JPH06123504A - Cryogenic refrigerator - Google Patents

Abstract

(57) [Abstract] [Purpose] Liquefied refrigerant storage tank (1) and refrigerator (6)
And the refrigerant gas evaporated in the tank (1) is supplied to the refrigerant circuit of the refrigerator (6) via the pipe (29) to be re-condensed, and the liquefied refrigerant is supplied via the pipe (28). In a cryogenic refrigerating device which is returned to the inside of the tank (1), the tank (1) is connected and separated between the tank side and the refrigerator side pipes (30) and (32) that are divided outside the tank (1).
The surrounding wall portion is not destroyed, and the refrigerator (6) can be inspected and repaired easily and at low cost. [Structure] The tank side pipe (3
0) and the freezer side pipes (32) can be pulled out, while both pipes (30) are reduced by cooling and cooling.
A joint (34) made of a shape memory alloy having a characteristic of holding (32) and a heater (37) for heating the joint (34) are provided to control power supply to the heater (37).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic system in which a refrigerant gas evaporated in a refrigerant tank for storing liquefied refrigerant is sucked into a refrigerant circuit of a refrigerator, liquefied by compression and expansion, and returned to the tank. The present invention relates to a refrigerating device, and more particularly, to a refrigerating device that can be separated from a tank.

[0002]

2. Description of the Related Art Recently, the use of superconducting magnets has attracted attention. In this superconducting magnet, liquid helium stored in the tank is used to cool and keep the superconductor used for the coil at a critical temperature, but since this liquid helium evaporates in the tank, this evaporated helium gas Must be cooled and condensed to be liquefied, and a cryogenic refrigerator is used for this purpose.

As an example of a refrigerator for cooling the helium gas to a condensing temperature, there is a conventional one, for example, US Pat. No. 4,223.
No. 540, etc., a pre-cooling refrigerator and a J-
There is a refrigerator combined with a T refrigerator. The above pre-cooling refrigerator is a GM cycle (Gifford McMahon cycle)
And a refrigerating machine such as an improved solve cycle. The helium gas (refrigerant gas) compressed by the compressor is adiabatically expanded by the expander, and the temperature drop of the gas causes the cryogenic cold level at the heat station. .

On the other hand, the JT refrigerator has a precooler for precooling by exchanging heat between the helium gas supplied from the compressor and the heat station of the expander in the precooling refrigerator, and the helium gas in a joule. Thomson inflates J-
A T-valve is connected to a closed circuit, and helium gas from the compressor is pre-cooled by a pre-cooler, and the pre-cooled helium gas is expanded by Joule-Thomson with a J-T valve to achieve 4K level cooling. Is generated.

When the evaporated helium gas in the tank is cooled by a refrigerator, conventionally, two refrigerant pipes are arranged in the tank so that one end of each refrigerant pipe opens in the tank, and both pipes are connected. By pulling the end out of the tank and connecting it in series with the refrigerant circuit of the J-T refrigerator, the inside of the tank becomes a part of the refrigerant circuit of the refrigerator, and the evaporated helium gas in the tank is J- While sucked into the refrigerant circuit of the T refrigerator and compressed by the compressor, the compressed helium gas is expanded by the JT valve to be cooled and liquefied, and this liquid helium is returned to the tank through the other pipe. It is done like this.

[0006]

However, in the conventional connection structure for the tank and the refrigerator, the two pipes are divided into the tank side pipe and the refrigerator side pipe outside the tank, respectively.
Both pipes are integrally connected by welding. For this reason, when removing the refrigerator from the tank for maintenance or trouble, it is necessary to disconnect each pipe from the welded part between the tank side and the refrigerator side pipes, and this disconnection work and re-welding work at the time of subsequent assembly Therefore, it is necessary to disassemble the radiation shield around the tank and the outer wall member for supporting the refrigerator on the outside of the refrigerator each time the refrigerator is removed, and there is a problem that the work is troublesome and the cost is high.

The present invention has been made in view of the above points, and an object of the present invention is to improve the connection structure between the tank side and the refrigerator side pipes divided outside the tank, thereby connecting the both pipes. The purpose of the present invention is to enable the separation to be performed without destroying the wall portion around the tank, and to facilitate the inspection and repair work of the refrigerator at low cost.

