A method for fabricating a cold mirror based on a Stirling refrigerator, a cold mirror device, and a dew point meter.

Abstract

This application discloses a method for fabricating a cold mirror based on a Stirling refrigerator, a cold mirror device, and a dew point meter, relating to the field of dew point detection technology. The method for fabricating a cold mirror based on a Stirling refrigerator involves welding a transition sleeve onto the outer circumference of the cold mirror body to form a cold mirror assembly. This assembly is then installed at the mounting port on the end face of the tube body and sealed by welding, thus integrating the cold mirror assembly with the Stirling refrigerator to obtain the cold mirror device. The cold mirror device fabricated by the method disclosed in this application eliminates the heat conduction or transition process between the cold source and the cold mirror body, avoiding energy attenuation and delay caused by the heat transfer medium. This significantly shortens the heat transfer path and time, thereby preventing temperature differences within the cold mirror body and greatly increasing the temperature drop rate of the cold mirror body. This results in a shorter detection cycle, more stable detection, and higher detection accuracy, making it suitable for industrial applications.

Description

Technical Field

[0001] This application relates to the field of dew point detection technology, specifically to a method for manufacturing a cold mirror based on a Stirling refrigerator, a cold mirror device, and a dew point meter. Background Technology

[0002] Common methods for expressing humidity include mixing ratio, water vapor partial pressure, mole fraction, relative humidity, and dew point temperature (the temperature at which water vapor and water reach equilibrium). Currently, the most commonly used method in industry is dew point temperature, and the instrument used to measure it is called a dew point meter. However, dew point measurement is easily affected by other physical quantities, such as ambient pressure and temperature, making it relatively difficult to detect.

[0003] A cold mirror dew point meter is an instrument used for measuring dew point. Its measurement principle utilizes the fact that gases with different moisture contents condense on a mirror surface at different temperatures. Using photoelectric detection technology, it detects the dew layer and measures the temperature at which condensation occurs, directly displaying the dew point. The cold mirror dew point meter employs a direct measurement method and is currently the most accurate and stable type of dew point meter, suitable for use as a standard dew point meter.

[0004] Traditional cold mirror dew point meters use liquid nitrogen, high-pressure gas throttling, semiconductor cold pumps, or mixed-refrigerant refrigerators as cold sources. Liquid nitrogen is difficult to obtain in remote industrial settings; high-pressure gas throttling refrigeration devices are bulky and consume gas quickly; the cooling characteristics of semiconductor cold pumps result in high power consumption at deep cryogenic temperatures, and the heat dissipation components, especially auxiliary refrigeration equipment, are large and heavy; mixed-refrigerant refrigeration devices also suffer from large size, weight, and low cooling efficiency. These problems make cold mirror dew point meters more suited for laboratory instruments and unsuitable for industrial field testing.

[0005] Currently, in commercially available cold mirror dew point meters, the cold mirror is installed at the cold end of the cold source device, with a heat-conducting medium filling the transition between the two. In this structure, there is always a temperature difference between the cold mirror and the cold head. Due to the thermal conduction delay, the surface temperature of the cold mirror drops slowly, resulting in longer single detection cycles, unstable detection, and poor detection accuracy. Summary of the Invention

[0006] The purpose of this application is to provide a method for manufacturing a cold mirror based on a Stirling refrigerator, a cold mirror device, and a dew point meter, in order to overcome the shortcomings of the prior art.

[0007] To achieve the above objectives, in a first aspect, this application provides a method for fabricating a cold mirror based on a Stirling refrigerator, the method comprising: A transition sleeve is welded onto the outer circumference of the cold mirror body to form a cold mirror assembly, and an installation port connecting to the working chamber is machined on the tube end face of the cold end of the Stirling refrigerator. The cold mirror assembly is installed in the mounting port and then welded and sealed.

[0008] As a further improvement to the above technical solution: In conjunction with the first aspect, in one possible implementation, the welding of a transition sleeve onto the outer peripheral surface of the cold mirror body to form a cold mirror assembly includes: The cold mirror body and the welding transition sleeve are processed separately, such that the outer diameter of the cold mirror body is larger than a preset size and / or the inner diameter of the welding transition sleeve is smaller than the preset size; The welding transition sleeve is fitted onto the outer peripheral surface of the cold mirror body; The welding transition sleeve is welded to the cold mirror body by vacuum brazing to form the cold mirror assembly.

