JP3287237B2 - Cryogenic refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic refrigerator for obtaining a cryogenic temperature by repeatedly introducing and expanding a high-pressure refrigerant gas.

[0002]

2. Description of the Related Art Conventionally, erbium 3 nickel (Er ₃ Ni) is used.
As shown in FIG. 11, there is a cryogenic refrigerator (cryo refrigerator) using a magnetic regenerator material such as the above. This cryogenic refrigerator has a first chamber in which a cold storage material is stored, and
A first displacer 3 enclosed in the cylinder 1 and a second displacer 7 enclosed in the second cylinder 5 having a second chamber communicating with the first chamber and containing a cold storage material.
It has. The first chamber of the first displacer 3 is connected to a high-pressure chamber 12 having an inlet 11 or a low-pressure chamber 14 having an outlet 13 via a valve stem 9 and a valve 10.

The switching of the communication path from the first chamber to the high-pressure chamber 12 or the low-pressure chamber 14 is performed by a synchronous motor 15.
The rotation is performed by rotating the valve 10.

The cryogenic refrigerator having the above configuration operates as follows. In FIG. 11, high-pressure refrigerant gas supplied from a compressor (not shown) or the like is introduced into the first chamber of the first displacer 3 from the inlet 11 via the valve 10 and the valve stem 9, It is cooled by exchanging cold energy with the cold storage material in the room (first stage). The refrigerant gas thus cooled is further guided to the second chamber in the second displacer 7 and exchanged with the cold storage material in the second chamber to be further cooled (second stage).

After that, the synchronous motor 15
As a result, the valve 10 is rotated, and the first chamber is communicated with the low-pressure chamber 14. Then, the high-pressure refrigerant gas introduced into the first chamber and the second chamber expands at a stretch, and the gas temperature decreases. Thus, the cold heat obtained by the expansion of the refrigerant gas is accumulated in the cold storage material. As described above, the introduction of the high-pressure refrigerant gas into the first chamber and the second chamber and the expansion thereof are repeated (that is, the refrigeration cycle is repeated) to obtain an ultra-low temperature.

In a cryogenic refrigerator having a structure as shown in FIG. 11, the distal end portion 24 of the second cylinder 5 is the place where it is most cooled, and is called a heat station.

[0007] Further, the cryogenic refrigerator described above is used as a precooling refrigerator, and the cryogenic refrigerator obtained by the precooling refrigerator is used.
K-level cold air is supplied to a Joule-Thomson circuit (hereinafter referred to as JT
There is a cryogenic refrigeration apparatus that obtains a cryogenic temperature of 4K level by further cooling using a circuit. As shown in FIG. 12, this cryogenic refrigerator has a pre-cooled refrigerator 101 having the same configuration as the cryogenic refrigerator shown in FIG.
02.

In the JT circuit 102, a high-pressure refrigerant gas (for example, helium gas) discharged from the compressor 103 is supplied to a first Joule-Thomson heat exchanger (hereinafter referred to as a JT circuit).
A heat station (pre-cooler heat station) 105 and a second J-T heat exchanger 106 of the pre-cooling refrigerator 101, which are cooled by performing heat exchange with the return gas refrigerant by the heat exchanger 104 and cooled to a level of 20K. Therefore, it is further cooled to reach a Joule-Thomson valve (hereinafter abbreviated as J-T valve) 107. The gas refrigerant, which has been rapidly expanded by the J-T valve 107 to have an extremely low temperature, is cooled by a cooler 10 provided in a heat station 108 to which cold air at a level of 20K obtained by the pre-cooling refrigerator 101 is supplied.
At 9, heat exchange is performed to cool the heat station 108 to the 4K level. Hereinafter, the heat station 108 cooled to the 4K level is referred to as a 4K heat station. After that, the gas refrigerant that has undergone heat exchange in the cooler 109 is subjected to heat exchange with the supply gas refrigerant in the second JT heat exchanger 106 and the first JT heat exchanger 104, and then the compressor 103 Return to

[0009]

However, in the above-mentioned conventional cryogenic refrigerator, when the cryogenic temperature is reduced to 20 K or less, a temperature amplitude is generated in a portion to be cooled in a refrigeration cycle of introducing and expanding the high-pressure refrigerant gas. . So, usually,
By increasing the weight of the heat station 24, the temperature amplitude of the portion to be cooled is reduced. However, as described above, if the weight of the heat station 24 is increased in order to cope with the temperature amplitude, another problem occurs in that the cool-down time at the time of startup becomes longer.

