Water vapor interference resistant sensor air chamber and dynamic dehumidification method thereof

Abstract

The invention provides a water vapor interference resistant sensor air chamber and a dynamic dehumidification method thereof.The sensor air chamber is characterized in that an acquisition control module, a temperature acquisition assembly and a heating and heat preservation assembly are arranged in an air chamber structure assembly, and the acquisition control module is connected with the temperature acquisition assembly and the heating and heat preservation assembly; the heating and heat preservation assembly is arranged on the outer side of the sensor, the collection control module carries out data processing and regulation and control parameter calculation, and precise moisture-proof control is achieved. Meanwhile, the invention discloses a dynamic dehumidification method. In combination with the change of sensor signals and the moisture condensation temperature under different temperature conditions, the heating and heat preservation assembly is started to heat the air chamber, so that the temperature of the air chamber is always higher than the dew point temperature and is fixed as the temperature difference value of the air chamber temperature and the environment temperature, and the moisture is effectively prevented from condensing in the air chamber or interfering a detection signal; the problem that the sensor is prone to false alarm in the humid environment is solved, data are stable and reliable in the humid environment, and detection precision and stability are improved.

Description

Technical Field

[0001] This invention relates to the technical field of sensor detection applications, and in particular to a sensor chamber resistant to water vapor interference and its dynamic dehumidification method. Background Technology

[0002] Photoionization sensors, with their high sensitivity and fast response, are widely used in gas detection in fields such as environmental monitoring and industrial safety. In environments with high water vapor content or humidity, water vapor can easily condense in the sensor's gas chamber due to temperature changes, adhering to the electrodes and UV lamp surfaces. Alternatively, water vapor can directly interfere with ion migration during the photoionization process, leading to signal drift, decreased sensitivity, increased noise, and even false alarms, thus affecting the sensor's detection reliability.

[0003] In existing technologies, temporary solutions to moisture interference often involve adding a waterproof semi-permeable membrane. However, the semi-permeable membrane is prone to saturation under continuous high humidity, whether inside the sensor or the air chamber, and cannot fundamentally prevent moisture from affecting the core detection components of the sensor. Using a combination of pump suction and water vapor molecular sieves for dehumidification can suppress the effects of moisture in a short time, but it is costly, has a short lifespan, and requires frequent replacement of molecular sieve spare parts. There are also methods that use continuous natural heating of the sensor, but long-term heating will cause device aging and a surge in power consumption.

[0004] Therefore, a sensor chamber capable of eliminating moisture interference and its dynamic implementation scheme are needed to improve the working stability of photoionization, infrared and other sensors in humid environments.

[0005] Utility model patent application number 202020468737.7 discloses a novel PID sensor system with a dehumidification structure, including a processor, an air chamber shell, a PID sensor, a pressure regulating valve, a sampling pump, a humidity sensor, a pressure sensor, a temperature sensor, and a heating element. The air chamber shell has an air outlet and an air inlet. The PID sensor is located inside the air chamber shell. The pressure regulating valve is located at the air inlet. The sampling pump is located at the air outlet. The humidity sensor, pressure sensor, and temperature sensor are disposed inside the air chamber shell and connected to the processor. The processor is connected to and controls the heating element. This utility model can reduce the error in PID sensor data caused by humidity, thereby improving data accuracy. However, the patent contains multiple components such as a pressure regulating valve, a sampling pump, and a humidity sensor, which not only increases hardware and maintenance costs and structural volume, affecting explosion-proof performance, but also easily leads to data errors due to the structural limitations of the humidity sensor and the slow and low-precision humidity control response of the heating element. Summary of the Invention

[0006] To address the technical problem that photoionization and infrared sensors are susceptible to moisture in humid environments, leading to errors, this invention proposes a sensor chamber resistant to moisture interference and its dynamic dehumidification method. The sensor chamber is dehumidified and moisture-proofed through flexible heating technology and dynamic temperature control technology.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a sensor chamber resistant to water vapor interference includes a chamber structure assembly. The chamber structure assembly is internally provided with a data acquisition and control module, a temperature acquisition component, and a heating and insulation component. The data acquisition and control module is connected to the temperature acquisition component and the heating and insulation component respectively. The heating and insulation component is disposed on the outside of the sensor. The data acquisition and control module performs data processing and adjustment parameter calculation to achieve precise moisture-proof control.

[0008] Preferably, the air chamber structure assembly includes a probe base, a protective cover, and a fixing sleeve. A temperature acquisition component and a sensor are installed on the probe base, and the protective cover is fixedly connected to the probe base through the fixing sleeve. The sensor, acquisition and control module, temperature acquisition component, and heating and insulation component are all arranged in the sensor air chamber formed by the probe base and the protective cover.

[0009] Preferably, the front end of the protective cover is provided with a metal explosion-proof mesh, through which gas enters the sensor gas chamber and meets the explosion-proof requirements; the protective cover and the probe base are metal structures and meet the explosion-proof requirements; the inner wall of the protective cover is coated with a hydrophobic treatment layer; a semi-permeable membrane is pasted on the front end of the sensor, and one side of the semi-permeable membrane is pasted on the heat insulation sleeve or inside the protective cover with adhesive.