[0009] In conjunction with the first aspect, in one possible implementation, fitting the welding transition sleeve onto the outer peripheral surface of the cold mirror body includes: The welding transition sleeve is placed in a heating furnace and heated to 750℃~800℃, and kept at that temperature for 1~1.5h; then the cold mirror body is immersed in liquid nitrogen for 2~5min. The cooled mirror body is placed on the heated welding transition sleeve, and the cooled mirror body is pressed into the welding transition sleeve by a pressure device.

[0010] In conjunction with the first aspect, in one possible implementation, the outer diameter of the cold mirror body is 0.01 to 0.05 mm larger than the preset size, and the inner diameter of the welding transition sleeve is 0.01 to 0.05 mm smaller than the preset size.

[0011] In conjunction with the first aspect, in one possible implementation, the method of welding the welding transition sleeve to the cold mirror body by vacuum brazing includes: The assembled welding transition sleeve and the cold mirror body are placed on a tooling inside a vacuum brazing furnace, and solder is added at the joint between the welding transition sleeve and the cold mirror body. Close the furnace chamber and vacuum heat for the preset time; After heating is complete, allow it to cool naturally.

[0012] In conjunction with the first aspect, in one possible implementation, the preset duration of furnace shutdown and vacuum heating includes: The vacuum brazing furnace was evacuated to 3 degrees Celsius. 10 -5 Pa~3 10 -4 Pa; Heat to 100℃~200℃ and preheat for 25~40 minutes; Heat to 500℃~580℃ and maintain the temperature for 1~1.5h; Heat to 820℃~880℃ and maintain the temperature for 10~20 minutes.

[0013] In conjunction with the first aspect, in one possible implementation, after the step of welding the welding transition sleeve to the cold mirror body by vacuum brazing to form the cold mirror assembly, the method further includes: A sealing test was performed on the cold mirror assembly; The surface of the cold mirror assembly is subjected to chromium plating. The mirror surface of the cold mirror body is ground.

[0014] In conjunction with the first aspect, in one possible implementation, the welding transition sleeve is made of the same material as the tube body.

[0015] To achieve the above objectives, in a second aspect, this application also provides a cold mirror apparatus, comprising: A Stirling refrigerator, wherein the cold end of the tube body of the Stirling refrigerator has an installation port, the installation port communicating with the working chamber of the tube body; and A cold mirror assembly includes a cold mirror body and a welding transition sleeve fitted onto the outer peripheral surface of the cold mirror body. The cold mirror body is installed to the mounting port of the tube body through the welding transition sleeve. The cold mirror body has a detection mirror surface at one end away from the working chamber, and the welding transition sleeve is welded to the tube body for sealing.

[0016] To achieve the above objectives, in a third aspect, this application also provides a dew point meter, including a detection device and the cold mirror device provided in the second aspect, wherein the detection device is disposed at the end of the tube body on which the cold mirror body is located.

[0017] Compared to existing technologies, the beneficial effects of this application are: This application provides a method for manufacturing a cold mirror based on a Stirling refrigerator, a cold mirror device, and a dew point meter. The method involves welding a transition sleeve onto the outer circumference of the cold mirror body to form a cold mirror assembly. This assembly is then installed at the mounting port on the end face of the tube body and sealed by welding, thus integrating the cold mirror assembly and the Stirling refrigerator into a single unit, resulting in the cold mirror device. Since the mounting port is connected to the working chamber, the cold mirror body extends directly into the working chamber after installation. This allows the cold source generated by the Stirling refrigerator to directly exchange heat with the cold mirror body within the working chamber, eliminating the need for heat conduction or transition between the cold source and the cold mirror body. This avoids energy attenuation and delay caused by the heat transfer medium, significantly shortening the heat transfer path and time. Consequently, it prevents temperature differences within the cold mirror body, greatly increasing the temperature drop rate and thus shortening the detection cycle, resulting in more stable and accurate detection.

[0018] In addition, the Stirling refrigeration system has high cooling efficiency and a moderate size, making it suitable for industrial applications. This makes dew point meters suitable for on-site industrial testing.

