a mechanism that changes the heat conduction characteristics. That is, the bellows structure is expanded and contracted by the deformation operation of the shape memory alloy support based on the temperature condition. The other basic configuration for changing the heat conduction characteristics and the role of the bellows structure regarding the heat conduction are the same as those in the above-described embodiments.

The mechanism for changing the heat conduction characteristic, that is, the mechanism for varying the heat conduction characteristic 36, comprises the cooling stage 13 and the cooling panel 1
4, a mechanically sufficient strength is provided on the basis of the good heat conductive support 51 and the low heat conductive connecting body 52.
The mechanism itself for changing the heat conduction characteristics is a good heat conduction support 5.
1 is composed of a good heat conductive contact 53, a good heat conductive bellows 54, and a shape memory alloy support 55.
These components are joined by welding or brazing, and are formed in an open structure so that a pressure difference does not occur between the inside and the outside of the good heat conduction bellows 54.

The shape memory alloy support 55 is formed, for example, in a coil shape, is located at the center of the good heat conductive bellows 54, and has a good heat conductive support 51 and a good heat conductive contact 5.
3 are provided with both ends fixed. The good heat conduction bellows 54 has a length that is short under normal ambient temperature conditions, that is, a temperature state of about room temperature or higher, so that the good heat conduction contact body 53 and the cooling panel 14 do not come into contact with each other.
In a state where the temperature is lowered, the length is extended, and the good heat conductive contact body 5 is formed.
3 and the cooling panel 14 are configured to be in close contact with each other. The good heat conduction bellows 54 is made of a material having good heat conduction properties, such as copper or a copper alloy.
2 are designed so that when cooled, the cooling panel has sufficient heat transfer properties to cool to the desired low temperature state.

In FIG. 14, (A) shows the mutual positional relationship of each component when the cryotrap is operating normally and cooling, and (B) shows each positional relationship when the cooling panel and the adsorption panel are heated and baked. 3 shows the mutual positional relationship of the components.

As shown in FIG. 14A, when the operation of the helium refrigerator 12 is started and the temperature of the shape memory alloy support 55 starts to decrease and reaches the transformation temperature of the shape memory alloy, the shape memory alloy support 55 is cooled. Is extended to extend the good heat conductive bellows 54, and the good heat conductive contact body 53 and the cooling panel 14 come into close contact with each other. As a result, the cooling panel 14 is cooled by heat conduction by the good heat conduction bellows 54. This state is maintained while the cryotrap is operating. When heating the cooling panel 14 and the suction panel 15, FIG.
As shown in FIG. 4 (B), usually, the helium refrigerator 12 is stopped and then heated to increase the temperature of the shape memory alloy support 55, and when the temperature exceeds the transformation temperature of the shape memory alloy, the shape memory alloy support is heated. The size of 55 is reduced and the good heat conductive contact 53 is separated from the cooling panel 14, so that the heat conduction is maintained in a state where heat conduction can be almost ignored. As described above, the heat transfer characteristic variable mechanism 36 can change the heat transfer characteristics according to the cooling time and the heating activation and heating baking so as to meet the conditions.

In the heat transfer characteristic varying mechanism 36 formed by applying the shape memory alloy support 55, in addition to the configuration shown in FIG. 14, the range of the force smaller than the recovery stress for the expansion and contraction of the shape memory alloy support 55. A gas such as helium may be sealed in the good heat conduction bellows 54 to an appropriate pressure within the inside, so that the heat conduction characteristics due to the convection of the gas can be additionally added.

The bellows structure of the heat transfer characteristic variable mechanism 36 can be arbitrarily modified. Also, the heat transfer characteristic variable mechanism 36 can be configured using a shape memory alloy support and a plurality of bellows structures, similarly to the heat transfer characteristic variable mechanism 31.

When the gas is sealed in the internal space of the bellows structure, the operation of the bellows becomes a problem when the cooling panel or the suction panel is heated and baked, and the shape memory alloy support 55 is deformed. When trying to shrink the heat conduction bellows 54, the outside of the bellows is vacuum,
This is a case where a force is exerted on the bellows itself to expand by an amount corresponding to the pressurized inside. In this case, if the recovery stress of the shape memory alloy support 55 is greater than the force in the direction in which the bellows expands due to the pressure difference between the inside and the outside of the bellows, there is no operational problem.

In the future, when the formability of the shape memory alloy is improved and a more free shape can be used,
By devising the overall shape and the cross-sectional shape, it is possible to secure the necessary heat conduction during cooling only by the heat conduction characteristics of the shape memory alloy support itself.