[0010] In the conventional cryogenic refrigeration apparatus, a temperature amplitude is generated in the portion to be cooled of the precooler heat station 105 in the refrigeration cycle of the precooler 101. Then, the temperature amplitude generated in the cooled part of the pre-cooler heat station 105 is 4K heat station 108.
And becomes a noise source for the object to be cooled such as a radio wave sensor for detecting radio waves from space attached to the 4K heat station 108. Therefore, conventionally, the 4K heat station 108 is dealt with by using high-purity copper as a material or increasing the size to increase the weight. Therefore, in addition to a long cool-down time at the time of startup, there is a problem that the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cryogenic refrigerator capable of reducing the temperature amplitude of a portion to be cooled without prolonging a cool down time at the time of starting.

[0012]

In order to achieve the above object, the cryogenic refrigerator according to the first aspect of the present invention can be closely attached to the end of the final heat station.
Of a simple metal in a high thermal conductivity metal structure
It is characterized in that a heat buffer material provided with a plate is provided. According to the above configuration, the temperature amplitude of the heat station is reduced by the action of the thermal buffer provided in close contact with the end of the final heat station. Thus, the temperature amplitude of the cooled portion is reduced without increasing the weight of the heat station, in other words, by suppressing the cool down time at the time of startup from being lengthened.

According to a second aspect of the present invention, in the cryogenic refrigerator according to the first aspect of the present invention, the disc made of a single metal is made of neodymium (Nd) alone. And According to the above arrangement, the heat cushioning material, has an erbium 3 nickel (Er ₃ Ni) and has the same specific heat and high enough thermal conductivity than the erbium 3 nickel (Er ₃ Ni), machining A disk is formed of neodymium (Nd) alone, which has high thermal conductivity.
Ru is formed attached to the metal structure in. Therefore, copper or the like with high workability should be used as the metal structure.
Thus, the heat buffering material is formed so as to match the shape of the tip of the heat station and to be in close contact therewith, and is attached in close contact with the tip of the heat station. Thus, the temperature amplitude of the portion to be cooled is reduced without increasing the weight of the heat station.

According to a third aspect of the present invention, in the cryogenic refrigerator according to the first aspect of the present invention, the metal single disk is formed of lead (Pb) alone. And According to the above configuration, the heat buffer material has a specific heat sufficient for the heat station at a temperature near 20 K and a heat conductivity sufficiently higher than that of the erbium 3 nickel (Er ₃ Ni), and is machined. A disc is formed of lead (Pb) alone, which has good thermal conductivity.
Ru is formed attached to the metal structure in. Therefore, copper or the like with high workability should be used as the metal structure.
Thus, the thermal buffer can be attached in close contact with the tip of the heat station. As a result, at a temperature near 20 K, the temperature amplitude of the portion to be cooled is reduced without increasing the weight of the heat station.

Further, in the cryogenic refrigerator according to the fourth aspect of the present invention, a heat buffer material is provided at the tip of the final heat station by dispersing a metal compound having a high specific heat in a single metal having a high thermal conductivity. It is characterized by. According to the above configuration,
Since the thermal buffer has a high thermal conductivity and a high specific heat, the temperature amplitude of the portion to be cooled is reduced without increasing the weight of the heat station. Further, by using a metal having good machinability as the single metal, the heat buffer material is formed so as to match the shape of the tip of the heat station and to be in close contact therewith, and is attached in close contact with the tip of the heat station.

Further, in the cryogenic refrigerator according to the fifth aspect of the present invention, a thermal buffer is provided at the tip of the final heat station by dispersing a single metal having a high specific heat in a single metal having a high thermal conductivity. It is characterized by. According to the above configuration, the thermal buffer formed using the simple metal having good machinability has high thermal conductivity and high specific heat, and also has good machinability. Therefore, the temperature amplitude of the portion to be cooled can be reduced without increasing the weight of the heat station by being closely attached to the tip of the heat station. Further, since the single metal having a high specific heat is dispersed in the single metal having a high thermal conductivity, the oxidation of the single metal is prevented.

According to a sixth aspect of the present invention, in the cryogenic refrigerator according to the fourth aspect of the present invention, the metal compound having a high specific heat is Er ₃ Co, ErNi, Er ₃ Ni, HoCu ₂ , HoA.
l ₂ , Ho ₂ Al, ErNi _0.8 Co _0.2 and ErNi _0.9 Co _0.1 . According to the above configuration, the metal compound dispersed in the single metal having a high thermal conductivity has a high specific heat equivalent to that of the erbium 3 nickel (Er ₃ Ni). Therefore, the formed thermal buffer material, in addition to the reduction of the temperature amplitude due to the single metal of high thermal conductivity,
High refrigerating capacity is maintained by the metal compound.

