CN214149641U - A measurement structure and refrigeration detector for toper dewar cold loss - Google Patents

Abstract

The utility model relates to a measurement structure for toper dewar cold loss, including the casing of mountable on the toper dewar, still include the liquid bearing cavity that can pour into the liquid nitrogen into, liquid bearing cavity partly arranges in the airtight cavity of casing, liquid bearing cavity another part is located outside the casing, just liquid bearing cavity is located tip in the casing is for can give the confession liquid end that the toper dewar supplied liquid, liquid bearing cavity's outer wall with the air heat insulation layer has between the inner wall of casing. Still provide a refrigeration detector, including the toper dewar, still include foretell a measurement structure for toper dewar cold loss, the casing is installed the heavy-calibre terminal surface department of toper dewar. The utility model discloses an use the air heat insulation layer, can reduce the cold volume loss of liquid nitrogen itself, and adopt sealed design, can make the cold head keep at the liquid nitrogen temperature, cold finger maintains certain temperature gradient to dewar cold loss under the simulation actual operating condition improves the accuracy of cold loss test.

Description

A measurement structure and refrigeration detector for toper dewar cold loss

Technical Field

The utility model relates to a low temperature and vacuum engineering technical field specifically are a measurement structure and refrigeration detector for toper dewar cold loss.

Background

The rapid refrigerator type throttling refrigeration detector mainly comprises an open type conical throttling refrigeration device and a conical Dewar, has the advantages of rapid starting, small volume, good reliability and the like, and is widely applied to infrared guidance. The conical Dewar is used for being matched with the open type conical throttling refrigerator, is an important component of the detector, and provides a low-temperature vacuum environment for the infrared chip. The cold loss is an important index for evaluating the performance of the Dewar, and the index is used for measuring the cold loss of the cold head part at low temperature through cold finger heat conduction or radiation to the atmosphere and the like. When the cold loss is too large, the temperature of the chip cannot be reduced to the working temperature, and the performance of the detector is reduced or even the detector cannot work. Dewar cold loss is generally tested by liquid nitrogen weighing method. And pouring liquid nitrogen into the Dewar cold finger, placing the Dewar on a precision electronic scale, acquiring a mass-time curve of the liquid nitrogen, and calculating the Dewar cold loss by combining the latent heat of the liquid nitrogen.

In the prior art, more column-type cold finger dewars suitable for Stirling refrigerators, linear refrigerators and the like are directly poured with liquid nitrogen and used for measuring the cold loss by a liquid nitrogen weighing method. For the conical cold finger dewar matched with the rapid throttling refrigerator, the axial length of the conical dewar is shorter, and the heat conduction loss is large; the opening area is large, the area of the cold plate is small, and the heat convection loss of the liquid nitrogen and the air is far greater than the cold quantity conducted by the cold plate and the liquid nitrogen. Therefore, the cold loss of the tapered dewar can not be accurately tested by directly pouring liquid nitrogen and using a liquid nitrogen weighing method.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a partial defect among the prior art can be solved at least to a measurement structure and refrigeration detector for toper dewar cold loss.

In order to achieve the above object, the embodiment of the present invention provides the following technical solutions: the utility model provides a measurement structure for toper dewar cold loss, includes the casing of mountable on the toper dewar, still includes the liquid bearing cavity that can pour into the liquid nitrogen, liquid bearing cavity partly arranges in the airtight cavity of casing, liquid bearing cavity another part is located outside the casing, just liquid bearing cavity is located tip in the casing is for can giving the confession liquid end that the toper dewar supplied liquid, liquid bearing cavity's outer wall with the air heat insulation layer has between the inner wall of casing.

Furthermore, the end face of the shell, which is opposite to the liquid supply end, is provided with an opening, and the opening of the shell is plugged with a cover plate.

Further, the cover plate is tightly connected with the shell through a first sealing ring.

Further, the first sealing ring is a metal sealing ring.

Further, the bottom of the shell close to the liquid supply end is provided with a conical sealing surface which can be matched and connected with the conical surface of the conical Dewar, and the conical sealing surface is tightly connected with the conical surface of the conical Dewar through a sealing assembly.

Further, the seal assembly comprises a seal groove formed by recessing the conical seal surface and a second seal ring arranged in the seal groove.

Further, the second sealing ring is an indium wire sealing ring.

The embodiment of the utility model provides another kind of technical scheme: the utility model provides a refrigeration detector, includes the toper dewar, still includes foretell a measurement structure that is used for the toper dewar cold loss, the casing is installed the heavy-calibre terminal surface department of toper dewar.

Further, the toper dewar includes the cold finger of toper dewar, locates the dewar cold head and the shroud of the small-bore terminal surface department of the cold finger of dewar the dewar cold finger with the dewar shell of dewar cold head, supply the liquid end and extend to the dewar cold head department.

Further, the housing is connected with the tapered dewar by a screw.

