A gas concentration detection device and detection method for a closed atmosphere

Abstract

The application relates to the technical field of gas concentration detection, and discloses a gas concentration detection device and method for a closed atmosphere, which comprises a metal bellows, a gas detection cavity, a gas sensor, and first, second and third control valves. One end of the metal bellows is fixed, and the other end can move in the telescopic direction to change the internal cavity volume by telescoping; the internal cavity is communicated with a closed cavity to be detected through the first control valve and communicated with the gas detection cavity through the third control valve; the gas inlet and outlet interfaces are communicated with the internal cavity through the second control valve and used for charging and discharging to preset the internal cavity air pressure. The gas sensor is arranged in the gas detection cavity. The application utilizes the metal bellows to passively adjust the detection gas path volume and exchange heat with the environment, controls the gas path on-off through the three control valves, separates the sensor from the pressure and temperature adjusting processes, reduces the influence of pressure and temperature fluctuations on the detection precision and the sensor safety, realizes continuous detection under the closed condition, and has the advantages of simple structure and low energy consumption.

Description

Technical Field

[0001] This application relates to the field of gas concentration detection technology, and in particular to a gas concentration detection device and method for use in a closed atmosphere. Background Technology

[0002] Gas concentration detection has wide applications in industrial production and environmental monitoring. Especially when conducting real-time gas monitoring in confined spaces, the accuracy of the results often faces severe challenges—the air pressure inside a confined space can rise sharply from near vacuum to several atmospheres, and the temperature can also fluctuate significantly. The output signals of most gas sensors are closely related to ambient air pressure and temperature. When sensors are directly exposed to such harsh environments, measurement results will exhibit significant deviations, requiring frequent calibration or reliance on complex compensation algorithms, increasing maintenance costs.

[0003] To address the aforementioned issues, some existing technologies have attempted to address these problems. Patent CN210071677U discloses a calibration-free online laser gas concentration measurement chamber, which connects the measurement chamber and the reference chamber via a bellows to maintain them at the same temperature and pressure. However, in this solution, the gas to be measured is directly introduced into the measurement chamber, the sensor is still directly subjected to harsh operating conditions, and the structure is complex, making it impossible to maintain or replace the sensor during system operation.

[0004] Patent CN115182820A discloses a zero-leakage bellows regulating valve pressure balancing compensation system. Addressing the issue of bellows in gas turbine fuel regulating valves being easily damaged by alternating pressure, the system uses a controller to compare the pressure inside the bellows with the main gas pressure of the valve in real time and dynamically control the opening and closing of the solenoid valve to achieve pressure balancing. However, the technical purpose of this solution is to protect the mechanical structure of the valve bellows itself, rather than to provide a stable working environment for the gas sensor. Its pressure balancing process relies on continuous dynamic interaction with an external high-pressure gas source, and the system is not completely sealed during operation, making it unsuitable for direct application in scenarios requiring zero-pollution, zero-leakage detection of low-concentration test atmospheres.

[0005] In summary, the existing technology lacks a gas concentration detection device that enables gas sensors to operate at normal temperature and pressure in a closed environment with drastic fluctuations in gas pressure and temperature, without consuming or contaminating the low-concentration atmosphere being measured, and allows for online maintenance of the sensor. Summary of the Invention

[0006] In view of this, this application proposes a gas concentration detection device and method for a closed atmosphere, in order to solve the problem that gas sensors in the prior art are difficult to achieve long-term stable and accurate detection in a closed environment with drastic fluctuations in air pressure and temperature.

[0007] The technical solution of this application is implemented as follows: In a first aspect, this application provides a gas concentration detection device for a closed atmosphere, including a metal bellows, a gas detection chamber, a gas sensor, a first control valve, a second control valve, and a third control valve. One end of the metal bellows is fixed, and the other end can move along its expansion and contraction direction so that the metal bellows can change its inner cavity volume by expansion and contraction. The metal bellows is provided with an inlet and outlet port; the inner cavity of the metal bellows is connected to the sealed cavity to be tested through the first control valve, and is connected to the gas detection chamber through the third control valve; the inlet and outlet port is connected to the inner cavity of the metal bellows through the second control valve. The inlet and outlet ports are used to fill the inner cavity of the metal bellows with gas and discharge gas from the inner cavity of the metal bellows, so as to preset the gas pressure inside the metal bellows. The gas sensor is disposed inside the gas detection chamber and is used to detect the gas concentration entering the gas detection chamber.

[0008] Based on the above technical solution, preferably, it also includes a guide support assembly, wherein one end of the metal bellows is fixedly supported on the guide support assembly, and the other end is movably supported on the guide support assembly along the extension and retraction direction of the metal bellows.

[0009] Based on the above technical solution, preferably, the guide support assembly includes a smooth rod slide and a sliding member slidably disposed on the smooth rod slide; one end of the metal bellows is fixedly connected to the smooth rod slide, and the other end is fixedly connected to the sliding member, wherein the sliding direction of the sliding member is set along the extension and retraction direction of the metal bellows.

[0010] Based on the above technical solution, preferably, it also includes a pressure detection element and a temperature detection element, wherein the detection ends of the pressure detection element and the temperature detection element are both connected to the inner cavity of the metal bellows, and are used to detect the gas pressure and temperature in the inner cavity of the metal bellows, respectively.

[0011] Based on the above technical solution, preferably, it also includes a controller, wherein the second control valve and the third control valve are both controlled valves, and the controller is electrically connected to the pressure detection element, the temperature detection element, the second control valve and the third control valve respectively.

[0012] Based on the above technical solution, preferably, the controller is configured to control the third control valve to open when the detected gas pressure and temperature are within a preset detection range.

[0013] Based on the above technical solution, preferably, the controller is further configured to control the third control valve to close when the detected gas pressure fluctuation exceeds a preset threshold, and to control the second control valve to open when the detected gas pressure reaches a preset pressure relief value.

[0014] Based on the above technical solution, preferably, the gas sensor is an optical gas sensor.

[0015] Based on the above technical solution, preferably, the gas detection chamber is provided with an installation interface for detachably installing the gas sensor, and the end of the metal bellows near the first control valve is provided with a connection interface for detachably connecting to the sealed cavity to be tested.