Further, by solving the problems of cost increase and complicated structure, the configuration using the shape memory alloy support 55 can be used together with the gas introduction mechanism according to the above-described embodiment.

Next, another embodiment of the cryotrap according to the present invention will be described with reference to FIGS. Due to the layout of the apparatus, it may be necessary to install the cryotrap at a different position from the vacuum pump. In such a case, the same improvement effect as described above can be obtained for the vacuum pump performance of the entire vacuum pumping apparatus. The embodiment shown in FIGS. 15 and 16 shows a configuration corresponding to such a case.

FIG. 15 shows a tenth embodiment of a cryotrap according to the present invention, and shows a configuration in which the cryotrap is directly attached to a container part of an evacuation apparatus. The cryotrap is provided on a base flange 61 for the cryotrap, and is mounted on the side of the vacuum exhaust device via a nipple 62 for the cryotrap. In FIG. 15, the helium refrigerator 12 is fixed to a base flange 61, and a cooling panel 63 and an adsorption panel 64 made of a hydrogen storage alloy are attached to the cooling stage 13 of the helium refrigerator 12 via, for example, a heat transfer characteristic variable mechanism 36. Can be Further, a through-type cooling panel 65 is disposed inside the nipple 62 for the cryotrap and above the suction panel 64 in the drawing. The cooling panel 65 prevents the surface of the adsorption panel 64 from being covered with water molecules in a short period of time, thereby preventing the exhaust performance of hydrogen molecules from being reduced, and keeping the probability of passing hydrogen molecules to the adsorption panel 64 good. Therefore, it is arranged so as to cover the suction panel 64 and has a chevron baffle or louver shape. Further, an internal heater unit 66 is arranged by utilizing a space inside the suction panel 64. Reference numeral 20 denotes the above-described current introduction terminal.

Also in the above embodiment, the helium refrigerator 12
A heat transfer characteristic variable mechanism 36 is provided as a connection portion (coupling portion) between the cooling stage 13 and the cooling panel 63, etc., so that the heat conduction characteristics thereof are changed according to cooling exhaust, heating baking, and the like. Be composed. For the heat transfer characteristic variable mechanism, each of the above-described configuration examples 31 can also be used.

FIG. 16 shows an eleventh embodiment of a cryotrap according to the present invention. Also in this embodiment, the cryotrap is directly attached to a container portion of an evacuation apparatus. In particular, in the present embodiment, the cryotrap is replaced with the vacuum vessel 6 without using the cryotrap nipple 62 described above.
7 is directly attached. Other configurations are substantially the same as those of the above-described tenth embodiment. Elements substantially the same as those described in the tenth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Omitted.

[0078]

As is apparent from the above description, according to the present invention, in the cryotrap, an adsorbing panel made of a hydrogen storage alloy is incorporated in the inside of the cryotrap container. Exhaust performance for molecules can be improved.

Further, a heating mechanism for reactivating the adsorption panel and performing heating baking of the cooling panel is provided. At the time of evacuation, the heat conduction characteristics between the helium refrigerator and the cooling panel are improved, and the reactivation and heating are performed. At the time of baking, a mechanism for changing the heat conduction characteristic is provided to reduce the heat conduction characteristic and protect the helium refrigerator, so that a cryotrap that is highly practical and useful as industrial equipment can be realized.

The heating mechanism also enables the gas emission from the cryotrap itself to be reduced, and an optimal cryotrap for a vacuum exhaust device whose ultimate pressure is 10 ⁻⁶ to 10 ⁻⁷ Pa or lower is obtained. It can be realized without significantly increasing the external size and cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a cryotrap according to the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the cryotrap according to the present invention.

FIG. 3 is a longitudinal sectional view showing a cryotrap according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a fourth embodiment of a cryotrap according to the present invention.

FIG. 5 is a longitudinal sectional view showing a fifth embodiment of a cryotrap according to the present invention.

FIG. 6 is a longitudinal sectional view illustrating a cryotrap according to a sixth embodiment of the present invention.

FIG. 7 is a longitudinal sectional view showing a seventh embodiment of a cryotrap according to the present invention.

FIG. 8 is a longitudinal sectional view showing an eighth embodiment of a cryotrap according to the present invention.

FIG. 9 is a longitudinal sectional view showing a ninth embodiment of a cryotrap according to the present invention.

10A and 10B are diagrams showing a first configuration example of a heat transfer characteristic variable mechanism, wherein FIG. 10A shows a good thermal contact state, and FIG. 10B shows a state in which heat conduction is reduced.

