A calibration dewar structure of a cryogenic temperature sensor and a cryogenic temperature sensor

Abstract

This invention belongs to the field of sensor technology, specifically disclosing a calibration Dewar structure for a low-temperature temperature sensor. The structure, housed within a Dewar, includes a heat sink, a cold head, and several pull rods. The cold head is located on top of the heat sink, and at least two cold heads are provided. One end of each pull rod is connected to the heat sink, and the other end is connected to the upper interior of the Dewar. This invention provides a calibration Dewar structure for a low-temperature temperature sensor. The multi-cold-head layout expands the heat exchange area, accelerates the cooling rate, and solves the problem of insufficient accuracy in simultaneous calibration of multiple sensors. The suspended pull rod structure removes the load-bearing burden from the cold heads, avoiding fatigue damage, performance degradation, and failure risks caused by long-term load-bearing, reducing system maintenance costs, and improving the continuity and reliability of calibration work.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a calibration Dewar structure for a low-temperature sensor and a low-temperature sensor. Background Technology

[0002] Calibrating low-temperature sensors typically requires operation in a specific low-temperature environment. A common method involves placing the sensor to be calibrated and a standard temperature sensor inside a vacuum Dewar flask, using a cryogenic cold head to cool the heat sink, thereby establishing a stable and uniform low-temperature field on the heat sink for sensor calibration. Currently, relatively low-cost calibration systems often employ a single cryogenic cold head design.

[0003] However, conventional single-cold-head calibration systems have significant limitations. First, the cooling capacity and heat exchange area of ​​a single cold head are limited, resulting in a slow cooling rate and low cooling efficiency for the entire system. More importantly, the thermal coupling between a single cold head and the heat sink is usually concentrated in a small area, which can easily lead to uneven temperature distribution on the heat sink. Areas far from the cold head connection point may have higher or unstable temperatures, directly affecting the accuracy and comparability when calibrating multiple sensors simultaneously.

[0004] Secondly, in terms of structural layout, most of these systems directly mount or place the heat sink, which serves as the main calibration platform, above the cold head. This structure, with the cold head below and the heat sink above, means that the entire weight of the heat sink and the numerous sensors mounted on it is continuously borne by the cold head and its internal precision moving parts during long-term operation. The cold head itself is not designed to withstand heavy mechanical loads, and long-term heavy loads can easily lead to fatigue damage, performance degradation, or even failure, increasing system maintenance costs and failure risks, and affecting the reliability of calibration work.

[0005] In summary, the calibration Dewar structure of existing low-temperature temperature sensors suffers from problems such as low cooling efficiency and poor temperature field uniformity due to the single cold head design, as well as the cold head being prone to damage due to long-term load-bearing caused by the top-mounted heat sink layout. Summary of the Invention

[0006] This invention provides a calibration Dewar structure for a low-temperature temperature sensor, which can solve the problems of low cooling efficiency and poor temperature field uniformity caused by the single cold head design in the existing calibration Dewar structure of low-temperature temperature sensors, as well as the cold head being easily damaged by long-term load due to the top-mounted heat sink layout.

[0007] In a first aspect, the present invention provides a calibration Dewar structure for a low-temperature temperature sensor, comprising: Dewar; A heat sink, located inside the Dewar, is used to carry a low-temperature sensor. A cold head, wherein the cold head is disposed on top of the heat sink, and at least two cold heads are provided; Several pull rods, one end of which is connected to a heat sink and the other end of which is connected to the upper part of the Dewar.

[0008] This invention provides a calibration Dewar structure for a low-temperature temperature sensor, which, compared to existing technologies, has, but is not limited to, the following beneficial effects: In the calibration Dewar structure of this low-temperature temperature sensor, the Dewar provides a stable, sealed low-temperature vacuum environment for the internal calibration structure and sensor. The heat sink, as the core platform for low-temperature sensor calibration, provides a stable low-temperature environment for the sensor to be calibrated. It is typically made of a metal with high thermal conductivity (such as oxygen-free copper), and its structural design must meet the requirements of temperature field uniformity and load-bearing stability. The cold head, as the core cooling component, connects to external cooling equipment (such as a GM refrigerator or a pulse tube refrigerator) and transfers cold energy to the heat sink through heat conduction, thereby establishing the required low-temperature field on the surface of the heat sink. Compared with the single cold head design in the prior art, the layout of at least two cold heads in this invention can effectively expand the coverage of cold energy transfer, increase the heat exchange area, and fundamentally improve the problem of limited cooling capacity and slow cooling rate of a single cold head. The tie rod serves as a suspension support component for the heat sink. One end is fixedly connected to the heat sink, and the other end is securely connected to the upper part of the Dewar. The heat sink and the sensor to be calibrated are suspended on the Dewar by means of suspension, which completely changes the layout mode of the existing technology where the cold head is below and the heat sink is above, and avoids the weight of the heat sink and the sensor from directly acting on the cold head and its internal precision components.