[0008]

In order to achieve the above-mentioned object, in the invention of claim 1, the pipe ends on the refrigerator side and the tank side can be withdrawn by expanding by heating and raising the temperature. In addition to providing a shape memory alloy joint that has the characteristic of shrinking by cooling and cooling and connecting and holding both pipes,
A heating means for heating the joint was provided, and the power supply to the heating means was controlled.

Specifically, according to the present invention, as shown in FIG. 1, a tank (1) for storing a cryogenic liquid refrigerant.
And a part of the refrigerant circuit, which is detachably attached to the tank (1), has a liquid refrigerant pipe (28) and a gas refrigerant pipe (29).
And a refrigerator (6) opened in the tank (1) via the gas refrigerant pipe (29) to suck the gas refrigerant evaporated in the tank (1) into the refrigerator (6). It is premised on a cryogenic refrigeration system that is compressed and expanded, and a liquid refrigerant is generated by the temperature drop due to the expansion and returned to the inside of the tank (1) through the liquid refrigerant pipe (28).

The liquid and gas refrigerant pipes (2
Each of 8) and (29) is divided into a tank side pipe (30) and a refrigerator side pipe (32) outside the tank (1).

Further, the tip ends of the tank side pipe (30) and the refrigerator side pipe (32) are fitted in the fitting hole (35) in a butted state so that the tank side pipe (30) and the refrigerator side are connected. A cylindrical joint (34) that detachably connects to the pipe (32) is provided, and the joint (34) is connected to the tank side pipe (30) and the refrigerator side pipe (32) from the fitting hole (35) due to temperature rise. ), While each tip end is detachably expanded, the tank side pipe (30) is inserted into the fitting hole (35) due to temperature decrease.
And the tip end of the refrigerator side pipe (32) is made of a shape memory alloy that can be contracted in a sealed state.

Further, heating means (37) for heating the joint (34) and power feeding means (38) for feeding power to the heating means (37) are provided.

In the invention of claim 2, the joint (3
4) is locked and fixed to the tip of the refrigerator side pipe (32) with the tip of the refrigerator side pipe (32) fitted in a part of the fitting hole (35).

According to the invention of claim 3, the joint (3
A coating layer (36) made of a soft metal such as copper is formed on the inner surface of the fitting hole (35) of 4), while the tank side pipe (30) and the refrigerator side pipe (32) are respectively provided on the outer peripheries of the respective tip portions. Cylindrical seal members (31) and (33) which can be fitted into the fitting hole (35) of the joint (34) are attached, and the joint (34) is attached to the outer periphery of the seal members (31) and (33). At least one sealing ridge (31a), (33a) is provided, which comes into contact with the coating layer (36) of the fitting hole (35) at the time of reduction.

In the invention of claim 4, the heating means (3
7) is a band heater wound around the outer periphery of the joint (34).

In the invention of claim 5, the joint (34)
Specifically, the shape memory alloy constituting the above is a nickel-titanium shape memory alloy.

[0017]

With the above structure, in the invention of claim 1, since the joint (34) is made of a shape memory alloy,
With the tip ends of the tank-side pipe (30) and the refrigerator-side pipe (32) fitted in the fitting holes (35) in a butt state, the joint (34) is formed by cooling the liquefied refrigerant in the tank (1). ) Is cooled, the joint (34) is contracted to fasten the tip ends of the tank side pipe (30) and the refrigerator side pipe (32) to the fitting hole (35) in a sealed state. Then, the tank side piping (30) and the refrigerator side piping (3
2) and are connected so that the refrigerant can flow.

On the other hand, when the pipes (30) and (32) are separated from each other in order to remove the refrigerator (6) for inspection or repair, the heating means (3) is supplied by the power supply means (38).
7) is fed to heat the joint (34) to raise its temperature.
With this temperature rise, the joint (34) expands and the fitting hole (35) has a large diameter, and the tip of each of the tank side pipe (30) and the refrigerator side pipe (32) extends from the fitting hole (35). The portion can be pulled out, and in this state, the connections of both pipes (30) and (32) may be separated.

Further, after that, when the pipes (30) and (32) are connected to each other for reattaching the refrigerator (6), the fitting hole (35) of the joint (34) is connected in the same manner as above. If the tip ends of both pipes (30) and (32) are fitted, the joint (34) is cooled and reduced by the cooling of the liquefied refrigerant in the tank (1), and both pipes are fitted into the fitting hole (35). The tip ends of (30) and (32) are fastened in a sealed state.

