CN114396825B

CN114396825B - Two-cavity type heat conduction switch for extremely low temperature equipment and extremely low temperature equipment

Info

Publication number: CN114396825B
Application number: CN202111658473.7A
Authority: CN
Inventors: 王永超; 郝镇齐; 张磊
Original assignee: Gewu Zhihan Suzhou Scientific Instrument Co ltd
Current assignee: Gewu Zhihan Suzhou Scientific Instrument Co ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2023-08-15
Anticipated expiration: 2041-12-30
Also published as: CN114396825A

Abstract

The invention discloses a two-cavity type heat conduction switch for very low temperature equipment and the very low temperature equipment, wherein the two-cavity type heat conduction switch for the very low temperature equipment comprises: an upper fixing plate, a lower fixing plate, an outer cavity wall and an inner cavity wall; the outer cavity wall is arranged between the upper fixing plate and the lower fixing plate, and the upper fixing plate, the lower fixing plate and the outer cavity wall form a closed cavity, namely an outer cavity; an external cavity heat conduction device is arranged in the external cavity; the inner cavity wall is arranged between the upper fixing plate and the lower fixing plate, and forms a closed cavity, namely an inner cavity, and is arranged inside the outer cavity wall; an internal chamber heat conduction device is arranged in the internal chamber. According to the invention, the active thermal switch and the passive thermal switch are combined, and the thermal switches in two different temperature ranges are combined, so that different heat conduction effects in a high temperature range and a low temperature range can be achieved, higher heat conduction efficiency is obtained in the high temperature range, and the low temperature system can be cooled more quickly in the high temperature range.

Description

Two-cavity type heat conduction switch for extremely low temperature equipment and extremely low temperature equipment

Technical Field

The invention relates to the field of low-temperature switches, in particular to a two-cavity type heat conduction switch for very low-temperature equipment and the very low-temperature equipment.

Background

With the rise of quantum computing, various countries in the world have a large number of layouts in the research and development of quantum computing; in the material science, the quantum behavior of new materials at extremely low temperatures is widely studied by the aggregate physicists of countries around the world; in the field of detectors, new forms of high resolution photon and radiation detectors are being developed in various countries. Whether it is a quantum computer, or a condensed state physical study, or a new type of detector, the study performed is in need of a very low temperature environment provided by a dilution refrigerator.

The current problems of dilution refrigerators are large equipment, long temperature rise and fall period and complex operation. The problem of long warm-up periods can be ameliorated in the industry by using suitable thermal switches. The thermal switch is a heat conduction switch, and in the cooling process of the equipment, a high temperature area with rapid cooling is needed, the thermal switch is turned on, and heat at the bottom of the equipment is transferred to a cold head of the equipment at the fastest speed. When the temperature reaches low temperature and the equipment refrigeration mode is changed, the thermal switch is required to be closed, and the thermal connection between the lowest temperature area of the equipment and the cold head with slightly higher upper temperature is disconnected. The thermal switches adopted at present are mechanical thermal switches, gas gap thermal switches, superconductive thermal switches, graphite thermal switches and memory alloy thermal switches.

The mechanical thermal switch adopts two smooth and softer heat conduction metal surfaces to contact and transfer heat, and is usually copper with gold plated surfaces, external driving force is adopted to enable the two metal surfaces to be tightly contacted, the external driving force is a part of manpower or engineering control electromagnetic driving, and the contact and non-contact of the two metal surfaces are controlled to achieve 'on' and 'off' of heat transfer. However, mechanical thermal switches add moving parts to the refrigerator environment, and reliability in long-term use is unknown in consideration of the influence of deformation due to temperature change.

Gas gap thermal switches are currently the most widely used type of thermal switch. The hot switch is connected between the cold end and the hot end through a sealing pipe, is inflated in the sealing pipe, conducts heat through internal gas, and is in an on state; the gas is pumped out of the sealed tube or adsorbed into the adsorbate, so that the tube is in a vacuum state, the heat conduction of the sealed tube is poor, and the thermal switch is in an off state.