[0016] Secondly, this application discloses a method for detecting gas concentration in a confined atmosphere, utilizing the gas concentration detection device for a confined atmosphere described in the first aspect, comprising the following steps: S1: Close the first control valve and the third control valve, open the second control valve, adjust the gas pressure in the inner cavity of the metal bellows through the inlet and outlet gas ports to make the gas pressure reach the preset pressure value, and then close the second control valve. S2: Open the first control valve to connect the sealed cavity to be tested with the inner cavity of the metal bellows, and keep the first control valve open until the gas pressure and temperature in the inner cavity of the metal bellows reach a stable state. S3: While keeping the first control valve open, open the third control valve to connect the inner cavity of the metal bellows with the gas detection chamber, so that the gas sensor can continuously detect the concentration of the gas to be tested.

[0017] This application has the following advantages over the prior art: (1) This application uses a retractable metal bellows to detect changes in the gas path volume. Three control valves control the gas path opening and closing of the sealed cavity to be tested, the gas inlet and outlet ports and the gas detection chamber respectively. The gas pressure inside the metal bellows is preset through the gas inlet and outlet ports, so that the gas sensor is isolated from the gas pressure and temperature regulation process. This helps to reduce the impact of drastic changes in gas pressure and temperature inside the sealed cavity to be tested on the detection accuracy and safety of the gas sensor. It can also perform continuous gas concentration detection under relatively sealed conditions. By adopting a passive gas pressure and temperature stabilization method, there is no need for external energy to drive the metal bellows to extend or retract or actively heat and cool it. The system structure is simple and reliable and has low energy consumption.

[0018] (2) By setting pressure and temperature sensors, the gas pressure and temperature inside the metal bellows are obtained in real time. Combined with the controller, the second and third control valves are automatically controlled, realizing the automation of preset gas pressure, stable state judgment, detection sequence control, and abnormal working condition identification. The controller automatically determines whether the detection conditions are met based on the detection data, reducing errors caused by manual judgment and operation, and improving the response speed, operation consistency, and automation level of the device.

[0019] (3) The controller is configured to open the third control valve only when the gas pressure and temperature are within the preset detection range. This achieves time decoupling between the gas pressure and temperature stabilization process and the gas concentration detection process, avoiding gas sensor detection before the pressure or temperature has stabilized. This improves the accuracy of the detection results and reduces the risk of sensor impact. When the detected pressure fluctuation exceeds the preset threshold, the controller closes the third control valve to quickly isolate and protect the gas sensor. When the pressure reaches the preset pressure relief value, the controller opens the second control valve for active pressure relief. This forms a graded protection mechanism consisting of abnormal isolation and overpressure relief, reducing the risk of gas sensor damage and overpressure operation of the device.

[0020] (4) Using an optical gas sensor for non-consumption or low-consumption concentration detection does not require the consumption of the gas to be measured, nor does it require the addition of reaction reagents to the detection gas path. This helps to maintain the original state of the low-concentration component to be measured in the closed atmosphere, reduces interference with the atmosphere to be measured during the detection process, and reduces the possibility of introducing impurity gases into the closed atmosphere.

[0021] (5) The gas sensor can be detachably installed via the mounting interface, and the detection device can be detachably and sealed to the sealed cavity under test via the connection interface. This facilitates the replacement, addition, and upgrading of the gas sensor, as well as the overall maintenance of the detection device. The first control valve can maintain the isolation of the sealed cavity under test during maintenance, reducing the impact of maintenance operations on the normal operation of the sealed cavity. In addition, the size of the metal bellows can be selected and adjusted according to the volume of the sealed cavity under test and the expected pressure fluctuation range, so that the device has no substantial limitations on the applicable gas pressure and temperature fluctuation range in terms of hardware, and has good versatility and expandability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1This is a top view of the gas concentration detection device for a closed atmosphere disclosed in an embodiment of this application; Figure 2 This is a side view of a gas concentration detection device for a closed atmosphere disclosed in an embodiment of this application; Figure label: 1. Metal bellows; 2. Gas detection chamber; 3. Gas sensor; 4. First control valve; 5. Second control valve; 6. Third control valve; 11. Inlet / outlet port; 7. Guide support assembly; 71. Smooth rod slide; 72. Sliding element; 8. Pressure detection element; 9. Temperature detection element; F1. Mounting interface; F2. Connection interface; G. Four-way pipe. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0026] In the description of the embodiments of this application, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" 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 the embodiments of this application 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 the embodiments of this application.

[0027] 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.

[0028] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0029] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0030] like Figure 1 As shown, combined with Figure 2 This application discloses a gas concentration detection device for a sealed atmosphere, including a metal bellows 1, a gas detection chamber 2, a gas sensor 3, a first control valve 4, a second control valve 5, and a third control valve 6.

[0031] The metal bellows 1 is made of a thermally conductive metal material and has an internal cavity for containing gas. One end of the metal bellows 1 is fixed, while the other end is movable along the axial direction of the metal bellows 1. When the movable end of the metal bellows 1 moves, the metal bellows 1 extends or shortens accordingly, thereby changing the internal volume of the metal bellows 1.

[0032] In this embodiment, the metal bellows 1 not only serves as a flexible connection and airtight isolation but also acts as a buffer volume for the detection gas path. When the sealed cavity to be tested is connected to the metal bellows 1, to prevent severe pressure shocks or pressure overshoots from damaging the gas sensor 3, it is necessary to ensure that the metal bellows 1 has a sufficient volume variation range to balance the pressure fluctuations of the cavity to be tested. Those skilled in the art know that in practical engineering applications, the initial pressure of the sealed cavity to be tested may be unknown or subject to certain pressure fluctuations. To ensure that the gas sensor always operates within a suitable pressure range (i.e., the target detection pressure), the detection device of this application cleverly utilizes the expandable characteristics of the metal bellows.

[0033] In practical applications, the initial gas pressure of the sealed cavity under test may vary within a certain range, for example, from a low-pressure state close to vacuum to a high-pressure state above atmospheric pressure. To ensure that the balanced pressure of the connected detection gas path remains within the suitable detection pressure range of gas sensor 3, the pre-charge gas pressure needs to be reasonably set based on the initial pressure range of the sealed cavity under test, the volume of the sealed cavity under test, and the range of volume variation of the metal bellows 1. P pre .

[0034] Let the volume of the sealed cavity to be measured be... V t The range of its initial gas pressure variation is [ , The minimum internal volume of a metal bellows is V. b The suitable detection pressure range for gas sensor 3 is [ P min , P max Before the test begins, the metal bellows is pre-filled with water at a pressure of [pressure value missing]. P pre Buffer gas.