[0009] This invention provides a calibration Dewar structure for a low-temperature temperature sensor. The multi-cold head layout expands the heat exchange area, accelerates the cooling rate, and solves the problem of insufficient accuracy in synchronous calibration of multiple sensors. The suspended tie rod structure removes the load on the cold head, avoiding fatigue damage, performance degradation, and failure risk caused by long-term load on the cold head, reducing system maintenance costs, and improving the continuity and reliability of calibration work.

[0010] Furthermore, there are two cold heads, and the two cold heads are arranged symmetrically with respect to the center of the heat sink.

[0011] Furthermore, the pull rod is made of carbon fiber.

[0012] Furthermore, the heat sink end face has multiple mounting position groups with different distances from the center along the center, and each mounting position group includes several mounting positions, which are used to install low temperature sensors or standard thermometers; Several mounting positions in each mounting position group are distributed on the same circumference, and the distance between two adjacent mounting positions in each mounting position group is the same.

[0013] Furthermore, the diameter of the heat sink is 20-40 cm.

[0014] Furthermore, a lead block heat accumulator is provided between the cold head and the heat sink.

[0015] Furthermore, the heat sink has a groove on its exterior, and a heating wire is installed inside the groove.

[0016] Furthermore, the calibration Dewar structure of the low-temperature temperature sensor also includes a temperature control PID system, which is connected to a standard thermometer located inside the Dewar and is used to perform PID control on the temperature inside the Dewar based on the temperature feedback from the standard thermometer.

[0017] Secondly, the present invention also provides a low-temperature temperature sensor, which is calibrated using the calibration Dewar structure of the low-temperature temperature sensor provided in the first aspect of the present invention. The low-temperature temperature sensor includes a temperature sensor body and a standard carbon ceramic thermometer connected in series with the temperature sensor body.

[0018] Furthermore, when the ambient temperature is no greater than 4.2K, the resistance value of the standard carbon ceramic thermometer is 2000-5000 ohms; When the ambient temperature is normal, the resistance of the standard carbon ceramic thermometer is 900-1100 ohms. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a cross-sectional view of the Dewar structure provided in an embodiment of the present invention; Figure 2 A schematic diagram of the installation structure of the heat sink, cold head, and lead block accumulator provided in an embodiment of the present invention; Figure 3 A schematic diagram of the installation structure of the heat sink, cold head, lead block heat accumulator and directional thermal conductive silicone pad provided in an embodiment of the present invention; Figure 4 A schematic diagram of the installation structure of the heat sink and heating wire provided in an embodiment of the present invention; Figure 5 This is a bottom view of the heat sink structure provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the installation structure of the Dewar and temperature control PID system provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a low-temperature temperature sensor provided in another embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Heat sink; 2. Cold block; 3. Tie rod; 4. Lead block accumulator; 5. Temperature control PID system; 6. Heating wire; 7. Temperature sensor body; 8. Standard carbon ceramic thermometer; 9. Directional thermal conductive silicone pad; 100. Dewar; 101. Heating wire; 102. Mounting position assembly. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings showing multiple embodiments according to this application. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," etc., in the description, claims, and accompanying drawings of this application are open-ended terms. Therefore, "comprising," "including," or "having" refers to, for example, a method or apparatus having one or more steps or elements, but is not limited to having only these one or more elements. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. 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 indicated technical features. 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, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication 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.

[0025] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.

[0026] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, B and / or C can represent: B existing alone, B and C existing simultaneously, or C existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0027] like Figure 1 As shown, an embodiment of the present invention provides a calibration Dewar structure for a low-temperature temperature sensor, including a Dewar 100, a heat sink 1, at least two cold heads 2, and several pull rods 3; The heat sink 1 is located inside the Dewar 100 and is used to support the low-temperature sensor to be calibrated. The cold head 2 is located on top of the heat sink 1, and there are at least two cold heads 2; one end of the pull rod 3 is connected to the heat sink 1, and the other end of the pull rod 3 is connected to the upper part of the inside of the Dewar 100.

[0028] In practical applications, the Dewar 100 provides a stable, sealed low-temperature vacuum environment for the internal calibration structure and sensor. The heat sink 1, as the core platform for low-temperature sensor calibration, provides a stable low-temperature environment for the sensor to be calibrated. It is typically made of a metal with high thermal conductivity (such as oxygen-free copper), and its structural design must meet the requirements of temperature field uniformity and load-bearing stability. The cold head 2, as the core cooling component, connects to external cooling equipment (such as a GM refrigerator or a pulse tube refrigerator), transferring cold energy to the heat sink 1 through heat conduction, thereby establishing the required low-temperature field on the surface of the heat sink 1. Compared to the single cold head design in existing technologies, the layout of at least two cold heads 2 in this embodiment effectively expands the coverage of cold energy transfer, increases the heat exchange area, and fundamentally improves the problem of limited cooling capacity and slow cooling rate of a single cold head. The tie rod 3 serves as a suspension support component for the heat sink 1. One end is fixedly connected to the heat sink 1, and the other end is securely connected to the upper part of the Dewar 100. The heat sink 1 and the sensor to be calibrated installed below it are suspended on the Dewar 100 by means of suspension, which completely changes the layout mode of the existing technology where the cold head is below and the heat sink is above, and avoids the weight of the heat sink and the sensor from directly acting on the cold head and its internal precision components.