The superconducting thermal switch utilizes the characteristic of poor heat conduction of the superconductor, after the superconductor in the switch enters a superconducting state, the switch is in an off state, and the superconductor is quenched by micro heating, so that the heat conduction is good, and the switch enters an on state.

Shape memory alloy thermal switch can be designed according to the characteristics of shape change of different temperatures through shape memory alloy, and is generally used for thermal switches in high temperature areas. When the temperature reaches a certain value, the shape memory alloy deforms, so that the state of the switch is changed from an on state to an off state.

The gas gap type thermal switch is divided into an open circulation type thermal switch and a closed type thermal switch, the open circulation type thermal switch can vacuumize the interior of the thermal switch through a vacuum pump set and deflate to finish the closing and opening of the switch, the closed type switch generally adsorbs heat conducting medium gas in a closed cavity when an adsorption device reaches a certain temperature, so that the heat conducting state of the thermal switch is changed into the closing state, and therefore the switching temperature of a heat pipe is certain.

Disclosure of Invention

An object of the present invention is to provide a two-chamber type heat conduction switch for a very low temperature apparatus and a new technical solution for a very low temperature apparatus.

According to a first aspect of the present invention there is provided a two-chamber thermally conductive switch for a very low temperature device comprising: an upper fixing plate, a lower fixing plate, an outer cavity wall, an inner cavity wall and an adsorption pump device;

the outer cavity wall is arranged between the upper fixing plate and the lower fixing plate, and the upper fixing plate, the lower fixing plate and the outer cavity wall form a closed cavity, namely an outer cavity; an external cavity heat conduction device is arranged in the external cavity, and the external cavity heat conduction device form an external switch;

the inner cavity wall is arranged between the upper fixing plate and the lower fixing plate, and forms a closed cavity, namely an inner cavity, and is arranged inside the outer cavity wall; an internal cavity heat conduction device is arranged in the internal cavity, and the internal cavity heat conduction device form an internal switch; the adsorption pump device is communicated with the inner cavity;

the interiors of the outer chamber and the inner chamber are filled with heat conducting gas; the adsorption pump device is internally provided with an adsorption material;

when the extremely low temperature equipment is at room temperature, the heat conducting gas is in a gaseous state, and at the moment, the states of the inner switch and the outer switch are both in an on state, namely a heat conducting state;

when the temperature of the extremely low temperature equipment is gradually reduced, the temperature in the outer cavity reaches a first preset value, the heat conducting gas in the outer cavity is liquefied, the air pressure in the outer cavity is reduced, the heat conducting capacity is reduced, and the outer switch is in an off state, namely a non-heat conducting state; the adsorption pump device heats the adsorption material, so that the adsorption material does not adsorb the heat-conducting gas in the internal cavity, and the internal switch is still in an on state, namely in a heat-conducting state;

when the temperature of the extremely low temperature equipment is gradually reduced and reaches a second preset value range, the adsorption pump device stops heating, and simultaneously the adsorption pump device adsorbs the heat-conducting gas in the inner cavity, so that the inner cavity is vacuumized, the air pressure is reduced, the heat-conducting capacity is reduced, and the inner switch is in an off state, namely a non-heat-conducting state; at this time, the inner switch and the outer switch of the two-cavity type heat conduction switch are both in an off state.

According to the technical scheme of the first aspect of the invention, the internal cavity heat conduction device comprises an upper heat conduction blade and a lower heat conduction blade, wherein the upper heat conduction blade is connected with the upper fixing plate, the lower heat conduction blade is connected with the lower fixing plate, and a gap of 50-1000um is arranged between the upper heat conduction blade and the lower heat conduction blade.

