Calibration device for sensors for monitoring carbon dioxide and working method thereof

Abstract

This invention provides a calibration device and its operating method for a sensor used to monitor carbon dioxide, relating to the field of sensor technology. The device includes: a first input terminal of a three-way solenoid valve connected to a monitoring air inlet; a second input terminal of the three-way solenoid valve connected to the output terminal of a CO2 filter; and the output terminal of the three-way solenoid valve connected to a sensor to be calibrated. The input terminal of the CO2 filter is connected to a calibration air inlet, and the CO2 filter is used to filter out CO2 from the gas. A calibration module is connected to the sensor to be calibrated. When the sensor needs calibration, the calibration module controls the three-way solenoid valve to close the first input terminal and open the second input terminal, allowing air entering through the calibration air inlet to pass through the CO2 filter before entering the sensor to be calibrated. The module collects the CO2 monitoring value of the sensor and, based on the CO2 monitoring value, determines that a stable state has been reached, controls the sensor to reset its zero point.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a calibration device for a sensor for monitoring carbon dioxide (CO2) and a working method thereof. Background Art

[0002] Sensors used to monitor CO2 content in the air generally use infrared detection principles and calibrate concentrations in a standard gas environment. Due to the good linear relationship, after processing with algorithms such as temperature compensation, the data accuracy can better meet the CO2 concentration monitoring requirements in outdoor environments.

[0003] During the long-term operation of the sensor module, there is an obvious signal drift phenomenon, which greatly affects the monitoring accuracy of the sensor. In this context, regular calibration of the sensor to reduce or eliminate the monitoring error caused by signal drift has become a key task affecting the performance of the equipment. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a calibration device for a sensor for monitoring CO2, so as to solve the technical problem that the sensor for monitoring CO2 in the prior art has obvious signal drift phenomenon, thereby affecting the monitoring accuracy. The device includes:

[0005] A three-way solenoid valve, wherein a first input end of the three-way solenoid valve is connected to a monitoring air inlet, a second input end of the three-way solenoid valve is connected to an output end of a CO2 filter device, and an output end of the three-way solenoid valve is connected to a sensor to be calibrated;

[0006] The input end of the CO2 filter device is connected to the calibration air inlet, and the CO2 filter device is used to filter out CO2 in the gas;

[0007] A calibration module is connected to the sensor to be calibrated. The calibration module is used to control the three-way solenoid valve to close the first input end and open the second input end when the sensor to be calibrated needs to be calibrated, so that the air entering through the calibration air inlet enters the sensor to be calibrated after passing through the CO2 filtering device, collects the CO2 monitoring value of the sensor to be calibrated, and controls the sensor to be calibrated to reset the zero point when it is judged that a stable state is reached according to the CO2 monitoring value.

[0008] The embodiment of the present invention also provides a working method of any of the above-mentioned calibration devices for sensors for monitoring CO2, so as to solve the technical problem that the sensors for monitoring CO2 in the prior art have obvious signal drift phenomenon, thereby affecting the monitoring accuracy. The method comprises:

[0009] When the sensor to be calibrated needs to be calibrated, the calibration module controls the three-way solenoid valve to close the first input end and open the second input end, so that the air entering through the calibration air inlet flows into the CO2 filtering device;

[0010] The CO2 in the air is filtered out by the CO2 filter device, and the filtered gas enters the sensor to be calibrated through the second input end of the three-way solenoid valve;

[0011] The calibration module collects the CO2 monitoring value of the sensor to be calibrated, and when it is judged that a stable state is reached according to the CO2 monitoring value, the sensor to be calibrated is controlled to reset the zero point.

[0012] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least: it is proposed to connect the CO2 filter device through a three-way solenoid valve, filter out CO2 from the air entering the calibration air inlet through the CO2 filter device, and the zero gas after removing CO2 enters the sensor to be calibrated through the three-way solenoid valve, and then collect the CO2 monitoring value of the sensor to be calibrated through the calibration module, and when it is judged that a stable state is reached according to the CO2 monitoring value, control the sensor to be calibrated to reset the zero point, thereby effectively eliminating the drift error, which is beneficial to ensuring the monitoring accuracy of the sensor equipment and the validity of the monitoring data; at the same time, it is possible to realize online remote calibration of the sensor without disassembling the equipment and returning it to the factory for calibration, which is beneficial to greatly improve the efficiency of sensor equipment calibration and effectively reduce operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 is a schematic structural diagram of a calibration device for a sensor for monitoring CO2 provided in an embodiment of the present invention;