[0035] To ensure that the balanced pressure of the detection gas path still meets the sensor's operating requirements under the most unfavorable operating conditions, the following two extreme cases need to be considered: Scenario 1: The sealed cavity under test is at its lowest initial pressure. For example, it is 0. After connection, the gas in the metal bellows 1 expands into the sealed cavity to be tested, and the metal bellows 1 contracts to its minimum volume. In the ultimate condition, the equilibrium pressure after mixing should not be lower than the sensor's minimum allowable operating pressure. P min 。 Based on the conservation of the total amount of gas before and after connection (under isothermal conditions), we use the most relaxed V here. b substitution and That is, using a representative volume V b This approximates the bellows volume under two limiting states. This is a safety-biased engineering approximation: on the low-pressure side, V... b Alternative This causes the calculated compensation capacity value to be too small, resulting in P pre The lower limit is conservative; on the high-voltage side, V b Alternative This causes the calculated buffer capacity to be underestimated, resulting in... P pre The upper limit is also somewhat conservative. Therefore, in reality... and It will also be able to satisfy, and thus: ,Right now: .

[0036] The second scenario: The sealed cavity under test is at its highest initial pressure. For example, if the pressure is 200 kPa, then the corresponding metal bellows 1 is at its minimum volume. After connection, the high-pressure gas in the sealed cavity to be tested enters the metal bellows 1, and the metal bellows 1 extends to its maximum volume. The ultimate limit state. The equilibrium pressure after mixing should not exceed the sensor's maximum allowable operating pressure. P max Similar to the first case, we can obtain: ,Right now: .

[0037] Using the two inequalities above, designers can determine the volume of the sealed cavity to be tested. V t The range of initial gas pressure variation is [ , And the suitable detection pressure range of gas sensor 3. P min , P max By working backwards, the minimum internal volume of the metal bellows is calculated to be V. b and appropriate pre-charge gas pressure P pre .

[0038] As some specific examples, let's assume the volume of the sealed cavity to be measured. V t The initial gas pressure range is 0–200 kPa, and the suitable detection pressure range for the gas sensor is 80 kPa to 120 kPa (close to atmospheric pressure). To ensure that the detection pressure falls within this range under various operating conditions, the initial volume of the metal bellows can be designed to be 8 L. Substituting the above data into the two inequalities:

[0039] For the first case ( ): 0×10+ P pre ×8≥80×(10+8), solving for 8, we get 80×(10+8). P pre ≥180 kPa.

[0040] For the second scenario ( ): 200×10+ P pre ×8≤120×(10+8), solving for 8, we get 120×(10+8). P pre ≤20 kPa.

[0041] In reality, the air pressure in the chamber being tested is [ , Between ], so P pre The air pressure setpoint should be taken within the calculated range of two values, i.e. [ The specific value depends on the relative volume ratio of the cavity under test and the metal bellows under natural conditions (1 atmosphere). A specific value is selected within this range. P pre When taking the value, the actual air pressure of the cavity to be measured can be considered. To determine, for example, let This allows us to obtain a solution that is on the safe side. P pre The value ensures that the balance pressure does not exceed the sensor's upper limit under the most unfavorable operating conditions.

[0042] Generally, V can be determined through the following steps. b The possible values ​​of: 1). According to P pre The calculation formula, substitute into [ P min , P max ], [ , ]and V t Numerical value; 2).V b Values ​​from V t Starting with / 2, we retrieve values ​​and substitute them. P pre Calculation formula calculates the corresponding P pre The value indicates whether it falls within the range of [0, preset pressure relief P]. 3) If it does not fall within this range, then increase V. b The value is iterated until it falls within the range of [0, preset pressure relief P], which is V. b Minimum allowed value.

[0043] Determine V b After obtaining the value, and combining it with the actual air pressure of the cavity under test, when Vt ≤ 100 kPa, use... Calculated P pre The value.

[0044] When Vt > 100 kPa, use Calculated P pre The value.

[0045] In special cases where the initial air pressure of the cavity to be measured cannot be obtained, only a conservative measurement can be adopted, and the initial volume of the bellows should be set to be at least 4 times the volume of the cavity to be measured. P pre A simple setting of 100 kPa will achieve stable air pressure at [[ P min , P max ] interval.

[0046] By changing the pre-charge gas pressure and the relative volume relationship between the metal bellows 1 and the sealed cavity to be tested, the device of this application can effectively adapt to sealed atmosphere detection scenarios with different initial pressures and different pressure fluctuation ranges. This design ensures that the pressure in the detection gas path can quickly and smoothly transition to the appropriate operating range of the sensor at the moment of connection to the cavity to be tested, avoiding sensor impact damage caused by excessive pressure difference, and significantly improving the stability and safety of detection.

[0047] The metal wall of the metal bellows 1 can exchange heat with its surrounding environment. When the temperature of the gas to be measured in the sealed cavity is higher than the ambient temperature, the gas entering or contacting the inner cavity of the metal bellows 1 can release heat to the surrounding environment through the metal wall; when the gas temperature is lower than the ambient temperature, the gas can absorb heat from the surrounding environment through the metal wall, thereby gradually bringing the gas temperature in the inner cavity of the metal bellows 1 closer to the ambient temperature. In a normal ambient temperature environment, this helps to stabilize the gas temperature entering the gas detection chamber 2 within the suitable operating temperature range of the gas sensor 3.

[0048] The metal bellows 1 is provided with an inlet / outlet port 11. The inner cavity of the metal bellows 1 is connected to the sealed cavity to be tested through the first control valve 4, and is connected to the gas detection chamber 2 through the third control valve 6; the inlet / outlet port 11 is connected to the inner cavity of the metal bellows 1 through the second control valve 5.

[0049] The first control valve 4 is used to control the gas flow between the sealed cavity under test and the metal bellows 1. During the preparation and preset gas pressure stages, the first control valve 4 can be closed to isolate the metal bellows 1 and the gas detection chamber 2 from the sealed cavity under test. During continuous detection, the first control valve 4 can be opened and kept open to maintain continuous communication between the sealed cavity under test and the metal bellows 1. During device maintenance, gas sensor 3 replacement, or gas detection chamber 2 maintenance, the first control valve 4 can be closed to isolate the detection device from the sealed cavity under test, thereby reducing the impact of maintenance on the normal operation of the equipment inside the sealed cavity under test.

[0050] The second control valve 5 is used to control the connection between the inlet / outlet port 11 and the inner cavity of the metal bellows 1. When the second control valve 5 is open, gas can be introduced into the inner cavity of the metal bellows 1 through the inlet / outlet port 11, and gas can also be discharged from the inner cavity of the metal bellows 1 through the inlet / outlet port 11. The gas can be discharged by vacuum pumping, exhausting device venting, or other methods that can reduce the gas pressure inside the metal bellows 1. The introduced gas can be nitrogen, argon, or other gases that do not react adversely with the gas to be tested.

