JPH0152670B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low temperature cooling device generally referred to as a cryostat, and particularly relates to an improvement of a low temperature cooling device having a double dewar structure.

A low-temperature cooling device with a double dewar structure is widely used for physical property and optical measurements at low temperatures, or for cooling type photoelectric conversion devices such as infrared detectors and infrared lasers.

As shown in Fig. 1, a conventional low-temperature cooling device with such a configuration has a metal airtight double cylindrical tank structure consisting of an outer cylindrical tank 1 made of, for example, stainless steel and an inner cylindrical tank 2 with a flange 3. None, the outer cylinder tank 1
A space 5 between the inner cylindrical tank 2 and the inner cylindrical tank 2 is evacuated through an exhaust pipe 4 and kept in a vacuum to insulate it from external heat. A refrigerant 11 such as liquid nitrogen or liquid oxygen is stored in the inner cylindrical tank 2, and an object to be cooled 6 consisting of, for example, an infrared detection element disposed on the vacuum side tank wall of the inner cylindrical tank 2 is placed in the inner cylindrical tank 2. A method of cooling through the second tank wall is used. 7 is an optical window.

By the way, in the above-mentioned structure, as shown in the figure, in order to reduce heat conduction between the flange 3 having a large heat capacity and the inner cylindrical tank 2, the inner cylindrical tank 2 is made thin and long. Thin tube part 8
An airtight hermetically sealed connection is made between the flange 3 and the connecting pipe portion 9 on the flange 3 side by, for example, heli-arc welding or soldering. Therefore, since the inner cylindrical tank 2 is suspended in the outer cylindrical tank 1 from the tip connection part 10, the low-temperature cooling device with such a structure has low mechanical strength against vibrations and shocks during transportation. was extremely weak. That is, due to vibrations and impacts during transportation, the heavy inner tubular tank 2 swings around the tip connecting portion 10 as a fulcrum, and due to this, each of the tip connecting portion 10 or the inner tubular tub 2 The disadvantage was that the connection part was easily damaged and the device lost its function.

An object of the present invention is to solve the above-mentioned conventional drawbacks by screwing a screw with a needle into the bottom of the outer tubular tank such that it can freely come into contact with the bottom of the inner tubular tub, and by screwing the screw together, the inner tubular tubular The purpose of the present invention is to provide a new low-temperature cooling device in which the bottom of the tank is engaged with and fixed to the bottom of the outer cylinder tank via a needle-equipped screw, and the handling such as transportation is facilitated.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a longitudinal cross-sectional view showing an embodiment of the low temperature cooling device according to the present invention, and parts equivalent to those in FIG. 1 are given the same reference numerals.

In the figure, numerals 1 and 2 are an outer cylindrical tank and an inner cylindrical tank with a flange 3 made of metal such as stainless steel. It is sealed airtight by screwing. Reference numeral 5 denotes a space that is evacuated from the exhaust pipe 4 and becomes an adiabatic vacuum. 11
numeral 6 represents a coolant such as liquid nitrogen, numeral 6 represents an object to be cooled such as an optical measurement sample or an infrared detection element, and numeral 7 represents an optical window.

However, in this embodiment, when transporting the cryogenic cooling device having the double cylindrical tank structure, the inner cylindrical tank 2 constructed in the outer cylindrical tank 1 is prevented from swinging due to vibrations or shocks during transportation. In order to prevent this, for example, a conical engagement groove 21 is provided at the bottom of the inner cylindrical tank 2, and a screw hole 22 is provided at the bottom of the outer cylindrical tank 1 facing the engagement groove 21, and the screw hole 22 A screw 23 with a needle 24 is screwed into the bottom engagement groove 21 of the inner cylindrical tank 2 so as to be able to freely come into contact therewith. Furthermore, in order not to impair the vacuum tightness between the outer tubular tank 1 and the inner tubular tub 2 due to the screw hole 22, a bellows 25 that can be expanded and contracted from the side of the needle 24 to the periphery of the screw hole 22 is provided as shown in the figure. It is attached to the vacuum side and is isolated from the vacuum side. For this reason, a packing 26 made of Teflon or the like is interposed so that the needle 24 does not rotate following the rotation of the screw 23.

Therefore, when transporting the low-temperature cooling device configured in this manner, the needle 2 is inserted into the bottom engagement groove 21 of the inner cylindrical tank 2 by turning the screw 23 with the needle 24.
4 are brought into contact and engaged and fixed, the inner cylindrical tank 2 will not swing due to vibrations, impacts, etc. during transportation, and safe transportation will be possible. Note that when using this device, the needle 24 is
If it is lowered so that it is not in contact with the bottom of the inner cylindrical tank 2, it will be in the same usage state as the conventional one.

FIG. 3 is a sectional view of a main part showing another embodiment of the needle-equipped screw structure of a low-temperature cooling device according to the present invention, and the same parts as in FIG. 2 are given the same reference numerals. The embodiment shown in FIG. 3 is different from that shown in FIG. 2 because one end of the screw 23 is made into a cylindrical shape so that the needle 24 is not rotated by the rotation of the screw 23. As shown in the figure, the needle 24 is held in a floating manner by interposing a slippery packing 32 made of Teflon or the like. It is clear that the structure of this embodiment can also achieve the same object as the embodiment shown in FIG. 2 above.

FIG. 4 is a sectional view of a main part showing another embodiment of the needle-equipped screw structure of a low-temperature cooling device according to the present invention, and the same parts as in FIG. 2 are given the same reference numerals. The embodiment shown in FIG. 4 differs from that shown in FIG.
The structure is such that a small thrust bearing 41 is interposed between the two. With the configuration of this embodiment, the same objective as that of the embodiment shown in FIG. 2 can be easily achieved.

As is clear from the above description, according to the present invention, the bottom of the inner tank in the outer tank can be easily fixed with a screw with a needle attached to the bottom of the outer tank. The inner cylindrical tank no longer swings while the device is being transported, unlike in the past, and the ease of handling the device is improved. Therefore, it is extremely advantageous to apply it to various low-temperature cooling devices (cryostats) having a double dewar structure. Particularly, it can be applied to an infrared detector having a double dewar structure, an infrared laser device, etc., and has a very remarkable effect.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view for explaining a conventional low-temperature cooling device, FIG. 2 is a vertical cross-sectional view showing an embodiment of the low-temperature cooling device according to the present invention, and FIG. 3 is a vertical cross-sectional view for explaining a low-temperature cooling device according to the present invention. FIG. 4 is a cross-sectional view of a main part showing still another embodiment of a threaded structure with a needle in a low-temperature cooling device according to the present invention. In the figure, 1 is an outer cylindrical tank, 2 is an inner cylindrical tank, 21 is an engaging groove, 22 is a screw hole, 23 is a screw, 24 is a needle, 25 is a bellows, 26 and 32 are packing, 31 is a rotating ball, and 41 indicates a thrust bearing.

Claims (1)

[Claims] 1. Double cylindrical tank structure consisting of an inner cylindrical tank that houses a liquid refrigerant inside and cools objects to be cooled through the tank wall, and an outer cylindrical tank, with a vacuum-tight configuration between the inner and outer cylindrical tanks. In the low-temperature cooling device, a screw with a needle is screwed into the bottom of the outer cylindrical tank so as to be able to freely come into contact with the bottom of the inner cylindrical tank, and by screwing the screw together, the bottom of the inner cylindrical tank is connected to the bottom of the inner cylindrical tank through the screw with the needle. 1. A low-temperature cooling device characterized by being engaged and fixed to the bottom of an outer cylindrical tank.