In this way, the tank side and refrigerator side pipes (30) and (32) are connected and separated from each other by the tank (1).
This can be done without breaking the surrounding wall parts, and the inspection and repair work of the refrigerator (6) can be performed easily and at low cost.

In the invention of claim 2, the joint (34)
Is fixed to the tip of the refrigerator side pipe (32), the joint (34) is always connected to the refrigerator side pipe (3).
2) or the refrigerator (6) can be handled integrally. Therefore, the joint (34) does not fall off when the refrigerator is removed or assembled, and both pipes (30), (3
The connection and disconnection of 2) can be easily performed, and the joint (34) is removed every time the refrigerator (6) is removed.
It is also possible to integrally remove and inspect and repair it. Moreover, since the joint (34) is provided at the tip of the refrigerator side pipe (32), the refrigerator (6)
At the time of removal, the joint (34) may be easily replaced with a new one, and the sealing effect of the joint (34) can be stably obtained.

In the invention of claim 3, the tank side pipe (3
0) and the refrigerator side pipe (32) are connected, both pipes (3
The cylindrical seal members (31) and (33) attached to the outer peripheries of the respective tip portions of (0) and (32) are fitted in the fitting holes (35) of the joint (34). In this state, when the joint (34) shrinks due to cold, the sealing ridges (31) around the seal members (31), (33)
a) and (33a) are fitting holes (3) of the joint (34).
5) The coating layer (36) made of a soft metal on the inner surface bites into and adheres to the coating layer (36), so that the coating layer (36) deforms so as to adhere to the outer periphery of the seal members (31) and (33). The sealing property of can be improved.

In the invention of claim 4, since the heating means (37) is a band heater wound around the outer periphery of the joint (34), the heating means (37) suitable for heating the joint (34) is specifically described. Easily obtained.

In the invention of claim 5, the joint (34)
Since the shape memory alloy constituting the is a nickel-titanium shape memory alloy, it is expanded by heating by the heating means (37),
A shape memory alloy having a function of being reduced by cooling can be specifically and easily obtained.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows the entire structure of a cryogenic refrigerating apparatus according to an embodiment of the present invention. This refrigerating apparatus is for cooling a superconducting coil of a superconducting magnet, and a helium tank (1) (which stores liquefied liquid helium (1) ( Dewar) and a refrigerator (6) attached to the helium tank (1), and a superconducting coil (Cs) is immersed in the helium tank (1) and stored therein with liquid helium. The superconducting coil (Cs) is cooled and held below the critical temperature by helium. A radiation shield (2) is arranged around the helium tank (1) with a space, and an outer wall member (3) is arranged outside the radiation shield (2) with a space. On the upper side of the tank (1), the distance between the tank (1) and the radiation shield (2) and the distance between the radiation shield (2) and the outer wall member (3) are made larger than the other portions, respectively, and this distance is large. An opening (4) is formed in the outer wall member (3) on the side, and the refrigerator (6) is fitted from the outside of the outer wall member (3) through the opening (4). In the operating state, the tank (1) and the outer wall member (3)
A vacuum state is maintained between and.

On the other hand, the refrigerator (6) is composed of a combination of a pre-cooling refrigerator (7) and a JT refrigerator (16) as shown in FIG. The above pre-cooling refrigerator (7)
Is composed of a GM (Gifford McMahon) cycle refrigerator, and compresses and expands the helium gas in order to precool the helium gas (refrigerant gas) in the JT refrigerator (16). This refrigerator (7) comprises a pre-cooling compressor (not shown) and an expander (8) attached to the upper wall of the outer wall member (3) connected in a closed circuit. The expander (8) includes a closed cylindrical case (9) arranged outside the outer wall member (3), and a large and small two-stage structure cylinder (10) connected to the case (9). Have. A high-pressure gas inlet (11) connected to the discharge side of the pre-cooling compressor and a low-pressure gas outlet (12) connected to the suction side of the case (9) are opened. Meanwhile, the cylinder (1
No. 0) penetrates the upper wall of the outer wall member (3) and extends to the inside thereof, and the tip of the large diameter portion (10a) is cooled and held at a predetermined temperature level in the first heat station (13).
Further, the tip of the small diameter portion (10b) is formed in the second heat station (14) which is cooled and held at a temperature level lower than that of the first heat station (13). (15) is the large diameter part (10
a) A mounting flange integrally formed at the base end portion, which seals and closes the opening (4) of the outer wall member (3) from the outside in an airtight manner.