[0015] Figure 2 is a schematic structural diagram of a specific calibration device for a sensor for monitoring CO2 provided in an embodiment of the present invention;

[0016] Figure 3 It is a flow chart of a calibration module provided by an embodiment of the present invention for controlling sensor calibration based on CO2 monitoring values;

[0017] Figure 4It is a schematic diagram of different data change stages of sensor calibration based on CO2 monitoring value control by a calibration module provided by an embodiment of the present invention;

[0018] Figure 5 It is a flow chart of a working method of a calibration device for a sensor for monitoring CO2 provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0020] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0021] In an embodiment of the present invention, a calibration device for a sensor for monitoring CO2 is provided, such as Figure 1 As shown, the device comprises:

[0022] A three-way solenoid valve 101, wherein a first input end of the three-way solenoid valve is connected to a monitoring air inlet 102, a second input end of the three-way solenoid valve 101 is connected to an output end of a CO2 filter 103, and an output end of the three-way solenoid valve 101 is connected to a sensor to be calibrated 104;

[0023] The input end of the CO2 filter device 103 is connected to the calibration gas inlet 105, and the CO2 filter device 103 is used to filter out CO2 in the gas;

[0024] The calibration module 106 is connected to the sensor to be calibrated 104. The calibration module 106 is used to control the three-way solenoid valve 101 to close the first input end and open the second input end when the sensor to be calibrated 104 needs to be calibrated, so that the air entering through the calibration air inlet 105 enters the sensor to be calibrated 104 after passing through the CO2 filter device 103, collects the CO2 monitoring value of the sensor to be calibrated 104, and controls the sensor to be calibrated to reset the zero point when it is judged that a stable state is reached according to the CO2 monitoring value.

[0025] Depend on Figure 1 As can be seen from the structure shown, in the embodiment of the present invention, it is proposed to connect the CO2 filtering device through a three-way solenoid valve, filter out CO2 from the air entering the calibration air inlet through the CO2 filtering device, and the zero gas after removing CO2 enters the sensor to be calibrated through the three-way solenoid valve, and then the CO2 monitoring value of the sensor to be calibrated is collected through the calibration module, and when it is judged that a stable state is reached according to the CO2 monitoring value, the sensor to be calibrated is controlled to reset the zero point, thereby effectively eliminating the drift error and facilitating the monitoring accuracy of the sensor equipment; at the same time, the monitoring pipeline can be opened or the calibration pipeline can be opened by switching the pipeline through the three-way solenoid valve, so that the sensor can be calibrated remotely online without disassembling the equipment and returning it to the factory for calibration, thereby greatly improving the efficiency of sensor equipment calibration and effectively reducing operation and maintenance costs.

[0026] In specific implementation, when the CO2 sensor has been running for a period of time and has large errors and needs to be calibrated or when the device receives a calibration instruction and needs to be calibrated, the calibration module controls the three-way solenoid valve to close the first input end, that is, to close the monitoring gas path, and at the same time open the second input end, that is, to open the calibration gas path, so that the gas passes through the CO2 filter device and enters the CO2 sensor to be calibrated, and then the zero point calibration process is performed based on the CO2 monitoring value of the sensor to be calibrated.

[0027] In specific implementation, in order to effectively remove the CO2 component of the inhaled gas and prevent moisture from entering the interior of the sensor to be calibrated, Figure 2 As shown, the CO2 filtering device 103 comprises:

[0028] A CO2 filter 1031, wherein the input end of the CO2 filter 1031 is connected to the calibration air inlet 105 via a first moisture filter 1032, and the CO2 filter is equipped with a CO2 absorption medium to filter out CO2 in the air entering through the calibration air inlet;

[0029] A second moisture filter 1033, the input end of the second moisture filter 1033 is connected to the output end of the CO2 filter 1031, the output end of the second moisture filter 1033 is connected to the second input end of the three-way solenoid valve 101, and the second moisture filter 1033 is used to filter out moisture in the gas flowing through the CO2 filter.