[0010] Preferably, the heating and heat preservation component includes a heater and a heat insulation sleeve. The heater is connected to a heater drive circuit and is placed around the sensor. The heater and the sensor are disposed inside the heat insulation sleeve, which is disposed inside a protective cover.

[0011] Preferably, the acquisition and control module includes an MCU control unit and an acquisition and control circuit board, a first temperature acquisition circuit, a second temperature acquisition circuit, a heating and insulation component, the first temperature acquisition circuit, the second temperature acquisition circuit, and the acquisition and control circuit board are all connected to the MCU control unit, the first temperature acquisition circuit and the second temperature acquisition circuit are connected to the temperature acquisition component, and the acquisition and control circuit board is connected to the sensor and the temperature acquisition component respectively.

[0012] Preferably, the acquisition and control circuit board includes a heater driving circuit and a sensor signal conditioning circuit, both of which are connected to the MCU control unit; the heater of the heating and insulation component is connected to the heater driving circuit, and the sensor signal conditioning circuit is connected to the sensor. The temperature acquisition component includes a first temperature sensor and a second temperature sensor. The first temperature sensor is connected to a first temperature acquisition circuit, and the second temperature sensor is connected to a second temperature acquisition circuit. The first temperature sensor is located below the acquisition control circuit board, away from the heater, to acquire the ambient temperature. The second temperature sensor is located near the heater of the heating and insulation component to acquire the temperature after heating.

[0013] Preferably, the heater driving circuit includes a MOSFET, the drain of which is connected to the heater in the heating and insulation component as an output, the source of which is grounded, the gate of which is connected to the control signal MCU_PWM of the MCU control unit through a resistor R51, and the gate of which is grounded through a parallel capacitor C50 and a resistor R50. Both the first and second temperature acquisition circuits use temperature chips. The input of the temperature chip is powered by VCC, and the output of the temperature chip obtains the Temp temperature signal through a current-limiting resistor, which is read by the MCU control unit and converted into a usable temperature value. The input and output of the temperature chip are grounded through a decoupling capacitor. The heater employs flexible heating technology and is made of carbon nanotubes, graphene, or polyimide films with high thermal conductivity, electrical conductivity, and chemical stability. The shape of the heater is adapted to the outer wall contour of the sensor's outer chamber. The second temperature sensor is located near the heat insulation sleeve, which is made of aluminum silicate fiber.

[0014] A dynamic dehumidification method for a sensor chamber resistant to water vapor interference is provided. When the chamber temperature T2, acquired by the second temperature acquisition circuit, is lower than the dew point temperature of the ambient air, water vapor in the air will condense into liquid water on the sensor surface. The chamber temperature is kept higher than the dew point temperature by heating the heater of the heating and insulation component, and is fixed as the temperature difference ΔT between the chamber temperature and the ambient temperature, i.e., chamber temperature T2 = ambient temperature T1 + ΔT, ensuring that the air inside the chamber is in an "unsaturated" state. The temperature difference ΔT can be dynamically adjusted, and the ambient temperature T1 is acquired by the first temperature acquisition circuit.

[0015] Preferably, closed-loop dynamic dehumidification control is achieved in five stages, including: Phase S1: Initial State Monitoring and Parameter Initialization Real-time temperature acquisition: The first temperature acquisition circuit continuously acquires the ambient temperature T1, and the second temperature acquisition circuit is bound to the heater to acquire the temperature of the air chamber T2 after dynamic heating. Temperature detection: After the MCU control unit is powered on, it triggers the self-test of the first temperature acquisition circuit and the second temperature acquisition circuit; Dynamic calculation of temperature difference ΔT: The value of temperature difference ΔT is dynamically adjusted based on the dynamically acquired ambient temperature T1. The correspondence between ambient temperature T1 and temperature difference ΔT can be obtained by looking up a table in the MCU control unit. Target temperature setting: The MCU control unit calculates the target temperature T_target=T1+ΔT for dynamic dehumidification of the air chamber, which serves as the reference for subsequent heating control; Stage S2: Heating Start-up Judgment Conditions The MCU control unit compares the air chamber temperature T2 with the target temperature T_target, and T2-T1 with the temperature difference ΔT in real time. Heating is triggered when both of the following conditions are met simultaneously: 1) If the air chamber temperature T2 < T_target, the air chamber temperature has not reached the target temperature; 2) T2-T1 < ΔT, there is a temperature difference between the heater and the gas chamber; If any condition is not met, maintain the current state and do not start heating or enter the heat preservation mode; Stage S3: Heating Regulation Logic The MCU control unit adjusts the duty cycle of the PWM signal to dynamically adjust the heating power of the heater. Stage S4: Dehumidification and Temperature Stabilization during the Heating Process Continuous monitoring and feedback: During heating, the MCU control unit collects the values ​​of ambient temperature T1 and air chamber temperature T2 once per second, monitoring these two key parameters in real time. 1) If changes in ambient temperature and humidity cause the temperature difference value ΔT to need to be updated, then the target temperature T_target will be corrected synchronously. 2) If the air chamber temperature T2 ≥ T1 + ΔT, then pause heating or switch to heat preservation mode; Phase S5: Low-power standby and fault protection.