That is, although not shown here, in the cylinder (10), each heat station (1
Free-type displacers (replacers) that partition and form expansion spaces are reciprocally fitted at positions corresponding to 3) and 14). On the other hand, case (9) above
A rotary valve that opens and closes each time it rotates and a valve motor that drives the rotary valve are housed therein. The rotary valve supplies the helium gas flowing in from the high pressure gas inlet (11) to each expansion space in the cylinder (10) or discharges the helium gas expanded in each expansion space from the low pressure gas outlet (12). To switch to. Then, by opening and closing this rotary valve, the high-pressure helium gas is expanded by Simon in each expansion space in the cylinder (10), and a temperature drop due to the expansion causes a cryogenic level of cold to be generated. First and second heat stations (13), (1
Hold in 4). That is, in the pre-cooling refrigerator (7), the high-pressure helium gas discharged from the compressor is used for the expander (8).
The temperature of the heat stations (13) and (14) is lowered by adiabatic expansion of the expander (8),
A pre-cooler (22) described later in the J-T refrigerator (16),
(24) is pre-cooled, and the expanded low-pressure helium gas is returned to the compressor and re-compressed.
A radiation shield (2) around the helium tank (1) is supported by the first heat station (13) of the cylinder (10) so as to be able to transfer heat.

On the other hand, the JT refrigerator (16) has about 4
A refrigerator that compresses and expands helium gas in order to generate K-level cold, and a JT compressor (not shown) that compresses helium gas, and the compressed helium gas used by Joule Thomson. Expander to expand (17)
It has and. The expander (17) is provided integrally with the mounting flange (15) of the expander (8) of the pre-cooling refrigerator (7) (see FIGS. 1 and 2).
A third JT heat exchanger (18) to (20) is provided. The respective J-T heat exchangers (18) to (20) are for exchanging heat with each other between the helium gases passing through the primary side, and the primary side of the first J-T heat exchanger (18) is J −
It is connected to the discharge side of the T compressor. The primary side of each of the first and second JT heat exchangers (18) and (19) is an adsorber (21) for removing contamination, and an expander in the precooling refrigerator (7). The first precooler (2) arranged on the outer periphery of the first heat station (13) of (8)
2) is connected. Similarly, the second and third J
Each primary side of the -T heat exchangers (19), (20) is an adsorber (23), and a second precooler (24) arranged on the outer periphery of the second heat station (14) of the expander (8). Connected through. Further, the third JT heat exchanger (2
The primary side of (0) is a JT valve (26) that expands high-pressure helium gas by Joule-Thomson through an adsorber (25).
It is connected to the. The opening of the J-T valve (26) is adjusted from the outside of the outer wall member (3) by the operation rod (26a). As shown in FIG. 2, the JT valve (26) is connected to the helium tank (1) through a liquid helium return pipe (28) as a liquid refrigerant pipe made of a stainless steel pipe. In addition, the inside of the helium tank (1) is connected to the above-mentioned third J- via a helium gas suction pipe (29) as a gas refrigerant pipe made of the same stainless steel pipe.
It is connected to the secondary side of the T heat exchanger (20). Then, the secondary side of the third J-T heat exchanger (20) passes through the secondary sides of the second and first J-T heat exchangers (19), (18), and then the suction of the J-T compressor. Connected to the side.

That is, in the JT refrigerator (16), a part of the refrigerant circuit is opened into the helium tank (1) through the liquid helium return pipe (28) and the helium gas suction pipe (29). Each of the third to first JT heat exchangers (20) to (18) of the expander (17) by sucking the helium gas evaporated in the tank (1) into the refrigerant circuit from the gas suction pipe (29). Intake compression through the secondary side into the JT compressor. In addition, the high-pressure helium gas compressed by the JT compressor is used for the first to the third J of the expander (17).
In the -T heat exchangers (18) to (20), heat is exchanged with the low-temperature and low-pressure helium gas toward the compressor side, and the expander (8) is respectively used in the first and second precoolers (22) and (24). ) First and second heat stations (1
After cooling by 3) and (14), the JT valve (26) expands it by Joule-Thomson to obtain liquid helium of about 4K, and this liquid helium is returned to the liquid helium return pipe (2).
It is designed to be returned to the tank (1) via 8).