[0019] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate this application and form part of the specification. They are used together with the following detailed description to explain this application. It should be understood that the following drawings only show some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings: Figure 1 A schematic diagram of a dew point meter provided in an embodiment of this application is shown; Figure 2 A partial structural schematic diagram of the cooling mirror device in the dew point meter provided in this application embodiment is shown; Figure 3 It shows Figure 2 A schematic diagram of the structure of the cold mirror assembly in the cold mirror device shown; Figure 4 A flowchart of the first method for fabricating a cold mirror based on a Stirling refrigerator, provided in an embodiment of this application, is shown. Figure 5 A flowchart of a second method for fabricating a cold mirror based on a Stirling refrigerator, provided in an embodiment of this application, is shown. Figure 6 A flowchart of the third method for fabricating a cold mirror based on a Stirling refrigerator, provided in an embodiment of this application, is shown. Figure 7 A flowchart of the fourth method for fabricating a cold mirror based on a Stirling refrigerator, provided in an embodiment of this application, is shown.

[0021] Explanation of reference numerals in the attached figures: 100. Cold mirror device; 110. Stirling refrigerator; 111. Tube body; 112. Mounting port; 113. Working chamber; 120. Cold mirror assembly; 121. Cold mirror body; 122. Welding transition sleeve; 200. Detection device; 210. Detection seat; 211. Measuring chamber; 212. Incident light channel; 213. Reflected light channel. Detailed Implementation

[0022] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the embodiments of this application.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0024] In the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] The present application will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0028] Example Please see Figure 1 , Figure 2 and Figure 3 This embodiment provides a dew point meter, specifically a cold mirror type dew point meter. The dew point meter obtains the humidity value by measuring the temperature at which the dew (frost) on the dew point sensor mirror reaches equilibrium with the water vapor in the gas.

[0029] In this embodiment, the dew point meter includes a detection device 200 and a cold mirror device 100. The cold mirror device 100 includes a Stirling refrigerator 110 and a cold mirror assembly 120. The cold end of the Stirling refrigerator 110 includes a tube 111, and the end face of the tube 111 is provided with a mounting port 112, which communicates with the working chamber 113 of the tube 111.

[0030] The cold mirror assembly 120 includes a cold mirror body 121 and a welding transition sleeve 122 fitted onto the outer circumferential surface of the cold mirror body 121. The cold mirror body 121 is installed in the mounting port 112 of the tube body 111 via the welding transition sleeve 122. The end of the cold mirror body 121 furthest from the working chamber 113 is provided with a mirror surface for inspection, and the welding transition sleeve 122 is welded to the tube body 111 in a sealed manner.

[0031] The aforementioned detection device 200 is disposed at one end of the tube body 111 where the cold mirror body 121 is located. The detection device 200 includes a detection seat 210, a mirror sensor (not shown), a light source (not shown), and a photoelectric sensor (not shown). The detection seat 210 is installed at the end of the tube body 111 where the cold mirror body 121 is located. The detection seat 210 and the mirror surface of the cold mirror body 121 form a measurement cavity 211. The detection seat 210 has an incident light channel 212 and a reflected light channel 213 communicating with the measurement cavity 211. The light source is installed on the detection seat 210. The light beam generated by the light source enters through the incident light channel 212, is reflected by the mirror surface, and exits through the reflected light channel 213. The photoelectric sensor is disposed on the detection seat 210 and located at the exit of the reflected light channel 213 to receive the reflected light beam. The mirror sensor is disposed on the mirror surface to detect the temperature of the mirror surface.

[0032] The dew point meter provided in this embodiment operates on the following principle: a light beam emitted from a light source is focused onto a mirror sensor at a fixed intensity. A Stirling refrigerator 110 acts as a cold source to cool the mirror sensor. When the mirror sensor cools, the scattering effect caused by condensation on the sensor reduces the intensity of the reflected light. The intensity of the reflected light is detected by a photodetector. The output signal of the optical system is used to precisely control the Stirling refrigerator 110 to heat or cool the mirror sensor. This keeps the mirror sensor in a dynamic equilibrium state where evaporation and condensation occur at the same rate. The temperature of the mirror sensor at this point is the dew point temperature of the gas being measured.

[0033] This embodiment also provides a cold mirror device 100, specifically a cold mirror device based on a Stirling refrigerator, the structure of which has been described above and will not be repeated here.

[0034] To more clearly describe the technical solution of this embodiment, this embodiment also provides a method for manufacturing a cold mirror based on a Stirling refrigerator, used to manufacture a cold mirror device 100.

[0035] Please refer to the following: Figure 4 The method for fabricating a cold mirror based on a Stirling refrigerator includes the following steps: S100: A transition sleeve 122 is welded onto the outer peripheral surface of the cold mirror body 121 to form a cold mirror assembly 120, and an installation port 112 communicating with the working chamber 113 is machined on the end face of the tube body 111 at the cold end of the Stirling refrigerator 110.