According to the technical scheme of the first aspect of the invention, the external cavity heat conduction device comprises an external cavity upper heat conduction wall and an external cavity lower heat conduction wall, wherein the external cavity upper heat conduction wall is connected with the upper fixing plate, the external cavity lower heat conduction wall is connected with the lower fixing plate, and a gap of 50-1000um is arranged between the external cavity upper heat conduction wall and the external cavity lower heat conduction wall.

According to the technical scheme of the first aspect of the invention, the lower heat conducting wall of the outer chamber and the upper heat conducting wall of the outer chamber are of circular tube structures, and the diameter of the lower heat conducting wall of the outer chamber is larger than that of the upper heat conducting wall of the outer chamber.

According to the technical scheme of the first aspect of the invention, the two-cavity type heat conduction switch comprises an adsorption material, an adsorption pump, a heating copper block, a thermometer, a heating wire and a signal connector, wherein one end of the adsorption pump penetrates through the outer cavity wall and the inner cavity wall to be communicated with the inner cavity, the adsorption material and the heating copper block are arranged in the adsorption pump, the heating wire and the thermometer are arranged in the heating copper block, and the heating wire and the thermometer are connected with the signal connector;

when the temperature of the very low temperature equipment reaches the temperature of liquefying the heat-conducting gas in the outer chamber, controlling the heating wire to heat through the signal connector, controlling the temperature of the heating copper block within a third preset value range, and enabling the adsorption material to be in a state of not adsorbing the heat-conducting gas, wherein the heat-conducting gas in the inner chamber can exchange heat;

when the temperature of the extremely low temperature equipment reaches a fourth preset value range, the heating wire is controlled to stop through the signal connector, the adsorption pump adsorbs the heat conduction gas in the inner cavity through the adsorption material, so that the inner switch is turned into an off state, namely a non-heat conduction state, and at the moment, the whole two-cavity type heat conduction switch is turned into an off state.

According to a first aspect of the present invention, the two-chamber heat transfer switch for a cryogenic device further comprises an internal chamber valve in communication with the internal chamber through the outer and inner chamber walls.

According to the first aspect of the invention, the two-chamber heat conduction switch for a cryogenic device further comprises an internal chamber valve, wherein the internal chamber valve is communicated with the internal chamber through the upper fixing plate or the lower fixing plate.

According to the first aspect of the invention, the two-chamber heat conduction switch for a very low temperature apparatus further comprises an external chamber valve, and the external chamber valve is communicated with the external chamber through the external chamber wall or the upper or lower fixing plate.

According to the technical scheme of the first aspect of the invention, the heat conduction gas in the outer chamber is nitrogen; the heat conducting gas filled in the inner chamber is inert gas.

According to the technical solution of the first aspect of the present invention, the outer chamber and the inner chamber are filled with a heat conducting gas.

According to a second aspect of the present invention, there is provided a very low temperature device in which the two-chamber type heat conduction switch for a very low temperature device of the first aspect of the present invention is provided.

According to the embodiment disclosed by the invention, the following beneficial effects are achieved:

through combining active thermal switch and passive thermal switch, combine the thermal switch of two different temperature intervals, can reach the different thermal conductance effect in high temperature region and low temperature region, obtain higher thermal conductance efficiency in high temperature region, be favorable to the low temperature system to cool down more fast in high temperature region.

Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

FIG. 1 is a schematic diagram of a two-chamber thermal conduction switch for a very low temperature device according to an embodiment;

fig. 2 is a schematic diagram of a two-chamber thermal conduction switch for a very low temperature device, according to an embodiment.

The figures are marked as follows:

the device comprises a 1-upper fixing plate, a 2-upper fixing threaded hole, a 3-outer cavity wall, a 4-adsorbing material, a 5-adsorbing pump, a 6-heating copper block, a 7-thermometer, an 8-heating wire, a 9-signal connector, a 10-outer cavity, an 11-inner cavity, a 12-lower fixing plate, a 13-outer cavity lower heat conducting wall, a 14-lower heat conducting blade, a 15-outer cavity valve, a 16-outer cavity upper heat conducting wall, a 17-inner cavity valve, a 18-upper heat conducting blade, a 19-inner cavity wall and a 20-lower fixing threaded hole.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.