[0051] The third control valve 6 is used to control the gas flow between the metal bellows 1 and the gas detection chamber 2. When the gas pressure and temperature in the metal bellows 1 have not yet reached the detection requirements of the gas sensor 3, the third control valve 6 is closed, isolating the gas sensor 3 from the gas flow where pressure or temperature may fluctuate drastically. After the gas pressure and temperature in the metal bellows 1 have stabilized, the third control valve 6 is opened, connecting the gas detection chamber 2 to the metal bellows 1. Through the coordinated operation of the first control valve 4, the second control valve 5, and the third control valve 6, the pressure and temperature stabilization space and the gas detection space are decoupled in time and space, providing hardware support for the sequential testing process of stabilizing pressure first and then detecting. This ensures the stability of the testing environment and protects the gas sensor 3 from damage caused by drastic pressure changes.

[0052] Gas sensor 3 is installed inside gas detection chamber 2 to detect the concentration of gas entering gas detection chamber 2. As a sensor housing space independently set relative to metal bellows 1, gas detection chamber 2 can be isolated from metal bellows 1 when the third control valve 6 is closed, thereby decoupling the gas pressure and temperature regulation process from the gas concentration detection process.

[0053] Before use, the device in this embodiment can close the first control valve 4 and the third control valve 6, open the second control valve 5, and inflate or depressurize the inner cavity of the metal bellows 1 through the inlet / outlet port 11 until the gas pressure inside the metal bellows 1 reaches a preset pressure value, and then close the second control valve 5. Subsequently, the first control valve 4 is opened to connect the sealed cavity to be tested with the metal bellows 1. The metal bellows 1 expands and contracts according to changes in gas pressure in the gas path and exchanges heat with the surrounding environment through its metal wall. After the gas pressure and temperature stabilize, the third control valve 6 is opened to connect the gas detection chamber 2 with the metal bellows 1, and the gas sensor 3 continuously detects the concentration of the gas to be tested. During continuous detection, the first control valve 4 remains open.

[0054] It should be noted that the metal bellows 1 does not rely on continuous gas exchange with the outside to regulate the gas pressure during normal detection. The second control valve 5 is closed after the preset gas pressure is reached. During normal detection, the sealed cavity to be tested, the metal bellows 1, and the gas detection chamber 2 constitute a relatively sealed detection gas path, which helps to prevent the low concentration of gas to be tested from leaking out or external gas from entering the detection gas path.

[0055] In summary, this embodiment uses a retractable metal bellows 1 to detect changes in the gas path volume. Three control valves control the gas flow to and from the sealed cavity under test, the inlet / outlet port 11, and the gas detection chamber 2. The gas pressure within the metal bellows 1 is preset via the inlet / outlet port 11, isolating the gas sensor 3 from the pressure and temperature regulation process. This helps reduce the impact of drastic pressure and temperature changes within the sealed cavity on the detection accuracy and safety of the gas sensor 3, and enables continuous gas concentration detection under relatively sealed conditions. By employing a passive pressure and temperature stabilization method, no external energy is required to drive the metal bellows' expansion or contraction, or for active heating or cooling. The system structure is simple, reliable, and energy-efficient.

[0056] In some embodiments, the gas concentration detection device in this embodiment further includes a guide support assembly 7. One end of the metal bellows 1 is fixedly supported on the guide support assembly 7, and the other end is movably supported on the guide support assembly 7 along the extension and retraction direction of the metal bellows 1.

[0057] The guide support assembly 7 is used to support the metal bellows 1 and guide the movement of the movable end of the metal bellows 1. When the metal bellows 1 expands or contracts, its movable end moves in a predetermined direction under the constraint of the guide support assembly 7, so as to reduce the possibility of lateral displacement, bending or torsion of the metal bellows 1 during expansion or contraction.

[0058] The guide support assembly 7 can be a guide rail, guide rod, linear slide, linear bearing assembly, or other structure capable of linearly guiding the movable end of the metal bellows 1. The metal bellows 1 and the guide support assembly 7 can be connected by threaded connection, flange connection, clamping connection, snap-fit, welding, or other fixed connection methods, which are not specifically limited in this embodiment.

[0059] The guide support assembly 7 supports both ends of the metal bellows 1, which can reduce the influence of the weight of the metal bellows 1 and its connecting pipes on the expansion and contraction of the metal bellows 1, allowing its movable end to move more smoothly with the changes in gas pressure in the gas path. At the same time, the guide support assembly 7 can also reduce the lateral load generated by the connecting pipes on the metal bellows 1, and improve the stress state of the metal bellows 1 during repeated expansion and contraction.

[0060] In this embodiment, the fixed end and movable end of the metal bellows 1 are supported by the guide support assembly 7, and the movement direction of the movable end is limited, thereby improving the smoothness of the extension and retraction movement of the metal bellows 1, reducing the possibility of lateral deviation, bending or twisting, which is beneficial to improving the stability of the air pressure regulation process and the service life of the metal bellows 1.

[0061] In some embodiments, this embodiment further describes the specific structure of the guide support assembly 7.

[0062] The guide support assembly 7 includes a smooth rod slide 71 and a slider 72 slidably disposed on the smooth rod slide 71. One end of the metal bellows 1 is fixedly connected to the smooth rod slide 71, and the other end is fixedly connected to the slider 72. The sliding direction of the slider 72 is arranged along the extension and retraction direction of the metal bellows 1.

[0063] The guide slide 71 may include a base and at least one guide rod disposed on the base, and a sliding member 72 is sleeved or slidably mounted on the guide rod. The sliding member 72 may cooperate with the guide rod through a linear bearing, a sliding sleeve, or a sliding hole, so that the sliding member 72 can reciprocate along the length direction of the guide rod.

[0064] The fixed end of the metal bellows 1 can be directly or indirectly fixed to the base or fixed bracket of the smooth rod slide 71, and the movable end of the metal bellows 1 can be directly or indirectly fixed to the sliding member 72. "Direct or indirect fixing" here includes, but is not limited to, fixing using clamps, flanges, connecting plates, threaded connectors, or welded structures. Therefore, this embodiment does not limit the connection between the metal bellows 1 and the smooth rod slide 71 and sliding member 72 to the use of specific clamps.

[0065] When the metal bellows 1 extends, its movable end drives the slider 72 to move away from the fixed end along the smooth rod; when the metal bellows 1 shortens, its movable end drives the slider 72 to move closer to the fixed end along the smooth rod. Since the sliding direction of the slider 72 is consistent with the extension and retraction direction of the metal bellows 1, the additional lateral resistance experienced by the metal bellows 1 when changing its internal volume is small.

