JPS63306362A - Cooling section structure of cryogenic refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cryogenic refrigerator used for freezing samples in the biological science field and cooling elements of electronic devices, and particularly for efficiently freezing objects to be cooled. Or it relates to a cooling part structure suitable for cooling.

[Conventional technology]

In the field of biological sciences, a method is usually adopted in which samples are immersed in liquid nitrogen and frozen. A Stirling refrigerator is used as the machine. In the cooling part of the refrigerator, a medium enclosed in a state separate from the operating part of the refrigerator is condensed and liquefied, and the object is frozen and stored by being led to a freezing storage box through a heat pipe. It has become.

[Problems to be Solved by the Invention] The above-mentioned prior art relates to a relatively large-capacity frozen storage, and does not take into account the rapid freezing of one or several samples for use in experiments or tests. In other words, the refrigerator and the storage are connected through heat exchange through a heat pipe, so it is fine if a dedicated space is secured for the storage, but when working on a desk, such as for quick freezing. has the disadvantage that it takes up too much space. In addition, when using a small amount of sample compared to the size of the storage, most of the cooling capacity of the refrigerator is used to remove heat from the atmosphere that enters from the storage or heat pipe. The electrical input supplied to the device will not be used effectively.

On the other hand, most storages are not completely sealed off from the atmosphere, and samples are cooled and frozen using air as a medium. The sample is frozen through movement, heat transfer between the heat pipe and storage air, and heat transfer between the cooling air and the sample. Therefore, each contact portion has thermal resistance, resulting in a loss of cooling energy and a time delay required for freezing the sample.

The object of the present invention is to solve the problems of the prior art mentioned above.

It is an object of the present invention to provide a structure for a cooling section of a cryogenic refrigerator that not only rapidly freezes a sample but also allows the cold energy of the refrigerator to be effectively used for cooling and freezing the sample.

[Means for solving problems]

The above object is achieved by effectively transmitting the cooling effect obtained in the expansion space of the refrigerator to the object to be cooled, that is, the sample to be cooled or frozen, and specifically as described below.

In addition to shortening the heat transfer distance between the end of the displacer cylinder, which serves as the cooling part of the refrigerator, and the object to be cooled, the medium interposed between the cooling part of the refrigerator and the object to be cooled has a high thermal conductivity. It is only necessary to select one that has a high heat transfer coefficient and a good heat transfer coefficient at the contact area between the cooling part and the object to be cooled. A medium having a high heat capacity may be used so that the temperature of the medium in the cooling tank does not change significantly due to the heat capacity of the body to be cooled when the body is stored.

Regarding the end structure of the cylinder, it is also effective to increase the heat transfer area by adding fins, etc., in order to effectively transfer the cooling effect obtained by the expansion of the working medium in the refrigerator to the medium interposed in the cooling tank. .

[Effect]

As mentioned in the section of the previous section, the expansion of the working medium within the refrigerator provides a cooling effect at the end of the displacer. That is, it is necessary to have a cooling tank structure that shortens the heat transfer distance between the object to be cooled and the cylinder that covers the end of the displacer, and also reduces the amount of heat that enters.

First, the cooling effect obtained by the expansion of the working medium at the end of the displacer cools the cylinder that covers it. As a result, the medium that is in contact with the cylinder and is present in the cooling tank is cooled until there is no temperature difference between the medium and the cylinder. At this time, the larger the area of contact between the cylinder and the intervening medium, the faster the temperature drop rate of the medium, although it depends on the cooling capacity of the refrigerator. Furthermore, the temperature within the medium changes from a distributed state to a uniform state due to convection.
The object to be cooled is immersed in the medium inside the cooling tank.