The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.

The existing gas gap type thermal switch of the active control switch has the problems of large volume and easy damage. Because the open-loop gas gap switch requires a pump stack at room temperature, the internal gases during pumping and deflation need to enter a gas circulation system. For closed thermal switches, it is classified into passive control switches and active control switches.

The passive control air gap type thermal switch is mainly characterized in that working gas is filled into the air gap type thermal switch, the gas is used as a transmission medium, the gas is in a gaseous state when the temperature is high, the thermal switch is in an on state, after the temperature is reduced to a certain value, the gas is liquefied, the thermal conductivity is reduced, and the thermal switch is in an off state. Therefore, the switch temperature of the passive control switch is certain, and the active control requirement cannot be met, but the passive control switch has the advantages of simple structure and convenient installation, and is suitable for commercialized and miniaturized equipment. The use demands of the existing very low temperature equipment are gradually increased, and active control demands are met for the thermal switch.

The active control air gap type closed thermal switch mainly uses an adsorption pump taking active carbon and the like as raw materials as a gas adsorption device, and when the switch state is required to be on, the adsorption pump is heated to release the gas adsorbed by the adsorption pump, so that the gas enters the thermal switch to conduct heat. Because the heated sorption pump is a relatively large heat source, the sorption pump is typically placed in a higher temperature area, or suspended in a vacuum environment using an airway support that communicates with the thermal switch cavity, or directly placed at room temperature outside the vacuum apparatus, which can result in increased apparatus volume. Meanwhile, as the device is arranged in the vacuum cavity of the very low temperature device, the complicated and long air pipe connecting structure can increase the air leakage risk of the vacuum system, and even the loss of heat transfer medium gas can be caused, so that the stability of the system is affected.

In order to meet the requirements of miniaturization, convenience and stability of an active control air gap type closed thermal switch, the invention realizes the exquisite air gap type thermal switch combining an extremely low temperature active control type with a passive control type through a smart design structure.

Embodiment one:

the present embodiment provides a two-chamber type heat conduction switch (hereinafter referred to as a thermal switch) for a very low temperature device, wherein in the field of low temperature devices, the very low temperature device can provide a temperature range of 1K or less, as shown in fig. 1, comprising: an upper fixing plate 1, a lower fixing plate 12, an outer cavity wall 3 and an inner cavity wall 19;

the outer cavity wall 3 is arranged between the upper fixing plate 1 and the lower fixing plate 12, and forms a closed cavity, namely an outer cavity 10; an external chamber heat conduction device is arranged in the external chamber 10, and the external chamber heat conduction device form an external switch;

the inner cavity wall 19 is arranged between the upper fixing plate 1 and the lower fixing plate 12, and forms a closed cavity, namely an inner cavity 11, and the inner cavity wall 19 is arranged inside the outer cavity wall 3; an internal chamber heat conduction device is arranged in the internal chamber 11, and the internal chamber heat conduction device form an internal switch; the interiors of the outer chamber and the inner chamber are filled with heat conducting gas; the adsorption pump device is internally provided with an adsorption material.

In some embodiments, the inner chamber wall 19 and the outer chamber wall 3 are each cylindrical stainless steel tubes and welded to the upper and lower fixing plates 1, 3.

The internal cavity heat conduction device comprises an upper heat conduction blade 18 and a lower heat conduction blade 14, wherein the upper heat conduction blade 18 is connected with the upper fixing plate 1, the lower heat conduction blade 14 is connected with the lower fixing plate 12, a gap of 50-1000um is arranged between the upper heat conduction blade 18 and the lower heat conduction blade 14, the upper heat conduction blade 18 and the lower heat conduction blade 14 are not contacted with each other, the gap is more preferably 50-200um, the gap is more compact in structure, the effect is better, the gap is too small, the processing difficulty is high, the cost is high, the installation is difficult, the gap is too large, the heat conductivity is poor, the structure is not compact, and the volume is huge.