According to a seventh aspect of the present invention, in the cryogenic refrigerator according to the fourth or fifth aspect, the heat buffer is provided with a high thermal conductivity structure provided at the end of the last heat station. And is integrally formed with the high thermal conductivity structure. According to the above configuration, the heat buffer material formed by dispersing a single metal or a metal compound having a high specific heat in a single metal having a high thermal conductivity is formed so as to match the tip shape of the heat station and to be in close contact therewith. It is cast into the recess of the high thermal conductivity structure to be integrally formed. In this way, the thermal buffer is closely attached to the tip of the heat station, and the temperature amplitude is reduced more efficiently.

[0019]

The cryogenic refrigerator of the invention according to claim 8 is a cryogenic refrigerator having a precooling refrigerator for precooling the cryogenic heat station and a Joule-Thomson circuit for further cooling the precooled cryogenic heat station. A cryogenic heat station, wherein
A heat buffer material according to any one of claims 7 to 10 is provided. According to the above configuration, the temperature amplitude generated in the heat station of the pre-cooling refrigerator in the refrigeration cycle of the pre-cooling refrigerator is reduced by the action of the heat buffer material and is not transmitted to the cryogenic heat station.
Alternatively, the temperature amplitude generated in the heat station of the pre-cooling refrigerator and transmitted to the cryogenic heat station,
It is reduced by the action of the thermal buffer. Thus, without increasing the weight of the cryogenic heat station,
In other words, the temperature of the cryogenic heat station can be stabilized by suppressing the cool down time at the time of startup from being lengthened.

The cryogenic refrigerator according to claim 9 is a cryogenic refrigerator having a precooling refrigerator for precooling the cryogenic heat station and a Joule-Thomson circuit for further cooling the precooled cryogenic heat station. The heat buffer of the invention according to any one of claims 1 to 7 is provided in a heat station of the precooling refrigerator. According to the above configuration, the temperature amplitude generated in the heat station of the pre-cooling refrigerator in the refrigeration cycle of the pre-cooling refrigerator is reduced by the action of the heat buffer material and is not transmitted to the cryogenic heat station. In this way, without increasing the weight of the cryogenic heat station or making high-purity copper,
The temperature of the cryogenic heat station can be stabilized.

A cryogenic refrigerator according to a tenth aspect of the present invention is a cryogenic refrigerator for precooling a cryogenic heat station, the refrigerant gas inside is cooled by the precool refrigerator, and the cooled refrigerant is cooled. In a cryogenic refrigerator having a Joule-Thomson circuit that further cools the pre-cooled cryogenic heat station with gas, a pipe between the heat station of the precooled chiller and the cryogenic heat station in the Joule-Thomson circuit includes: A heat buffer material according to any one of claims 1 to 7 is provided. According to the above configuration, the temperature amplitude generated in the heat station of the pre-cooling refrigerator and transmitted to the refrigerant gas in the Joule-Thomson circuit is provided in a pipe between the heat station and the cryogenic heat station in the Joule-Thomson circuit. It is reduced by the action of the provided thermal buffer. Therefore, the temperature amplitude of the refrigerant gas is not transmitted to the cryogenic heat station.

The invention according to claim 11 is the invention according to claim 8
The cryogenic refrigerator according to any one of claims 10 to 10 , wherein a plurality of the cryogenic heat stations exist, and the Joule-Thompson circuit cools all the cryogenic heat stations. Features. According to the above configuration, the temperature amplitude generated in the heat station of the pre-cooling refrigerator, the temperature amplitude transmitted to the plurality of cryogenic heat stations, or the temperature amplitude transmitted to the refrigerant gas in the Joule-Thomson circuit is the heat amplitude. It is reduced by the action of thermal buffer provided in the piping of each station, each cryogenic heat station or Joule-Thomson circuit. In this way, the occurrence of a temperature amplitude for each cryogenic heat station is prevented.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is an enlarged view of the tip of a cylinder in the cryogenic refrigerator of the present embodiment. In this cryogenic refrigerator, a heat buffer material 32 formed in a plate shape is attached to a side surface 31 a of a heat station 31.