[0066] In some embodiments, a limiting structure may be provided on the guide slide 71 to limit the maximum travel of the slider 72, preventing the metal bellows 1 from exceeding its maximum allowable elongation or minimum compression. The limiting structure may be a mechanical limit block, a limit switch, or a position sensor. The limiting structure is optional and does not constitute a necessary limitation of this embodiment.

[0067] In this embodiment, a linear guide structure is formed by a smooth rod slide 71 and a sliding member 72, which enables the movable end of the metal bellows 1 to move smoothly back and forth along its extension and retraction direction. This achieves support and guidance for the metal bellows 1 with a relatively simple mechanical structure, and reduces the motion resistance and non-axial deformation of the metal bellows 1 during the extension and retraction process.

[0068] In some embodiments, the gas concentration detection device in this embodiment further includes a pressure detection element 8 and a temperature detection element 9.

[0069] It is worth noting that the fixed end of the metal bellows 1 is connected to a four-way pipe G, which has four branches. The first branch is connected to the sealed cavity to be tested through the first control valve 4, the second branch is connected to the gas detection chamber 2 through the third control valve 6, the third branch is connected to the inner cavity of the metal bellows 1, and the fourth branch is connected to the pressure detection element 8 and the temperature detection element 9.

[0070] The detection ends of pressure detection element 8 and temperature detection element 9 are both connected to the fourth branch of the four-way pipe G, thereby connecting to the inner cavity of the metal bellows 1, and are used to detect the gas pressure and temperature inside the metal bellows 1, respectively. Pressure detection element 8 and temperature detection element 9 can be set separately, or they can be integrated into an integrated detection instrument with pressure detection and temperature detection functions.

[0071] Pressure sensing element 8 can be a pressure gauge, pressure sensor, vacuum gauge, compound pressure gauge, or other device capable of detecting gas pressure. Temperature sensing element 9 can be a thermocouple, resistance temperature detector, temperature sensor, or other device capable of detecting gas temperature.

[0072] The pressure sensing element 8 and temperature sensing element 9 can be directly installed on the metal bellows 1, or they can be installed on a connecting pipe that communicates with the inner cavity of the metal bellows 1. The only requirement is that their sensing ends can obtain the gas pressure and temperature corresponding to the inner cavity of the metal bellows 1.

[0073] During the preset pressure stage, pressure sensor 8 can be used to determine whether the gas pressure inside the metal bellows 1 has reached the preset pressure value. After opening the first control valve 4 to connect the sealed cavity to be tested with the metal bellows 1, pressure sensor 8 and temperature sensor 9 can be used to monitor pressure and temperature changes in the connected gas path. When the gas pressure and temperature enter the preset detection range, or when the fluctuation amplitude within the preset time period does not exceed the corresponding stability threshold, the gas pressure and temperature can be considered to have reached a stable state, thus allowing the third control valve 6 to be opened.

[0074] During continuous testing, pressure sensor 8 and temperature sensor 9 can also continuously monitor the operating status of the gas path. When abnormal pressure or temperature changes occur in the sealed cavity under test, the corresponding test data can be obtained in a timely manner, so as to isolate the gas detection chamber 2 or depressurize the metal bellows 1 through the control valve.

[0075] In this embodiment, the gas pressure and temperature inside the metal bellows 1 are obtained in real time through the pressure detection element 8 and the temperature detection element 9. This provides data for preset gas pressure, stable state judgment, detection timing control and abnormal working condition identification, thereby improving the monitorability of the gas concentration detection device's operating status and the reliability of the detection process.

[0076] In some embodiments, the gas concentration detection device in this embodiment further includes a controller. The second control valve 5 and the third control valve 6 are both controlled valves, and the controller is electrically connected to the pressure detection element 8, the temperature detection element 9, the second control valve 5, and the third control valve 6, respectively.

[0077] Specifically, the controller can be connected to the pressure sensor 8 and the temperature sensor 9 via a signal connection to receive the pressure detection signal output by the pressure sensor 8 and the temperature detection signal output by the temperature sensor 9; the controller can be connected to the second control valve 5 and the third control valve 6 via a control connection to control the second control valve 5 and the third control valve 6 to open or close respectively.

[0078] The second control valve 5 and the third control valve 6 can be solenoid valves, electric valves, pneumatic valves, or other valves that can switch on / off states in response to control commands output by the controller. The first control valve 4 can also be a solenoid valve or other controlled valve, but in this embodiment, it is not required that the first control valve 4 be connected to the controller.

[0079] The controller can be a programmable logic controller, a microcontroller, an industrial control computer, an embedded controller, or other control device with signal acquisition and control command output functions. The controller can store parameters such as preset pressure values, preset detection pressure ranges, preset detection temperature ranges, pressure fluctuation thresholds, and preset pressure relief values.

[0080] During operation, the controller determines the current gas state based on the detection data provided by pressure sensor 8 and temperature sensor 9, and controls the second control valve 5 and the third control valve 6 according to the determination result. This transforms the process of manually reading instruments, manually determining the stable state, and manually operating valves into an automatic detection and control process.

[0081] In this embodiment, the controller collects pressure and temperature detection signals and controls the opening and closing of the second control valve 5 and the third control valve 6 to realize the automated control of the detection gas path, reduce errors caused by manual judgment and operation, and improve the response speed, operation consistency and automation of the gas concentration detection device.

[0082] In some embodiments, the controller is configured to open the third control valve 6 when the detected gas pressure and temperature are within a preset detection range.

[0083] The preset detection range can be set according to the allowable operating pressure range and allowable operating temperature range of the gas sensor 3, or a narrower optimal detection range can be set within the allowable operating range. For example, when the gas sensor 3 is suitable for operation near normal temperature and pressure, the preset detection range can be set near normal temperature and pressure.

[0084] After opening the first control valve 4 to connect the sealed cavity to be tested with the metal bellows 1, the controller continuously or periodically acquires the detection values ​​of the pressure sensor 8 and the temperature sensor 9. When both the pressure and temperature detection values ​​are within the corresponding preset detection range, the controller determines that the current gas path status meets the gas detection requirements and outputs an opening command to the third control valve 6 to connect the metal bellows 1 with the gas detection chamber 2.

[0085] Furthermore, the controller can also determine whether the gas pressure and temperature remain stable within a preset time period. For example, the controller will only open the third control valve 6 when the pressure and temperature detection values ​​are both within their respective preset detection ranges over multiple consecutive sampling periods, and the change between adjacent detection values ​​does not exceed the corresponding threshold. This prevents the third control valve 6 from opening prematurely when the gas pressure or temperature only briefly crosses the preset detection range.

