Rapid cooling Dewar assembly and infrared detector

Abstract

The invention provides a rapid cooling Dewar assembly. The rapid cooling Dewar assembly comprises a Dewar shell, a cold finger and a cold disc, wherein the cold finger and the cold disc are arranged in the Dewar shell; the cold finger comprises a cold finger air cylinder backflow section and a cold finger air cylinder cold end, the cold finger air cylinder cold end is in a conical funnel shape, the small-caliber end of the cold finger air cylinder cold end is connected with the cold finger air cylinder backflow section, and the cold disc is installed at the large-caliber end of the cold finger air cylinder cold end. According to the Dewar assembly, the cold end of the cold finger air cylinder is designed to be of the conical funnel structure, the fluid disturbance of cold fluid at the cold end is increased through the structural design, the residence time of the cold fluid in the cold finger is prolonged, and therefore the cooling capacity of the cold fluid can be fully utilized, heat exchange between the cold fluid and the cold disc is enhanced, and the cooling effect of the Dewar cold head is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared detectors, and in particular relates to a fast-cooling Dewar component and an infrared detector. Background Art

[0002] Infrared detectors are widely used in infrared thermal imagers, infrared forward and night vision, missile guidance, space applications and other civil and military equipment. Dewar components provide a low-temperature, vacuum working environment for infrared detectors and are important components of infrared detectors. Dewar uses its heat preservation principle and is widely used in vacuum packaging of infrared detector chips. Its structure is divided by function, including optical system, vacuum system, cold chain system, etc. Each functional system works together to provide a low-temperature, vacuum insulation environment for the chip.

[0003] Based on the needs of the 80K rapid cooling project, there are high requirements for the heat transfer of the Dewar cold head, but the existing Dewar structure cannot meet the needs of rapid cooling effect of the cold head. Summary of the invention

[0004] The purpose of the present invention is to provide a Dewar assembly with rapid cooling, which can at least solve some of the defects existing in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A rapid cooling dewar assembly comprises a dewar shell, and a cold finger and a cold plate in the dewar shell; the cold finger comprises a cold finger cylinder reflux section and a cold finger cylinder cold end, the cold finger cylinder cold end is in a conical funnel shape, the small-diameter end of the cold finger cylinder cold end is connected to the cold finger cylinder reflux section, and the cold plate is installed at the large-diameter end of the cold finger cylinder cold end.

[0007] Furthermore, the above-mentioned rapid cooling Dewar assembly also includes a refrigerator liquid outlet component for discharging cold fluid, the refrigerator liquid outlet component extends into the cold finger and the liquid outlet end is located in the cold end of the cold finger cylinder.

[0008] Furthermore, the liquid outlet component of the refrigerator includes a liquid outlet pipe and a fixed block, the fixed block is located at the bottom of the reflux section of the cold finger cylinder, and the liquid outlet pipe passes through the fixed block and the reflux section of the cold finger cylinder in sequence and extends to the cold end of the cold finger cylinder.

[0009] Furthermore, a throttling element is provided at the liquid outlet end of the liquid outlet pipe.

[0010] Furthermore, the fixing block is a petal-type clamping ring structure.

[0011] Furthermore, a stagnation zone is formed on the disk surface of the cold disk facing the cold end of the cold finger cylinder, and a plurality of grooves are arranged at intervals in the stagnation zone. A plurality of ribs protruding toward one side of the cold finger are also arranged on the disk surface of the cold disk facing the cold end of the cold finger cylinder, and a plurality of the ribs are located outside the stagnation zone.

[0012] Furthermore, a cold shield is provided in the Dewar shell, and the cold shield includes a conical barrel section and a prismatic barrel section connected from top to bottom, and the bottom of the prismatic barrel section has a connecting portion extending radially outward, and the connecting portion has a group of relatively distributed first connecting edges and a group of relatively distributed second connecting edges, and the radial width of the first connecting edge along the prismatic barrel section is smaller than the radial width of the second connecting edge along the prismatic barrel section.

[0013] Furthermore, the Dewar housing comprises a detachably connected cold finger housing and a window frame, the cold finger is placed in the cold finger housing, the cold plate and the cold shield are placed in the window frame, and a window piece is provided on the top of the window frame.