According to the above scheme, further, the upper fixing plate 1, the lower fixing plate 12 and the internal chamber heat conduction device are all made of copper materials, the three heat conduction devices can be connected in a welded mode, the air tightness is good, specifically, the upper heat conduction blade 18 and the lower heat conduction blade 14 are made of copper materials, in fig. 1, the internal chamber heat conduction device is a triangular wedge scheme, a parallel blade scheme or a ring-shaped tubular scheme like the external cavity wall 3, the core points are that the heat transfer surfaces of the upper heat conduction blade and the lower heat conduction blade are not contacted, but the gap is small enough, the larger the relative area is, the better, the smaller the spare gas space of the whole cavity is, and the better the smaller the spare gas space of the whole cavity is.

Specifically, the heat conducting device for the inner chamber comprises an upper heat conducting wall 16 of the outer chamber and a lower heat conducting wall 13 of the outer chamber, wherein the upper heat conducting wall 16 of the outer chamber is connected with the upper fixing plate 1, the lower heat conducting wall 13 of the outer chamber is connected with the lower fixing plate 12, a gap of 50-1000um is arranged between the upper heat conducting wall 16 of the outer chamber and the lower heat conducting wall 13 of the outer chamber, wherein the gap is more preferably 50-200um, the structure of the gap is more compact, the effect is better, the gap is smaller, the processing difficulty is high, the cost is high, the installation is not easy, the gap is too large, the heat conductivity is poor, the structure is not compact, and the volume is huge.

In some embodiments, the lower heat conducting wall 13 of the outer chamber and the upper heat conducting wall 16 of the outer chamber are both in a circular tube structure, may be specifically stainless steel tubes, are connected with the middle of the upper fixing plate 1 and the lower fixing plate 12 in a welding manner, have relatively good heat conductivity, ensure the air tightness of the cavity, and have a certain gap, and the diameter of the lower heat conducting wall 13 of the outer chamber is larger than that of the upper heat conducting wall 16 of the outer chamber, so that the lower heat conducting wall 13 of the outer chamber and the upper heat conducting wall are not in direct contact.

Preferably, the two-cavity type heat conduction switch for the very low temperature equipment further comprises an adsorption pump device, the adsorption pump device comprises an adsorption material 4, an adsorption pump shell 5, a heating copper block 6, a thermometer 7, a heating wire 8 and a signal connector 9, one end of the adsorption pump shell 5 penetrates through the outer cavity wall 3 and the inner cavity wall 19 to be communicated with the inner cavity 11, the adsorption pump 5 is provided with the adsorption material 4 and the heating copper block 6, the heating copper block 6 is provided with the heating wire 8 and the thermometer 7, and the heating wire and the thermometer are connected with the signal connector 9 to facilitate signal connection.

In some embodiments, the two-chamber thermally conductive switch for a cryogenic apparatus further comprises an internal chamber valve 17, the internal chamber valve 17 communicating with the internal chamber 11 through the outer chamber wall 3 and the inner chamber wall 19, as depicted in fig. 1.

Of course, in other embodiments, the internal chamber valve 17 is arranged in other ways, as shown in fig. 2, and the two-chamber type heat conduction switch for a cryogenic apparatus further includes an internal chamber valve 17, where the internal chamber valve 17 communicates with the internal chamber 11 through the upper fixing plate 1 or the lower fixing plate 12.

In some embodiments, the interior chamber 11 is evacuated, drained and filled with helium through the interior chamber valve 17.

The two-chamber type heat conduction switch for the very low temperature equipment further comprises an external chamber valve 15, wherein the external chamber valve 15 passes through the external chamber wall 3 or the upper fixing plate 1 or the lower fixing plate 12 to be communicated with the external chamber 10, and the external chamber is vacuumized, leaked and inflated.