[0086] Before the third control valve 6 is opened, the gas detection chamber 2 where the gas sensor 3 is located is isolated from the metal bellows 1. Therefore, the pressure or temperature fluctuations generated when the sealed chamber to be tested is just connected to the metal bellows 1 are not likely to directly affect the gas sensor 3.

[0087] In this embodiment, the third control valve 6 is opened only when the gas pressure and temperature meet the preset detection conditions. This decouples the gas pressure and temperature stabilization process from the gas concentration detection process, preventing the gas sensor 3 from performing detection before the pressure or temperature has stabilized. This helps improve the accuracy of the detection results and reduces the risk of the gas sensor 3 being impacted.

[0088] In some embodiments, the controller is further configured to close the third control valve 6 when the detected gas pressure fluctuation exceeds a preset threshold, and to open the second control valve 5 when the detected gas pressure reaches a preset pressure relief value.

[0089] During normal continuous testing, both the first control valve 4 and the third control valve 6 are in the open state, and the sealed cavity to be tested, the metal bellows 1, and the gas detection chamber 2 are interconnected. When the gas pressure in the sealed cavity to be tested changes, the metal bellows 1 expands and contracts to change its internal volume, thereby buffering the pressure change in the detection gas path.

[0090] When the pressure change exceeds the normal adjustment capability of the metal bellows 1, or the pressure fluctuation may affect the normal detection of the gas sensor 3, the controller controls the third control valve 6 to close, so as to isolate the gas detection chamber 2 from the metal bellows 1, in order to prevent abnormal pressure from continuing to act on the gas sensor 3.

[0091] The pressure fluctuation range can be determined based on the deviation of the current pressure from the reference pressure, or based on the difference between the maximum and minimum pressure values ​​within a preset time period. For example, when using 1 atm as the reference pressure, a fluctuation exceeding 20% ​​of the reference pressure can be used as an example condition for closing the third control valve 6. This example value does not constitute a limitation of this application, and the actual threshold can be determined based on the pressure resistance and detection accuracy of the gas sensor 3.

[0092] When the gas pressure rises further and reaches the preset pressure relief value, the controller opens the second control valve 5, connecting the inner cavity of the metal bellows 1 to the pressure relief pipeline or gas recovery device through the inlet / outlet port 11, thereby releasing some gas and reducing the pressure in the detection gas path. The preset pressure relief value can be determined based on the allowable pressure of the metal bellows 1, connecting pipeline, control valve, and other pressure-bearing components. For example, 2 atm can be used as a preset pressure relief value, but it is not limited to this.

[0093] To prevent the gas to be tested from being directly released into the surrounding environment, the inlet and outlet ports 11 can be connected to a gas recovery container, a tail gas treatment device, or a closed pressure relief container. This not only enables pressure relief under abnormal operating conditions but also reduces the diffusion of the gas to be tested into the external environment.

[0094] After the pressure returns to a safe range, the controller can close the second control valve 5. Once the pressure and temperature return to the preset detection range and reach a stable state, the controller can reopen the third control valve 6 to resume continuous detection.

[0095] This embodiment achieves rapid isolation and protection of the gas sensor 3 by closing the third control valve 6 when the pressure fluctuates abnormally, and actively vents the pressure by opening the second control valve 5 when the pressure reaches the preset pressure relief value. This forms a graded protection mechanism consisting of abnormal isolation and overpressure relief, which helps to reduce the risk of damage to the gas sensor 3 and overpressure operation of the device.

[0096] In some embodiments, the gas sensor 3 in this embodiment is an optical gas sensor 3.

[0097] The optical gas sensor 3 can determine the concentration of the gas to be measured by detecting the absorption, transmission, reflection, or scattering characteristics of the gas to be measured to light of a specific wavelength. For example, the optical gas sensor 3 can be an infrared absorption gas sensor 3, a laser absorption spectroscopy gas sensor 3, or other optical sensors suitable for detecting confined atmospheres.

[0098] In some embodiments, the optical gas sensor 3 includes a light source, an optical detection channel, and a photodetector. The gas to be measured enters or is distributed in the optical detection channel. The detection light emitted by the light source passes through the gas to be measured and is received by the photodetector. The gas sensor 3 calculates the concentration of the gas to be measured based on the change in the intensity or spectral change of the detection light.

[0099] Compared to sensors that require chemical or electrochemical reactions to detect gas concentration, optical gas sensors typically do not consume the analyte gas or require the addition of reaction reagents to the detection gas path. In closed detection scenarios with low concentrations of the analyte gas, this reduces the possibility of concentration changes caused by the sensor consuming the analyte component, and also reduces the risk of the sensor introducing other substances into the closed atmosphere.

[0100] The optical gas sensor 3 can select the corresponding detection band according to the type of gas to be measured. One or more optical gas sensors 3 can also be set in the gas detection chamber 2 to detect one or more gas components respectively.

[0101] In this embodiment, an optical gas sensor 3 is used to perform non-consumption or low-consumption concentration detection of the gas to be tested. This helps to maintain the original state of the low-concentration component to be tested in the closed atmosphere, reduce interference with the atmosphere to be tested during the detection process, and reduce the possibility of introducing impurity gases into the closed atmosphere.

[0102] In some embodiments, the gas detection chamber 2 is provided with an installation interface F1 for detachably installing the gas sensor 3, and the end of the metal bellows 1 near the first control valve 4 is provided with a connection interface F2 for detachably connecting to the sealed chamber to be tested.

[0103] The mounting interface F1 can be a KF vacuum interface, flange interface, threaded interface, clamp interface, or other detachable sealed interface. In one specific embodiment, the mounting interface F1 is a KF quick-release standard vacuum interface, and the gas sensor 3 is mounted to the gas detection chamber 2 via a sealing ring and clamp. When it is necessary to replace or add the gas sensor 3, the clamp can be released and the original gas sensor 3 can be removed without disassembling the entire gas detection device.

[0104] The gas detection chamber 2 can be equipped with one or more mounting interfaces F1. When multiple mounting interfaces F1 are provided, multiple gas sensors 3 of the same or different types can be installed according to the detection requirements. Sealing plugs can also be installed on unused mounting interfaces F1. Thus, the type and number of gas sensors 3 can be adjusted according to the type of gas to be measured and the detection requirements.