[0036] The steps for processing the cold mirror assembly 120 and the mounting port 112 described above are not restricted by order and can be performed simultaneously.

[0037] S200: Install the cold mirror assembly 120 into the mounting port 112 and weld it in place.

[0038] It should be noted that traditional cold mirrors generally use abrasive steel as the base material, with an additional coating applied to the surface before grinding to achieve a high degree of surface finish. Cold mirrors manufactured using this process have high corrosion resistance and strength, but this also makes it difficult to connect the cold mirror to the Stirling tube 111. Therefore, existing technology typically involves machining a groove at one end of the cold mirror to fit the end of the tube 111, allowing the cold mirror to be directly installed at the end of the tube 111. The installation gap is sealed and fixed using low-temperature structural adhesive to eliminate thermal conduction barriers between the end of the tube 111 and the cold mirror. Although this method can accelerate the temperature drop of the cold mirror, the existing low-temperature structural adhesive bonding process is not mature and often results in pore leakage, shortening the maintenance cycle of the Stirling refrigerator 110. Moreover, the cold mirror of the cold mirror dew point meter needs to be heated for rewarming in addition to cooling. Generally, electric heating tape is used for rewarming. When the rewarming temperature reaches 40°C, the firmness of the low-temperature structural adhesive will decrease. The Stirling refrigerator 110 is filled with a refrigerant medium of 1.8MPa~2.5MPa. Under the impact of gas pressure, the low-temperature structural adhesive is prone to leakage, and even the cold head may break off, which has a great impact on personnel safety and instrument safety.

[0039] Therefore, in this embodiment, to solve the problem of joining the cold mirror body 121 to the tube body 111, a welding transition sleeve 122 is fitted onto the outer circumferential surface of the cold mirror body 121, and an installation port 112 communicating with the working chamber 113 of the Stirling refrigerator 110 is machined on the end face of the tube body 111. After the cold mirror assembly 120 is installed in the installation port 112, the welding transition sleeve 122 is welded to the tube body 111 to seal it, preventing leakage of the refrigerant in the working chamber 113 when the Stirling refrigerator 110 is working. This embodiment uses a welding transition to seal the tube body 111, eliminating the need to consider the problem of difficulty in connecting the cold mirror body 121 and the tube body 111.

[0040] Please refer to the following: Figure 5 Specifically, step S100 above: welding a transition sleeve 122 onto the outer peripheral surface of the cold mirror body 121 to form the cold mirror assembly 120 includes the following steps: S110: Process the cold mirror body 121 and the welding transition sleeve 122 respectively, so that the outer diameter of the cold mirror body 121 is larger than the preset size and the inner diameter of the welding transition sleeve 122 is smaller than the preset size.

[0041] The outer circumferential surface of the cold mirror body 121 is machined into an outer cylindrical surface, and the welding transition sleeve 122 is machined into a matching inner cylindrical surface. The preset dimensions are the standard dimensions that allow the outer and inner cylindrical surfaces to be assembled. In this embodiment, the outer diameter of the cold mirror body 121 is machined to be larger than the preset dimension, and the inner diameter of the welding transition sleeve 122 is machined to be smaller than the preset dimension. The purpose is to ensure that the cold mirror body 121 and the welding transition sleeve 122 form an interference fit after assembly, resulting in a tighter bond.

[0042] In some embodiments, the outer diameter of the cold mirror body 121 may be machined to be larger than the preset size, and the inner diameter of the welding transition sleeve 122 may be machined to the preset size; or the outer diameter of the cold mirror body 121 may be machined to the preset size, and the inner diameter of the welding transition sleeve 122 may be machined to be smaller than the preset size, which can also achieve an interference fit.

[0043] Specifically, in this embodiment, the outer diameter of the cold mirror body 121 is 0.01 to 0.05 mm larger than the preset size, and the inner diameter of the welding transition sleeve 122 is 0.01 to 0.05 mm smaller than the preset size.

[0044] Optionally, the outer diameter of the cold mirror body 121 is greater than a preset size by 0.015mm, 0.02mm, 0.023mm, 0.027mm, 0.031mm, 0.035mm, 0.039mm, 0.04mm, 0.044mm or 0.048mm.