[0030] In specific implementation, the CO2 filter is built with a CO2 absorption medium, which can be in any form and can absorb CO2. In order to further ensure that the CO2 component in the gas can be effectively absorbed, the CO2 absorption medium can be N aOH powder, that is, the anhydrous NaOH content in the CO2 filter is high. The CO2 component in the air is absorbed by the NaOH powder in the CO2 filter through chemical reaction, which can effectively remove the CO2 component of the inhaled gas. At this time, the gas entering the CO2 sensor is zero gas after CO2 is removed. The chemical reaction process is as follows:

[0031] 2NaOH+CO2=Na2CO3+H2O

[0032] The moisture generated during the chemical reaction is blocked by the second moisture filter 1033 and will not enter the interior of the sensor.

[0033] When implementing it, Figure 2 As shown, the calibration device for the sensor for monitoring CO2 also includes:

[0034] A filter 107 connected to the sensor to be calibrated 104, and the filter 107 is used to filter out impurities in the gas flowing through the sensor to be calibrated 104;

[0035] The air pump 108 is connected to the filter 107 , and is used to provide air pressure conditions for the gas inhaled by the sensor 104 to be calibrated.

[0036] In specific implementation, after the zero gas after removing CO2 is passed into the sensor to be calibrated, the CO2 monitoring value of the CO2 sensor gradually decreases. In order to accurately and effectively calibrate the sensor, it is proposed that when the change of the CO2 monitoring value is judged to be stable within a certain range, the calibration is considered successful, the sensor to be calibrated is controlled to reset the zero point, and the valid data read is marked as the error value. For example, the calibration module judges the different change stages of the CO2 monitoring value through the following structure, and the calibration module includes:

[0037] A calibration process determination unit, used for determining whether to enter a calibration process according to a first change in the CO2 monitoring value;

[0038] A stabilization judgment unit, used for judging whether the CO2 monitoring value has entered a stabilization state according to a second change of the CO2 monitoring value if a calibration process is entered;

[0039] The stable state judgment unit is used to judge whether the multiple CO2 monitoring values ​​sampled continuously reach the preset data index if entering the stable state, and judge whether the CO2 monitoring value reaches the stable state if reaching the preset data index.

[0040] In specific implementation, in order to accurately determine whether the calibration process has been entered so as to effectively calibrate the sensor, the calibration process judgment unit is used to calculate the absolute difference between the CO2 monitoring value at the current moment and the CO2 monitoring value at the previous moment within a first preset time period; when a continuous preset number of absolute differences are all greater than a first preset threshold, it is determined that the calibration process has been entered; otherwise, that is, if a continuous preset number of absolute differences are not greater than the first preset threshold within the first preset time period after the calibration air inlet is opened, it is determined that the calibration process has not been entered and the calibration failure is returned.

[0041] In specific implementation, the size of the first preset duration can be determined according to specific needs, for example, it can be 30 seconds, 1 minute, etc. The size of the first preset threshold can also be determined according to specific needs, for example, it can be 4 ppm. The size of the preset number can also be determined according to specific needs, for example, it can be 3, 4, etc.

[0042] In specific implementation, in order to accurately judge whether the change of CO2 monitoring value tends to be stable, the stabilization judgment unit is used to judge that the CO2 monitoring value has entered a stable state within a second preset time after entering the calibration process, if the absolute difference between the CO2 monitoring value at the current moment and the CO2 monitoring value at the previous moment is less than a second preset threshold value; otherwise, that is, if the absolute difference is not less than the second preset threshold value within the second preset time after the calibration air inlet is opened, it is judged that it has not entered a stable state, and the calibration failure is returned.

[0043] In specific implementation, the second preset duration may be determined according to specific requirements, for example, 3 minutes, 4 minutes, etc. The second preset threshold may also be determined according to specific requirements, for example, 1 ppm.