[0029] In this application, the multi-cold head layout expands the heat exchange area, accelerates the cooling rate, and solves the problem of insufficient accuracy in synchronous calibration of multiple sensors; the suspended tie rod structure removes the load on the cold head, avoids fatigue damage, performance degradation and failure risk caused by long-term load on the cold head, reduces system maintenance costs, and improves the continuity and reliability of calibration work.

[0030] The working principle of this embodiment is as follows: The calibration system is assembled inside a Dewar 100. The vacuum insulation properties of the Dewar 100 reduce interference from the external environment on the internal low-temperature field, ensuring the sealing and stability of the calibration environment. During assembly, the heat sink 1 is suspended and fixed inside the Dewar 100 by several tie rods 3, leaving the heat sink 1 in a suspended state with no weight acting on the cold head 2. The cold head 2 is connected to an external refrigeration device and is located on top of the heat sink 1. During operation, after the external refrigeration device is activated, the cooling energy is transferred to the heat sink 1 through the cold head 2. Simultaneously, several cold heads 2 transfer cooling energy to the heat sink 1 from at least two positions (preferably symmetrical positions), allowing the cooling energy to diffuse evenly on the surface of the heat sink 1, quickly establishing a stable and uniform low-temperature field. Once the temperature of the heat sink 1 reaches the required low temperature for calibration and stabilizes, the low-temperature sensor to be calibrated, installed at the corresponding position on the heat sink 1 (e.g., the bottom of the heat sink 1), can then begin precise calibration. Through structural optimization, the entire system not only solves the problems of slow cooling and uneven temperature field in existing technologies, but also avoids the risk of damage to the cold head under load, greatly improving the efficiency, accuracy and reliability of low temperature sensor calibration.

[0031] like Figure 2As shown, in some embodiments of the present invention, a lead block heat accumulator 4 is provided between the cold head 2 and the heat sink 1.

[0032] In practical applications, the lead block heat accumulator 4 refers to a heat storage component made of lead blocks, which is fitted between the bottom of the cold head 2 and the top of the heat sink 1. It can achieve close thermal contact with the cold head 2 and the heat sink 1, aiming to buffer the cooling output of the cold head 2, balance the temperature changes of the heat sink 1, and ensure the uniformity of the temperature field on the surface of the heat sink 1. Among them, the lead block material has excellent heat storage performance and thermal conductivity characteristics, which can quickly absorb the cold energy transferred by the cold head 2 and release it evenly to the heat sink 1. At the same time, its moderate thermal inertia can effectively alleviate the instantaneous fluctuations in the cold energy transfer process and avoid sudden local temperature changes in the heat sink 1.

[0033] During actual calibration, there may be slight differences in the cooling start-up time and cooling rate of the two cold heads 2. If the cold heads 2 are directly connected to the heat sink 1, this difference will be directly transmitted to the heat sink 1, resulting in different cooling rates for areas of the heat sink 1 corresponding to different cold heads 2. This leads to uneven temperature distribution on the bottom surface of the heat sink 1, affecting the accuracy of sensor calibration. The lead block heat accumulator 4 can act as a buffer medium for cold energy transfer. When the two cold heads 2 cool down asynchronously, the cold energy released by the cold head 2 that cools down faster will be temporarily absorbed by the lead block heat accumulator 4, while the cold head 2 that cools down slower can gradually replenish the cold energy. After the lead block heat accumulator 4 evenly distributes the absorbed cold energy, it then stably transfers it to the entire heat sink 1, thereby eliminating the temperature difference caused by the inconsistent cooling of the two cold heads and ensuring that the temperature of each area on the surface of the heat sink 1 changes synchronously and is evenly distributed.

[0034] like Figure 2 As shown, in some embodiments of the present invention, the volume of the lead block heat accumulator 4 is three times that of the heat sink 1.

[0035] In practical applications, the volume of the lead block heat accumulator 4 is set to be three times that of the heat sink 1. This is based on considerations of heat storage capacity and cold energy buffering effect. The main purpose is to ensure that the lead block heat accumulator 4 can store sufficient cold energy to fully exert its buffering and temperature equalization functions and adapt to the cooling output characteristics of the dual cold heads. The volume of the lead block heat accumulator 4 needs to be in a reasonable proportion to the volume of the heat sink 1. If the volume is too small, its heat storage capacity will be insufficient, and it will not be able to effectively absorb the cold energy difference caused by the inconsistent cooling of the dual cold heads, making it difficult to achieve temperature field balance. If the volume is too large, it will increase the overall weight of the structure, occupy too much space inside the Dewar 100, and may also increase cold energy loss, affecting the system's cooling efficiency. Therefore, setting its volume to three times that of the heat sink 1 balances heat storage effect and structural practicality.