Compared with the prior art, the beneficial effects of the utility model are that: through using the air heat insulating layer, can reduce the cold volume loss of liquid nitrogen itself, and adopt sealed design, can make the cold head keep at the liquid nitrogen temperature, cold finger maintains certain temperature gradient to the dewar cold loss under the simulation actual operating condition improves the accuracy of cold loss test.

Drawings

Fig. 1 is a schematic view of a measurement structure for the cold loss of a tapered dewar according to an embodiment of the present invention, which is cooperatively connected with the tapered dewar;

in the reference symbols: 1-cover plate, 2-metal sealing ring, 3-liquid bearing cavity, 4-shell, 5-screw, 6-conical sealing surface, 7-indium wire, 8-Dewar cold finger, 9-Dewar cold head, 10-Dewar shell; 11-insulating layer of air.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Referring to fig. 1, an embodiment of the present invention provides a measurement structure for conical dewar cold loss, including a housing mountable on a conical dewar and a liquid-holding cavity 3 capable of being filled with liquid nitrogen, a part of the liquid-holding cavity 3 is disposed in a sealed chamber of the housing, another part of the liquid-holding cavity 3 is disposed outside the housing, and an end portion of the liquid-holding cavity 3 disposed in the housing is a liquid supply end capable of supplying liquid to the conical dewar, and an air heat insulation layer 11 is disposed between an outer wall of the liquid-holding cavity 3 and an inner wall of the housing. In this embodiment, it has the air heat insulation layer 11 to hold between the outer wall of sap cavity 3 and the inner wall of casing, certain interval has between the inner wall of sap cavity 3 and casing promptly, so in airtight cavity, because the cooling of liquid nitrogen, the cavity pressure reduces and forms negative pressure seal, the air flow in the cavity reduces, the liquid nitrogen in the sap cavity 3 is heat-conduction with the cold volume transmission mode of atmospheric environment, because air heat conduction thermal resistance is big again, be equivalent to having increased one deck air heat insulation layer 11 outside the sap cavity 3, thereby the cold volume loss of the interior liquid nitrogen of sap cavity 3 that significantly reduces. Preferably, what adopt is that liquid-bearing column provides liquid-bearing chamber 3, and this liquid-bearing column is rectangular form, and relative cavity in the casing, its diameter is little, and liquid nitrogen pours into liquid-bearing chamber 3 in from the entrance that liquid-bearing chamber 3 is located outside the casing into, and its confession liquid end supplies liquid nitrogen to the toper dewar, and liquid-bearing chamber 3's high design has guaranteed that whole structure bears sufficient liquid nitrogen in order to cool off the test dewar, and the opening diameter is little, and liquid nitrogen and atmospheric environment's convection heat transfer loss is less, promotes measurement accuracy.

In order to optimize the above scheme, please refer to fig. 1, an end surface of the housing opposite to the liquid supply end has an opening, and the opening of the housing is plugged with a cover plate 1. Preferably, the cover plate 1 is tightly connected with the housing through a first sealing ring. The plugging needs to be sealed and plugged, so a first sealing ring is used for sealing, the first sealing ring is used for eliminating a gap between the cover plate 1 and the shell, and specifically, the first sealing ring can be a metal sealing ring 2, such as an indium wire sealing ring, so that the sealing performance at low temperature can be ensured.

As an optimized solution of the embodiment of the present invention, please refer to fig. 1, a conical sealing surface 6 capable of being connected with the conical surface of the conical dewar is disposed at the bottom of the casing close to the liquid supply end, and the conical sealing surface 6 is tightly connected with the conical surface of the conical dewar through a sealing assembly. In this embodiment, the tapered sealing surface 6 may be fitted to a tapered cold finger of a dewar to allow the two to fit closely. Similarly, a sealing assembly is required to seal after fitting to ensure the accuracy of measurement.

In order to further optimize the above solution, referring to fig. 1, the sealing assembly includes a sealing groove formed by recessing on the conical sealing surface 6, and a second sealing ring disposed in the sealing groove. In this embodiment, the seal assembly includes two parts, one is a seal groove formed on the tapered seal surface 6, and the other part is a second seal ring, where the second part is distinguished from the first part for convenience of description, and no other limitation is implied. The sealing effect is achieved by arranging the groove on the conical sealing surface 6 and then arranging the sealing ring in the groove, the sealing ring can be prevented from sliding down by selecting the groove to arrange, the sealing ring has the function of eliminating a gap between the conical sealing surface 6 and the conical surface of the conical Dewar and is eliminated in an extrusion mode, and the sealing principle of the first sealing ring is also the same. Preferably, the second sealing ring is an indium wire sealing ring, and the sealing of the low-temperature cold loss test structure and the Dewar cold finger 8 can be guaranteed by the indium wire sealing ring. Preferably, a plurality of sealing grooves and a plurality of second sealing rings can be arranged, and each sealing groove is arranged along the upward extending direction of the inclination of the conical sealing surface, so that a better sealing effect can be achieved.