[0044] In specific implementation, in order to accurately determine whether the change of the CO2 monitoring value has reached a stable state, the stable state judgment unit is used to divide the multiple CO2 monitoring values ​​sampled continuously into two groups of data according to the collection time sequence after determining that the CO2 monitoring value has entered a stable state, and when it is determined that the two groups of data meet the following preset data indicators, it is determined that the CO2 monitoring value has reached a stable state:

[0045] Calculating a first average value of one set of data and calculating a second average value of another set of data, wherein an absolute value of a difference between the first average value and the second average value is less than a third preset threshold;

[0046] Calculate a first variance of one set of data, and calculate a second variance of another set of data, wherein a ratio of the first variance to the second variance follows an F distribution;

[0047] Calculate the covariance of the multiple CO2 monitoring values ​​sampled continuously, and the covariance Q LB Statistics (Q LB The statistic is used for pure randomness test, also known as white noise test. LB The statistic is used to test whether the sequence values ​​with a delay period less than or equal to m are independent (uncorrelated) of each other. If the sequence is a purely random sequence, it means that the past behavior of the sequence has no effect on future development) is less than the fourth preset threshold.

[0048] In specific implementation, the number of the above-mentioned multiple CO2 monitoring values ​​sampled continuously can be determined according to specific needs. The larger the number, the greater the accuracy. For example, 60 CO2 monitoring values ​​can be sampled continuously.

[0049] In specific implementation, after determining that the CO2 monitoring value enters a stable state, the sensor to be calibrated is calibrated in the following manner. For example, a calibration unit is used to set a new deviation value of the sensor to be calibrated to the original deviation value of the sensor to be calibrated minus the average value of a plurality of continuously sampled CO2 monitoring values, so as to reset the zero point of the sensor to be calibrated.

[0050] In the specific implementation, the calibration module determines whether the CO2 monitoring value change has entered different stages based on the CO2 monitoring value. Figure 3 As shown, the process includes the following steps:

[0051] 1. The calibration module controls the three-way solenoid valve to switch the pipeline, opens the calibration air inlet, and the signal acquisition board (i.e., the calibration module) continuously samples the sensor to be calibrated, with a sampling interval of 100 milliseconds.

[0052] 2. The program (i.e., the calibration module) determines whether to enter the calibration process: This step only needs to record the current CO2 concentration value and the previous CO2 concentration value. When the absolute difference between the current CO2 concentration value and the previous CO2 concentration value is greater than 4ppm (i.e., the above-mentioned first preset threshold), continue to monitor data changes. When the deviation (i.e., the absolute difference) of three consecutive groups (i.e., the above-mentioned preset number) of data is greater than 4ppm, the monitoring program (i.e., the calibration module) confirms that it has entered the calibration process. Figure 4 As shown; if the calibration process is not entered within 1 minute (i.e. the first preset time length mentioned above) after the calibration air inlet is opened, the calibration fails.

[0053] 3. Determine whether it has entered a stabilization process: This step also only needs to record the current CO2 concentration value and the previous CO2 concentration value. When the absolute difference between the current CO2 concentration value and the previous CO2 concentration value is less than 1ppm (i.e., the second preset threshold value mentioned above), it is confirmed that it has entered a stabilization process. Figure 4If the air inlet does not stabilize within 3 minutes (i.e. the second preset time) after the calibration air inlet is opened, the calibration fails.

[0054] 4. Determine whether a stable state has been reached: After entering this step, 60 consecutive sampling CO2 concentration data need to be recorded. After collecting 60 data (A1, A2, A3, ..., A60), rollingly collect the current time and the 60 groups of data before the current time as the data set for judging whether the time series is stable. The data set is divided into 1 group of 30 data in sequence, and a total of 2 groups of data are recorded as X1 (A1, A2, ..., A30) and X2 (A31, A32, ..., A60); To judge whether the data set is stable, the following three indicators (i.e. the above-mentioned preset data indicators) must be met at the same time to determine that it has entered a stable state, such as Figure 4 As shown; if the air does not stabilize within 8 minutes after the calibration air inlet is opened, the calibration fails:

[0055] (1) The average values ​​of the two sets of data are independent of the time series: the average value of one set of data is u1 = E(X1), and the average value of the other set of data is u2 = E(X2); that is, it is necessary to test whether u1 is equal to u2, hoping to support the assumption that u1 = u2, which can be achieved based on the empirical value |u1-u2| < 1ppm (i.e., the third preset threshold mentioned above);

[0056] (2) The variances of the two sets of data are independent of the time series: the variance of one set of data is σ1 = VAR(X1), and the variance of the other set of data is σ2 = VAR(X2); that is, we need to test whether σ1 is equal to σ2, hoping to support the hypothesis that σ1 = σ2. The ratio of the sample variances follows the F distribution, so we will test the null hypothesis that σ1^2 / σ2^2 = 1. We set the significance level α = 0.05 for the test (the larger sample variance is used as the numerator of the F test statistic)