[0036] like Figures 3-4 As shown, in some embodiments of the present invention, the cold head 2 includes a primary cold head 201 and a secondary cold head 202 disposed below the primary cold head 201, wherein the secondary cold head 202 is disposed between the primary cold head 201 and the heat sink 1. Among them, a lead block heat accumulator 4 is provided between the secondary cold head 202 and the heat sink 1, and a directional heat-conducting silicone pad 9 is also provided between the secondary cold head 202 and the lead block heat accumulator 4.

[0037] The primary cold head 201 connects to an external refrigerator, receiving the cooling energy from it and stably transferring it to the secondary cold head 202 below. This ensures that the cooling capacity of the external refrigerator is efficiently and stably supplied to the Dewar 100. The secondary cold head 202 receives the cooling energy from the primary cold head 201 and transfers it to the lead block accumulator 4. Its structural design is adaptable to the installation dimensions of both the primary cold head 202 and the lead block accumulator 4, ensuring continuous cooling energy transfer. The directional thermal conductive silicone pad 9 is a flexible thermally conductive component with directional thermal conductivity. It is fitted between the secondary cold head 202 and the lead block accumulator 4 and can be made of silicone with a high thermal conductivity. Its purpose is to enhance the thermal contact between the secondary cold head 202 and the lead block accumulator 4, achieving directional and efficient cooling energy transfer, while also filling the tiny gaps between them to reduce cooling energy loss.

[0038] The cold head 2 is designed as a hierarchical structure with a primary cold head 201 and a secondary cold head 202, and a directional thermally conductive silicone pad 9 is added to further optimize the cold energy transfer efficiency and temperature field stability. The primary cold head 201 is connected to an external refrigerator and can stably receive external cold energy input, avoiding interruptions or fluctuations in cold energy transfer caused by unstable connection between the cold head and the refrigerator. After receiving the cold energy from the primary cold head 201, the secondary cold head 202 efficiently transfers the cold energy to the lead block heat accumulator 4 through the directional thermally conductive silicone pad 9. The directional thermal conductivity of the silicone pad 9 allows the cold energy to be concentrated and conducted along the direction from the secondary cold head 202 to the lead block heat accumulator 4, reducing the loss caused by the diffusion of cold energy to the surrounding area. At the same time, its flexible characteristics can be adapted to the contact surface between the secondary cold head 202 and the lead block heat accumulator 4, eliminating the thermal resistance caused by the gap between the contact surfaces, making the cold energy transfer smoother and more uniform.

[0039] The combination of the graded cold head structure and the directional heat-conducting silicone pad 9 enables the transfer of cold energy from the external refrigeration unit to the heat sink 1 to be more efficient and complete, further alleviating the problem of inconsistent cooling between the two cold heads and ensuring that the lead block heat accumulator 4 can receive cold energy evenly and distribute it to the heat sink 1.

[0040] like Figures 1-4 As shown, in some embodiments of the present invention, there are two cold heads 2, and the two cold heads 2 are arranged symmetrically with respect to the center of the heat sink 1.

[0041] Specifically, the symmetrical layout of the cold heads 2 refers to having the top center of the heat sink 1 as the center of symmetry, with the two cold heads 2 located on opposite sides of the same straight line passing through the center, and the distances from the two cold heads 2 to the center being equal. Simultaneously, the contact area and connection tightness between the cold heads 2 and the lead block heat accumulator 4 are consistent to ensure the symmetry of cold energy transfer efficiency. The heat sink 1 is preferably circular, with its geometric center being the top center. This structural design facilitates the realization of a symmetrical cold head layout and provides the optimal structural basis for uniform cold energy diffusion. Compared to non-circular heat sinks, circular heat sinks ensure that the conduction distance is consistent in all directions when cold energy radiates and diffuses from the symmetrical cold head positions, further guaranteeing the uniformity of the temperature field.

[0042] In detail, this symmetrical arrangement is based on the physical characteristics of cold energy conduction. When the cold energy output synchronously from the two cold heads 2 is transferred to the heat sink 1 through the lead block accumulator 4, a symmetrical cold energy distribution field is formed inside the heat sink 1. This prevents cold energy accumulation or conduction lag in localized areas, effectively eliminating the temperature difference between the edge and center of the heat sink. Simultaneously, the symmetrical layout ensures a uniform distribution of the cooling load between the two cold heads 2, preventing the reduction in cooling efficiency caused by overloading a single cold head, extending the lifespan of the cold heads, and reducing the risk of equipment failure. Furthermore, combined with the suspension support structure of the tie rod 3 and the heat storage and buffering function of the lead block accumulator 4, this symmetrical layout further enhances the overall stability of the system. While ensuring a uniform supply of cold energy, it prevents structural deformation caused by uneven stress or temperature fluctuations in the heat sink 1, providing a precise and stable low-temperature environment for simultaneous calibration of multiple sensors and significantly improving the accuracy of calibration results.

[0043] like Figures 1-4 As shown, in some embodiments of the present invention, the pull rod 3 is a pull rod made of carbon fiber.