[0105] It should be noted that the fixed end of the metal bellows 1 is connected to the first control valve 4, the third control valve 6, the pressure detection element 8 and the temperature detection element 9 respectively through the four-way pipe G. The end of the four-way pipe G near the first control valve 4 is provided with a connection interface F2 for detachable connection with the sealed cavity to be tested.

[0106] The connection interface F2 can be a KF vacuum interface, flange interface, threaded interface, or other airtight detachable connection structure. The first control valve 4 can be located between the connection interface F2 and the metal bellows 1, or the connection interface F2 can be located on the side of the first control valve 4 away from the metal bellows 1. As long as the first control valve 4 is closed, the sealed cavity to be tested can be isolated from the testing device to be maintained.

[0107] When maintenance of gas detection chamber 2 or replacement of gas sensor 3 is required, the first control valve 4 can be closed to isolate the detection device from the sealed chamber under test. Then, gas detection chamber 2, gas sensor 3, or other components can be disassembled and maintained. During maintenance, the sealed chamber under test can remain sealed, thereby reducing the impact of the maintenance process on the operating status of the equipment inside the sealed chamber under test.

[0108] When the entire testing device needs to be replaced, the first control valve 4 can be closed, and the metal bellows 1 and its connecting components can be removed from the sealed cavity to be tested via the connection interface F2. The new testing device can be reinstalled through the connection interface F2 of the same specification, thereby improving the versatility and replacement efficiency of the device.

[0109] In this embodiment, the gas sensor 3 can be detachably installed through the installation interface F1, and the detection device and the sealed cavity to be tested can be detachably sealed through the connection interface F2. This facilitates the replacement, addition and upgrading of the gas sensor 3, and also facilitates the overall maintenance of the detection device. At the same time, the first control valve 4 can be used to maintain the isolation state of the sealed cavity to be tested, reducing the impact of maintenance operations on the normal operation inside the sealed cavity.

[0110] Furthermore, the dimensions of the metal bellows 1 (including the minimum and maximum inner cavity volumes) can be selected and adjusted according to the volume of the sealed cavity to be tested and the expected pressure fluctuation range. Therefore, the gas concentration detection device of this application has no substantial limitations on the applicable gas pressure and temperature fluctuation range in terms of hardware, and basically depends on the design requirements of the system, and has good versatility and expandability.

[0111] This application also provides a method for detecting gas concentration in a closed atmosphere. The method uses the gas concentration detection device described in the above embodiments and includes the following steps.

[0112] Step S1: Preset the gas pressure inside the metal bellows 1.

[0113] Specifically, by closing the first control valve 4 and the third control valve 6, opening the second control valve 5, and adjusting the gas pressure inside the metal bellows 1 through the inlet / outlet port 11, the gas pressure inside the metal bellows 1 is brought to a preset pressure value, and then the second control valve 5 is closed.

[0114] The preset pressure value can be determined based on the volume of the sealed cavity to be tested, the initial gas pressure of the sealed cavity to be tested, the minimum and maximum internal volumes of the metal bellows 1, and the target detection pressure. The target detection pressure can be set within the suitable operating pressure range of the gas sensor 3, for example, near atmospheric pressure.

[0115] Adjusting the gas pressure via the inlet / outlet port 11 can include either filling the inner cavity of the metal bellows 1 with gas or discharging gas from the inner cavity of the metal bellows 1. In one specific embodiment, the original gas in the inner cavity of the metal bellows 1 is first extracted through the inlet / outlet port 11, and then nitrogen or argon is filled into the inner cavity of the metal bellows 1 to bring the gas pressure inside the metal bellows 1 to a preset pressure value.

[0116] Before formal testing, the metal bellows 1 and gas detection chamber 2 can be purged with gas. Specifically, with the first control valve 4 closed, the original gas in the metal bellows 1 can be extracted through the second control valve 5 and the inlet / outlet port 11, and then replaced with replacement gas. The second control valve 5 is then closed and the third control valve 6 is opened, allowing the replacement gas to enter the gas detection chamber 2 to replace the original gas in the chamber. The third control valve 6 is then closed, and the second control valve 5 is opened again for extraction and filling. This process can be repeated once or multiple times to reduce the impact of residual air or other impurities in the metal bellows 1 and gas detection chamber 2 on the test results.

[0117] After gas replacement is completed, close the third control valve 6, open the second control valve 5, and adjust the gas pressure in the metal bellows 1 to the final preset pressure value through the inlet / outlet gas interface 11, then close the second control valve 5. The above gas replacement process is a preferred process and does not need to be performed for every test.

[0118] This step ensures that the preset pressure process does not affect the sealed cavity under test by closing the first control valve 4; and that the gas extraction, gas filling, and pressure changes during the preset pressure process do not directly affect the gas sensor 3 by closing the third control valve 6.

[0119] Step S2: Connect the sealed cavity to be tested and stabilize the gas state.

[0120] Specifically, by opening the first control valve 4, the sealed cavity to be tested is connected to the inner cavity of the metal bellows 1, and the first control valve 4 is kept open until the gas pressure and temperature in the inner cavity of the metal bellows 1 reach a stable state.

[0121] After the first control valve 4 is opened, a connecting gas path is formed between the sealed cavity to be tested and the metal bellows 1. Since the gas pressure in the metal bellows 1 has been preset according to the volume of the sealed cavity to be tested and the initial gas pressure, the gas pressure after the sealed cavity to be tested is connected to the metal bellows 1 can enter the vicinity of the target detection pressure.

[0122] When the gas pressure changes, the metal bellows 1 extends or shortens to change its internal volume, thus buffering the gas pressure changes in the connected gas path. At the same time, the metal wall of the metal bellows 1 exchanges heat with the surrounding environment, causing the gas temperature inside the metal bellows 1 to gradually approach the ambient temperature.

[0123] The stability of gas pressure and temperature can be determined using pressure sensor 8 and temperature sensor 9. In one embodiment, the gas is considered to have reached a stable state when both pressure and temperature are within a preset detection range. In another embodiment, a stable state is determined when the fluctuation range of gas pressure within a preset time does not exceed one resolution of pressure sensor 8, and the fluctuation range of gas temperature within a preset time does not exceed 0.1°C.

[0124] If pressure detection element 8 and temperature detection element 9 are not set, the gas pressure and temperature in the metal bellows 1 can be stabilized after the first control valve 4 is opened, according to the stabilization waiting time determined in the pre-test.

[0125] It should be noted that in this step, the first control valve 4 remains open after it is opened, and is not closed after the gas pressure and temperature reach a stable state. Therefore, during subsequent testing, the sealed cavity under test can remain continuously connected to the metal bellows 1.