[0057] The elements of the inspection are as follows:

[0058] H0:σ1^2 / σ2^2=1

[0059] H1:σ1^2 / σ2^2≠1

[0060] Test statistic: F = larger sample variance / smaller sample variance;

[0061] The rejection region is F>Fα / 2;

[0062] (3) Covariance COV(XtXt+k) = γ k Independent of time series: Calculate the autocorrelation coefficient γ of 60 consecutive sampled CO2 concentration data series k (k=1,2,3,…58);

[0063]

[0064] Where t is the sampling time; k is the order of the interval; n is the total number of samples in the observation sequence; A t is the tth sample measurement value; is the mean of all sampled measurements; A t+k is the measurement value of the (t+k)th sample.

[0065] According to Q LB Statistics

[0066]

[0067] Where m is Q LB The degrees of freedom of the statistic; k is the order of the interval.

[0068] We set the significance level α = 0.05 for the test. LB < 2 α (i.e., the fourth preset threshold), we can accept the assumption that the autocorrelation coefficients are all 0, and χ 2 It is the degree of deviation between the actual observed value of the statistical sample and the theoretical inference value.

[0069] 5. After completing the above 4 steps, the new b value (i.e. deviation value) of the device model (i.e. the sensor to be calibrated) = the original b value of the device minus the average value of (A1, A2, A3, ..., A60).

[0070] In this embodiment, a working method of any of the above-mentioned calibration devices for monitoring CO2 sensors is also provided, such as Figure 5 As shown, the method comprises the following steps:

[0071] S501: When the sensor to be calibrated needs to be calibrated, the calibration module controls the three-way solenoid valve to close the first input end and open the second input end, so that the air entering through the calibration air inlet flows into the CO2 filtering device;

[0072] S502: Filtering CO2 in the air by the CO2 filtering device, and the filtered gas enters the sensor to be calibrated through the second input end of the three-way solenoid valve;

[0073] S503: Collecting the CO2 monitoring value of the sensor to be calibrated through the calibration module, and when it is determined according to the CO2 monitoring value that a stable state is reached, controlling the sensor to be calibrated to reset the zero point.

[0074] The embodiment of the present invention achieves the following technical effects: it proposes to connect a CO2 filter device through a three-way solenoid valve, filter out CO2 from the air entering the calibration air inlet through the CO2 filter device, and the zero gas after removing CO2 enters the sensor to be calibrated through the three-way solenoid valve, and then collects the CO2 monitoring value of the sensor to be calibrated through the calibration module, and when it is judged that a stable state is reached according to the CO2 monitoring value, controls the sensor to be calibrated to reset the zero point, thereby effectively eliminating the drift error, which is beneficial to ensuring the monitoring accuracy of the sensor equipment and the validity of the monitoring data; at the same time, it is possible to realize online remote calibration of the sensor without disassembling the equipment and returning it to the factory for calibration, which is beneficial to greatly improve the efficiency of sensor equipment calibration and effectively reduce operation and maintenance costs.