The material of the thermal buffer material 32 has a higher thermal conductivity than erbium 3 nickel (Er ₃ Ni) for reducing the temperature amplitude of the heat station 31 and at least erbium 3 for maintaining a high refrigerating capacity. Nickel (Er
_It must have a high specific heat of about ₃ Ni) and be capable of machining. FIG. 2 shows the specific heat and the thermal conductivity of the metal used as the thermal buffer material 32 as shown in FIG.
(Er ₃ Ni). Here, as shown in FIG. 2, in general, rare earth alloys other than neodymium (Nd) have poor mechanical workability such as cutting, drilling and polishing. Therefore, in order to form the thermal buffer 32 by cutting, polishing, or the like, the following measures are required.

(1) Use of Simple Metal As shown in FIG. 2, neodymium metal has a high specific heat of about erbium 3 nickel (Er ₃ Ni) and a thermal conductivity of 10 times that of erbium 3 nickel (Er ₃ Ni). Double to 20 times as high.
Therefore, neodymium metal alone is most suitable as a material for a thermal buffer for low-temperature applications that can be used even at extremely low temperatures near 4K. Moreover, it has sufficient machinability,
It is possible to form the heat buffer material 32 which matches the shape of the side surface 31a of the heat station 31 and can be adhered to. That is, the neodymium metal can form the optimum thermal buffer material 32 by itself.

Although lead (Pb) has a high thermal conductivity, the specific heat is almost zero near 4K. However, 2
In the vicinity of 0K, it has sufficient specific heat as a heat station. Therefore, lead (Pb) can be sufficiently used as a material for a heat buffer material for high-temperature applications used near 20K.

In the above example, neodymium (N
d) or lead (Pb) is used alone as the thermal buffer material 32. As shown in FIG. 3, a disk 33 made of neodymium (Nd) or lead (Pb) has a high thermal conductivity. copper
The metal structure 3 which is formed by (Cu) or the like so as to match the shape of the side surface 31a of the heat station 31 and to be in close contact therewith.
4 to form the heat buffer material 32.

(2) Dispersion use As described above, erbium cobalt (Er ₃ Co), erbium nickel (ErNi), erbium 3 nickel (Er ₃ N)
i), holmium aluminum (HoAl ₂ ), holmium copper
Rare earth metal compounds such as (HoCu ₂ ), holmium 2 aluminum (Ho ₂ Al), erbium nickel alloy (ErNi _0.8 Co _0.2 ), and erbium nickel alloy (ErNi _0.9 Co _0.1 ) have high specific heat but low machinability. Not good.

Therefore, as shown in FIG. 4, these rare earth metal compounds 35 form small-diameter spheres or grains, and have a higher heat than erbium 3 nickel (Er ₃ Ni) such as lead (Pb) or indium (In). The metal lump is formed by dispersing in the metal 36 having conductivity and good machinability. Metal block thus created, having both erbium 3 nickel (Er ₃ Ni) of approximately the specific heat and erbium 3 nickel (Er ₃ Ni) than the high thermal conductivity. Therefore, it functions as a good thermal buffer. Further, since the rare earth metal compound having poor machinability is dispersed in a metal having good machinability, the metal lump has such machinability that the heat buffer material 32 can be formed. Therefore, by cutting and polishing the metal lump, the side surface 31 of the heat station 31 is cut.
It is possible to form the heat buffer material 32 that matches the shape of a and can be adhered to.

In the above description, a metal lump is formed by dispersing a rare earth metal compound having poor machinability in a metal having good machinability, but the neodymium metal, which is a rare earth metal having good machinability, is formed. (Nd) is lead (Pb) with good machinability
It does not matter even if the metal lump is formed by dispersing in a metal. By doing so, the machinability and the refrigerating capacity are lower than in the case of using lead (Pb) metal alone or neodymium (Nd) metal alone, but a new effect of preventing the oxidation of neodymium (Nd) is obtained. be able to.

(3) Casting Use Rare earth metal compounds having poor machinability are dispersed in small heat-resistant single metal such as lead (Pb) or indium (In) in the form of small spheres or particles. Although the machinability can be enhanced by forming the metal mass in such a manner, it is hard to say that sufficient machinability can be obtained as compared with the above-mentioned metal having good machinability. Therefore, as shown in FIG. 5, as described above, a metal lump in which a rare earth metal compound is dispersed in a single metal having a high thermal conductivity or a metal lump in which the neodymium (Nd) is dispersed in lead (Pb) metal (both metal lump). Metal lump 37
A metal structure 3 made of copper or neodymium (Nd) having high thermal conductivity and good machinability.
8 is cast. By doing so, the heat buffer capacity of the metal block 37 is further improved, and
Higher machinability can be obtained. Therefore, by forming the high thermal conductivity metal structure 38 by cutting or polishing, the heat station 3
It is possible to form the heat buffer material 32 that matches the shape of the one side surface 31a and can be closely attached.