[0126] Step S3: Continuously detect the concentration of the gas to be tested.

[0127] Specifically, while keeping the first control valve 4 open, the third control valve 6 is opened to connect the inner cavity of the metal bellows 1 with the gas detection chamber 2, and the gas sensor 3 continuously detects the concentration of the gas to be tested.

[0128] After the third control valve 6 is opened, the sealed cavity to be tested, the metal bellows 1, and the gas detection chamber 2 form a continuously connected detection gas path. The gas sensor 3 detects the gas to be tested that enters or is distributed in the gas detection chamber 2 and continuously outputs the gas concentration detection result.

[0129] During continuous detection, both the first control valve 4 and the third control valve 6 remain open, while the second control valve 5 remains closed. The metal bellows 1 expands and contracts in response to changes in the gas pressure within the sealed cavity being tested, buffering gas pressure changes by altering the internal cavity volume. Furthermore, the metal bellows 1 continuously exchanges heat with the surrounding environment through its metal wall, thereby maintaining the gas pressure and temperature entering the gas detection chamber 2 within a suitable detection range.

[0130] When using the optical gas sensor 3, continuous detection can be performed without significantly consuming the gas to be measured, making it suitable for long-term monitoring of low-concentration gases in closed cavities.

[0131] During continuous detection, gas pressure and temperature can be monitored in real time via pressure sensor 8 and temperature sensor 9. When the gas pressure and temperature are within the preset detection range, the third control valve 6 remains open.

[0132] When the gas pressure fluctuation exceeds a preset threshold, the controller closes the third control valve 6 to isolate the gas detection chamber 2 from the metal bellows 1, protecting the gas sensor 3. When the gas pressure reaches a preset pressure relief value, the controller opens the second control valve 5, discharging some gas through the inlet / outlet port 11 to reduce the pressure in the detection gas path. After the pressure returns to normal, the second control valve 5 closes; once the gas pressure and temperature stabilize again, the third control valve 6 can be reopened to resume continuous detection.

[0133] When maintenance is required on gas sensor 3 or gas detection chamber 2, continuous detection can be stopped and the first control valve 4 closed to isolate the detection device from the sealed chamber under test. Then, the third control valve 6 can be closed, or the corresponding gas path can be vented as needed for maintenance. Gas sensor 3 can then be removed through mounting interface F1. After maintenance, the gas replacement, pressure preset, connection stabilization, and continuous detection steps can be repeated.

[0134] This embodiment stabilizes the gas state by pre-setting the gas pressure inside the metal bellows 1, connecting it to the sealed cavity to be tested, and utilizing the volume change of the metal bellows 1 and heat exchange through the metal pipe wall. Then, while the first control valve 4 is continuously open, the third control valve 6 is opened for continuous detection. This achieves the timing coordination between gas state regulation and sensor detection, enabling the gas sensor 3 to continuously monitor the sealed atmosphere under relatively stable pressure and temperature conditions, and to implement sensor isolation and active pressure relief under abnormal pressure.

[0135] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A gas concentration detection device for a confined atmosphere, characterized in that, It includes a metal bellows, a gas detection chamber, a gas sensor, a first control valve, a second control valve, and a third control valve; One end of the metal bellows is fixed, and the other end can move along its expansion and contraction direction so that the metal bellows can change its inner cavity volume by expansion and contraction. The metal bellows is provided with an inlet and outlet port; the inner cavity of the metal bellows is connected to the sealed cavity to be tested through the first control valve, and is connected to the gas detection chamber through the third control valve; the inlet and outlet port is connected to the inner cavity of the metal bellows through the second control valve. The inlet and outlet ports are used to fill the inner cavity of the metal bellows with gas and discharge gas from the inner cavity of the metal bellows, so as to preset the gas pressure inside the metal bellows. The gas sensor is disposed inside the gas detection chamber and is used to detect the gas concentration entering the gas detection chamber.

2. The gas concentration detection device for a closed atmosphere as described in claim 1, characterized in that: It also includes a guide support assembly, one end of which is fixedly supported by the guide support assembly, and the other end is movably supported by the guide support assembly along the extension and retraction direction of the metal bellows.

3. The gas concentration detection device for a closed atmosphere as described in claim 2, characterized in that: The guide support assembly includes a smooth rod slide and a sliding member slidably disposed on the smooth rod slide; one end of the metal bellows is fixedly connected to the smooth rod slide and the other end is fixedly connected to the sliding member, and the sliding direction of the sliding member is set along the extension and retraction direction of the metal bellows.

4. The gas concentration detection device for a closed atmosphere as described in claim 1, characterized in that: It also includes a pressure detection element and a temperature detection element, the detection ends of which are connected to the inner cavity of the metal bellows, and are used to detect the gas pressure and temperature in the inner cavity of the metal bellows, respectively.

5. The gas concentration detection device for a closed atmosphere as described in claim 4, characterized in that: It also includes a controller, wherein the second control valve and the third control valve are both controlled valves, and the controller is electrically connected to the pressure detection element, the temperature detection element, the second control valve and the third control valve respectively.

6. The gas concentration detection device for a closed atmosphere as described in claim 5, characterized in that: The controller is configured to open the third control valve when the detected gas pressure and temperature are within a preset detection range.

7. The gas concentration detection device for a closed atmosphere as described in claim 6, characterized in that: The controller is also configured to close the third control valve when the detected gas pressure fluctuation exceeds a preset threshold, and to open the second control valve when the detected gas pressure reaches a preset pressure relief value.

8. The gas concentration detection device for a closed atmosphere as described in claim 1, characterized in that: The gas sensor is an optical gas sensor.

9. The gas concentration detection device for a closed atmosphere as described in claim 1, characterized in that: The gas detection chamber is provided with an installation interface for detachably installing the gas sensor, and the end of the metal bellows near the first control valve is provided with a connection interface for detachably connecting to the sealed cavity to be tested.

10. A method for detecting gas concentration in a confined atmosphere, utilizing the gas concentration detection device for a confined atmosphere as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Close the first control valve and the third control valve, open the second control valve, adjust the gas pressure in the inner cavity of the metal bellows through the inlet and outlet gas ports to make the gas pressure reach the preset pressure value, and then close the second control valve. S2: Open the first control valve to connect the sealed cavity to be tested with the inner cavity of the metal bellows, and keep the first control valve open until the gas pressure and temperature in the inner cavity of the metal bellows reach a stable state. S3: While keeping the first control valve open, open the third control valve to connect the inner cavity of the metal bellows with the gas detection chamber, so that the gas sensor can continuously detect the concentration of the gas to be tested.

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