[0014] Furthermore, the cold finger shell has a containing space for accommodating a getter at a location corresponding to the cold end of the cold finger cylinder, and the cold finger shell has an exhaust pipe at a location corresponding to the reflux section of the cold finger cylinder.

[0015] In addition, the present invention also provides an infrared detector, including the above-mentioned rapid cooling Dewar assembly.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) In the rapid cooling Dewar assembly provided by the present invention, the cold end of the cold finger cylinder is designed as a conical funnel structure. This structural design increases the fluid disturbance of the cold fluid at the cold end and prolongs the residence time of the cold fluid in the cold finger, thereby fully utilizing the cold capacity of the cold fluid, strengthening the heat exchange between the cold fluid and the cold plate, and improving the cooling effect of the Dewar cold head.

[0018] (2) In the rapid cooling Dewar assembly provided by the present invention, the cold shield is designed as an integrated structure that is wide at the bottom and narrow at the top, and the four sides of the lower part are cut to reduce the thermal mass of the cold shield and reduce the cold loss on the heat conduction path of the cold shield.

[0019] (3) In the rapid cooling Dewar assembly provided by the present invention, rib columns and groove structures are designed on the surface of the cold plate to destroy the film heat exchange between the cold fluid and the cold plate, thereby enhancing the convective heat transfer coefficient between the cold plate and the cold fluid, thereby accelerating the heat transfer speed and reducing the heat transfer time.

[0020] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a structural schematic diagram of the Dewar assembly of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the cold shield in the Dewar assembly of the present invention;

[0023] Figure 3 It is a schematic diagram of the structure of the cold plate in the Dewar assembly of the present invention;

[0024] Figure 4 It is a structural schematic diagram of the cold end of the cold finger cylinder in the Dewar assembly of the present invention;

[0025] Figure 5 It is a structural schematic diagram of the return flow section of the cold finger cylinder in the Dewar assembly of the present invention;

[0026] Figure 6 It is a schematic diagram of the structure of the fixed block of the liquid outlet component of the refrigerator in the Dewar assembly of the present invention;

[0027] Figure 7 This is a simulation effect diagram of the pressure distribution inside the cold finger of the Dewar assembly of the present invention;

[0028] Figure 8 This is a simulation effect diagram of the flow velocity distribution in the cold finger of the Dewar assembly of the present invention;

[0029] Fig. 9 It is a simulation effect diagram of the flow velocity distribution in the cold finger of the Dewar assembly of the present invention.

[0030] Explanation of the reference numerals in the accompanying drawings: 1. cold finger housing; 2. cold finger cylinder reflux section; 3. getter; 4. cold finger cylinder cold end; 5. lead ring; 6. cold plate; 7. ceramic substrate; 8. cold screen; 9. window frame; 10. window sheet; 11. liquid outlet pipe; 12. exhaust pipe; 13. fixing block; 14. pressing block; 15. conical cylinder section; 16. prismatic cylinder section; 17. connecting part; 18. annular flange; 19. groove; 20. rib column; 21. first connecting edge; 22. second connecting edge. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0035] Embodiment 1:

[0036] like Figure 1 , Figure 4 and Figure 5 As shown, this embodiment provides a rapid cooling dewar assembly, including a dewar shell, a cold finger and a cold plate 6, wherein the cold finger and the cold plate 6 are arranged inside the dewar shell, the cold finger includes a cold finger cylinder reflux section 2 and a cold finger cylinder cold end 4, the cold finger cylinder cold end 4 is in a conical funnel shape, the small-diameter end of the cold finger cylinder cold end 4 is connected to the cold finger cylinder reflux section 2, and the cold plate 6 is installed at the large-diameter end of the cold finger cylinder cold end 4. The cold finger cylinder reflux section 2 can adopt a cylindrical structure with an inner diameter D, and the inner diameter D value depends on the outer diameter of the liquid outlet pipe 11 of the refrigerator liquid outlet component and the design value of the reflux gap. In the present embodiment, the cold fluid generated by the refrigerator enters the cold finger. Since the cold end 4 of the cold finger cylinder is in the shape of a conical funnel, the diameter of the end close to the cold plate 6 is large. Therefore, compared with the existing conventional cylindrical or conical cold finger structure with a small top and a large bottom, the cold finger structure design of the present embodiment can make the cold fluid stay in the cold end 4 of the cold finger cylinder for a longer time, and at the same time, it can also increase the fluid disturbance of the cold fluid in the cold end 4 of the cold finger cylinder, so as to make full use of the cold amount of the cold fluid, improve the utilization efficiency of the cold fluid, strengthen the heat exchange between the cold fluid and the cold plate 6, and thus make the Dewar cold head have a faster cooling effect.