As shown in FIG. 2, the liquid helium return pipe (28) and the helium gas suction pipe (29) are both outside of the helium tank (1) and are connected to the tank side pipe (30) and the refrigerator side pipe (30). 32) and 32).

That is, two tank-side pipes (30) and (30) are hung and supported side by side on the upper wall of the helium tank (1), and the lower end of each pipe (30) is It is opened in the tank (1) and the other end thereof penetrates the upper wall of the tank (1) on the refrigerator (6) side and extends to the outside thereof.
On the other hand, in the JT refrigerator (16), a pair of left and right refrigerator side pipes (32) and (32) are respectively provided on the tank side pipe (3).
It is provided so as to correspond to 0) and (30). The two refrigerator side pipes (32), (32) are respectively connected to the JT valve (26) of the JT refrigerator (16) and the secondary side of the third JT heat exchanger (20). All of them extend to the helium tank (1) side.

As shown in FIGS. 1 and 3, a cylindrical tank-side sealing member (31) is provided on the outer periphery of the tip of each tank-side pipe (30), and the tip of each refrigerator-side pipe (32). Refrigerator-side seal members (33) of the same shape are attached to the outer periphery of the parts in a hermetically sealed state by welding. These seal members (31) and (33) are joints (3
It is possible to fit in the fitting hole (35) of 4). Figure 3
As shown in the enlarged view in FIG. 3, a plurality of (5 in the figure) sealing projections (31) are provided on the outer periphery of the tank-side sealing member (31).
a), (31a), ... Also, the refrigerator side seal member (3
3), the same number of sealing ridges (33a), (33)
a), ... Are formed side by side with an interval in the center line direction. Each of these ridges (31a), (33a)
When the joint (34) is contracted, it digs into and adheres to the coating layer (36) of the fitting hole (35).

Tank side pipes (3) of the liquid helium return pipe (28) and the helium gas suction pipe (29)
0) and the refrigerator side pipe (32) are respectively locked to the refrigerator (6) side by locking means (not shown).
4) and (34) are separably connected. Each of the joints (34) has a cylindrical shape having a fitting hole (35), and the tank side pipe (3) is provided inside the fitting hole (35).
0) and each seal member (3) of the refrigerator side pipe (32)
The tank-side pipe (30) and the refrigerator-side pipe (32) are fitted by fitting 1) and (33) approximately half each from the center line direction.
To connect helium in a flowable manner. The liquid helium return pipe (28) and the helium gas suction pipe (29) are connected to each other by connecting the pipes (30) and (32) to each other at the joints (34).

In the joint (34), the seal members (31), (33) at the respective ends of the tank side pipe (30) and the refrigerator side pipe (32) can be removed from the fitting hole (35) by the temperature rise. On the other hand, the sealing members (31) and (33) are inserted into the fitting hole (35) by lowering the temperature below the Mf transformation point.
Is made of, for example, nickel-titanium shape memory alloy having a reversible shape memory effect or a two-way shape memory effect of shrinking in a sealable state. Further, a coating layer (36) made of a soft metal such as copper is formed on the inner surface of the fitting hole (35), and the coating layer (36) is on the tank side when the joint (34) is cooled and contracted. Piping (3
0) and the pipes (32) on the refrigerator side are deformed so as to come into close contact with the outer peripheries of the seal members (31), (33).

A band heater (37) as a heating means for heating the joint (34) is wound around the outer periphery of each joint (34). This heater (37)
A power supply means (38) for supplying power to the heater (37) is connected to the power supply terminal (38), which is mounted on the mounting flange (15) of the expander (8) of the pre-cooling refrigerator (7). 39).