[0045] Optionally, the inner diameter of the welding transition sleeve 122 is smaller than the preset size by 0.012mm, 0.018mm, 0.02mm, 0.026mm, 0.03mm, 0.036mm, 0.039mm, 0.04mm, 0.045mm or 0.049mm.

[0046] It should be understood that the above are merely illustrative examples and are not intended to limit the scope of protection of this application.

[0047] S120: Fit the welding transition sleeve 122 onto the outer peripheral surface of the cold mirror body 121.

[0048] S130: The welding transition sleeve 122 is welded to the cold mirror body 121 by vacuum brazing to form the cold mirror assembly 120.

[0049] Please refer to the following: Figure 6 Furthermore, step S120 above: fitting the welding transition sleeve 122 onto the outer peripheral surface of the cold mirror body 121 includes the following steps: S121: Place the welding transition sleeve 122 in a heating furnace and heat it to 750℃~800℃, and keep it at a constant temperature for 1~1.5h; then immerse the cold mirror body 121 in liquid nitrogen for 2~5min.

[0050] Specifically, the welding transition sleeve 122 is placed in a vacuum brazing furnace and heated under vacuum to prevent oxidation during heating. Utilizing the principle of thermal expansion and contraction, the inner diameter of the welding transition sleeve 122 expands due to heat. The cooled mirror body 121 is immersed in liquid nitrogen for cooling, allowing it to cool completely. Again, utilizing the principle of thermal expansion and contraction, the outer diameter of the cooled mirror body 121 shrinks. Furthermore, since the cooling time for the cooled mirror body 121 is relatively short, to ensure synchronization of the two processes, the cooling of the cooled mirror body 121 should be performed when the heating of the welding transition sleeve 122 is almost complete.

[0051] In some embodiments, the heating temperature of the welding transition sleeve 122 can be selected as 750°C to 760°C.

[0052] Optionally, the heating temperature of the welding transition sleeve 122 can also be selected as 751℃, 752.4℃, 753℃, 753.5℃, 753.8℃, 754℃, 754.6℃, 754.8℃, 755℃, 755.5℃ or 755.8℃.

[0053] In some embodiments, the isothermal duration during the heating process of the welding transition sleeve 122 can be selected as 1.1h, 1.2h, 1.3h or 1.4h.

[0054] In some embodiments, the immersion time of the cold mirror body 121 in liquid nitrogen can be selected as 3 minutes or 4 minutes.

[0055] It should be understood that the above are merely illustrative examples and are not intended to limit the scope of protection of this application.

[0056] S122: Place the cooled mirror body 121 onto the heated welding transition sleeve 122, and press the cooled mirror body 121 into the welding transition sleeve 122 using a pressure device.

[0057] Therefore, in this embodiment, the welding transition sleeve 122 and the cold mirror body 121 adopt a combination of hot fitting and cold fitting processes, so that the welding transition sleeve 122 and the cold mirror body 121 form an interference fit.

[0058] Please refer to the following: Figure 7 Furthermore, step S130 above, which involves welding the transition sleeve 122 to the cold mirror body 121 using vacuum brazing to form the cold mirror assembly 120, includes the following steps: S131: Place the assembled welding transition sleeve 122 and the cold mirror body 121 into the tooling inside the vacuum brazing furnace, and add solder to the joint between the welding transition sleeve 122 and the cold mirror body 121.

[0059] Specifically, the assembled welding transition sleeve 122 and the cold mirror body 121 are positioned on the fixture inside the vacuum brazing furnace using special tools, and 40%~50% silver-based solder is added at the joint between the welding transition sleeve 122 and the cold mirror body 121.

[0060] S132: Close the furnace chamber and set the preset vacuum heating time.

[0061] Specifically, first, evacuate the vacuum brazing furnace to 3... 10 -5 Pa~3 10 -4 Pa; then heat to 100℃~200℃, preheat for 25~40min; raise the temperature to 500℃~580℃ and keep it constant for 1~1.5h; raise the temperature to 820℃~880℃ and keep it constant for 10~20min.

[0062] Furthermore, the heating time to 500℃~580℃ should be controlled within 30~50 minutes, and then the temperature should be kept constant. The heating time to 820℃~880℃ should be controlled within 30~50 minutes, and then the temperature should be kept constant.

[0063] S133: After heating is complete, allow it to cool naturally.