[0044] Specifically, carbon fiber tie rods refer to tie rods made of carbon fiber, which possesses low density, high strength, low thermal conductivity, and excellent low-temperature resistance. Tie rods supported by carbon fiber offer several advantages: their low density significantly reduces the rod's weight, preventing interference with the suspension posture of heat sink 1 and the internal force balance of Dewar 100; their high strength ensures stable support of the overall weight of heat sink 1 and the sensor to be calibrated, guaranteeing no deformation or breakage during long-term suspension; and their low thermal conductivity effectively blocks heat transfer between the Dewar 100 and the external environment, preventing external heat from entering the Dewar 100 through the tie rod and interfering with the stability of the low-temperature field.

[0045] In detail, the material selection is based on the core requirements of the low-temperature calibration system. Combined with the suspension support function of the tie rod 3, it achieves dual assurance of support reliability and temperature field stability. Compared with metal tie rods, the low thermal conductivity of carbon fiber tie rods reduces heat conduction loss. Combined with the vacuum insulation properties of Dewar 100, it further isolates external temperature interference, maintaining the stability of the low-temperature field on the surface of heat sink 1, providing a precise environment for calibration work. Its high strength and lightweight characteristics ensure stable support for the heat sink and sensor while reducing the overall system load, avoiding additional load on the internal connection structure of Dewar 100. Furthermore, the low-temperature resistance of carbon fiber material is suitable for the extreme low-temperature environment inside Dewar 100, preventing the material from becoming brittle and failing at low temperatures.

[0046] like Figure 4 As shown, in some embodiments of the present invention, a groove is provided on the outside of the heat sink 1, and a heating wire 101 is provided in the groove. The heating wire 101 is preferably constantan wire.

[0047] The grooves on the outside of the heat sink 1 are recessed structures used to accommodate and fix the heating wire 101. Their positions conform to the outer contour of the heat sink 1, and the width and depth of the grooves are adapted to the dimensions of the heating wire 101. This ensures that the heating wire 101 fits tightly against the surface of the heat sink 1, guaranteeing efficient heat conduction while preventing the heating wire 101 from loosening or shifting, thus ensuring the stability of the heating process. Preferably, the heating wire 101 is spirally wound around the outside of the heat sink 1 and embedded in the grooves. It can be made of constantan wire. By applying electricity and heating, it provides temperature compensation and precise adjustment for the heat sink 1, achieving precise control of the temperature field and meeting the requirements of different calibration temperatures.

[0048] During the calibration of the low-temperature sensor, the cooling effect of the cold head 2 alone is insufficient to achieve precise control of certain specific calibration temperatures, and when the temperature of the heat sink 1 is lower than the target calibration temperature, it cannot quickly recover. However, the spirally wound heating wire 101 can form a comprehensive and uniform contact with the heat sink 1, and when energized, it can uniformly release heat, providing overall heating compensation for the heat sink 1. For example, during temperature recovery, power can be supplied to the heating wire 101 after the temperature reaches 273K to accelerate the recovery. The spiral structure design ensures that the heating wire 101 is more evenly distributed on the outside of the heat sink 1, resulting in more balanced heat transfer and preventing localized overheating or uneven heating of the heat sink 1, thus ensuring that the surface temperature field of the heat sink 1 remains stable and uniform.

[0049] like Figure 5 As shown, in some embodiments of the present invention, the heat sink 1 end face has a plurality of mounting position groups 102 at different distances from the center, each mounting position group 102 includes a plurality of mounting positions, which are used to mount a low temperature sensor or a standard thermometer. Several mounting positions in each mounting position group 102 are distributed on the same circumference, and the distance between two adjacent mounting positions in each mounting position group 102 is the same.

[0050] Furthermore, each mounting position group 102 can be used to install different models of low-temperature sensors, and the low-temperature sensors installed in the same mounting position group 102 are of the same model. That is, the low-temperature sensors to be calibrated and their standard thermometers of the same model are installed in the same mounting position group 102, so that the low-temperature sensors to be calibrated and their standard thermometers of the same model are installed on the same circumference.

[0051] Specifically, the multiple mounting positions 102 arranged along the center of the heat sink 1 end face are mounting structures for mounting the low-temperature sensor to be calibrated and the standard thermometer. Each mounting position group 102 corresponds to a circle with a fixed distance from the center of the heat sink 1, and the multiple mounting position groups 102 form a concentric circular layout with different radii. More specifically, the end face of the heat sink 1 is preferably the bottom surface of the heat sink 1, that is, the side of the heat sink 1 facing away from the cold head 2.

[0052] Each mounting position group 102 contains several mounting positions evenly distributed on a corresponding circumference, with the same distance between adjacent mounting positions. This ensures that all sensors within the same mounting position group 102 are located in the same temperature-uniform area on the heat sink 1, guaranteeing the consistency and comparability of calibration data. Each mounting position group 102 can accommodate different models of low-temperature sensors, and the low-temperature sensors installed in the same mounting position group 102 are of the same model. That is, the same model of low-temperature sensor to be calibrated and its corresponding standard thermometer are installed in the same mounting position group 102, ensuring that the same model of sensor and standard thermometer are in the same uniform temperature field on the same circumference, thereby achieving synchronous calibration of multiple different models of sensors.