[0033] (4) and a specific heat of about high thermal conductivity and erbium 3 nickel (Er ₃ Ni) than the gas in the dispersion used the erbium 3 nickel (Er ₃ Ni) of heat cushioning function and high refrigeration capacity A thermal buffer having a holding function can also be obtained by filling a rare earth metal with a low-boiling gas.

As shown in FIG. 6, a metal container 39 which matches the shape of the side surface 31a of the heat station 31 and can be adhered thereto is formed of a metal having high thermal conductivity and good machinability, such as a copper alloy. . And this metal container 3
9, the particles 40 of the neodymium (Nd) or the rare earth metal compound described above are filled together with the low-boiling gas 41. The low-boiling gas has an application temperature of 30.
When the temperature is higher than K, argon (Ar) is suitable. When the applied temperature is around 20K, helium (He) and hydrogen (H ₂ ) are used.
Alternatively, neon (Ne) is suitable, and helium (He) is suitable when the application temperature is around 4K. in this way,
By dispersing the rare earth metal compound particles 40 in the low boiling point gas 41, the heat conductivity is improved by the convection of the gas and the condensation generated at the temperature and pressure of the gas, and the temperature distribution becomes uniform.

As described above, in the present embodiment,
The thermal buffer material 32 is formed of a single metal having high specific heat and high thermal conductivity and good machinability such as neodymium (Nd) or lead (Pb), or particles of a rare earth metal compound having high specific heat. The thermal buffer material 32 is formed by a metal lump in which metal 35 is dispersed in a metal 36 having high thermal conductivity and good machinability, or a metal structure having high thermal conductivity and good machinability. The metal block 37 is cast into the object 38 to form the heat buffer material 32, or a metal container 39 made of a metal having high heat conductivity and good machinability.
A heat buffer material 32 is formed by filling particles 40 of neodymium (Nd) or a rare earth metal compound having a high specific heat together with a low boiling point gas 41. Then, the heat buffer material 32 thus formed is attached to the side surface 31a of the heat station 31 in close contact. Therefore, the temperature amplitude of the portion to be cooled can be reduced without increasing the weight of the heat station 31, in other words, without increasing the cool-down time at the time of startup.

Next, in a cryogenic refrigeration system as shown in FIG. 12, for example, a 20K level cold air obtained by a pre-cooling refrigerator is further cooled using a JT circuit to obtain a 4K level cryogenic temperature. A description will be given of how to prevent the temperature amplitude from occurring in the 4K heat station. As a method for preventing the temperature amplitude in the cryogenic refrigeration apparatus as described above, there is the following method. (a) A heat buffer is provided on the end face of the 4K heat station. (b) A heat buffer is provided on the pre-cooler heat station side of the 4K heat station. (c) Provide a thermal buffer in the pre-cooler heat station. (d) Provide a thermal buffer in the JT circuit between the precooler heat station and the 4K heat station.

FIG. 7 shows a case where a thermal buffer 53 is provided between the end face of the 4K heat station 51 and the object 52 to be cooled attached to this end face. By doing so, the temperature amplitude generated in the 4K heat station 51 is reduced by the action of the thermal buffer material 53, and is prevented from being transmitted to the object to be cooled 52. Therefore, when the object to be cooled 52 is a sensor such as a radio wave sensor, noise with respect to this sensor can be reduced. The heat buffer 53
Any of the above-mentioned types of thermal buffer materials (1) using a metal alone, (2) using a dispersion, (3) using a casting, and (4) using a dispersion in a gas may be used. Further, the material may be appropriately selected from the above-mentioned materials according to the shape and the cooling temperature of the 4K heat station 51 and the object to be cooled 52, and used.

FIG. 8 shows a case where a thermal buffer 56 is provided on the pre-cooler heat station side of the 4K heat station 55. By doing so, the temperature distribution of the heat transmitted from the pre-cooler heat station (not shown) to the 4K heat station 55 becomes uniform, and the temperature amplitude generated in the pre-cooler heat station is transmitted to the 4K heat station 48. Can be prevented. The heat buffer material 56 is formed in a ring shape and has a size of 4K as shown in FIG.
The 4K heat station 55 may be fitted in a groove provided on the outer periphery of the heat station 55, or may be formed in a disk shape.
The 4K heat station 55 may be provided between the precooler heat station and a connecting portion 57 connected to the precooler heat station. The type and material of the thermal buffer 56 are not particularly limited, and may be appropriately selected and used from the types and materials described above according to the purpose.