[0064] Optionally, adding 46% silver-based solder at the joint between the welding transition sleeve 122 and the cold mirror body 121 results in a better welded bond. Then, the furnace evacuation is shut off, and the vacuum inside the furnace is evacuated to 3... 10 -5 Pa; preheat at 150℃ for 30 min; increase the temperature to 550℃ within 45 min and hold for 1 h; increase the temperature to 850℃ within 40 min and hold for 15 min, then allow to cool naturally.

[0065] Please see Figure 2 , Figure 3 and Figure 5 In some embodiments, after step S130 above, which involves welding the welding transition sleeve 122 to the cold mirror body 121 by vacuum brazing to form the cold mirror assembly 120, the following steps are also included: S140: Perform a sealing test on the cold mirror assembly 120.

[0066] Specifically, the sealing performance of the joint between the cold mirror body 121 and the welding transition sleeve 122 is tested. The testing methods include helium mass spectrometry leak detection or hydraulic pressure testing.

[0067] The cold mirror assembly 120 fabricated in this embodiment achieves a leak level of 8.3 according to helium mass spectrometry. 10 -9 pa.m 3 / s, can withstand pressure of 22MPa in oil pressure test, and has excellent sealing and welding strength.

[0068] S150: A chromium plating treatment is applied to the surface of the cold mirror assembly 120 to improve the hardness and wear resistance of the cold mirror assembly 120.

[0069] Furthermore, after the chromium plating is completed, the external dimensions of the cold mirror assembly 120 are machined to fit the mounting port 112.

[0070] S160: Grind the mirror surface of the cold mirror body 121.

[0071] Among them, by grinding the mirror surface, the smoothness of the mirror surface is made to reach 0.0125, so as to obtain higher detection accuracy.

[0072] In some embodiments, to improve heat conduction efficiency, the cold mirror body 121 may be made of copper as a substrate. The cold mirror body 121 made of copper as a substrate has a certain strength and high thermal conductivity.

[0073] However, the thin-walled tube 111 of the Stirling refrigerator 110 experiences high-frequency friction from the internal energy storage tube during operation, and it often operates at low temperatures. Since lubricating media cannot be added between the tube 111 and the energy storage tube (to prevent ice blockage), dry friction is the only option. This necessitates strong wear resistance in the tube 111. A common practice is to use stainless steel as the base for the tube 111, process it into tube 111, perform heat treatment, and then hone the inner hole to a mirror finish. However, stainless steel is inherently difficult to weld with copper, and the heat treatment further complicates the welding process. Therefore, in this embodiment, a welding transition sleeve 122 is fitted over the cold mirror body 121 to form a weldable cold mirror assembly 120. During welding, the cold mirror assembly 120 is connected to the tube 111 via the welding transition sleeve 122. This allows for conventional welding between the cold mirror assembly 120 and the tube 111, significantly strengthening the connection and ensuring safety and sealing.

[0074] Optionally, the welding transition sleeve 122 is made of the same material as the pipe body 111. Further, the welding transition sleeve 122 is selected to be made of stainless steel.

[0075] Specifically, when welding the transition sleeve 122 to the tube body 111 of the Stirling refrigerator 110, a welding fixture is first used for fixing. Since the transition sleeve 122 and the tube body 111 are made of the same material, laser welding can be used for welding. 0.1mm~0.4mm 316L stainless steel welding wire is used, and low-power spot welding (preferably 80W) is used. During welding, 5N argon gas is used to purge and isolate oxygen and lower the temperature to prevent excessive oxidation at the weld.

[0076] The cold mirror fabrication method based on the Stirling refrigerator described above integrates the cold mirror assembly 120 with the Stirling refrigerator 110, making the cold mirror assembly 120 fused to the Stirling refrigerator 110 and becoming part of the cold end of the Stirling refrigerator 110. Therefore, the cooling energy generated by the Stirling refrigerator 110 is directly deposited on the cold mirror body 121, eliminating the need for heat conduction or transition between the cold source and the cold mirror body 121. This avoids energy attenuation and delay caused by the heat transfer medium, significantly shortening the heat transfer path and time, preventing temperature differences in the cold mirror body 121, and greatly increasing the temperature drop rate of the cold mirror body 121. As a result, the mirror surface of the cold mirror body 121 can quickly form a dew point. When applied to a dew point meter, the intensity of reflected and scattered light within the measuring chamber 211 changes rapidly in a short time. The dew point detection algorithm can accurately determine the dew point temperature of the measured gas based on the light intensity changes, shortening the detection cycle, improving detection stability, and increasing detection accuracy.