The object to be cooled is cooled until there is no difference in temperature between the object and the medium. The degree of heat transfer between the cylinder and the medium, and between the medium and the object to be cooled, that is, the rate of temperature change, is determined by natural convection heat transfer that governs the main heat transfer, so the natural convection heat transfer rate becomes high, and the required cooling temperature The cooling rate can be increased by selecting a medium that does not solidify. In addition, by selecting a medium with high heat capacity, the time from starting the refrigerator to reaching the required cooling temperature will be longer, but even if there is a problem such as a power outage, the temperature of the object to be cooled will not rise sharply. .

The heat transfer coefficient and heat capacity have been described above, but it goes without saying that a liquid is effective as a medium for making these effects effective.

Heat intrusion occurs from the wall separating the cooling tank and the atmosphere, or from the object to be cooled if a part of the object is exposed to the atmosphere. The latter is difficult to avoid because it depends on how the refrigerator is used, but the former can be prevented by constructing the cooling tank itself as a vacuum container.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

First, the configuration of a Stirling refrigerator will be described with reference to FIG.

The piston 13 is composed of a coil 7 and a permanent magnet 8, and is vibrated by a near motor 9. The piston 13 is supported by a spring 14, and when vibrated at the natural frequency of the piston mass-spring system, it resonates and the working gas in the compression space 10 is compressed. The compression heat generated during compression is removed by the cooler 11,
The pressure change of the working gas due to compression is transmitted to the expansion space 6 via the non-metallic sliding members 2, 2' provided with ventilation holes and the porous metallic member 3. At this time, due to the pressure loss within the porous metal member 3, a pressure difference is generated between both ends of the displacer 1, which is composed of one member 2.2', 3.4, and becomes an excitation force for vibration. When the displacer 1 vibrates, the working gas relatively passes through the porous metal member 3. When the piston 13 reaches the top dead center and begins to descend, the working gas in the compression space 10 and the expansion space 6 expands, but if the displacer 1 reciprocates with respect to the piston 13 while maintaining a certain phase difference, the cylinder Cooling capacity will be obtained in the upper part of 5. This is a reverse Stirling cycle, and as the displacer 1 moves, the working gas reciprocates between the low-temperature expansion space 6 and the high-temperature compression space 10. Therefore.

The cooling capacity of the expansion space 6 is wasted to cool down the heat of compression in the compression space 10, but when the working gas passes through the porous metal member 3 in the displacer 1,
The cooling capacity of the working gas is stored in the porous metal member 3, and the working gas is cooled when it flows from the compression space 10 to the expansion space 6, thereby increasing the cooling capacity during expansion. becomes possible. That is, by arranging a porous metal member within the displacer 1, it can serve as a regenerator for a reverse Stirling cycle. Further, since the porous metal member 3 has a large wetted area, that is, a heat transfer area for one flow of working gas, it functions very effectively as a regenerator.

Furthermore, it will be constructed from a single member.

In addition, if the sliding characteristics between the porous metal member 3 that becomes the regenerator part and the cylinder 5 are not good, non-metallic sliding members may be attached to both ends and the outer periphery of the porous metal member 3 as in this embodiment. You can easily solve the problem. Moreover, the pressure difference that becomes the driving force of the displacer 1 described above is
It can be easily adjusted by changing the length or diameter of the porous metal member 3.

FIG. 2 shows a cross-sectional view of the cooling section, and the displacer 1 has a built-in regenerator 3 that serves as the cooling section of the refrigerator.
Cylinder 5. It has fins 15 and a vacuum layer 16 for increasing the heat transfer area of the cylinder 5, and is composed of a cooling tank 19 attached to a cooling section. The cooling tank 19 is filled with a liquid medium 17, and the liquid medium 17 contains the object to be cooled 1.
A container 41120 containing 8 is soaked. Due to the expansion of the working medium inside the expansion space 4 and the reciprocating movement of the displacer 1, the cylinder 5 becomes a cooling section.

Liquid medium 1 first comes into contact with the cylinder 5 wall and the fins 15
7. Cool. The temperature of the liquid medium 17 gradually becomes equal to that of the cylinder 5 due to convection and heat conduction.
The cooling time is determined by the relationship between the heat capacity of the refrigerator and the cooling capacity of the refrigerator. As cooling of the liquid medium 17 progresses, the object to be cooled 1
8 will be cooled or frozen through a container 20.