[0016] Preferably, the self-testing method of the first and second temperature acquisition circuits is as follows: the first and second temperature acquisition circuits continuously acquire 3 sets of data at 100ms intervals. If the fluctuation value of each set of data is ≤0.2℃, the temperature acquisition circuit is determined to be normal, and the average value of the 3 sets of data is taken as the initial ambient temperature T1 and the initial air chamber temperature T2. If the fluctuation value is >0.2℃ or the data exceeds the range of "-40℃~60℃", the acquisition is determined to be faulty, and the abnormal protection is triggered. The correspondence between ambient temperature T1 and condensation temperature is stored in the MCU control unit. When the ambient temperature T1 is collected, the condensation temperature under the highest humidity of 99%RH is recorded as the temperature difference value ΔT. In stage S4, the MCU control unit dynamically adjusts the duty cycle of the PWM signal based on the difference between "T_target-T2". 1) When T_target-T2>3℃: Output a PWM signal with a duty cycle of 80%; 2) When 1℃≤T_target-T2≤3℃: output a PWM signal with a duty cycle of 50%; 3) When T_target - T2 < 1℃: Output a PWM signal with a duty cycle of 30%; The MCU control unit collects the air chamber temperature T2 every 100ms and updates the duty cycle synchronously. The stage S5 includes standby dehumidification: when in low power mode, if the air chamber temperature T2 drops below the target temperature T_target-1℃, the MCU control unit triggers "intermittent heating", that is, heating for 5 seconds and pausing for 20 seconds; Abnormal protection: If any of the following occurs, heating will be stopped immediately and an alarm will be triggered: temperature acquisition circuit failure, heater malfunction, abnormal calculation of temperature difference ΔT; Recovery mechanism: After the anomaly is resolved, the MCU control unit re-executes the initialization process of stage S1, and after confirming that the parameters are normal, it restarts heating automatically.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: The sensor achieves moisture-proof and interference-free operation through flexible heating technology and dynamic temperature control technology. The sensor chamber includes a sensor, probe base, protective cover, fixing sleeve, semi-permeable membrane, first temperature acquisition circuit, second temperature acquisition circuit, acquisition control circuit, heater, and heat insulation sleeve. By combining changes in the sensor signal and the condensation temperature of water vapor under different temperature conditions, the flexible heating component is activated to heat the chamber containing the sensor. Combined with real-time temperature acquisition by the temperature detection module, and the temperature control module adjusting the heating power of the flexible heating component based on the temperature control algorithm of the algorithm processing unit, this effectively prevents water vapor from condensing inside the chamber or interfering with the detection signal. This solves the problem of false alarms caused by sensors in humid environments, ensuring stable and reliable data in humid conditions and improving detection accuracy and stability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the sensor gas chamber of the present invention.

[0020] Figure 2 This invention provides control principle diagrams for the internal and external components of the acquisition and control circuit board.

[0021] Figure 3 This is a flowchart of the dynamic dehumidification method of the present invention.

[0022] Figure 4 This is a circuit diagram of the heater drive circuit of the present invention.

[0023] Figure 5 This is a circuit diagram of the temperature acquisition circuit of the present invention.

[0024] In the diagram, 1 is the sensor, 2 is the probe base, 3 is the protective cover, 4 is the fixing sleeve, 5 is the semi-permeable membrane, 6 is the first temperature acquisition circuit, 7 is the second temperature acquisition circuit, 8 is the acquisition control circuit board, 9 is the heater, and 10 is the heat insulation sleeve. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 like Figure 1As shown, a sensor chamber resistant to water vapor interference is disclosed. The sensor chamber provides an explosion-proof, sealed space for gas detection, and a sensor 1 for gas concentration detection is installed inside the sensor chamber. The invention includes a chamber structure assembly, which internally houses a data acquisition and control module, a temperature acquisition component, and a heating and insulation component. The data acquisition and control module is connected to both the temperature acquisition component and the heating and insulation component, which is located on the outside of the sensor 1. The temperature acquisition component is used to detect the sensor chamber. The heating and insulation component heats and insulates the sensor chamber, i.e., the interior of the chamber structure assembly. Because humidity has a significant impact at different locations, the humidity obtained varies depending on the location within the chamber, making accurate humidity values ​​impossible to obtain. Therefore, this invention does not consider humidity acquisition but instead uses the temperature difference combined with the MCU's internal settings for water vapor condensation (or water vapor saturation) conditions at different temperatures. For example, under normal atmospheric pressure conditions of 30°C, a water vapor saturation temperature of 5°C at 40% RH humidity and 7°C at 99% RH humidity, the saturation temperature is automatically matched to 7°C. This means that if the dynamic heating temperature is above 7°C, condensation will not form into water droplets, thus preventing false alarms. In addition, two conditions are needed for water vapor to turn into water: one is the presence of a carrier, and the other is the conditions for condensation. If the temperature difference between the inside and outside is within a certain range, fog (small water droplets) will form. If the temperature difference is higher than the condensation value, fog will not form. The key is to combine the outside temperature with the inside temperature to continuously maintain a higher temperature than the outside temperature, thus preventing fog formation. The data acquisition and control module receives temperature data collected by the temperature acquisition component and executes temperature control commands. The data acquisition and control module has a moisture-proof algorithm unit to complete data processing and control parameter calculation, achieving precise moisture-proof control.