Next, the operation of the above embodiment will be described. In the utilization state of the superconducting magnet, the superconducting coil (Cs) of the superconducting magnet is cooled and maintained below the critical temperature by the liquid helium in the helium tank (1). Also, two tank side pipes (30) and (30) and a refrigerator side pipe (3
2) and (32) are joints (34) and (3), respectively.
4) is connected (see FIG. 5) to form a continuous liquid helium return pipe (28) and a helium gas suction pipe (29), and the helium gas evaporated in the helium tank (1) is stored in the tank. The JT refrigerator (1) is sucked in from the helium gas suction pipe (29) opening in (1).
It is supplied to the refrigerant circuit of 6), where it is cooled and liquefied by compression and expansion. The liquid helium is returned to the tank (1) through the liquid helium return pipe (28). As a result, the liquid helium is stored in the tank (1) in a predetermined amount or more, and the superconducting coil (Cs) is stably cooled below the critical temperature.

The operation of the refrigerator (6) will be described in more detail. In the steady operation state, the pre-cooling refrigerator (7) is used.
The high-pressure helium gas supplied from the compressor in the above expands in each expansion space of the expander (8), and the temperature drop accompanying the expansion of this gas causes the first heat station (13) of the cylinder (10) to reach a predetermined temperature level. And the second heat station (14) is the first heat station (13)
Each is cooled to a lower temperature level. First above
With the cooling of the heat station (13), the temperature of the radiation shield (2) that is in contact with the heat station (7) so as to be able to transfer heat drops, which causes the inside of the helium tank (1) to be shielded from the outside. To be done.

On the other hand, at the same time, the JT refrigerator (1
In 6), the high-pressure helium gas discharged from the compressor enters the primary side of the first JT heat exchanger (18) and is heat-exchanged with the low-pressure helium gas on the secondary side toward the compressor side. It is cooled from room temperature 300K to about 50K, and then enters the first precooler (22) on the outer periphery of the first heat station (13) of the expander (8) and is further cooled. This cooled gas enters the primary side of the second J-T heat exchanger (19) and is cooled to about 15 K by heat exchange with the low pressure helium gas on the secondary side, and then expanded (8 ) Second
The second precooler (24) around the heat station (14)
It enters and is cooled further. After this, the gas is the third JT
It enters the primary side of the heat exchanger (20) and is further cooled by heat exchange with the low pressure helium gas on the secondary side.
To the T valve (26). In this JT valve (26), the high-pressure helium gas is throttled and expanded by Joule-Thomson into liquid helium of about 4K, and this liquid helium is passed through the liquid helium return pipe (28) to the tank (1). Is supplied to. Further, the helium gas evaporated in the tank (1) passes through the helium gas suction pipe (29) to the third J
It is sucked into the secondary side of the -T heat exchanger (20), sucked into the compressor via the secondary sides of the second and first J-T heat exchangers (19), (18), and compressed. It

When removing the refrigerator (6) from the outer wall member (3) for inspection or repair, the joint of the mounting flange (15) with the outer wall member (3) is removed. Also,
Before and after this, in order to disconnect the connection between the tank side pipe (30) and the refrigerator side pipe (32) in each of the liquid helium return pipe (28) and the helium gas suction pipe (29), the above-mentioned mounting flange ( 15) Power supply terminal (39)
A power source is connected to the heater (37) to supply power to the heater (37) through the power supply means (38), and the heat generated by the heater (37) heats and raises each joint (34) to, for example, about 100 ° C. Since each joint (34) is made of a shape memory alloy that has the characteristic of expanding when the temperature rises and contracting when the temperature falls, as shown in FIG. 4, the joint (34) expands as the temperature rises, and The fitting hole (35) has a large diameter, and the sealing members (31) and (33) at the respective tips of the tank side pipe (30) and the refrigerator side pipe (32) can be extracted from the fitting hole (35). Becomes In this state, when the refrigerator (6) is pulled out from the opening (4) of the outer wall member (3), the tank side pipes (30) and the refrigerator side pipes (32) are automatically separated accordingly. .