[0037] As a specific implementation, the Dewar assembly of this embodiment also includes a refrigerator liquid outlet component for discharging cold fluid, the refrigerator liquid outlet component extends into the cold finger and the liquid outlet end is located in the cold finger cylinder cold end 4. The cold fluid generated by the refrigerator refrigeration enters the cold finger cylinder cold end 4 of the cold finger through the refrigerator liquid outlet component, exchanges heat with the cold plate 6 at the upper end of the cold finger, and then the cold fluid flows back out of the cold finger through the cold finger cylinder reflux section 2, and so on and so forth, to achieve cooling of the Dewar cold head (cold plate, cold screen). With the Dewar assembly of this embodiment, the refrigerator and the Dewar can be placed separately, and the two only need to be connected through the refrigerator liquid outlet component, so the relative installation position of the Dewar and the refrigerator is more flexible.

[0038] In some embodiments, Figure 1 As shown, the liquid outlet component of the refrigerator includes a liquid outlet pipe 11 and a fixed block 13. The fixed block 13 is located at the bottom of the cold finger cylinder reflux section 2. The liquid outlet pipe 11 passes through the fixed block 13 and the cold finger cylinder reflux section 2 in sequence, and extends to the cold end 4 of the cold finger cylinder. The other end of the liquid outlet pipe 11 is connected to the refrigerator. Specifically, a cold finger flange for connecting to the Dewar shell is provided at the bottom of the cold finger. The fixed block 13 is located in the cold finger flange and connected to the cold finger cylinder reflux section 2. The pressing block 13 is designed to press on the fixed clamp ring 14. The pressing block 14 is a hollow structure and is fixedly connected to the cold finger flange. Optimally, a throttling element is connected to the liquid outlet end of the liquid outlet pipe 11. When working, the gas coming out of the throttling element at the end of the liquid outlet pipe 11 first flows back through the channel between the liquid outlet pipe 11 and the cold finger, and then passes through the gap of the fixed block 13 and the gap in the middle of the pressing block 14 in sequence to be discharged to the external environment.

[0039] Optimized, such as Figure 6 As shown, the fixed block 13 can be designed as a petal-type clamping ring structure. The petal-type structural design can ensure the refrigeration-grade gas refrigeration generated by the throttling element. The pressure difference between the back pressure and the atmospheric pressure after throttling is less than 100 kPa, and the refrigeration temperature reaches the boiling point temperature, avoiding the influence of high back pressure on the refrigeration temperature; further, the fixed block 13 can be designed to be made of low thermal conductivity non-metallic material. The design of low thermal conductivity non-metallic material can effectively reduce the cold loss of low-temperature gas in the liquid outlet pipe 11 through the fixed block 13. The low thermal conductivity non-metallic material can be selected but not limited to peek (polyetheretherketone), polytetrafluoroethylene, etc.

[0040] In a preferred embodiment, the structure of the cold plate 6 is improved at the same time. Figure 3As shown, a concave-convex structure is arranged on the disk surface of the cold plate 6 facing the cold end 4 of the cold finger cylinder; in some embodiments, a stagnation zone is formed on the disk surface of the cold plate 6 facing the cold end 4 of the cold finger cylinder, and a plurality of grooves 19 are arranged at intervals in the stagnation zone, wherein the grooves 19 may be countersunk holes, strip grooves or annular grooves, and the cold plate 6 is usually disc-shaped, and each of the grooves 19 is preferably arranged in the stagnation zone to form a disc shape. Of course, each groove 19 may also be arranged into other shapes according to the actual situation of the cold plate 6; a plurality of ribs 20 protruding toward one side of the cold finger are also provided on the disk surface of the cold plate 6 facing the cold end 4 of the cold finger cylinder, and a plurality of the ribs 20 are located outside the stagnation zone, wherein the ribs 20 may be convex ribs or strip convex ridges, and each rib 20 is arranged to form a multi-circle annular structure. In this embodiment, the rib column 20 is designed on the side of the cold plate 6 for heat exchange with the cold fluid, which is beneficial to strengthening the convective heat exchange between the cold plate 6 and the cold fluid. At the same time, the design of the groove 19 can destroy the film heat exchange between the cold fluid and the cold plate 6 during heat exchange, thereby enhancing the heat exchange between the cold fluid and the cold plate 6, thereby accelerating the heat transfer speed and reducing the heat transfer time.