[0053] In low-temperature sensor calibration, it is often necessary to calibrate multiple different sensor models simultaneously. Existing technologies can only calibrate the same model of temperature sensor at a time. In this solution, multiple mounting position groups 102 are distributed in concentric circles of different radii around the center of the heat sink 1. The mounting positions on each circle are evenly distributed, and combined with a dual-cold-head design, this ensures consistent temperature across all mounting positions within the same mounting position group 102 on the same circle. Furthermore, sensors of the same model to be calibrated and their standard thermometers are installed in the same mounting position group 102. The errors of all sensors of that model within the same group can be accurately calibrated directly using the measurement data from the standard thermometer. Different mounting position groups 102 can house different models of sensors, enabling simultaneous calibration of multiple sensor models and significantly improving calibration efficiency.

[0054] like Figures 1-4As shown, in some embodiments of the present invention, the diameter of the heat sink 1 is 20-40 cm.

[0055] Specifically, the heat sink 1 is preferably a circular structure, and its diameter can be flexibly adjusted within the range of 20-40cm according to actual calibration requirements. For example, a 30cm diameter can be used when calibrating 30 sensors at a time, and a 25cm diameter can be used when calibrating 20 sensors, adapting to different batch calibration scenarios. This diameter range significantly expands the bearing area of ​​the heat sink 1 end face, solving the problem that traditional 5cm diameter heat sinks can only install 3-4 sensors and have low calibration efficiency. In addition, due to the symmetrical layout of the two cold heads and the equal spacing of the sensor mounting positions around the circumference, the heat sink surface can still form a uniform and stable low temperature field even after the diameter of the heat sink 1 is increased compared to the prior art.

[0056] In detail, traditional 5cm diameter heat sinks, due to their small area, can only accommodate a limited number of sensors for calibration, and only sensors of the same model can be calibrated, significantly restricting batch calibration work. This embodiment, however, increases the heat sink diameter, allowing for simultaneous calibration of more sensors and enabling the simultaneous calibration of different sensor models, significantly improving calibration efficiency. More importantly, the symmetrical cold heads can simultaneously transfer cooling from both sides of the top of the heat sink. Combined with the uniform cooling effect of the lead blocks, this ensures sufficient diffusion of cooling across the 20-40cm diameter heat sink surface. Furthermore, the equidistant sensor mounting layout ensures temperature consistency across all areas of the heat sink. In addition, the weight of the heat sink within this diameter range can be stably supported by carbon fiber tie rods, preventing excessive support load due to the increased heat sink size. This aligns with the overall suspension structure, further ensuring system stability and providing reliable support for batch high-precision calibration.

[0057] like Figure 6 As shown, in some embodiments of the present invention, the calibration Dewar structure of the low-temperature temperature sensor further includes a temperature control PID system 5. The temperature control PID system 5 is connected to a standard thermometer located inside the Dewar 100 and is used to perform PID control on the temperature inside the Dewar 100 based on the temperature feedback from the standard thermometer. That is, during the cooling calibration stage, the temperature control PID system 5 can specifically control the standard thermometer to stabilize at a specific temperature point and maintain it constant, accurately collecting parameter data at the corresponding temperature and providing a reliable anchor point for the calibration curve.

[0058] Specifically, the temperature control PID system 5 can preset key low-temperature points, prioritizing commonly used calibration nodes such as 77K and 4.2K, and achieves precise temperature locking and stable maintenance through closed-loop control logic. During the cooling process, when the standard thermometer detects that the temperature is close to the preset point, the temperature control PID system 5 can fine-tune the power of the external cooling equipment and the heat storage buffer state of the lead block heat accumulator 4 to stabilize the temperature at the target value and maintain it for more than 10 minutes. At the same time, it monitors the temperature difference change of the standard thermometer in real time until the temperature difference is continuously monitored to be less than 0.001K. After confirming that the temperature has reached a stable state, it simultaneously records the accurate temperature value of the standard thermometer and the resistance value of the sensor to be calibrated. The temperature stabilization time and temperature difference threshold can be flexibly adjusted according to the calibration accuracy requirements to ensure the accuracy and repeatability of data acquisition at special points.

[0059] In detail, existing conventional systems lack precise temperature control and stability determination mechanisms, especially at extremely low temperatures such as 4.2K. Even slight temperature deviations can lead to a significant increase in sensor resistance measurement errors, affecting the fitting accuracy of the calibration curve. This application, however, leverages the high-precision adjustment capabilities of its temperature-controlled PID system to achieve precise locking at points such as 77K and 4.2K. Through maintaining a constant temperature for more than 10 minutes and a stability determination with a temperature difference less than 0.001K, it ensures that the collected temperature and corresponding resistance values ​​have extremely high reliability. These precise data points serve as key anchor points for the calibration curve, effectively improving the accuracy of curve fitting and making the temperature-resistance correspondence of the sensor under calibration more accurate, thereby enhancing the overall calibration accuracy of the sensor.