Placing the cold loss test tool and the dewar on a precision electronic balance for weighing, recording a time-mass curve, and calculating the dewar cold loss according to the following formula:

Q＝1000×r×△m/△t

wherein r is 197.6J/g, latent heat of vaporization of liquid nitrogen; Δ m is the change in weight of liquid nitrogen in g; delta t is the time required for the weight change of the liquid nitrogen, and the unit is s; q is Dewar cold loss in mW.

Referring to fig. 1, an embodiment of the present invention provides a refrigeration detector, including a conical dewar and the above-mentioned measuring structure for the cold loss of the conical dewar, wherein the shell is installed at a large-caliber end surface of the conical dewar. In this embodiment, through using foretell measurement structure, it has the air heat insulation layer 11 to hold between the outer wall of sap cavity 3 and the inner wall of casing, certain interval has between the inner wall of sap cavity 3 and casing promptly, so in airtight cavity, because the cooling of liquid nitrogen, cavity pressure reduces and forms negative pressure seal, the air flow in the cavity reduces, the liquid nitrogen in the sap cavity 3 is heat-conduction with the cold volume transmission mode of atmospheric environment, because air heat conduction thermal resistance is big again, be equivalent to increased one deck air heat insulation layer 11 outside the sap cavity 3, thereby the cold volume loss of the interior liquid nitrogen of the sap cavity 3 that significantly reduces. Preferably, what adopt is that liquid-bearing column provides liquid-bearing chamber 3, and this liquid-bearing column is rectangular form, and relative cavity in the casing, its diameter is little, and liquid nitrogen pours into liquid-bearing chamber 3 in from the entrance that liquid-bearing chamber 3 is located outside the casing into, and its confession liquid end supplies liquid nitrogen to the toper dewar, and liquid-bearing chamber 3's high design has guaranteed that whole structure bears sufficient liquid nitrogen in order to cool off the test dewar, and the opening diameter is little, and liquid nitrogen and atmospheric environment's convection heat transfer loss is less, promotes measurement accuracy.

As an optimization scheme of the embodiment of the present invention, please refer to fig. 1, the tapered dewar includes a tapered dewar cold finger 8, a dewar cold head 9 disposed at a small-caliber end face of the dewar cold finger 8, and a dewar housing 10 covering the dewar cold finger 8 and the dewar cold head 9, and the liquid supply end extends to the dewar cold head 9. In this embodiment, the liquid supply end is extended to the dewar cold head 9 during assembly, so that the liquid nitrogen in the liquid bearing cavity 3 is only contacted with the dewar cold head 9, but not contacted with the dewar cold finger 8, thereby maintaining the low temperature of the cold head and the temperature gradient of the cold finger, simulating the loss of cold quantity of the cold head under the actual work of the detector, and improving the accuracy of the cold loss test.

To further optimize the above solution, referring to fig. 1, the housing is connected to the tapered dewar by screws 5. In the embodiment, the measuring structure is connected with the conical Dewar through the screw 5, so that the installation is simple and convenient.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (10)

1. A measurement structure for conical dewar cold loss comprising a housing mountable on a conical dewar, characterized in that: still include the liquid bearing chamber that can pour into the liquid nitrogen, liquid bearing chamber some is arranged in the airtight cavity of casing, liquid bearing chamber another part is located outside the casing, just liquid bearing chamber is located tip in the casing is for can giving the confession liquid end that the toper dewar supplied liquid, liquid bearing chamber's outer wall with air heat insulation layer has between the inner wall of casing.

2. The measurement structure for tapered dewar cold loss according to claim 1, wherein: the end face of the shell, which is opposite to the liquid supply end, is provided with an opening, and the opening of the shell is plugged with a cover plate.

3. The measurement structure for tapered dewar cold loss according to claim 2, wherein: the cover plate is tightly connected with the shell through a first sealing ring.

4. A measurement structure for tapered dewar cold loss according to claim 3 wherein: the first sealing ring is a metal sealing ring.

5. The measurement structure for tapered dewar cold loss according to claim 1, wherein: the bottom of the shell close to the liquid supply end is provided with a conical sealing surface which can be matched and connected with the conical surface of the conical Dewar, and the conical sealing surface is tightly connected with the conical surface of the conical Dewar through a sealing assembly.

6. The measurement structure for tapered dewar cold loss according to claim 5, wherein: the sealing assembly comprises a sealing groove formed by sinking the conical sealing surface and a second sealing ring arranged in the sealing groove.

7. The measurement structure for tapered dewar cold loss according to claim 6, wherein: the second sealing ring is an indium wire sealing ring.

8. A refrigeration probe comprising a tapered dewar characterized by: further comprising a measurement structure for the cold loss of a tapered dewar as claimed in any one of claims 1 to 7, said housing being mounted at the large caliber end face of said tapered dewar.

9. The refrigerant detector as set forth in claim 8, wherein: the conical dewar comprises a conical dewar cold finger, a dewar cold head arranged on the small-caliber end face of the dewar cold finger and a cover cap, the dewar cold finger and the dewar shell of the dewar cold head, and the liquid supply end extends to the dewar cold head.

10. The refrigerant detector as set forth in claim 8, wherein: the shell is connected with the conical Dewar through a screw.

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