When the refrigerator (6) thus removed from the outer wall member (3) is inspected or repaired and then attached again, each joint (34) and each heater (3)
The combination of 7) is exchanged with a new one, and each joint (34) is supplied by supplying power to the heater (37) as described above.
The refrigerator (6) is inserted into the opening (4) of the outer wall member (3) in the state where the refrigerator is expanded. At this time, since the joints (34) are in the expanded state, the tank side pipe (30) and the refrigerator are fitted into the fitting hole (35) of the joint (34) as the refrigerator (6) is fitted and inserted. The sealing members (31) and (33) at the respective ends of the side pipe (32) are fitted smoothly.
When the power supply to the heater (37) is stopped in this state, each joint (34) is cooled by the liquid helium in the tank (1) and the inner diameter of the fitting hole (35) becomes smaller at the Mf transformation point or lower. The sealing members (31) and (33) of the tank-side pipe (30) and the refrigerator-side pipe (32) are fastened in a sealed state to the fitting hole (35), and each of Tank side piping (30) and each refrigerator side piping (3
2) and are connected so that helium can flow. In this state, as shown in FIG. 5, when the joint (34) contracts, the sealing ridges (31a) and (33a) on the outer circumferences of the seal members (31) and (33) fit into the joint (34). Coating layer (3) made of a soft metal on the inner surface of the hole (35)
6) Bites into and adheres to 6), and the coating layer (36) is deformed so as to adhere to the outer periphery of the seal members (31) and (33), which improves the sealability of the joint (34). it can.

Therefore, in this embodiment, it is not necessary to destroy the outer wall member (3) around the tank (1) when connecting and disconnecting the tank-side and refrigerator-side pipes (30) and (32), and the refrigerator is not required. The inspection and repair work of (6) can be performed easily and at low cost.

Further, since the joint (34) is heated by the band heater (37) wound around the outer periphery thereof, a heating means suitable for heating the joint (34) can be easily obtained.

The joints (34) are attached to the tip of the refrigerator side pipe (32) and the seal member (33) of the refrigerator side pipe (32) is provided in a part of the fitting hole (35) in advance. You may make it lock-fix in the fitted state. By doing so, the joint (34) can always be handled integrally with the refrigerator side pipe (32), and the refrigerator (6)
The joint (34) does not fall off during removal or assembly, and the pipes (30) and (32) can be easily connected and separated. Also, each joint (34)
Is provided at the tip of the refrigerator side pipe (32), and the power supply terminal (39) to the heater (37) for heating the joint (34) is attached to the attachment flange (15) of the refrigerator (6). Therefore, each time the refrigerator (6) is removed, these can be integrally removed together, and the inspection and repair thereof can be facilitated. Moreover, since the joint (34) is arranged at the tip of the refrigerator side pipe (32), the joint (34) can be easily replaced with a new one when the refrigerator (6) is removed. , Joint (3
There is an advantage that the sealing effect of 4) can be stably obtained.

[0044]

As described above, according to the first aspect of the present invention, the tank for storing the liquefied refrigerant and the refrigerator for generating the cryogenic temperature are provided, and the refrigerant gas evaporated in the tank is piped. In a cryogenic refrigeration system in which the refrigerant pipe is taken into the refrigerant circuit of the refrigerator and cooled by compression and expansion to be reliquefied, and the liquefied refrigerant is returned to the tank through a pipe, The tank side pipe and the refrigerator side pipe are divided by and the ends of each pipe on the tank side and the refrigerator side can be extracted by expanding by heating and heating, while both pipes are reduced by cooling and cooling. By providing a joint made of a shape memory alloy having a holding property, further providing a heating means for heating this joint, and by controlling the power supply to this heating means,
When removing the refrigerator for inspection or repair, the tank side and refrigerator side pipes can be connected and disconnected without destroying the wall part around the tank. It is possible to achieve simplification and cost reduction.

According to the second aspect of the invention, the joint is locked and fixed to the tip of the refrigerator side pipe while the tip of the refrigerator side pipe is fitted in a part of the fitting hole. By doing so, the joint can always be handled integrally with the refrigerator side piping or the refrigerator, and it is easy to connect and disconnect both pipes without dropping the joint when removing or assembling the refrigerator. In addition to removing the refrigerator, the joint can also be removed for easy inspection and repair, and the joint can be easily replaced with a new one to improve the joint sealing effect. It can be stably obtained.

According to the third aspect of the present invention, the coating layer made of a soft metal such as copper is formed on the inner surface of the fitting hole of the joint, while the joints are formed on the outer circumferences of the respective tip portions of the refrigerator side pipe and the tank side pipe. Attach a cylindrical seal member that can be fitted in the fitting hole, and on the outer periphery of this seal member,
By providing at least one sealing ridge that bites into and adheres to the coating layer of the fitting hole when the joint is reduced, the coating layer is deformed so as to closely adhere to the outer periphery of the seal member, and the joint sealability is improved. You can

According to the invention of claim 4, since the heating means is a band heater wound around the outer circumference of the joint, the heating means suitable for heating the joint can be specifically and easily obtained.