[0041] Furthermore, an annular flange 18 is provided on one side of the cold plate 6 close to the cold end 4 of the cold finger cylinder, and the annular flange 18 is used to connect with the cold end 4 of the cold finger cylinder. At the same time, the ribs 20 and the grooves 19 on the cold plate 6 are both located in the area enclosed by the annular flange 18.

[0042] In an optional implementation manner, for the infrared detector, a cold shield 8 is further provided in the dewar housing, and the cold shield 8 is mainly used to suppress stray light. In this embodiment, the cold shield 8 is designed as an integrated structure with a wide bottom and a narrow top, and the bottom of the cold shield 8 is widened. Specifically, Figure 1 and Figure 2 As shown, the cold shield 8 includes a conical barrel section 15 and a prismatic barrel section 16 connected from top to bottom, wherein the prismatic barrel section 16 can be formed by cutting the bottom of the conical barrel section 15. Through this structural design, the thermal mass of the cold shield 8 is reduced, and the cold loss on the heat conduction path is reduced; further, the bottom of the prismatic barrel section is designed to have a connecting portion extending radially outward, and the connecting portion 17 is used to connect with the cold plate 6. At the same time, the connecting portion is designed to have a group of relatively distributed first connecting edges 21 and a group of relatively distributed second connecting edges 22, and the radial width of the first connecting edge 21 along the prismatic barrel section 16 is smaller than the radial width of the second connecting edge 22 along the prismatic barrel section 16. In this way, the contact area between the first connecting edge 21 with a smaller extension width in the connecting portion 17 and the cold plate 6 is reduced. By widening the bottom of the cold shield 8 and reducing its contact area with the cold plate 6, the cold loss on the heat conduction path of the cold shield 8 is effectively reduced.

[0043] In an optional embodiment, the Dewar housing includes a detachably connected cold finger housing 1 and a window frame 9, the cold finger is placed in the cold finger housing 1, the cold plate 6 and the cold screen 8 are placed in the window frame 9, and a window sheet 10 is provided on the top of the window frame 9. The cold finger housing 1 has a receiving space for accommodating a getter 3 at a location corresponding to the cold end 4 of the cold finger cylinder, and the getter 3 is installed in the receiving space, and an exhaust pipe 12 is provided on the cold finger housing 1 at a location corresponding to the reflux section 2 of the cold finger cylinder.

[0044] Furthermore, the above-mentioned rapid cooling Dewar assembly also includes a lead ring 5, and the lead ring 5 is arranged between the cold finger housing 1 and the window frame 9.

[0045] The simulation effect analysis of the pressure and flow rate in the cold finger of the Dewar assembly of this embodiment is carried out, wherein the inner diameter of the liquid outlet pipe 11 is designed to be 0.3mm, the outer diameter is 0.5mm, the throttling aperture is 0.08mm, the diameter of the channel 2 of the reflux section of the cold finger cylinder is 2mm, the injection distance is 0.8mm, the cone angle of the cold end 4 of the cold finger cylinder is 120°, the inlet conditions are 30Mpa, 150K, nitrogen, and the outlet conditions are 0.1Mpa, 300K; the simulation effect of the pressure distribution in the cold finger is as follows Figure 7 As shown in Figure 2, the simulation effect of the flow velocity distribution in the cold finger is as follows: Figure 8 and Fig. 9 As shown, Fig. 9 This is the effect picture after magnification.