The liquid medium 17 may be one that does not solidify at the required cooling temperature or freezing temperature of the object 18 to be cooled. It is only necessary to determine the filling amount, and in particular, if the amount of the object to be cooled 18 is small, it will be smaller than before and can be frozen quickly. Furthermore, if the cooling tank 19 is made of a material that can withstand the pressure difference between the vacuum layer 16 and the atmospheric pressure and has low conductivity, it is possible to reduce the amount of heat intrusion.

Figure 3 is an example in which no sliding material is provided on the outer periphery of the porous metal member, and only the displacer portion is taken out and shown. It has a structure in which it is attached to a non-metallic sliding member 2 carved with.

The outer diameter of the porous metal member 3 is made slightly smaller than the outer diameter of the non-metallic sliding member 2 in order to avoid any sliding trouble with the cylinder 5 portion. Naturally, in order to prevent the working gas from passing between the porous metal member 3 and the cylinder, the flow path resistance in the gap between the cylinder and the cylinder is made larger than the flow path resistance inside the porous metal member 3. Needless to say, the external dimensions should be set so as to satisfy the following. Even a displacer with a simple structure like the one in this embodiment can sufficiently fulfill the role of a regenerator in the reverse Stirling cycle by using the porous metal member 3.

FIG. 4 shows an embodiment in which no sliding material is provided at both ends and the outer periphery of the porous metal member. However, in order to improve the sliding characteristics with the cylinder 5, piston rings 15 are installed near both ends.In this embodiment, the displacer 1 and the regenerator are completely integrated, and the assembly is easy. Work can be simplified. In addition, when forming a porous metal material into a displacer that also serves as a regenerator, there is no functional problem at all even if the ventilation holes on the outer periphery are blocked due to processing. Since it is possible to prevent the coolant from flowing into the gap between the coolant 3 and the cylinder 5, a decrease in the cool storage capacity can be prevented.

FIG. 5 shows an embodiment of the cooling section structure of a Stirling refrigerator used for cooling computer elements. The structure of the refrigerator part is the same as that of the embodiment shown in FIG. 2, and the cooling tank 19 having a vacuum layer 16 is also the same. However, unlike applications in the field of biological science, the single cooled body 18' rarely comes in and out, so it does not come into contact with the end of the cylinder 5, which is the cooling part of the refrigerator. It is. The signal line 21 of the object to be cooled 18' is connected to the outside through a signal terminal 23 attached to a terminal seat 22 attached to the cooling tank 19 and separating the inside of the cooling tank 19 from the atmosphere. In the case of this embodiment, the object to be cooled 18' is directly attached to the cooling part of the refrigerator and is surrounded by the vacuum layer 16, so that a sufficient cooling effect can be obtained even without the liquid medium 17. Can be done. however.

If a trouble occurs on the refrigerator side and the refrigerator is stopped during calculation by the computer, unlike in the field of biological sciences, a sudden rise in temperature cannot be avoided because the object to be cooled 18' itself is a heating element. Therefore, as in the first embodiment, the liquid medium 17 is sealed in the cooling tank 19, and even when the system is stopped, the cooling effect due to the heat capacity of the liquid medium 17 can be utilized to prevent a sudden temperature rise. Furthermore, in this embodiment, since the cooling tank 19 is a closed container, it is filled with a medium having an evaporation temperature at the same level as the required cooling temperature, or at a slightly higher level, and the cooling effect due to the latent heat of evaporation prevents a significant temperature rise during shutdown. It is also possible to prevent this.

Another embodiment is shown in FIG. 6. This embodiment is applied when it is desired to further cool only a part of the sample in a system such as a frozen storage. Unlike the embodiment, the atmosphere outside the cooling tank 24 is at the temperature inside the frozen storage, so the influence of the intruding heat is not significant.Therefore, the cooling tank 24 is not provided with a vacuum layer for heat insulation.