FIG. 9 shows a case where a heat buffer material 62 is provided at the tip of a precooler heat station 61. By doing so, the temperature distribution of the heat transmitted from the pre-cooler heat station 61 to the 4K heat station 63 becomes uniform, and the temperature amplitude generated in the pre-cooler heat station 61 can be prevented from being transmitted to the 4K heat station 63. . The type and material of the thermal buffer 62 are not particularly limited, and may be appropriately selected and used from the types and materials described above according to the purpose.

FIG. 10 shows a case where a thermal buffer is provided in the JT circuit. A thermal buffer 68 is provided on at least one of the downstream pipe 66 and the upstream pipe 67 of the JT valve 65.
Alternatively, a thermal buffer 69 is provided. This heat buffer material 68,6
9, for example, have a high specific heat of about erbium 3 nickel (Er ₃ Ni), the thermal conductivity of erbium 3 nickel (Er ₃
Using neodymium (Nd) metal, which is 10 to 20 times as high as Ni) and has sufficient machinability, piping 66,
It is formed in a cylindrical shape having an inner diameter substantially equal to the outer diameter of 67. Then, the pipe 66 or the pipe 67 is inserted into and attached to the cylindrical heat buffer members 68 and 69. By doing so, the temperature amplitude generated in the refrigerant gas during heat exchange between the pre-cooler heat station 70 and the refrigerant gas in the JT circuit is reduced. Therefore, no heat amplitude occurs in the 4K heat station 71 due to heat exchange between the refrigerant gas and the 4K heat station 71.

Further, a plurality of 4K heat stations are connected in parallel to one pre-cooling refrigerator, and a plurality of coolers are provided downstream of the JT valve in the JT circuit. There is a cryogenic refrigeration device that is attached to a station in series. In such a cryogenic refrigerator, (a) a thermal buffer is provided on the end face of the 4K heat station, (b) a thermal buffer is provided on the pre-cooler heat station side of the 4K heat station, and (c) a pre-cooler heat is provided. Provision of thermal buffer material at station (d) Applying thermal buffer material to JT circuit in combination with the pre-cooler heat station or each 4K heat station as appropriate to generate temperature amplitude for each 4K heat station Can be prevented.

[0042]

As is clear from the above description , the cryogenic refrigerator according to the first aspect of the present invention is formed at the tip of the final heat station so as to be able to adhere to the heat station.
Attach a metal single disk in a metal structure with high thermal conductivity
Since the heat buffer material is provided, the temperature amplitude of the heat station is reduced by the action of the heat buffer material. Therefore, the temperature amplitude of the cooled portion can be reduced without increasing the weight of the heat station, in other words, by suppressing the cool-down time at startup from becoming long.

Further, in the cryogenic refrigerator according to the second aspect of the present invention, since the disk made of a single metal is made of only neodymium (Nd), the disk is made of erbium 3 nickel (Er ₃ Ni). Has the same specific heat as erbium-3
It has sufficiently higher thermal conductivity than nickel (Er ₃ Ni) and has good machinability. Therefore, the thermal buffer material is
By forming the metal structure using copper or the like having high workability so as to match the shape of the tip of the heat station and to be in close contact therewith, the metal structure can be closely attached to the tip of the heat station, and the weight of the heat station can be reduced. Can be reduced without increasing the temperature.

Further, in the cryogenic refrigerator according to the third aspect of the present invention, since the disk made of a single metal is made of only lead (Pb), the disk is made of the heat station at a temperature near 20K. Erbium 3 nickel (Er ₃ Ni), and has a sufficiently high thermal conductivity and good machinability. Therefore, the heat buffer can be attached to the end of the heat station in close contact with the tip of the heat station using copper or the like having high workability as the metal structure. Can be reduced without increasing the temperature.

Further, in the cryogenic refrigerator according to the fourth aspect of the present invention, a thermal buffer made by dispersing a metal compound having a high specific heat in a single metal having a high thermal conductivity is provided at the end of the final heat station. Further, the temperature amplitude of the portion to be cooled can be reduced without increasing the weight of the heat station. Further, the heat buffering material has good machinability, and can be formed so as to match the shape of the tip of the heat station and to be in close contact therewith.

Further, in the cryogenic refrigerator according to the fifth aspect of the present invention, a thermal buffer made by dispersing a single metal having a high specific heat in a single metal having a high thermal conductivity is provided at the end of the final heat station. Further, the temperature amplitude of the portion to be cooled can be reduced without increasing the weight of the heat station. Further, since the heat buffer material is formed by dispersing a single metal having a high specific heat in a single metal having a high thermal conductivity, the oxidation of the single metal is prevented. Further, the heat buffer material has good machinability, and can be formed so as to match the shape of the tip of the heat station and to be in close contact therewith. Therefore, it can be attached in close contact with the heat station tip.