[0046] Depend on Figure 7 It can be seen that after the high-pressure fluid is ejected through the throttle hole, the pressure decays rapidly to atmospheric pressure in the direction of the flow velocity. Except for the jet section, the pressure in the expansion chamber is uniform. It can be seen that the pressure in the expansion chamber is normal under the structure of the present invention, and there is no problem of excessive back pressure. Figure 8 and Fig. 9 It can be seen that after the fluid is ejected from the throttle hole and flows to the surface of the cold plate 6, the fluid flows along the wall and forms obvious turbulence near the cold end 4 of the cold finger cylinder. The existence of turbulence can significantly improve the heat transfer coefficient of the cold fluid in the expansion chamber, which is beneficial to enhance the convective heat exchange between the cold plate 6 and the cold fluid.

[0047] Embodiment 2:

[0048] This embodiment also provides an infrared detector, including the fast cooling Dewar assembly provided in the above embodiment 1, and the detector chip is packaged on the cold plate 6 of the Dewar assembly. Obviously, the infrared detector also includes a refrigerator and other structures, which is a conventional design in the field and will not be described in detail here.

[0049] Furthermore, the infrared detector further comprises a ceramic substrate 7, and the ceramic substrate 7 is electrically connected to the detector chip. In some embodiments, the detector chip, the ceramic substrate 7 and the cold plate 6 can be arranged in a stacked manner.

[0050] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A rapid cooling Dewar assembly, characterized in that: It includes a dewar shell, and a cold finger and a cold plate in the dewar shell; the cold finger includes a cold finger cylinder reflux section and a cold finger cylinder cold end, the cold finger cylinder cold end is in a conical funnel shape, the small-diameter end of the cold finger cylinder cold end is connected to the cold finger cylinder reflux section, and the cold plate is installed at the large-diameter end of the cold finger cylinder cold end.

2. The rapid cooling Dewar assembly according to claim 1, characterized in that: It also includes a refrigerator liquid outlet component for discharging cold fluid, wherein the refrigerator liquid outlet component extends into the cold finger and the liquid outlet end is located in the cold end of the cold finger cylinder.

3. The rapid cooling Dewar assembly according to claim 2, characterized in that: The liquid outlet component of the refrigerator includes a liquid outlet pipe and a fixed block. The fixed block is located at the bottom of the reflux section of the cold finger cylinder. The liquid outlet pipe passes through the fixed block and the reflux section of the cold finger cylinder in sequence and extends to the cold end of the cold finger cylinder.

4. The rapid cooling Dewar assembly according to claim 3, characterized in that: A throttling element is provided at the liquid outlet end of the liquid outlet pipe.

5. The rapid cooling Dewar assembly according to claim 3, characterized in that: The fixing block is a petal-type clamping ring structure.

6. The rapid cooling Dewar assembly according to claim 1, characterized in that: A stagnation zone is formed on the disk surface of the cold disk facing the cold end of the cold finger cylinder, and a plurality of grooves are arranged at intervals in the stagnation zone. A plurality of ribs protruding toward one side of the cold finger are also arranged on the disk surface of the cold disk facing the cold end of the cold finger cylinder, and a plurality of the ribs are located outside the stagnation zone.

7. The rapid cooling Dewar assembly according to claim 1, characterized in that: A cold shield is also provided in the Dewar shell, and the cold shield includes a conical barrel section and a prismatic barrel section connected from top to bottom, and the bottom of the prismatic barrel section has a connecting portion extending radially outward, and the connecting portion has a group of relatively distributed first connecting edges and a group of relatively distributed second connecting edges, and the radial width of the first connecting edge along the prismatic barrel section is smaller than the radial width of the second connecting edge along the prismatic barrel section.

8. The rapid cooling Dewar assembly according to claim 1, characterized in that: The Dewar housing comprises a detachably connected cold finger housing and a window frame, the cold finger is placed in the cold finger housing, the cold plate and the cold shield are placed in the window frame, and a window sheet is provided on the top of the window frame.

9. The rapid cooling Dewar assembly according to claim 7, characterized in that: The cold finger shell is provided with a receiving space for accommodating a getter at a position corresponding to the cold end of the cold finger cylinder, and the cold finger shell is provided with an exhaust pipe at a position corresponding to the reflux section of the cold finger cylinder.

10. An infrared detector, characterized in that: A Dewar assembly for rapid cooling comprising the rapid cooling assembly described in any one of claims 1 to 9.

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