According to the invention of claim 5, the shape memory alloy forming the joint is a nickel-titanium shape memory alloy, so that a shape memory alloy having a function of expanding by heating of the heating means and contracting by cooling is provided. Specifically easily obtained.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an enlarged main part in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the overall configuration of a cryogenic refrigeration system in an example.

FIG. 3 is a perspective view showing a joint and a seal member before joining.

FIG. 4 is a cross-sectional view showing a joint and a seal member before joining.

FIG. 5 is a cross-sectional view showing a joint and a seal member after joining.

FIG. 6 is a refrigerant circuit diagram showing the overall configuration of a cryogenic refrigeration system.

[Explanation of symbols]

 (1) Helium tank (3) Outer wall member (6) Refrigerator (7) Precooling refrigerator (16) JT refrigerator (28) Liquid helium return pipe (liquid refrigerant pipe) (29) Helium gas suction pipe (gas Refrigerant pipe) (30) Tank side pipe (31), (33) Shield member (31a), (33a) Protrusion (32) Refrigerator side pipe (34) Joint (35) Fitting hole (37) Heater (38 ) Power supply means (CS) Superconducting coil

Claims (5)

[Claims] 1. A tank (1) for storing a liquid refrigerant at an extremely low temperature level, and a tank (1) detachably attached to the tank (1), wherein a part of the refrigerant circuit is a liquid refrigerant pipe (28) and a gas refrigerant pipe (29). ) And a refrigerator (6) opened in the tank (1) via the gas refrigerant pipe (29) to suck the gas refrigerant evaporated in the tank (1) into the refrigerator (6). To compress and expand, and the expansion causes a temperature drop to generate a liquid refrigerant, and the tank (1) passes through the liquid refrigerant pipe (28).
In the cryogenic refrigeration system in which the liquid and gas refrigerant pipes (28) and (29) are respectively divided into a tank side pipe (30) and a refrigerator side pipe (32) outside the tank (1). The tank side pipe (30) and the refrigerator side pipe are fitted in the fitting hole (35) by fitting the respective tip portions of the tank side pipe (30) and the refrigerator side pipe (32) in a butt state. A cylindrical joint (34) for detachably connecting with (32) is provided, and the joint (34) is fitted with a fitting hole (35) due to a temperature rise.
From the tank side pipe (30) and the refrigerator side pipe (32), the respective tip portions are detachably expanded, and at the same time, the tank side pipe (30) and the refrigerator side pipe (32) are inserted into the fitting hole (35) due to the temperature drop. A heating means (37) for heating the joint (34), which is made of a shape memory alloy that shrinks each of the distal end portions of the joint in a sealable state.
And a power feeding means (38) for feeding power to the heating means (37). 2. The cryogenic refrigeration system according to claim 1, wherein the joint (34) is provided at the tip of the refrigerator side pipe (32), and the refrigerator side pipe (32) is provided at a part of the fitting hole (35). A cryogenic refrigerating device, wherein the distal end portion of the is locked and fixed in a fitted state. 3. The cryogenic refrigerator according to claim 1, wherein a coating layer (36) made of a soft metal such as copper is formed on the inner surface of the fitting hole (35) of the joint (34). The fitting holes (3) of the joint (34) are respectively provided on the outer peripheries of the tip ends of the tank side pipe (30) and the refrigerator side pipe (32).
5) Cylindrical seal members (31), (3) that can be fitted inside
3) is attached to the outer periphery of the seal members (31) and (33) for at least one seal that bites into the coating layer (36) of the fitting hole (35) and closely adheres when the joint (34) is reduced. A cryogenic refrigeration system, characterized in that it is provided with ridges (31a), (33a), respectively. 4. The cryogenic refrigerator according to claim 1, 2 or 3, wherein the heating means (37) is a band heater wound around the outer periphery of the joint (34). 5. The cryogenic refrigerator according to claim 1, 2, 3 or 4, wherein the joint (34) is made of nickel-titanium shape memory alloy.