In the cryogenic refrigerator according to the present invention, the metal compound having a high specific heat is HoCu ₂ , Er ₃ C.
_{o, ErNi, Er 3 Ni,} HoAl 2, Ho 2 Al, since it is one of ErNi _0.8 Co _0.2 and ErNi _0.9 Co _0.1, the elemental metal with the high thermal conductivity, the erbium 3 nickel
A metal compound having a high specific heat equivalent to (Er ₃ Ni) is dispersed to form the thermal buffer. Therefore, the thermal buffering material can reduce the temperature amplitude of the portion to be cooled and maintain a high refrigeration capacity.

In the cryogenic refrigerator according to the seventh aspect of the present invention, a single metal having a high specific heat or a single metal having a high specific heat is provided in a concave portion of a high thermal conductivity structure provided at the end of the final heat station. Since the thermal buffer material formed by dispersing the metal compound is cast, the thermal buffer material is closely attached to the tip of the heat station, and the temperature amplitude is reduced more efficiently.

[0049]

According to a cryogenic refrigerator of the invention according to claim 8 , a cryogenic heat station precooled by a precooler is provided with the heat buffer material according to any one of claims 1 to 7. With the provision, the temperature amplitude generated in the heat station of the pre-cooling refrigerator in the refrigeration cycle of the pre-cooling refrigerator can be reduced by the action of the heat buffer material so as not to be transmitted to the cryogenic heat station. Alternatively, the temperature amplitude generated in the heat station of the pre-cooling refrigerator and transmitted to the cryogenic heat station can be reduced by the action of the heat buffer material. Therefore, it is possible to stabilize the temperature of the cryogenic heat station without increasing the weight of the cryogenic heat station, in other words, by suppressing an increase in the cool-down time at startup. Further, it is not necessary to form the cryogenic heat station with high-purity copper, so that the cost can be reduced. That is, according to the present invention, when a radio wave sensor for detecting radio waves from space is used as the object to be cooled, the heat amplitude can be easily and inexpensively prevented from being a noise source for the object to be cooled. is there.

The cryogenic refrigerator according to the ninth aspect of the present invention provides a heat station for a pre-cooling refrigerator for pre-cooling a cryogenic heat station according to any one of the first to seventh aspects. Since the material is provided, the temperature amplitude generated in the heat station of the pre-cooling refrigerator can be reduced by the action of the heat buffer material so that the temperature is not transmitted to the cryogenic heat station. Therefore, the temperature of the cryogenic heat station can be stabilized without increasing the weight of the cryogenic heat station or using high-purity copper.

Further, the cryogenic refrigerator according to the tenth aspect of the present invention is the cryogenic refrigerator, wherein the heat station of the pre-cool refrigerator and the cryogenic heat in the Joule-Thomson circuit for cooling the cryogenic heat station with the refrigerant gas cooled by the pre-cool refrigerator. the pipe between the stations, according to claim 1 to claim
7 , the temperature amplitude generated in the heat station of the pre-cooling refrigerator and transmitted to the refrigerant gas in the Joule-Thompson circuit is reduced by the action of the heat buffer material. it can. Therefore, the temperature amplitude of the refrigerant gas in the Joule-Thomson circuit is not transmitted to the cryogenic heat station.

The cryogenic refrigerator according to claim 11 is the cryogenic refrigerator according to any one of claims 8 to 10 , wherein a plurality of the cryogenic heat stations are provided, Since the Thomson circuit cools all cryogenic heat stations, the temperature amplitude generated in the pre-cooled refrigerator heat station, the temperature amplitude transmitted to multiple cryogenic heat stations, or in the Joule-Thomson circuit The temperature amplitude transmitted to the refrigerant gas can be reduced by the action of the heat buffer provided on the heat station, each cryogenic heat station, or the piping of the Joule-Thomson circuit. Therefore, it is possible to prevent the occurrence of temperature amplitude for a plurality of cryogenic heat stations.

[Brief description of the drawings]

FIG. 1 is an enlarged view of the vicinity of a heat station in a cryogenic refrigerator according to the present invention.

FIG. 2 is a diagram showing specific heat and thermal conductivity of a metal used as a thermal buffer.

FIG. 3 is a cross-sectional view showing an example of the thermal buffer shown in FIG.