11A and 11B are diagrams showing a second configuration example of the heat transfer characteristic varying mechanism, wherein FIG. 11A shows a good thermal contact state, and FIG. 11B shows a state in which heat conduction is reduced.

FIG. 12 is a diagram illustrating a third configuration example of the heat transfer characteristic variable mechanism.

FIG. 13 is a diagram illustrating a fourth configuration example of the heat transfer characteristic variable mechanism.

14A and 14B are diagrams showing a fifth configuration example of the heat transfer characteristic varying mechanism, wherein FIG. 14A shows a good thermal contact state, and FIG. 14B shows a state in which heat conduction is reduced.

FIG. 15 is a longitudinal sectional view showing a tenth embodiment of a cryotrap according to the present invention.

FIG. 16 is a longitudinal sectional view showing an eleventh embodiment of a cryotrap according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Cryotrap container 12 Helium refrigerator 13 Cooling stage 14, 14A Cooling panel 15 Adsorption panel 16 External heater unit 21 Internal heater unit 31, 36 Mechanism for changing heat conduction characteristics (Heat transmission characteristic variable mechanism) 32 Gas introduction mechanism 37 Passage Shaped cooling panel

Claims (15)

[Claims] 1. A helium refrigerator having a cooling panel, wherein the cooling panel is cooled by the helium refrigerator, and water molecules in a container to be evacuated are exhausted by utilizing a gas condensation action. In a cryotrap, an adsorbing panel made of a hydrogen storage alloy is incorporated therein, and the adsorbing panel exhausts hydrogen molecules. 2. The cryotrap according to claim 1, wherein the suction panel is provided on an inner surface of the cryotrap container. 3. The suction panel according to claim 1, wherein the suction panel is provided in good thermal contact with the cooling panel, and the temperature of the suction panel is substantially equal to the temperature of the cooling panel. The cryotrap according to 1. 4. The cooling panel according to claim 1, wherein the cooling panel is located in front of the suction panel.
4. The cryotrap according to any one of items 3 to 3. 5. The cryotrap according to claim 4, wherein the cooling panel located in front of the suction panel is formed in a shape having a high probability of passage of the exhaust gas to the suction panel. 6. The cryotrap according to claim 1, further comprising a heating mechanism for activating heating of the suction panel and heating baking of the cooling panel. 7. The helium refrigerator and the cooling panel are coupled by a mechanism that changes heat conduction characteristics, wherein the mechanism that changes heat conduction characteristics heats the adsorption panel and the cooling panel by the heating mechanism. 7. The cryotrap according to claim 6, wherein the heat conduction characteristics are reduced. 8. The mechanism for changing a heat conduction characteristic is a heat conduction member including an expansion and contraction portion that can be expanded and contracted by gas pressure, and when the gas is supplied by an external gas supply / discharge mechanism, the expansion and contraction portion expands. The heat conducting member connects the helium refrigerator and the cooling panel in terms of heat conduction, and when the gas is discharged by the gas supply / discharge mechanism, the expansion / contraction portion shrinks and the heat conducting member moves the helium refrigerator. 8. The cryotrap according to claim 7, wherein the cryotrap is configured to shut off the cooling panel from the heat sink. 9. The cryotrap according to claim 8, wherein the expansion and contraction portion is made of at least one bellows. 10. The mechanism for changing a heat transfer characteristic,
A heat conductive member including a telescopic part that can be expanded and contracted by ambient temperature, wherein the telescopic part extends when the heating mechanism is in a non-heating state, and the heat conductive member moves the helium refrigerator and the cooling panel in terms of heat conduction. Connected to each other, wherein when the heating mechanism is in a heat-generating state, the expansion and contraction portion shrinks, and the heat conduction member is configured to cut off the helium refrigerator and the cooling panel at a heat conduction surface. 7. The cryotrap according to 7. 11. The cryotrap according to claim 10, wherein said elastic portion is a shape memory alloy support. 12. The cryotrap according to claim 11, wherein the expansion and contraction portion is configured by a combination of the shape memory alloy support and a bellows. 13. A gas supply / discharge mechanism is provided outside, and the gas supply / discharge mechanism supplies gas to or discharges gas from the space in the bellows, and expands / contracts the shape memory alloy support. 13. The cryotrap according to claim 12, wherein the bellows expands and contracts to change the heat conduction characteristic in combination with the following. 14. The cryotrap according to claim 9, wherein said bellows is a good heat conduction bellows. 15. The cooling temperature of the cooling panel is 55 to 1
The cryotrap according to claim 1, wherein the range is about 60K.