[0077] In addition, the Stirling Refrigeration Unit 110 has high cooling efficiency, and its compact size makes it suitable for industrial applications. This allows the dew point meter to be used for on-site industrial testing.

[0078] Please see Figures 1 to 7 Compared with the prior art, the cold mirror device 100 and dew point meter provided in this embodiment also have the following advantages: (a) Increased cooling rate: After adopting the cold mirror device 100 provided in this embodiment, the temperature drop rate of the cold mirror body 121 is significantly improved. A comparison using a Stirling refrigerator 110 of the same power as the cold source reveals that, with the cold mirror device 100 provided in this embodiment, the temperature drop rate of the cold mirror body 121 (from room temperature to -90°C) is more than 70% higher than that of the structure without the cold mirror device 100. This is because the cold head of the traditional Stirling refrigerator 110 has a certain heat capacity. During cooling, the temperature of the cold head must first be lowered before heat exchange occurs with the cold mirror, thus slowing down the cooling rate of the cold mirror. Before using the cold mirror device 100 provided in this embodiment, it took approximately 23 minutes for the surface temperature of the cold mirror body 121 to drop from room temperature to -90°C. However, with the cold mirror device 100 provided in this embodiment, the surface temperature of the cold mirror body 121 drops from room temperature to -90°C in only 7 minutes.

[0079] (ii) Shortened dew point detection cycle: Because the cooling rate of the cold mirror body 121 is greatly improved, the dew point detection cycle is significantly shortened. Taking the -80℃ dew point detection as an example, after using the cold mirror device 100 provided in this embodiment, the mirror surface of the cold mirror body 121 can reach -90℃ in 7 minutes. At this time, the dew point has already formed on the mirror surface of the cold mirror body 121. After a short period of constant temperature and calculation, the accurate dew point temperature of the gas being measured can be obtained within 10 minutes. In contrast, traditional cold mirror dew point meters require 25 to 30 minutes to detect the -80℃ dew point.

[0080] (III) Improved stability of dew point meter: Because traditional cold mirror dew point meters have a slow cooling rate of the cold mirror, the formation of dew point on the surface of the cold mirror body 121 is slow during low-temperature dew point detection, resulting in weak changes in the intensity of reflected and scattered light from the light source. Therefore, dew point temperature compensation needs to be added to the algorithm to ensure the accuracy of dew point detection. When the performance of the cold source changes, the rate of dew point formation also changes, and the original compensation value no longer matches the current dew point change, leading to deviations in dew point detection. Using the cold mirror device 100 provided in this embodiment, the cooling rate of the cold mirror body 121 is accelerated, allowing for rapid dew point formation. The intensity of reflected and scattered light from the light source changes drastically in a short time, making it easy for the optical detection device to capture the formation of dew point. The dew point temperature of the measured gas can be accurately detected without adding dew point temperature compensation data. Even when the performance of the cold source changes or deteriorates, the rapid temperature drop of the cold mirror body 121 ensures that the dew point still forms quickly, guaranteeing the long-term stability of the instrument.

[0081] (iv) The reliability of the Stirling Refrigeration Unit 110 has been improved: After adopting the cold mirror device 100 provided in this embodiment, the sealing performance at the weld between the cold mirror assembly 120 and the tube body 111 can reach 5. 10 -9 pa.m 3 The pressure resistance at the joint reaches 3.6 MPa after oil pressure testing, meeting the leakage rate requirements of the refrigerant in the Stirling refrigerator 110 (no leakage at the joint even when the tube 111 deforms). Even when the cold mirror assembly 120 is heated (65°C), it maintains excellent sealing and firmness. Therefore, the cold mirror device 100 provided in this embodiment effectively prevents leakage and separation at the joint between the cold mirror assembly 120 and the tube 111, greatly improving the stability and safety of the Stirling refrigerator 110 during long-term use.

[0082] The optional embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present application are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present application, various simple modifications can be made to the technical solutions of the embodiments of the present application, and these simple modifications all fall within the protection scope of the embodiments of the present application.

[0083] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the embodiments of this application will not describe the various possible combinations separately.

[0084] Furthermore, various different implementation methods of the embodiments of this application can be combined arbitrarily, as long as they do not violate the spirit of the embodiments of this application, they should also be regarded as the content disclosed in the embodiments of this application.