Of course, it goes without saying that by providing a vacuum layer, the cooling effect of the refrigerator can be further enhanced.

In the case of this embodiment, if the object to be cooled 25 can be placed directly into the cooling layer 24, it can be brought into contact with the cylinder 5, which is a cooling section, so that a better cooling effect can be expected.

〔Effect of the invention〕

According to the invention, a reciprocating movement of the displacer.

A cooling tank is attached to a cooling section of a cryogenic refrigerator in which cooling capacity is obtained at the end of the cylinder by the expansion of a working medium in an expansion space composed of a displacer and a cylinder,
Furthermore, the cooling tank was filled with a liquid medium. As a result, the heat transfer distance between the cooling part of the refrigerator and the object to be cooled can be shortened, and the liquid medium filled in the tank can act as a heat conduction and cylinder.

By selecting a material that communicates well with the object to be cooled, rapid cooling or freezing becomes possible. Also.

The effect can be further improved by making the end of the cylinder, which serves as the cooling part, have a twin structure to increase the heat transfer area.

Furthermore, since the heat and weight of the medium can be increased by turning it into a liquid, even if there is a problem such as a power outage, the temperature of the object to be cooled will not rise significantly.

By configuring the cooling tank as a vacuum container, there is an effect of reducing intrusion heat. ′ゞ

[Brief explanation of the drawing]

Fig. 1 is a new view of a cryogenic refrigerator, Fig. 2 is a sectional view showing an embodiment of the present invention and the cooling section structure of a cryogenic refrigerator used in the bioscience field, and Fig. 3 is a new view of the cryogenic refrigerator. FIG. 4 is a sectional view of the displacer section. A cross-sectional view of another embodiment of the displacer section, FIG. 5 is a cross-sectional view of one embodiment when used for semiconductor cooling, and FIG.
FIG. 3 is a cross-sectional view of another embodiment of the invention. 1...Displacer, 5...Cylinder, 6...
Expansion space, 16... Vacuum chamber, 17... Liquid medium, 1
8.18'/θ.../i Bird Space 2nd Massage l...Ice Ashi-Sa

Claims (1)

[Claims] 1. An expansion space is formed by a regenerator, a displacer, and a cylinder surrounding it, and the cylinder end is 1. A cooling unit structure for a cryogenic refrigerator, which is configured to obtain cooling capacity at the cylinder, and is characterized in that a container having a space is provided in contact with the tip of the cylinder. 2. The cooling unit structure of a cryogenic refrigerator according to claim 1, wherein a vacuum layer is formed around the outer periphery of the container attached to the tip of the cylinder. structure. 3. In the cooling part structure of the cryogenic cooler as set forth in claims 1 and 2, of the cylinder surrounding the displacer, the distal end portion from the bottom dead center of the displacer is connected to the container. A cooling section structure of a cryogenic refrigerator characterized by being configured in a space of. 4. In the cooling unit structure of a cryogenic refrigerator as set forth in claim 3, the tip portion of the cylinder configured in the space of the container has a finned structure. Cooling section structure. 5. In the cooling part structure of a cryogenic refrigerator as set forth in claims 1, 2, 3, and 4, a liquid medium is sealed in the space attached to the cylinder part. The cooling part temperature of a cryogenic refrigerator characterized by: 6. In the cooling section structure of a cryogenic refrigerator as set forth in claim 5, the cooling effect is achieved by immersing the object to be cooled in whole or in part in a liquid medium sealed in the space. A cooling section structure of a cryogenic refrigerator characterized by: 7. In the cooling section structure of a cryogenic refrigerator as set forth in claims 5 and 6, the freezing temperature of the enclosed medium is lower than the required cooling temperature of the object to be cooled. Cooling section structure of low temperature refrigerator.