In some embodiments, the outer chamber 10 and the inner chamber 11 are filled with a heat-conducting gas, preferably, the outer chamber 10 is filled with nitrogen, and the inner chamber 11 is filled with an inert gas, specifically, argon, helium, or neon, wherein helium is the most preferred choice.

The upper fixing plate 1 and the lower fixing plate 12 are respectively provided with an upper fixing threaded hole 2 and a lower fixing threaded hole 20, which are used for fixing the thermal switch on an upper cold plate and a lower cold plate of the very low temperature equipment, so that the upper fixing plate and the lower fixing plate of the thermal switch are in good thermal contact with the upper cold plate and the lower cold plate of the equipment, and when the thermal switch is in an on state, heat of a lower structure of the equipment can be transferred to the upper part at a faster speed, thereby achieving the effect of improving the cooling speed.

According to the above scheme, further, be provided with upper fixing screw hole 2 on upper portion fixed plate 12, be provided with lower fixing screw hole 20 on lower part fixed plate 12 for fix the hot switch on two cold plates about the very low temperature equipment, make the upper portion fixed plate 12 of hot switch, lower part fixed plate 12 and two cold plates about the equipment have fine thermal contact, when the hot switch is the state of opening like this, can transmit the heat of equipment lower part structure to upper portion with faster speed to reach the effect that improves the cooling rate.

when the temperature of the extremely low temperature equipment is gradually reduced and reaches a second preset value range, the adsorption pump device stops heating, and simultaneously the adsorption pump device adsorbs the heat-conducting gas in the inner cavity, so that the inner cavity is vacuumized, the air pressure is reduced, the heat-conducting capacity is reduced, and the inner switch is in an off state, namely a non-heat-conducting state; at this time, the heat conduction is accomplished to two cavity formula heat conduction switches, the interior switch of two cavity formula heat conduction switches and outer switch all are in the state of closing.

According to the scheme of the previous step, when the temperature of the very low temperature equipment reaches the temperature of the liquefaction of the heat conduction gas in the outer chamber, the heating wire is controlled to heat through the signal connector, and the temperature of the heating copper block is controlled to be within a third preset value range, so that the adsorption material is in a state of not adsorbing the heat conduction gas, and the heat conduction gas in the inner chamber can exchange heat;

Wherein, two cavity formula heat conduction switch "on" state and "off" state specifically mean: the "on" state is a state of good heat conduction, and the "off" state is a state of poor heat conduction; the two-cavity type heat conduction switch is essentially a heat conduction switch, namely a switch for controlling heat conduction.

According to the two-chamber type heat conduction switch for very low temperature equipment, in some embodiments, the working principle and working procedure of more specific application are as follows:

1. when the whole system of the extremely low temperature equipment is cooled, the system of the whole extremely low temperature equipment is at room temperature, the inner switch and the outer switch of the thermal switch are in the open state, namely in the heat conduction state, the heat conduction gas arranged in the outer cavity is nitrogen, the heat conduction gas arranged in the inner cavity is helium, the whole system of the extremely low temperature equipment is operated, cooling is started, the cold head of the extremely low temperature equipment takes away the heat at the upper part of the system, the temperature is reduced, and the heat at the lower part of the extremely low temperature equipment is conducted to the upper part through the thermal switch due to the existence of the temperature gradient.

2. When the temperature of the copper plate of the upper fixing plate 1 reaches the liquid nitrogen temperature, namely the first preset temperature, the first preset temperature is generally the liquefaction temperature of the heat conducting gas in the outer chamber, nitrogen in the outer chamber 10 is liquefied and settled at the upper part, the lower temperature in the outer chamber 10 is also above the liquid nitrogen temperature, and when the liquid nitrogen is settled to the lower part and then absorbs heat and evaporates, the liquid nitrogen enters the upper fixing plate 1, and the heat of the copper plate of the lower fixing plate 12 is brought to the copper plate of the upper fixing plate 1 in a reciprocating manner, so that good heat transfer is formed. Until the temperature of the copper plate of the lower fixing plate 12 reaches below the liquid nitrogen temperature, the vapor pressure of the liquid nitrogen in the outer chamber 10 is reduced, the heat conduction is reduced, the partial pressure of the gas in the chamber after liquefaction is reduced, the gas between the upper and lower heat conducting plates is reduced, the heat conduction is deteriorated due to the reduction of the gas molecules, and at this time, the outer switch of the thermal switch is in the off state.