[0027] The gas chamber structure assembly includes a probe base 2, a protective cover 3, and a fixing sleeve 4, forming a sensor gas chamber. The probe base 2 is used to install the temperature acquisition component and the sensor 1; the front end of the protective cover 3 is a metal explosion-proof mesh, through which gas enters the sensor gas chamber and meets explosion-proof requirements. The fixing sleeve 4 is used to fix the protective cover 3. Under the condition of the threaded clamping of the fixing sleeve 4, the probe base 2 and the protective cover 3 with the metal explosion-proof mesh form an explosion-proof structure, and the circuit, sensor, heating components, etc. are placed inside this explosion-proof structure. The setting of the explosion-proof mesh and explosion-proof cavity prevents inaccurate humidity acquisition. The gas chamber structure assembly is a metal structure and meets explosion-proof requirements. The inner wall of the protective cover 3 is coated with a hydrophobic layer to reduce water vapor adhesion. A "water barrier" is formed on the surface of the hydrophobic layer to reduce the adhesion or penetration of water into the sensor. The hydrophobic layer is made of materials such as polydimethylsiloxane (PDMS) and methyltriethoxysilane. A semi-permeable membrane 5 is attached to the front end of the sensor 1 to prevent condensation or dust from entering the sensor. The semi-permeable membrane 5 has an adhesive backing, usually 3M adhesive, which is pasted onto the heat insulation sleeve or fixed inside the protective cover 3, as long as it is between the sensor 1 and the metal explosion-proof mesh.

[0028] The acquisition and control module is responsible for acquiring the concentration signal collected by the sensor 1, and simultaneously obtaining the ambient temperature and heating temperature, and outputting heating control for the heating and insulation component. Figure 2 As shown, the acquisition and control module includes an MCU control unit, an acquisition and control circuit board 8, a first temperature acquisition circuit 6, and a second temperature acquisition circuit 7. The heating and insulation component, the first temperature acquisition circuit 6, the second temperature acquisition circuit 7, and the acquisition and control circuit board 8 are all connected to the MCU control unit. The acquisition and control circuit board 8 includes a heater drive circuit and a sensor signal conditioning circuit, both of which are connected to the MCU control unit. The first temperature acquisition circuit 6 and the second temperature acquisition circuit 7 acquire the ambient temperature and the temperature of the heated sensor chamber, respectively. The first temperature acquisition circuit 6 is fixed to the temperature acquisition component away from the heater, while the second temperature acquisition circuit 7 needs to be closer to the heater. The heating and insulation component is connected to the heater drive circuit, which drives and controls the heater, controlled by PWM output from the MCU control unit. The MCU control unit provides signal acquisition and algorithm processing. The sensor signal conditioning circuit is connected to sensor 1 and includes a signal amplification circuit and an ADC acquisition unit. This is to enable the MCU control unit to acquire the weak analog signal acquired by the sensor for signal amplification and AD conversion.

[0029] like Figure 4 As shown, the heater drive circuit includes a MOSFET Q50. The drain of the MOSFET is connected to the heater 9 in the heating and insulation component as the output. The source of the MOSFET is grounded. The gate of the MOSFET is connected to the control signal MCU_PWM of the MCU control unit through a resistor R51. The gate of the MOSFET is grounded through a parallel capacitor C50 and a resistor R50.

[0030] The control signal MCU_PWM is a PWM signal output from the MCU control unit, which controls MOSFET Q50 to heat the flexible heater. The heater is powered by VCC_5V. The MOSFET Q50 is model AO3480C, but other MOSFET models are also acceptable. Resistor R51 is for current limiting. Grounding capacitor C50 and resistor R50 allows the N-MOSFET to return to zero quickly, resulting in a more complete PWM square wave signal.

[0031] The first temperature acquisition circuit 6 and the second temperature acquisition circuit 7 are both TC1047 temperature chips, powered by VCC. The output Temp temperature signal is read by the MCU and converted into a usable temperature value. Capacitors C60 / C61 are simple decoupling capacitors to prevent slight voltage or signal fluctuations or interference. Resistor R60 is a current-limiting resistor. The capacitors and resistors protect the circuit.

[0032] Both the first temperature acquisition circuit 6 and the second temperature acquisition circuit 7 are connected to the temperature acquisition component, which includes a first temperature sensor and a second temperature sensor. The first temperature sensor is connected to the first temperature acquisition circuit 6, and the second temperature sensor is connected to the second temperature acquisition circuit 7. The temperature sensors used are high-precision thermocouples or platinum resistance temperature sensors with a detection accuracy of not less than ±0.5℃. The first temperature sensor is located on the board below the acquisition control circuit board 8, away from the heating source, and acquires the ambient temperature. The second temperature sensor is placed near the heating source of the heating and insulation component, that is, near the heat insulation sleeve, to acquire the temperature after heating.

[0033] Sensor 1 is a gas acquisition unit that converts ambient gas concentration signals into electrical signals for the MCU control unit to read. Sensor 1 is either a photoionization PID sensor or an NDIR infrared sensor that is sensitive to humidity.

[0034] The heating and insulation component includes a heater 9 and a heat insulation sleeve 10. The heater 9 is connected to a heater drive circuit and is controlled by a heating drive on a circuit board. The heater is placed around the sensor and near the air inlet to provide heating. The heater 9 and sensor 1 are housed inside the heat insulation sleeve 10, which surrounds the heater 9 and sensor 1 and can be tucked into the protective cover 3. The heat insulation sleeve 10 is simply fitted between the sensor and the protective cover. The heater 9 employs flexible heating technology, utilizing the Joule effect of flexible materials to allow electrons to move under the influence of an electric field and collide with phonons, converting electrical energy into heat energy, thus achieving efficient and uniform heating. The heater 9 needs to be made of materials with high thermal conductivity, electrical conductivity, and chemical stability, such as carbon nanotubes, graphene, or polyimide films. Flexible heating technology combines a flexible substrate with conductive heating materials, enabling it to be bent, folded, and fit irregular surfaces to achieve uniform temperature control. The core principle is to balance "flexible form" with "stable heating." The heater 9 must be in close contact with the sensor 1, and the vent at the front end of the heater 9 facilitates gas entry into the sensor 1. The shape of the heater 9 is adapted to the contour of the outer wall of the air chamber, enabling uniform heating with high fit and high heating efficiency. The heating power of the heater 9 is less than 3W. The heat insulation sleeve 10 is made of aluminum silicate fiber to reduce heat loss during the heating process and improve moisture-proof and dehumidification efficiency, and it can adapt to the air chamber structure components and humid working environments.

[0035] Example 2 A dynamic dehumidification method for a sensor chamber resistant to water vapor interference: Based on the aforementioned sensor chamber resistant to water vapor interference, and considering the core requirement of avoiding water vapor condensation in the sensor chamber, this method focuses on precise temperature control and anti-condensation. Through temperature acquisition and dynamic heating in synergy, efficient dehumidification is achieved without affecting the detection accuracy within the chamber. Specifically, when the second temperature value (T2) acquired by the second temperature acquisition circuit 7 is lower than the dew point temperature of the ambient air, water vapor in the air will condense into liquid water on the chamber wall or the surface of components (sensor surface, near the air inlet). Because this method is based on the optical principles of PID photoionization or NDIR infrared sensors, the entry of condensed water will cause optical path deflection or changes in ionization energy, affecting detection accuracy. The method maintains a second temperature (T2) consistently above the dew point temperature through heating, and by fixing the temperature difference ΔT between the air chamber and the ambient temperature, it fundamentally blocks the path of water vapor condensation—that is, it keeps the second temperature T2 equal to the first temperature T1 + ΔT (the temperature difference ΔT can be dynamically adjusted). This ensures that the air inside the air chamber is in an "unsaturated" state, preventing water vapor condensation and accelerating the evaporation of existing trace amounts of water vapor. The dynamic dehumidification method of this invention achieves closed-loop dynamic dehumidification control in five stages: Phase S1: Initial State Monitoring and Parameter Initialization Real-time temperature acquisition: The first temperature acquisition circuit 6 (outdoor environment) continuously acquires the ambient temperature T1, and the second temperature acquisition circuit 7 is bound to the heater to acquire the sensor chamber temperature T2 after dynamic heating; the second temperature acquisition circuit 7 is relatively close to the heating component, and the acquired temperature can represent the heating temperature.

[0036] Temperature Judgment: After the MCU control unit is powered on, it first triggers a self-test of the dual temperature acquisition circuit: the first and second temperature acquisition circuits continuously acquire three sets of data (100ms interval). If the fluctuation value of each set of data is ≤0.2℃, the acquisition circuit is considered normal, and the average value of the three sets of data is taken as the initial ambient temperature T1 and the initial air chamber temperature T2. The average value is taken after three or more acquisitions to prevent inaccurate initial values ​​due to temperature fluctuations or erroneous acquisitions in a single acquisition. If the fluctuation value is >0.2℃ or the data exceeds the "-40℃~60℃" range, an acquisition fault is determined, and abnormal protection is triggered. Dynamic calculation of temperature difference ΔT: Temperature difference ΔT is the difference between the temperature of the air chamber and the ambient temperature when water vapor condenses into liquid water. When the surface temperature of an object is lower than the dew point temperature of the air, water vapor in the air will condense into liquid water on the object's surface. The higher the temperature and the greater the humidity, the lower the temperature difference ΔT. The temperature difference ΔT is dynamically adjusted based on the dynamically acquired ambient temperature T1. The corresponding relationship can be found in a table within the MCU control unit. That is, the temperature difference ΔT is obtained based on the acquired ambient temperature T1. The temperature difference ΔT is obtained from the memory of the MCU control unit, based on the ambient temperature T1. Ignoring atmospheric pressure, temperature and humidity determine the condensation temperature. Since humidity is not acquired, the MCU control unit stores the correspondence between ambient temperature and condensation temperature. When the temperature is acquired, the condensation temperature value under the worst-case scenario (maximum humidity 99% RH) is recorded as the temperature difference ΔT.

[0037] Target temperature setting: The MCU control unit calculates the target temperature for dynamic dehumidification of the air chamber, T_target=T1+ΔT, as the reference for subsequent heating control.

[0038] Stage S2: Heating Start-up Judgment Conditions The MCU control unit compares the air chamber temperature T2 with the target temperature T_target, and T2-T1 with the temperature difference ΔT in real time. Heating is triggered when both of the following conditions are met simultaneously: 1) If the air chamber temperature T2 < T_target, the air chamber temperature has not reached the dehumidification target temperature, and there is a risk of water vapor condensation. 2) T2-T1<ΔT, there is a temperature difference between the heater and the air chamber, which ensures that heat can be transferred from the heater to the air chamber and avoids the heater burning dry; If any condition is not met, maintain the current state and do not start heating or enter the heat preservation mode.

[0039] Stage S3: Heating Regulation Logic The MCU control unit can dynamically adjust the heating power of the heater by adjusting the duty cycle of the PWM signal. The MCU control unit dynamically adjusts the duty cycle of the PWM signal (with the frequency fixed at 1kHz) based on the difference between "T_target - T2". 1) When T_target-T2>3℃ (large temperature difference, rapid heating required): output a PWM signal with a duty cycle of 80%, and the heater operates at 80% of its rated power; 2) When 1℃≤T_target-T2≤3℃ (moderate temperature difference, requiring stable heating): output a PWM signal with a duty cycle of 50%, and the heater operates at 50% of its rated power; 3) When T_target-T2 < 1℃ (temperature difference is small, close to the target temperature): output a PWM signal with a duty cycle of 30%, and the heater operates at 30% of its rated power to avoid overheating; The PWM signal is amplified by the MOSFET and transmitted to the heater. The MCU control unit collects the air chamber temperature T2 every 100ms and updates the duty cycle synchronously to ensure that the heating rate is stable at "0.5~1℃ / s" and avoids the drift of the air chamber detection element, i.e., sensor 1, caused by a sudden temperature rise.

[0040] Stage S4: Dehumidification and Temperature Stabilization during the Heating Process Continuous monitoring and feedback: During heating, the MCU control unit collects the ambient temperature T1 and the air chamber temperature T2 once per second, monitoring these two key parameters in real time. 1) If changes in ambient temperature and humidity cause the temperature difference value ΔT to need to be updated (e.g., a sudden increase in humidity), then the target temperature T_target is adjusted synchronously to ensure that "T2 > dew point temperature" is always satisfied. 2) If the temperature of the gas chamber T2 ≥ T1 + ΔT (the temperature difference between the heater and the gas chamber is too large, which can easily lead to local overheating), then stop heating or switch to "heat preservation mode" (low power heating) to avoid excessive temperature fluctuations in the gas chamber that could affect the detection accuracy.

[0041] Enhanced water vapor evaporation: By maintaining the chamber temperature T2 consistently higher than the ambient temperature T1+ΔT, the chamber's capacity to hold water vapor is increased. Trace amounts of liquid water already adhering to the chamber walls rapidly evaporate into gas, exiting with the chamber structure or dispersing evenly in the air, preventing condensation and accumulation. Heated water vapor flows; the higher chamber temperature accelerates this flow, causing water vapor to escape. Temperature changes create differences in air density and a water vapor partial pressure gradient, propelling water vapor from higher to lower temperature regions.

[0042] Phase S5: Low-power standby and fault protection Standby dehumidification: When the system is in a low-power mode (such as during the detection interval), if the air chamber temperature T2 drops below T_target-1℃, the MCU control unit triggers "intermittent heating" (such as heating for 5 seconds and pausing for 20 seconds) to maintain the dehumidification effect with the lowest power consumption and avoid repeated start-stop to prevent component damage.

[0043] Abnormal protection: If any of the following situations occur, heating will be stopped immediately and an alarm will be triggered to ensure system safety: Temperature acquisition circuit malfunction (abnormal T1 or T2 data, such as exceeding 60℃ or no data); Heater runaway (T2 continues to rise and exceeds the target temperature T_target+10℃); The temperature difference ΔT is calculated abnormally (e.g., below 5℃, the dehumidification effect cannot be guaranteed).

[0044] Recovery mechanism: After the fault is resolved (such as replacing the faulty temperature sensor or restarting the system), the MCU needs to re-execute the initialization process of stage S1. Only after confirming that the parameters are normal can the heating be restarted automatically.

[0045] In tests conducted in humid environments (relative humidity above 99%RH), the sensor of this invention exhibits virtually no false alarm rate and significantly improved detection accuracy compared to traditional sensors without heating control.

[0046] In summary, this invention achieves constant temperature control of the gas chamber through flexible heating components and temperature control algorithms, effectively solving the problem of false alarms caused by water vapor or humid environments affecting photoionization sensors. It has the advantages of simple structure, precise control, and strong adaptability, and can be widely used in gas detection scenarios in various humid environments.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sensor chamber resistant to water vapor interference, comprising a chamber structure assembly, characterized in that, The air chamber structure component is equipped with a data acquisition and control module, a temperature acquisition component, and a heating and insulation component. The data acquisition and control module is connected to the temperature acquisition component and the heating and insulation component respectively. The heating and insulation component is set on the outside of the sensor (1). The data acquisition and control module performs data processing and adjustment parameter calculation to achieve precise moisture control.

2. The sensor chamber resistant to water vapor interference according to claim 1, characterized in that, The air chamber structure component includes a probe base (2), a protective cover (3) and a fixing sleeve (4). A temperature acquisition component and a sensor (1) are installed on the probe base (2). The protective cover (3) is fixedly connected to the probe base (2) through the fixing sleeve (4). The sensor (1), the acquisition control module, the temperature acquisition component, and the heating and heat preservation component are all set in the sensor air chamber formed by the probe base (2) and the protective cover (3).

3. The sensor chamber resistant to water vapor interference according to claim 2, characterized in that, The front end of the protective cover (3) is provided with a metal explosion-proof mesh, and the gas enters the sensor gas chamber through the metal explosion-proof mesh and meets the explosion-proof requirements; the protective cover (3) and the probe base (2) are metal structures and meet the explosion-proof requirements; the inner wall of the protective cover (3) is coated with a hydrophobic treatment layer; a semi-permeable membrane (5) is pasted on the front end of the sensor (1), and one side of the semi-permeable membrane (5) is pasted on the heat insulation sleeve or inside the protective cover (3) with adhesive backing.

4. The sensor chamber resistant to water vapor interference according to any one of claims 1-3, characterized in that, The heating and heat preservation component includes a heater (9) and a heat insulation sleeve (10). The heater (9) is connected to the heater drive circuit and is placed around the sensor (1). The heater (9) and the sensor (1) are set inside the heat insulation sleeve (10), and the heat insulation sleeve (10) is set inside the protective cover (3).

5. The sensor chamber resistant to water vapor interference according to claim 4, characterized in that, The acquisition and control module includes an MCU control unit and an acquisition and control circuit board (8), a first temperature acquisition circuit (6), and a second temperature acquisition circuit (7). The heating and heat preservation component, the first temperature acquisition circuit (6), the second temperature acquisition circuit (7), and the acquisition and control circuit board (8) are all connected to the MCU control unit. The first temperature acquisition circuit (6) and the second temperature acquisition circuit (7) are connected to the temperature acquisition component. The acquisition and control circuit board (8) is connected to the sensor (1) and the temperature acquisition component, respectively.

6. The sensor chamber resistant to water vapor interference according to claim 5, characterized in that, The acquisition control circuit board (8) includes a heater driving circuit and a sensor signal conditioning circuit. Both the heater driving circuit and the sensor signal conditioning circuit are connected to the MCU control unit. The heater (9) of the heating and heat preservation component is connected to the heater driving circuit, and the sensor signal conditioning circuit is connected to the sensor (1). The temperature acquisition component includes a first temperature sensor and a second temperature sensor. The first temperature sensor is connected to the first temperature acquisition circuit (6), and the second temperature sensor is connected to the second temperature acquisition circuit (7). The first temperature sensor is located below the acquisition control circuit board (8) and away from the heater (9) to acquire the ambient temperature. The second temperature sensor is located near the heater (9) of the heating and heat preservation component to acquire the temperature after heating.

7. The sensor chamber resistant to water vapor interference according to claim 6, characterized in that, The heater drive circuit includes a MOS transistor. The drain of the MOS transistor is connected to the heater (9) in the heating and heat preservation component as the output. The source of the MOS transistor is grounded. The gate of the MOS transistor is connected to the control signal MCU_PWM of the MCU control unit through the resistor R51. The gate of the MOS transistor is grounded through the parallel capacitor C50 and resistor R50. The first temperature acquisition circuit (6) and the second temperature acquisition circuit (7) are both temperature chips. The input terminal of the temperature chip is powered by VCC, and the output terminal of the temperature chip obtains the Temp temperature signal through a current-limiting resistor, which is read by the MCU control unit and converted into a usable temperature value. The input terminal and the output terminal of the temperature chip are respectively grounded through a decoupling capacitor. The heater (9) adopts flexible heating technology. The heater (9) is a carbon nanotube, graphene or polyimide film with thermal conductivity, electrical conductivity and chemical stability. The shape of the heater (9) is adapted to the outer wall contour of the sensor air chamber. The second temperature sensor is close to the heat insulation sleeve (10). The heat insulation sleeve (10) is made of aluminum silicate fiber.

8. A dynamic dehumidification method utilizing the water vapor interference-resistant sensor chamber as described in claims 1-7, characterized in that, When the air chamber temperature T2 collected by the second temperature acquisition circuit (7) is lower than the dew point temperature of the ambient air, the water vapor in the air will condense into liquid water on the sensor surface; the air chamber temperature is always higher than the dew point temperature by the heater (9) of the heating and insulation component, and is fixed as "the temperature difference between the air chamber temperature and the ambient temperature ΔT", that is, the air chamber temperature T2 = the ambient temperature T1 + ΔT, to ensure that the air inside the air chamber is in an "unsaturated" state; among which, the temperature difference ΔT can be dynamically adjusted, and the ambient temperature T1 is collected by the first temperature acquisition circuit (6).

9. The dynamic dehumidification method according to claim 8, characterized in that, Five stages are used to achieve closed-loop dynamic dehumidification control, including: Phase S1: Initial State Monitoring and Parameter Initialization Real-time temperature acquisition: The first temperature acquisition circuit (6) continuously acquires the ambient temperature T1, and the second temperature acquisition circuit (7) is bound to the heater to acquire the temperature of the air chamber T2 after dynamic heating; Temperature judgment: After the MCU control unit is powered on, it triggers the self-test of the first temperature acquisition circuit (6) and the second temperature acquisition circuit (7); Dynamic calculation of temperature difference ΔT: The value of temperature difference ΔT is dynamically adjusted based on the dynamically acquired ambient temperature T1. The correspondence between ambient temperature T1 and temperature difference ΔT can be obtained by looking up a table in the MCU control unit. Target temperature setting: The MCU control unit calculates the target temperature T_target=T1+ΔT for dynamic dehumidification of the air chamber, which serves as the reference for subsequent heating control; Stage S2: Heating Start-up Judgment Conditions The MCU control unit compares the air chamber temperature T2 with the target temperature T_target, and T2-T1 with the temperature difference ΔT in real time. Heating is triggered when both of the following conditions are met simultaneously: 1) If the air chamber temperature T2 < T_target, the air chamber temperature has not reached the target temperature; 2) T2-T1 < ΔT, there is a temperature difference between the heater and the gas chamber; If any condition is not met, maintain the current state and do not start heating or enter the heat preservation mode; Stage S3: Heating Regulation Logic The MCU control unit adjusts the duty cycle of the PWM signal to dynamically adjust the heating power of the heater. Stage S4: Dehumidification and Temperature Stabilization during the Heating Process Continuous monitoring and feedback: During heating, the MCU control unit collects the values ​​of ambient temperature T1 and air chamber temperature T2 once per second, monitoring these two key parameters in real time. 1) If changes in ambient temperature and humidity cause the temperature difference value ΔT to need to be updated, then the target temperature T_target will be corrected synchronously. 2) If the air chamber temperature T2 ≥ T1 + ΔT, then pause heating or switch to heat preservation mode; Phase S5: Low-power standby and fault protection.

10. The dynamic dehumidification method according to claim 9, characterized in that, The self-testing method of the first temperature acquisition circuit (6) and the second temperature acquisition circuit (7) is as follows: control the first temperature acquisition circuit (6) and the second temperature acquisition circuit (7) to continuously acquire 3 sets of data at 100ms intervals. If the fluctuation value of each set of data is ≤0.2℃, the temperature acquisition circuit is judged to be normal, and the average value of the 3 sets of data is taken as the initial ambient temperature T1 and the initial air chamber temperature T2; if the fluctuation value is >0.2℃ or the data exceeds the range of "-40℃~60℃", the acquisition is judged to be faulty and the abnormal protection is triggered. The correspondence between ambient temperature T1 and condensation temperature is stored in the MCU control unit. When the ambient temperature T1 is collected, the condensation temperature under the highest humidity of 99%RH is recorded as the temperature difference value ΔT. In stage S4, the MCU control unit dynamically adjusts the duty cycle of the PWM signal based on the difference between "T_target-T2". 1) When T_target-T2>3℃: Output a PWM signal with a duty cycle of 80%; 2) When 1℃≤T_target-T2≤3℃: output a PWM signal with a duty cycle of 50%; 3) When T_target - T2 < 1℃: Output a PWM signal with a duty cycle of 30%; The MCU control unit collects the air chamber temperature T2 every 100ms and updates the duty cycle synchronously. The stage S5 includes standby dehumidification: when in low power mode, if the air chamber temperature T2 drops below the target temperature T_target-1℃, the MCU control unit triggers "intermittent heating", that is, heating for 5 seconds and pausing for 20 seconds; Abnormal protection: If any of the following occurs, heating will be stopped immediately and an alarm will be triggered: temperature acquisition circuit failure, heater malfunction, abnormal calculation of temperature difference ΔT; Recovery mechanism: After the anomaly is resolved, the MCU control unit re-executes the initialization process of stage S1, and after confirming that the parameters are normal, it restarts heating automatically.

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