[0075] Obviously, those skilled in the art should understand that the modules or steps of the above-mentioned embodiments of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order from that here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. In this way, the embodiments of the present invention are not limited to any specific combination of hardware and software.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A calibration device for a sensor for monitoring CO2, characterized in that: include: A three-way solenoid valve, wherein a first input end of the three-way solenoid valve is connected to a monitoring air inlet, a second input end of the three-way solenoid valve is connected to an output end of a CO2 filter device, and an output end of the three-way solenoid valve is connected to a sensor to be calibrated; The input end of the CO2 filter device is connected to the calibration air inlet, and the CO2 filter device is used to filter out CO2 in the gas; a calibration module connected to the sensor to be calibrated, wherein the calibration module is used to control the three-way solenoid valve to close the first input end and open the second input end when the sensor to be calibrated needs to be calibrated, so that the air entering through the calibration air inlet enters the sensor to be calibrated after passing through the CO2 filter device, collects the CO2 monitoring value of the sensor to be calibrated, and controls the sensor to be calibrated to reset the zero point when it is judged that a stable state is reached according to the CO2 monitoring value; The calibration module comprises: A calibration process determination unit, used for determining whether to enter a calibration process according to a first change in the CO2 monitoring value; A stabilization judgment unit, used for judging whether the CO2 monitoring value has entered a stabilization state according to a second change of the CO2 monitoring value if a calibration process is entered; A stable state judgment unit, used to judge whether the multiple CO2 monitoring values ​​sampled continuously reach a preset data index if entering a stable state, and if reaching the preset data index, judge that the CO2 monitoring value reaches a stable state; The calibration process judgment unit is used to calculate the absolute difference between the CO2 monitoring value at the current moment and the CO2 monitoring value at the previous moment within a first preset time length; when a continuous preset number of absolute differences are greater than a first preset threshold, it is judged to enter the calibration process; The stabilization judgment unit is used to judge that the CO2 monitoring value has entered a stabilization state if the absolute difference between the CO2 monitoring value at the current moment and the CO2 monitoring value at the previous moment is less than a second preset threshold value within a second preset time period after entering the calibration process; The stable state judgment unit is used to divide the continuously sampled multiple CO2 monitoring values ​​into two groups of data in the order of collection time after judging that the CO2 monitoring value has entered a stable state, and judge that the CO2 monitoring value has reached a stable state when the two groups of data simultaneously meet the following preset data indicators: Calculating a first average value of one set of data, and calculating a second average value of another set of data, wherein an absolute value of a difference between the first average value and the second average value is less than a third preset threshold; Calculate a first variance of one set of data, and calculate a second variance of another set of data, wherein a ratio of the first variance to the second variance follows an F distribution; Calculate the covariance of the plurality of CO2 monitoring values ​​sampled continuously, the QLB statistic of the covariance is less than a fourth preset threshold, the fourth preset threshold is x 2 α, χ 2 It is the degree of deviation between the actual observed value of the statistical sample and the theoretical inference value, and α is the significance level; Q LB The calculation formula of the statistic is as follows: Where m is Q LB The degrees of freedom of the statistic; k is the order of the interval, γ k is the autocorrelation coefficient of the sequence formed by the multiple CO2 monitoring values ​​sampled continuously, n is the total sampling number of the multiple CO2 monitoring values ​​sampled continuously, and t is the sampling time.

2. The calibration device for a sensor for monitoring CO2 according to claim 1, characterized in that: The calibration module further includes: The calibration unit is used to set the new deviation value of the sensor to be calibrated to the original deviation value of the sensor to be calibrated minus the average value of a plurality of continuously sampled CO2 monitoring values, so as to reset the zero point of the sensor to be calibrated.

3. The calibration device for a sensor for monitoring CO2 according to any one of claims 1 to 2, characterized in that: The CO2 filtering device comprises: A CO2 filter, wherein the input end of the CO2 filter is connected to the calibration air inlet through a first moisture filter, and the CO2 filter is equipped with a CO2 absorption medium to filter out CO2 in the air entering through the calibration air inlet; A second moisture filter, the input end of the second moisture filter is connected to the output end of the CO2 filter, the output end of the second moisture filter is connected to the second input end of the three-way solenoid valve, and the second moisture filter is used to filter out moisture in the gas flowing through the CO2 filter.

4. The calibration device for a sensor for monitoring CO2 according to claim 3, characterized in that: The CO2 absorption medium is N a OH powder.

5. The calibration device for a sensor for monitoring CO2 according to any one of claims 1 to 2, characterized in that: Also includes: A filter connected to the sensor to be calibrated, the filter being used to filter out impurities in the gas flowing through the sensor to be calibrated; An air pump is connected to the filter, and is used to provide air pressure conditions for the gas inhaled by the sensor to be calibrated.

6. A working method of a calibration device for a sensor for monitoring CO2 according to any one of claims 1 to 5, characterized in that: include: When the sensor to be calibrated needs to be calibrated, the calibration module controls the three-way solenoid valve to close the first input end and open the second input end, so that the air entering through the calibration air inlet flows into the CO2 filtering device; The CO2 in the air is filtered out by the CO2 filter device, and the filtered gas enters the sensor to be calibrated through the second input end of the three-way solenoid valve; The calibration module collects the CO2 monitoring value of the sensor to be calibrated, and when it is judged that a stable state is reached according to the CO2 monitoring value, the sensor to be calibrated is controlled to reset the zero point.

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