3. At this time, the thermal switch of the inner chamber 11 is still in an on state, but since the temperature of the whole system of the very low temperature equipment has reached the liquid nitrogen temperature, the heating wire is controlled to start heating by the signal connector, the temperature of the heating copper block is controlled to be about 70K, namely, the third preset value range can be 60-80K, so that the activated carbon adsorbent is not in an adsorption state, the inner chamber 11 has enough helium gas as heat exchange gas, at this time, the heat of the lower fixing plate 12 and the lower system is transferred to the lower heat conducting blade 14 through contact heat transfer, the heat of the lower heat conducting blade 14 is transferred to the helium gas of the inner chamber 11, the helium gas transfers the heat to the upper heat conducting blade 18, and the heat is transferred to the whole system of the very low temperature equipment through contact heat transfer.

4. When the temperature of the lower part of the entire system of the very low temperature apparatus reaches the design temperature, for example: the very low temperature equipment is a very low temperature dilution refrigerator, the lower temperature reaches a temperature area of 5-10K, namely, a fourth preset value range is 5-10K, the heating wire can be turned off, the heating wire is stopped to heat, the temperature of the adsorption pump is gradually reduced, the adsorption material can generally enable active carbon, the active carbon can gradually adsorb helium in the inner cavity 11 when the temperature of the adsorption pump is reduced, the state of the thermal switch of the inner cavity 11 is changed into an off state, so that the state of the whole thermal switch is changed into an off state, the adsorption pump adsorbs heat conducting gas in the inner cavity through the adsorption material and enables the inner cavity to be changed into a vacuum state, so that the inner switch is changed into an off state, namely, a non-heat conducting state, and at the moment, the whole two-cavity type thermal conduction switch is changed into the off state. The next mode and state of operation can be entered for very low temperature equipment.

According to the design of the two-cavity type heat conduction switch for the extremely low-temperature equipment, the active heat switch and the passive heat switch are combined, and the heat switches in two different temperature ranges are combined, so that different heat conduction effects in a high-temperature region and a low-temperature region can be achieved, higher heat conduction efficiency is obtained in the high-temperature region, and the low-temperature system can be cooled more quickly in the high-temperature region.

The invention innovatively proposes a form that the vacuum adsorption pump is closely attached to the thermal switch, rather than a form that the vacuum adsorption pump is connected through a relatively easy-to-damage air pipe, so that the vacuum adsorption pump is not easy to collide and damage, and the system stability can be improved. The advantages are met, meanwhile, as the passive thermal switch is arranged outside the active thermal switch, when the temperature is lower than the liquid nitrogen temperature and the passive thermal switch is in a closed state, the outer chamber is equivalent to a vacuum heat preservation layer, and the direct contact heat transfer between the activated carbon adsorption pump and the refrigerating cavity of the inner chamber can be reduced. At the same time, thinner stainless steel materials are used as the cylinder structures of the inner chamber and the outer chamber, so that the heat of the activated carbon adsorption pump is transmitted to the copper plate as little as possible in the heating state, and meanwhile, the heat leakage between the upper fixing plate 1 and the lower fixing plate 12 in the closing state of the thermal switch is reduced, and the on-off ratio of the thermal switch is improved.

Embodiment two:

the present embodiment provides an extremely low temperature apparatus in which the two-chamber type heat conduction switch for an extremely low temperature apparatus according to any one of embodiment 1 is provided.