[0060] like Figure 6 As shown, in some embodiments of the present invention, the temperature control PID system 5 is connected to components such as the standard thermometer and constantan heating wire inside the Dewar 100 via a connector to achieve stable interaction of signal transmission and control commands, while ensuring the sealing performance of the Dewar 100.

[0061] Specifically, the aviation connector can be a sealed aviation connector adapted to low-temperature environments and vacuum conditions. It consists of two parts: a plug and a socket. The socket is fixedly installed at the pre-set interface on the side wall of the Dewar 100 and connects to the signal and power supply lines of components such as the standard thermometer and constantan heating wire inside the Dewar 100. The plug connects to the signal output and power control terminals of the temperature control PID system 5. After the plug and socket are mated, they can be fixed by a locking structure to form a sealed and stable connection link. The internal structure of the aviation connector can adopt a multi-core structure, corresponding to temperature signal transmission lines, heating wire power supply lines, and refrigeration equipment control lines, etc., to achieve integrated connection of multiple lines. At the same time, the sealing parts of the aviation connector can be made of low-temperature resistant rubber material, which can adapt to the extreme low-temperature environment inside the Dewar 100 and avoid the degradation of sealing performance at low temperatures.

[0062] In detail, the use of a sealed aviation connector enables stable signal and power transmission through integrated wiring. The connector's sealed structure prevents external air from entering the Dewar 100, maintaining an internal vacuum environment. Combined with the Dewar 100's own thermal insulation properties, this ensures the low-temperature field is unaffected by external interference. Simultaneously, the connector's locking structure prevents wiring from detaching due to vibration or impact. The multi-core integrated design facilitates wiring installation, inspection, and replacement, reducing maintenance difficulty. It also effectively isolates signal interference between different lines, ensuring accurate transmission of the standard thermometer's temperature signal to the PID controller, and efficient transmission of the controller's adjustment commands to the actuator.

[0063] In addition, such as Figure 7 As shown, the present invention also provides a low-temperature temperature sensor, which is calibrated using the calibration Dewar structure of the low-temperature temperature sensor described above. Specifically, the low-temperature temperature sensor includes a temperature sensor body 7 and a standard carbon ceramic thermometer 8 connected in series with the temperature sensor body 7.

[0064] Specifically, the core characteristic of negative temperature coefficient (NTC) temperature sensors (i.e., existing low-temperature temperature sensors) is that their resistance decreases as temperature increases, and there is a fixed nonlinear relationship between resistance and temperature (characterized by a calibration curve). Temperature measurement essentially involves acquiring the sensor's resistance value and using the calibration curve to infer the temperature value. Therefore, in existing low-temperature sensor calibration systems, under high-temperature conditions, the resistance of NTC thermometers is relatively small. For example, the resistance of a carbon ceramic thermometer is only about 1000Ω at high temperatures, and that of a zirconium oxynitride thermometer is only about 80Ω. At this point, inherent errors in the acquisition circuit (such as wire resistance and chip accuracy errors) and resistance fluctuations caused by environmental interference account for a relatively large proportion of the total resistance, ultimately translating into a significant temperature deviation, reaching 2K at room temperature. To solve this problem, a standard carbon ceramic thermometer 8 is connected in series with the temperature sensor body 7. This standard carbon ceramic thermometer 8 is a calibrated carbon ceramic thermometer. To address the issue of low base resistance, a standard carbon ceramic thermometer 8 is connected in series to increase the total resistance base and reduce the proportion of relative error. Since the absolute value of the resistance of a negative temperature coefficient sensor remains constant with temperature change, the temperature calculation deviation corresponding to the same resistance change will be significantly reduced when the base resistance is increased. To address the issue that the total resistance includes the resistance value of the standard carbon ceramic thermometer 8 after connecting it in series, a reverse correction is performed during the calibration curve production stage. The resistance value at the corresponding temperature in the calibrated carbon ceramic thermometer curve is subtracted to ensure that the final temperature calculation is based on the resistance change of the temperature sensor body 7 itself and does not affect the original temperature-resistance correspondence. This technical solution ultimately aims to increase the total resistance base to reduce errors and correct for errors, thereby ensuring accuracy and minimizing the acquisition deviation at room temperature. In practical applications, the acquisition deviation at room temperature can be reduced from 2K to 0.5K.

[0065] In detail, the connection between the temperature sensor body 7 and the standard carbon ceramic thermometer 8 can be made as follows: the temperature sensor body 7 and the standard carbon ceramic thermometer 8 form a series circuit through a connecting wire, that is, one pin of the temperature sensor body 7 is fixedly connected to one pin of the standard carbon ceramic thermometer 8 through the connecting wire, forming the core part of the series structure; in addition, one end of the series circuit (which can be another pin of the temperature sensor body 7) is connected to the input port composed of "U-in" and "I-in" through the connecting wire to receive the input current and voltage of the calibration system; the other end of the series circuit (which can be another pin of the standard carbon ceramic thermometer 8) is connected to the output port composed of "U-out" and "I-out" through the connecting wire to form a complete current path, ensuring that the calibration system can collect the total current and total voltage of the series circuit.