Claims

1. A method for fabricating a cold mirror based on a Stirling refrigerator, characterized in that, The method includes: A transition sleeve (122) is welded onto the outer peripheral surface of the cold mirror body (121) to form a cold mirror assembly (120), and an installation port (112) communicating with the working chamber (113) is machined on the end face of the tube body (111) at the cold end of the Stirling refrigerator (110). The cold mirror assembly (120) is installed in the mounting port (112) and then welded and sealed. After the cold mirror assembly (120) is installed, the cold mirror body (121) extends directly into the working chamber (113), so that the cold source generated by the Stirling refrigerator (110) during operation can directly exchange heat with the cold mirror body (121) in the working chamber (113).

2. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 1, characterized in that, The process of fitting and welding a transition sleeve (122) onto the outer peripheral surface of the cold mirror body (121) to form the cold mirror assembly (120) includes: The cold mirror body (121) and the welding transition sleeve (122) are respectively processed so that the outer diameter of the cold mirror body (121) is larger than the preset size and / or the inner diameter of the welding transition sleeve (122) is smaller than the preset size; The welding transition sleeve (122) is fitted onto the outer peripheral surface of the cold mirror body (121); The welding transition sleeve (122) and the cold mirror body (121) are welded together by vacuum brazing to form the cold mirror assembly (120).

3. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 2, characterized in that, The step of fitting the welding transition sleeve (122) onto the outer peripheral surface of the cold mirror body (121) includes: The welding transition sleeve (122) is placed in a heating furnace and heated to 750℃~800℃, and kept at that temperature for 1~1.5h; then the cold mirror body (121) is immersed in liquid nitrogen for 2~5min; The cooled mirror body (121) is placed on the heated welding transition sleeve (122), and the cooled mirror body (121) is pressed into the welding transition sleeve (122) by a pressure device.

4. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 2 or 3, characterized in that, The outer diameter of the cold mirror body (121) is 0.01~0.05mm larger than the preset size, and the inner diameter of the welding transition sleeve (122) is 0.01~0.05mm smaller than the preset size.

5. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 2, characterized in that, The method of welding the welding transition sleeve (122) and the cold mirror body (121) together by vacuum brazing includes: The assembled welding transition sleeve (122) and the cold mirror body (121) are placed on a tooling inside a vacuum brazing furnace, and solder is added at the joint between the welding transition sleeve (122) and the cold mirror body (121). Close the furnace chamber and vacuum heat for the preset time; After heating is complete, allow it to cool naturally.

6. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 5, characterized in that, The preset duration for vacuum heating after closing the furnace includes: The vacuum brazing furnace was evacuated to 3 degrees Celsius. 10 -5 Pa~3 10 -4 Pa; Heat to 100℃~200℃ and preheat for 25~40 minutes; Heat to 500℃~580℃ and maintain a constant temperature for 1~1.5 hours; Heat to 820℃~880℃ and maintain the temperature for 10~20 minutes.

7. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 2, characterized in that, After the process of welding the welding transition sleeve (122) and the cold mirror body (121) together by vacuum brazing to form the cold mirror assembly (120) further includes: A sealing test was performed on the cold mirror assembly (120); The surface of the cold mirror assembly (120) is subjected to chromium plating. The mirror surface of the cold mirror body (121) is polished.

8. The method for fabricating a cold mirror based on a Stirling refrigerator according to claim 1, characterized in that, The welding transition sleeve (122) is made of the same material as the tube body (111).

9. A cold mirror apparatus, characterized in that, The cold mirror is manufactured according to the method for fabricating a Stirling refrigerator according to any one of claims 1-8, wherein the cold mirror apparatus comprises: A Stirling refrigerator (110) has a mounting port (112) on the end face of the tube body (111) at the cold end of the Stirling refrigerator (110), and the mounting port (112) is connected to the working chamber (113) of the tube body (111); and The cold mirror assembly (120) includes a cold mirror body (121) and a welding transition sleeve (122) fitted on the outer peripheral surface of the cold mirror body (121). The cold mirror body (121) is installed in the mounting port (112) of the tube body (111) through the welding transition sleeve (122). The cold mirror body (121) is provided with a detection mirror at one end away from the working chamber (113), and the welding transition sleeve (122) is welded to the tube body (111).

10. A dew point meter, characterized in that, It includes a detection device (200) and a cold mirror device according to claim 9, wherein the detection device (200) is disposed at one end of the tube body (111) where the cold mirror body (121) is located.

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