In summary, the invention provides a two-cavity type heat conduction switch for very low temperature equipment, which combines an active heat switch and a passive heat switch to achieve the effect of two-stage cooling. The main characteristic of the thermal switch is that the thermal switch is mainly provided with a double-layer cavity structure, and two different working mediums are respectively used in the two cavities: such as helium and nitrogen, so that the thermal switch can have two switching points. In the cooling process of the extremely low temperature equipment, in order to enable the nitrogen in the outer cavity to have higher heat conductivity in the high temperature area, the thermal switch is in an on state, after the nitrogen liquefying temperature is reached, the nitrogen in the outer thermal switch cavity is liquefied, the thermal switch is disconnected, the vacuum state is kept in the cavity, and a vacuum layer is formed, wherein the vacuum layer can reduce heat transfer of the activated carbon adsorption pump to the inner thermal switch cavity. The internal thermal switch is an active thermal switch and is connected to an external activated carbon adsorption pump through a thin tube via an outer vacuum layer. The active carbon adsorption pump is provided with a heating wire and a thermometer, helium in the active carbon is released by heating the heating wire, and the helium is not adsorbed by heating, so that the aim of controlling the on-off of the inner side thermal switch is fulfilled.

While certain specific embodiments of the invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A two-chamber thermally conductive switch for use in cryogenic equipment, comprising: an upper fixing plate, a lower fixing plate, an outer cavity wall, an inner cavity wall and an adsorption pump device;

2. The two-chamber thermal conduction switch for cryogenic equipment of claim 1, wherein the internal chamber thermal conduction means comprises an upper thermal conduction blade and a lower thermal conduction blade, the upper thermal conduction blade being connected to the upper fixed plate, the lower thermal conduction blade being connected to the lower fixed plate, a gap of 50-1000um being provided between the upper thermal conduction blade and the lower thermal conduction blade.

3. The two-chamber thermal conduction switch for cryogenic equipment of claim 2, wherein the external chamber thermal conduction means comprises an external chamber upper thermal conduction wall and an external chamber lower thermal conduction wall, the external chamber upper thermal conduction wall being connected to the upper fixed plate, the external chamber lower thermal conduction wall being connected to the lower fixed plate, a gap of 50-1000um being provided between the external chamber upper thermal conduction wall and the external chamber lower thermal conduction wall.

4. A two-chamber thermal conduction switch for cryogenic equipment according to claim 3, wherein the outer chamber lower thermal conduction wall and the outer chamber upper thermal conduction wall are both circular tube structures and the outer chamber lower thermal conduction wall is larger in diameter than the outer chamber upper thermal conduction wall.

5. A two-chamber thermal conduction switch for cryogenic equipment according to claim 3, characterized in that the sorption pump means comprises a sorption pump, a heating copper block, a thermometer, a heating wire and a signal connector, one end of the sorption pump communicating with the internal chamber through the outer and inner chamber walls, the heating copper block being arranged in the sorption pump, the heating copper block having a heating wire and a thermometer arranged therein, the heating wire and thermometer being connected with the signal connector;

6. The two-chamber thermally conductive switch for a cryogenic apparatus of claim 1, further comprising an internal chamber valve in communication with the internal chamber through the outer and inner chamber walls.

7. The two-chamber thermally conductive switch for a cryogenic apparatus of claim 1, further comprising an internal chamber valve in communication with the internal chamber through either the upper or lower fixed plate.

8. The two-chamber thermally conductive switch for a cryogenic apparatus of claim 1, further comprising an external chamber valve in communication with an external chamber through the external chamber wall or upper or lower fixed plate.

9. The two-chamber thermally conductive switch for cryogenic equipment of claim 1, wherein the thermally conductive gas inside the external chamber is nitrogen; the heat conducting gas filled in the inner chamber is inert gas.

10. A very low temperature apparatus, characterized in that a two-chamber type heat conduction switch for a very low temperature apparatus as claimed in any one of claims 1 to 9 is provided in the very low temperature apparatus.