[0066] The specific principle is as follows: a constant current or excitation voltage is input through "I-in" and "U-in", and the total current and total voltage of the series circuit are collected through "I-out" and "U-out". Based on Ohm's law (R_total = U_total / I_total), the total resistance value of "temperature sensor body 7 + standard carbon ceramic thermometer 8" is calculated, providing raw data for subsequent curve correction.

[0067] The aforementioned connecting wires must be low-resistance, low-temperature-coefficient wires to avoid introducing additional errors due to wire resistance, and to ensure that the total resistance value collected only includes the resistance of the temperature sensor body 7 itself and the resistance value of the standard carbon ceramic thermometer 8.

[0068] The above solution addresses the issues of low resistance and large temperature difference in negative temperature coefficient thermometers under high-temperature (normal-temperature) conditions by connecting a standard carbon ceramic thermometer 8 in series with the temperature sensor body 7, thereby significantly improving the accuracy of temperature detection and calibration in the normal-temperature range.

[0069] like Figure 7 As shown, in some embodiments of the present invention, when the ambient temperature is no greater than 4.2K, the resistance value of the standard carbon ceramic thermometer 8 is 2000-5000 ohms. When the ambient temperature is normal, the resistance of the standard carbon ceramic thermometer 8 is 900-1100 ohms.

[0070] In practical applications, the ambient temperature is the temperature of the environment in which the standard carbon ceramic thermometer 8 is located. In this application, the ambient temperature can be the temperature inside the Dewar 100. This ambient temperature is precisely controlled by an external refrigeration unit connected to the first-stage cold head 201, in conjunction with a lead block heat accumulator 4, heating wire 101, and other structures.

[0071] The resistance of the standard carbon ceramic thermometer 8 changes with ambient temperature. Therefore, to ensure calibration accuracy, during the calibration of the low-temperature sensor (composed of the temperature sensor body 7 and the standard carbon ceramic thermometer 8 connected in series), the standard carbon ceramic thermometer 8 is made of the same material as the temperature sensor body 7. Thus, during calibration, the overall resistance of the low-temperature sensor formed by the temperature sensor body 7 and the standard carbon ceramic thermometer 8 connected in series is approximately twice the resistance of the temperature sensor body 7 itself. During the calibration curve generation stage, a reverse correction is required by subtracting the resistance value of the standard carbon ceramic thermometer 8 curve corresponding to the ambient temperature. This ensures that the final temperature calculation is based solely on the resistance change of the temperature sensor body 7 itself, without affecting its original temperature-resistance relationship, providing an accurate reference for calibration.

[0072] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A calibration Dewar structure for a low-temperature temperature sensor, characterized in that, include: Dewar (100); A heat sink (1) is located inside a Dewar (100) and is used to carry a low-temperature sensor. A cold head (2) is located on top of the heat sink (1), and at least two cold heads (2) are provided; Several pull rods (3), one end of which is connected to the heat sink (1) and the other end of which is connected to the upper part of the inside of the Dewar (100).

2. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, The cold head (2) is provided in two parts, and the two cold heads (2) are arranged symmetrically with respect to the center of the heat sink (1).

3. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, The pull rod (3) is made of carbon fiber.

4. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, The heat sink (1) has multiple mounting position groups (102) along the center on its end face, each mounting position group (102) including several mounting positions, which are used to install low temperature sensors or standard thermometers. Several mounting positions in each mounting position group (102) are distributed on the same circumference, and the distance between two adjacent mounting positions in each mounting position group (102) is the same.

5. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, The diameter of the heat sink (1) is 20-40cm.

6. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, A lead block accumulator (4) is provided between the cold head (2) and the heat sink (1).

7. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, The heat sink (1) has a groove on its outside, and a heating wire (101) is provided in the groove.

8. The calibration Dewar structure for a low-temperature temperature sensor according to claim 1, characterized in that, It also includes a temperature control PID system (5), which is connected to a standard thermometer signal located in the Dewar (100) and is used to perform PID control on the temperature in the Dewar (100) based on the temperature feedback from the standard thermometer.

9. A low-temperature temperature sensor, characterized in that, The calibration is performed using the calibration Dewar structure of the low-temperature temperature sensor according to any one of claims 1-8, characterized in that it includes a temperature sensor body (7) and a standard carbon ceramic thermometer (8) connected in series with the temperature sensor body (7).

10. A low-temperature temperature sensor according to claim 9, characterized in that, When the ambient temperature is no greater than 4.2K, the resistance value of the standard carbon ceramic thermometer (8) is 2000-5000 ohms; When the ambient temperature is normal, the resistance of the standard carbon ceramic thermometer (8) is 900-1100 ohms.

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