FIG. 4 is a cross-sectional view of a heat buffer different from that of FIG. 3;

FIG. 5 is a cross-sectional view of a heat buffer different from FIGS. 3 and 4;

FIG. 6 is a cross-sectional view of a thermal buffer different from FIGS. 3, 4 and 5;

FIG. 7 shows 4 in the cryogenic refrigerator using the JT circuit.
It is explanatory drawing in the case of providing a thermal buffer on the end surface of K heat station.

FIG. 8 shows a cryogenic refrigerator using a JT circuit.
It is explanatory drawing in the case of providing a thermal buffer on the side of the preheater heat station of K heat station.

FIG. 9 is a diagram illustrating a case where a heat buffer is provided in a pre-cooler heat station in a cryogenic refrigerator using a JT circuit.

FIG. 10 is an explanatory diagram in the case where a thermal buffer is provided in the JT circuit in the cryogenic refrigerator using the JT circuit.

FIG. 11 is a diagram showing a cryo refrigerator as a cryogenic refrigerator.

FIG. 12 is a diagram showing a cryogenic refrigerator using a JT circuit.

[Explanation of symbols]

31 ... heat station, 32, 53, 56, 62, 6
8,69: thermal buffer, 33: neodymium or lead disk, 34,38: metal structure with high thermal conductivity, 35: rare earth metal compound, 36: metal with high thermal conductivity,
37: Metal lump, 39: High thermal conductivity metal container, 40: Neodymium or rare earth metal compound particles, 41: Low boiling point gas, 51, 55, 63, 71 4K
Heat station, 61, 70: Pre-cooler heat station, 65: J-T valve.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-298765 (JP, A) JP-A-3-174486 (JP, A) JP-A-7-146020 (JP, A) JP-A-7-146 260266 (JP, A) JP-A-3-148567 (JP, A) JP-A-2-38051 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 9/00 F25B 9 / 00 395

Claims (11)

(57) [Claims] The tip of the 1. A final heat station, heating
High thermal conductivity gold
A cryogenic refrigerator characterized in that a heat buffer comprising a disk made of a single metal is provided in a metal structure . 2. The cryogenic refrigerator according to claim 1, wherein the disk made of a single metal is made of Nd alone. 3. The cryogenic refrigerator according to claim 1, wherein the metal single disk is formed of Pb alone. 4. A cryogenic refrigerator comprising a heat buffer provided at the tip of a final heat station, wherein a metal compound having a high specific heat is dispersed in a single metal having a high thermal conductivity. 5. A cryogenic refrigerator characterized in that a thermal buffer made by dispersing a single metal having a high specific heat in a single metal having a high thermal conductivity is provided at the end of the final heat station. 6. The cryogenic refrigerator according to claim 4, wherein the metal compound having a high specific heat is Er ₃ Co, ErNi, Er ₃ Ni,
HoAl ₂ , HoCu ₂ , Ho ₂ Al, ErNi _0.8 Co _0.2 and ErN
A cryogenic refrigerator characterized by any one of i _0.9 Co _0.1 . 7. The cryogenic refrigerator according to claim 4, wherein the heat buffer material is cast into a recess of a high thermal conductivity structure provided at a tip of a final heat station, and A cryogenic refrigerator characterized by being integrally formed with a high thermal conductivity structure. 8. A cryogenic heat station (51, 55).
A pre-cooling refrigerator for pre-cooling, and a cryogenic refrigerator having a Joule-Thomson circuit for further cooling the pre-cooled cryogenic heat station (51, 55), wherein the cryogenic heat station (51, 55) comprises: A cryogenic refrigerator comprising the thermal buffer according to any one of claims 1 to 7 . 9. A pre-cooling refrigerator for pre-cooling a cryogenic heat station, and a cryogenic refrigerator having a Joule-Thomson circuit for further cooling the pre-cooled cryogenic heat station. A cryogenic refrigerator comprising the thermal buffer according to any one of claims 1 to 7 . 10. A pre-cooling refrigerator for pre-cooling a cryogenic heat station (71), and a refrigerant gas inside is cooled by the pre-cooling refrigerator, and the cryogenic heat station pre-cooled by the cooled refrigerant gas. A cryogenic refrigerator having a Joule-Thomson circuit for further cooling (71), wherein a pipe between the heat station (70) of the pre-cooled refrigerator and the cryogenic heat station (71) in the Joule-Thomson circuit is provided. A cryogenic refrigerator provided with the thermal buffer according to any one of claims 1 to 7 . 11. The cryogenic refrigerator according to claim 8, wherein a plurality of said cryogenic heat stations are provided, and said Joule-Thomson circuit cools all the cryogenic heat stations. A cryogenic refrigerator characterized by the following: