Long-acting gas alarm with self-calibration function

Abstract

The invention relates to a long-acting fuel gas alarm with a self-calibration function, and belongs to the technical field of fuel gas leakage alarms, and the long-acting fuel gas alarm comprises a laser methane sensor which is used for outputting a first detection signal in real time, and the first detection signal represents the gas concentration value of methane gas; the catalytic sensor is used for outputting a second detection signal in real time, the second detection signal represents the voltage value of the combustible gas, and the catalytic sensor and the laser methane sensor are installed in the same detection area; the mechanical sealing structure is used for dynamically controlling the on-off of a gas channel of the catalytic sensor according to the gas concentration value; and the self-calibration algorithm module is used for carrying out zeroing processing on the catalytic sensor when the gas concentration value meets a zeroing condition, and carrying out calibration processing on the catalytic sensor when the gas concentration value meets a calibration condition. The gas alarm has the beneficial effects that the detection cost of a user is reduced, and the self-calibration of the gas alarm is realized.

Description

Technical Field

[0001] This application relates to the technical field of gas leak alarms, and in particular to a long-lasting gas alarm with self-calibration function. Background Technology

[0002] In the urban gas sector, the vast majority of gas alarms with gas concentration display functions use catalytic combustion sensors to detect leaks of natural gas or liquefied petroleum gas.

[0003] Catalytic combustion gas sensors have advantages such as small size, high cost performance, wide gas detection range, good linearity, signal output unaffected by temperature and humidity, wide operating temperature range, long history and mature technology, and simple circuitry. They are widely used in the field of gas alarms. Their basic principle is that the heat generated by gas combustion causes a change in the resistance of the platinum wire.

[0004] However, catalytic combustion gas detectors also have drawbacks. From a detection principle perspective, when a target gas is present, it undergoes vigorous combustion under the action of a catalyst. This process consumes the catalyst, and over time, this can cause the zero point of the output signal to drift and sensitivity to decrease. Catalytic combustion gas detectors are also susceptible to the influence of certain substances, such as silicides, sulfides, and Freon, which can also lead to changes in sensitivity or even failure over time. Due to their structure, when a catalytic combustion gas detector is subjected to severe impact or shock, the zero point of the output signal will shift significantly. Because of the broad spectrum of catalytic sensors, they are easily affected by interference from other external gases in the low concentration measurement range, leading to large measurement errors. Therefore, all of the above factors can alter the technical performance of catalytic combustion gas detectors, thereby affecting their detection and alarm accuracy, and preventing them from meeting standard requirements. Therefore, relevant national standards stipulate that gas detectors, especially those based on the catalytic combustion principle, must be calibrated regularly.

[0005] Currently, the calibration method for catalytic combustion gas detectors generally involves professional technicians using specialized equipment to test and calibrate the product at the engineering site or in a laboratory. This process includes two basic operations: zeroing and full calibration. Zeroing refers to ensuring that there is no sensible gas in the surrounding environment, and that the sensor output signal is "zero." Full calibration refers to the process of adjusting the sensor's output information to match the alarm's displayed value at a predetermined known gas concentration.

[0006] During calibration, a calibration hood is typically used to cover the sensing component of the product under test. First, a zero-point gas at a certain flow rate is applied for zeroing, then a standard gas at a certain flow rate is applied to adjust the full scale. The zero-point gas is then applied again to check if the displayed value is "0," and then the standard gas is applied again to check if the displayed value matches the concentration of the standard gas. The calibration process for gas alarms is relatively complex, using hazardous gases, and is time-consuming, labor-intensive, and expensive. It must rely on professional personnel and specialized equipment, and be conducted periodically to prevent product quality issues from occurring within the predetermined timeframe.

[0007] Because relevant standards stipulate that gas alarms must be inspected at certain intervals to ensure the normal use of the products, users have to spend a lot of money on testing every year; in addition, if the product is taken to a laboratory for testing, the place will lose its safety monitoring for a short period of time. Summary of the Invention

[0008] To reduce users' detection costs and enable self-calibration of gas alarms, this application provides a long-lasting gas alarm with self-calibration function, employing the following technical solution: A long-lasting gas alarm with self-calibration function includes: A laser methane sensor is used to output a first detection signal in real time, the first detection signal representing the gas concentration value of methane gas; A catalytic sensor is used to output a second detection signal in real time, the second detection signal representing the voltage value of the combustible gas, and the catalytic sensor and the laser methane sensor are installed in the same detection area; A mechanical seal structure is used to dynamically control the opening and closing of the gas channel of the catalytic sensor according to the gas concentration value; The self-calibration algorithm module is used to perform zero-adjustment processing on the catalytic sensor when the gas concentration value meets the zero-adjustment conditions, and to perform calibration processing on the catalytic sensor when the gas concentration value meets the calibration conditions.

[0009] By adopting the above technical solution, the laser methane sensor, with its high precision and unique methane response, can provide an accurate methane concentration benchmark in real time. The catalytic sensor, when the gas channel is open, detects combustible gases within the detection area, overcoming the limitations of a single sensor in terms of detection range and accuracy in low concentration ranges. Both sensors are installed in the same detection area, ensuring consistency of the detection environment and comparability of data. The mechanical seal structure dynamically controls the opening and closing of the catalytic sensor's gas channel based on the gas concentration value output by the laser methane sensor. This protects the catalytic sensor from external environmental interference when detection is not needed, thus extending its service life, and allows for timely channel opening when detection is required, ensuring real-time and effective detection. When the gas concentration value meets the zeroing conditions, the self-calibration algorithm module zeroes the catalytic sensor, effectively eliminating errors caused by zero-point drift. When the calibration conditions are met, calibration is performed, ensuring the detection accuracy of the catalytic sensor during long-term use and avoiding false alarms or missed alarms due to sensor performance degradation. By innovatively integrating a laser methane sensor and a catalytic sensor, and supplementing them with a mechanical seal structure and a self-calibration algorithm module, the reliability, longevity, and intelligence of gas detection are improved, thereby reducing users' detection costs and enabling the gas alarm to self-calibrate and extend its service life.

[0010] Optionally, the specific steps for dynamically controlling the opening and closing of the gas channel of the catalytic sensor based on the gas concentration value include: When the gas concentration value is greater than the calibration threshold, the gas channel of the catalytic sensor is opened; when the gas concentration value is less than a preset value, the gas channel of the catalytic sensor is closed. The preset value is less than the calibration threshold. When the gas concentration is zero, the gas channel of the catalytic sensor is controlled to open and close according to preset timing conditions.

[0011] By adopting the above technical solution, the gas channel can be dynamically controlled based on the output concentration value of the laser methane sensor, thereby reducing catalyst consumption and interference from the catalytic sensor and extending its service life.

[0012] Optionally, when the gas concentration value meets the zeroing conditions, the specific steps for zeroing the catalytic sensor include: When the gas concentration is zero, and after the gas channel is opened and a first delay is set, multiple zero-point voltages of the catalytic sensor are obtained at a predetermined sampling frequency, and the zero-point voltage V1 is obtained after filtering. After the gas channel is closed and a second delay is set, multiple zero-point voltages of the catalytic sensor are obtained at the predetermined sampling frequency, and the zero-point voltage V2 is obtained after filtering. Determine whether the difference between V1 and V2 is within the predetermined error range; If yes, keep it; otherwise, discard it. Based on V1 and V2 retained within the first set time window, the average zero-point voltage of the first set time window is calculated as the current zero-point correction amount V0 of the catalytic sensor.

[0013] By adopting the above technical solution, when the first detection signal of the laser methane sensor is "zero", it means that there is no target gas methane in the environment. If the second detection signal of the catalytic sensor has an output value, it means that the zero point of the catalytic sensor has drifted. Under the conditions of opening and closing the gas channel, the zero point value is further compared and judged. Then, the average value of the zero point voltage in the first set time window is used as the current zero point correction amount of the catalytic sensor, thereby eliminating the zero point drift using an algorithm. In addition, the purpose of closing the gas channel and the set second delay is to consume the residual gas in the gas channel.

[0014] Optionally, the specific steps for calibrating the catalytic sensor when the gas concentration value meets the calibration conditions include: After the gas concentration value stabilizes and reaches the predetermined calibration range, multiple gas concentration values ​​Vb and corresponding multiple voltage values ​​Vc are obtained at predetermined time intervals. The gas channel of the catalytic sensor is in the open state. The calibration range = [the calibration threshold value, the range of the laser methane sensor]; The sensitivity coefficient of the catalytic sensor is calculated based on multiple Vb values ​​and their corresponding Vc values.

[0015] By adopting the above technical solution, once the gas concentration value stably reaches the predetermined calibration range, it is considered that test gas has been applied to the gas alarm. Then, based on multiple Vb values ​​and corresponding Vc values ​​collected at predetermined time intervals, the sensitivity coefficient of the catalytic sensor is calculated, thereby achieving full calibration of the catalytic sensor. By utilizing the advantages of both sensors to complement each other's disadvantages, the sensitivity coefficient of the catalytic sensor is dynamically adjusted to eliminate the influence of the external environment on the catalytic sensor, ensuring that the catalytic sensor is always in a state of accurate gas concentration detection. The calibration process can be triggered by leaked gas or by the user periodically applying gas of uncertain concentration for self-testing. In this way, without the participation of professional personnel, professional equipment, or external application of a fixed concentration of test gas, automatic zeroing and full calibration of the catalytic sensor can be achieved solely by the auxiliary laser methane sensor, thereby reducing the user's detection costs.

[0016] Optionally, the specific steps for calculating the sensitivity coefficient of the catalytic sensor based on multiple Vb and their corresponding Vc include: Calculate the sensitivity coefficient k for each Vb value and the corresponding Vc value, k = Vb / (Vc - V0); The average value of the sensitivity coefficients of the second set time window is calculated based on the k values ​​of different sampling points stored within the second set time window, wherein the change in the sensitivity coefficients stored within the second set time window is not greater than a set threshold.

[0017] By adopting the above technical solution, if the variation between sensitivity coefficients is greater than the set threshold, it is considered to be occasional data, i.e., untrue data, and should be discarded and not included in the averaging calculation, thereby improving the accuracy and authenticity of the sensitivity coefficients.

[0018] Optionally, the long-lasting gas alarm also includes: The control algorithm module is used to determine whether the gas concentration value exceeds the range of the laser methane sensor; if not, the actual concentration value output by the gas alarm is the gas concentration value of the laser methane sensor; if so, the actual concentration value output by the gas alarm is the corrected gas concentration value y corresponding to the catalytic sensor. V0 is the average sensitivity coefficient calculated using the catalytic sensor during detection, V0 is the zero-point correction amount for the most recent first set time window, and V is the voltage value corresponding to the second detection signal when the gas concentration value exceeds the range of the laser methane sensor.

[0019] By adopting the above technical solution and using the range of the laser methane sensor as the switching point for the operation of the two sensors, the measurement accuracy in the low concentration range is guaranteed, and the service life of the catalytic sensor in non-essential conditions is effectively extended, thereby achieving accurate and reliable detection across the entire range.

[0020] Optionally, the control algorithm module is also used to perform the following operations: When the laser methane sensor is in the detection state, if the actual concentration value output by the gas alarm is not less than the first set alarm threshold value, an alarm signal is output. When the gas is under the detection state of the catalytic sensor, if the actual concentration value output by the gas alarm is not less than the second set alarm threshold value, then an alarm signal is output. If the calculated sensitivity coefficient of the catalytic sensor is less than the set sensitivity threshold, an end-of-life warning signal will be output.

[0021] In summary, this application includes at least one of the following beneficial technical effects: 1. Automatic calibration can be achieved by utilizing occasional gas leaks, without the need for professional personnel, specialized equipment, or the application of a fixed concentration of test gas externally, thus achieving a maintenance-free effect and reducing usage and maintenance costs; 2. By sealing the gas channel of the catalytic sensor with a mechanical seal structure, the influence of dust and other interfering substances on the catalytic sensor is solved, as well as the passivation problem during long-term use is solved, thus delaying passivation and extending the service life. 3. By automatically zeroing, the problem of zero drift caused by factors such as vibration and impact is solved.

[0022] 4. At low concentrations, the problem of low detection accuracy of gas alarms at low concentrations can be solved by using a laser methane sensor.

[0023] 5. By utilizing the obtained sensitivity coefficient, a lifespan reminder for the gas alarm was implemented. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of an embodiment of this application. Detailed Implementation

[0025] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figure 1 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0026] This application discloses a long-lasting gas alarm with self-calibration function. (Refer to...) Figure 1 This long-lasting gas alarm includes a laser methane sensor, a catalytic sensor, a mechanical seal structure, a self-calibration algorithm module, and a control algorithm module.

[0027] The laser methane sensor and the catalytic sensor are installed in the same detection area, or they can be designed to be housed in a single structural housing. The laser methane sensor outputs a first detection signal in real time, representing the methane gas concentration. The catalytic sensor outputs a second detection signal in real time, representing the voltage of the combustible gas. A mechanical seal structure dynamically controls the opening and closing of the gas channel of the catalytic sensor based on the gas concentration. A self-calibration algorithm module is used to zero-adjust the catalytic sensor when the gas concentration meets the zero-adjustment conditions, and to calibrate the catalytic sensor when the gas concentration meets the calibration conditions.

[0028] Specifically, the laser methane sensor utilizes an existing modular product. This module is based on Tunable Semiconductor Laser Absorption Spectroscopy (TDLAS) technology, employing high-sensitivity spectroscopy to suppress high-frequency background noise. It integrates a high-performance laser probe and a specially processed gas chamber, enabling the measurement of molecular absorption lines and high-precision methane gas concentration analysis, completely eliminating cross-interference and poisoning failure. It boasts advantages such as small size, high response speed (ms-level), high accuracy (ppm-level), low power consumption (mW-level), long lifespan, and strong environmental adaptability. Employing adaptive sensor hardware and software algorithms, it requires no calibration throughout its entire lifecycle, with a detection range of 0%LEL to 20%LEL and an accuracy of 0.1%LEL (equivalent to 50ppm). Currently, laser methane sensors are widely used in household gas alarms, directly outputting digital gas concentration signals. They are simple to use and cost-effective, with the added cost far exceeding the expense of a single professional calibration.

[0029] Catalytic combustion gas sensors come in many models, and their application circuits are mature. They use a Whitworth bridge circuit, then amplify the analog signal, and then process it digitally to display the concentration data.

[0030] It should be noted that the display, alarm, communication, linkage output control, and power supply circuits of the laser methane sensor, catalytic sensor, and gas alarm itself are all implemented using conventional circuits, and will not be described in detail in this application.

[0031] Mechanical seal structures are conventional opening and closing structures for gas channels. For example, they can be based on the principle of a camera shutter, where the opening and closing of the shutter is controlled by a circuit, thereby controlling the opening or closing of the gas passage; or they can be based on the principle of an electric valve, where the air inlet of the sensor is connected to the output end of the electric valve, and the air inlet end of the electric valve is connected to the atmosphere. The opening and closing of the electric valve is controlled by a circuit, thereby realizing the opening and closing of the gas passage of the sensor, etc. The specific method is not limited.

[0032] The specific steps for dynamically controlling the opening and closing of the gas channel of the catalytic sensor based on the gas concentration value include: When the gas concentration value is greater than the calibration threshold, the gas channel of the catalytic sensor is opened; when the gas concentration value is less than a preset value, the gas channel of the catalytic sensor is closed. The preset value is less than the calibration threshold. When the gas concentration is zero, the gas channel of the catalytic sensor is opened and closed according to the preset timing conditions.

[0033] To facilitate understanding, examples are provided to illustrate the operation of the mechanical seal structure before and after calibration, with the preset value example being 0.3%LEL and the calibration threshold example being 10%LEL.

[0034] Specifically, when the gas concentration exceeds the calibration threshold, the system enters calibration mode. For example, the test gas concentration slowly increases from 0%LEL to 15%LEL. The process is as follows: when the gas concentration is less than 0.3%LEL (preset value), the mechanical seal mechanism is controlled to close the gas passage; when the gas concentration rises to 6%LEL, the opening condition (10%LEL) is not met, so the gas passage remains closed; when the gas concentration rises to 10%LEL (calibration threshold), the opening condition is met, and the mechanical seal mechanism is controlled to open the gas passage; if the gas concentration is still greater than 10%LEL, the gas passage remains open.

[0035] Subsequently, the test gas dissipates, and the gas concentration decreases. When the gas concentration is greater than 10% LEL, the gas passage is open; when the gas concentration is less than 10% LEL, for example, 6% LEL, the gas passage remains open because the closing condition is not met; when the gas concentration is less than 0.3% LEL, the closing condition is met, and the mechanical seal structure closes the gas passage. In other words, the opening / closing of the mechanical seal structure is related to the trend of gas concentration change.

[0036] Because catalytic sensors have a broad spectrum of activity, interfering gases in daily life can cause some signal changes. Although the concentration of interfering gases is generally small and occasional, at low concentrations, if both the reference value (measured by the laser sensor) and the target value (output of the catalytic sensor) deviate, the calculation results will be more biased. Taking advantage of the linear characteristic of catalytic sensors, the higher the concentration at the calibration point, the smaller the impact of its own data error on the detection results. Therefore, to fully ensure the accuracy of sensitivity, calibration is performed at a value greater than the calibration threshold but less than the range of the laser methane sensor.

[0037] When the gas concentration is zero, the mechanical seal structure can be controlled to open / close periodically, for example, closing for T1 time (e.g., 4 hours) and opening for T2 time (e.g., 30 minutes). Since the opening / closing of the mechanical seal structure occurs when the gas concentration is zero, and the external gas concentration is uncontrollable, the closing time T1 and opening time T2 are not continuous, and even their lengths are not expected. However, this does not affect the operation of the algorithm; that is, the opening and closing times are not precisely defined, but only describe one scenario. If, during the timed opening process, the gas concentration exceeds the calibration threshold, the opening and closing conditions of the gas channel are switched to calibration mode, meaning that sensitivity calibration can also be performed at this time.

[0038] When the gas concentration value meets the zeroing conditions, the specific steps for zeroing the catalytic sensor include: When the gas concentration is zero, and after the gas channel is opened and a first set delay is elapsed, multiple zero-point voltages V1 of the catalytic sensor are obtained at a predetermined sampling frequency, and after the gas channel is closed and a second set delay is elapsed, multiple zero-point voltages V2 of the catalytic sensor are obtained at the same sampling frequency. Determine whether the difference between V1 and V2 is within the predetermined error range; if so, retain it, otherwise discard it. Based on V1 and V2 retained in the first set time window, the average zero-point voltage of the first set time window is calculated as the current zero-point correction amount V0 of the catalytic sensor.

[0039] For example, within 30 minutes before the mechanical seal structure is opened (i.e., the current state is still closed after a relatively long period of closure), the purpose of the extended closure is to dissipate any remaining sealed gas and prevent it from affecting the output signal of the catalytic sensor. Multiple zero-point voltages are obtained according to the sampling frequency, and after filtering, a zero-point voltage V2 is obtained. Within 10 minutes before the closure (i.e., the current state is open), multiple zero-point voltages are obtained according to the sampling frequency, and after filtering, a zero-point voltage V1 is obtained. Then, it is determined whether the difference between V1 and V2 is within a predetermined error range. If it is, it is retained; otherwise, it is discarded. Then, based on the retained V1 and V2 within the first set time window, the average value of the zero-point voltages within the first set time window is calculated as the current zero-point correction amount V0 of the catalytic sensor.

[0040] The specific steps for calibrating the catalytic sensor when the gas concentration value meets the calibration conditions include: After the gas concentration value stabilizes and reaches the predetermined calibration range, multiple gas concentration values ​​Vb and corresponding voltage values ​​Vc are obtained at predetermined time intervals. The gas channel of the catalytic sensor is in the open state, and the calibration range = [calibration threshold value, range of the laser methane sensor]; for example, if the calibration range is 10%LEL to the range of the laser methane sensor 20%LEL, then the calibration threshold value can be 10%LEL. Calculate the sensitivity coefficient k for each Vb value and the corresponding Vc value, k = Vb / (Vc - V0); The average value of the sensitivity coefficients within the second set time window is calculated based on the k values ​​of different sampling points stored within the second set time window. The variation of the sensitivity coefficients stored within the second set time window is not greater than a set threshold.

[0041] Furthermore, stable concentration refers to the concentration that remains stable over a certain period of time. This application addresses the issue in related technologies that require professional personnel and specialized equipment for inspection and calibration. Therefore, it allows calibration during gas leaks or user-initiated tests. However, since the concentration of the gas leak or the applied test gas is not fixed and may be constantly changing at an uncontrollable rate, calibration can only be performed using the concentration at a stable state. Data that is unstable or below the calibration range detected by the laser methane sensor should be discarded during calibration.

[0042] The first and second time windows can be preset using the alarm, such as 30 days, 15 days, or 5 days, to ensure that the sensitivity coefficients and zero-point corrections at different sampling points have a certain timeliness and prevent data from being too old from affecting the current detection.

[0043] Furthermore, the purpose of setting the change in sensitivity coefficients stored within the second set time window to not exceed a set threshold is that sensitivity generally does not undergo abrupt changes but is a gradual process. Therefore, if the detected sensitivity value changes abruptly or the change exceeds the set threshold (e.g., 10%) within the limited time, it is considered occasional or unreliable data and should be discarded, not included in the averaging calculation.

[0044] The control algorithm module determines whether the gas concentration value exceeds the range of the laser methane sensor. If not, the actual concentration value output by the gas alarm is the gas concentration value of the laser methane sensor; if so, the actual concentration value output by the gas alarm is the corrected gas concentration value y corresponding to the catalytic sensor. V0 is the average sensitivity coefficient calculated using the catalytic sensor for the most recent second set time window, V0 is the zero-point correction for the most recent first set time window, and V is the voltage value corresponding to the second detection signal when the gas concentration value exceeds the range of the laser methane sensor.

[0045] In addition, the control algorithm module will also trigger alarms: for example, when in the laser methane sensor detection state, if the actual concentration value output by the gas alarm is not less than the first set alarm threshold, an alarm signal will be output; when in the catalytic sensor detection state, if the actual concentration value output by the gas alarm is not less than the second set alarm threshold, an alarm signal will be output; if the calculated sensitivity coefficient of the catalytic sensor is less than 50% of the set sensitivity threshold, such as the factory setting value, a lifespan expiration reminder signal will be output.

[0046] The implementation principle of this embodiment is as follows: Initially, when the gas concentration value of the laser methane sensor is 0, it means that there is no target gas methane in the environment. According to the preset timing conditions, the mechanical seal structure is controlled to open and close the gas channel of the catalytic sensor. After the gas channel is opened and after a set first delay, multiple zero-point voltages of the catalytic sensor are obtained at a predetermined sampling frequency and filtered to obtain zero-point voltage V1. After the gas channel is closed and after a set second delay, multiple zero-point voltages of the catalytic sensor are obtained at the sampling frequency and filtered to obtain zero-point voltage V2. It is then determined whether the difference between V1 and V2 is within a predetermined error range. If so, it is retained; otherwise, it is discarded. Then, based on the retained V1 and V2 within the first set time window, the average value of the zero-point voltages in the first set time window is calculated as the current zero-point correction amount V0 of the catalytic sensor. When the target gas is present in the environment, and the laser methane sensor detects that the target gas has stably reached the predetermined calibration range, it is considered as the concentration of the test gas currently applied. Multiple gas concentration values ​​Vb and corresponding voltage values ​​Vc are obtained at predetermined time intervals. The sensitivity coefficient k corresponding to each Vb value and the corresponding Vc value is calculated. Then, according to the k values ​​of different sampling points stored in the second set time window, the average value of the sensitivity coefficient of the second set time window is calculated. If the gas concentration value detected by the laser methane sensor is stable within the calibration range and does not exceed the range of the laser methane sensor, the catalytic sensor will be continuously calibrated. At this time, the laser methane sensor is always in working condition, and the actual concentration value output by the gas alarm is the concentration value detected by the laser methane sensor.

[0047] When the laser methane sensor detects that the gas concentration value exceeds its range, the catalytic sensor is activated for concentration detection. At this time, the catalytic sensor utilizes the sensitivity corresponding to the most recent second set time window obtained earlier. The value and the zero-point correction amount V0 corresponding to the most recent first set time window are used to obtain the correction concentration value. At this point, the actual concentration value output by the gas alarm is the corrected concentration value of the catalytic sensor.

[0048] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce a good effect.

[0049] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features.

Claims

1. A long-lasting gas alarm with self-calibration function, characterized in that, include: A laser methane sensor is used to output a first detection signal in real time, the first detection signal representing the gas concentration value of methane gas; A catalytic sensor is used to output a second detection signal in real time, the second detection signal representing the voltage value of the combustible gas, and the catalytic sensor and the laser methane sensor are installed in the same detection area; A mechanical seal structure is used to dynamically control the opening and closing of the gas channel of the catalytic sensor according to the gas concentration value; The self-calibration algorithm module is used to perform zero-adjustment processing on the catalytic sensor when the gas concentration value meets the zero-adjustment conditions, and to perform calibration processing on the catalytic sensor when the gas concentration value meets the calibration conditions.

2. A long-lasting gas alarm with self-calibration function according to claim 1, characterized in that, The specific steps for dynamically controlling the opening and closing of the gas channel of the catalytic sensor based on the gas concentration value include: When the gas concentration value is greater than the calibration threshold value, the gas channel of the catalytic sensor is opened; when the gas concentration value is less than a preset value, the gas channel of the catalytic sensor is closed. The preset value is less than the calibration threshold value. When the gas concentration is zero, the gas channel of the catalytic sensor is controlled to open and close according to preset timing conditions.

3. A long-lasting gas alarm with self-calibration function according to claim 2, characterized in that, When the gas concentration value meets the zeroing conditions, the specific steps for zeroing the catalytic sensor include: When the gas concentration is zero, and after the gas channel is opened and a first delay is set, multiple zero-point voltages of the catalytic sensor are obtained at a predetermined sampling frequency, and the zero-point voltage V1 is obtained after filtering. After the gas channel is closed and a second delay is set, multiple zero-point voltages of the catalytic sensor are obtained at the predetermined sampling frequency, and the zero-point voltage V2 is obtained after filtering. Determine whether the difference between V1 and V2 is within the predetermined error range; If yes, keep it; otherwise, discard it. Based on V1 and V2 retained within the first set time window, the average zero-point voltage of the first set time window is calculated as the current zero-point correction amount V0 of the catalytic sensor.

4. A long-lasting gas alarm with self-calibration function according to claim 1, characterized in that, The specific steps for calibrating the catalytic sensor when the gas concentration value meets the calibration conditions include: After the gas concentration value stabilizes and reaches the predetermined calibration range, multiple gas concentration values ​​Vb and corresponding multiple voltage values ​​Vc are obtained at predetermined time intervals. The gas channel of the catalytic sensor is in the open state. The calibration range = [the calibration threshold value, the range of the laser methane sensor]; The sensitivity coefficient of the catalytic sensor is calculated based on multiple Vb values ​​and their corresponding Vc values.

5. A long-lasting gas alarm with self-calibration function according to claim 4, characterized in that, The specific steps for calculating the sensitivity coefficient of the catalytic sensor based on multiple Vb and their corresponding Vc include: Calculate the sensitivity coefficient k for each Vb value and the corresponding Vc value, k = Vb / (Vc - V0); The average value of the sensitivity coefficients of the second set time window is calculated based on the k values ​​of different sampling points stored within the second set time window, wherein the change in the sensitivity coefficients stored within the second set time window is not greater than a set threshold.

6. A long-lasting gas alarm with self-calibration function according to claim 1, characterized in that, The long-lasting gas alarm also includes: The control algorithm module is used to determine whether the gas concentration value exceeds the range of the laser methane sensor; if not, the actual concentration value output by the gas alarm is the gas concentration value of the laser methane sensor; if so, the actual concentration value output by the gas alarm is the corrected gas concentration value y corresponding to the catalytic sensor. V0 is the average sensitivity coefficient calculated using the catalytic sensor during detection, V0 is the zero-point correction amount for the most recent first set time window, and V is the voltage value corresponding to the second detection signal when the gas concentration value exceeds the range of the laser methane sensor.

7. A long-lasting gas alarm with self-calibration function according to claim 6, characterized in that, The control algorithm module is also used to perform the following operations: When the laser methane sensor is in the detection state, if the actual concentration value output by the gas alarm is not less than the first set alarm threshold value, an alarm signal is output. When the gas is under the detection state of the catalytic sensor, if the actual concentration value output by the gas alarm is not less than the second set alarm threshold value, then an alarm signal is output. If the calculated sensitivity coefficient of the catalytic sensor is less than the set sensitivity threshold, an end-of-life warning signal will be output.

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