CN112782357A - Automatic calibration method and device for gas sensor - Google Patents
Automatic calibration method and device for gas sensor Download PDFInfo
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Abstract
The invention provides an automatic calibration method and device for a gas sensor, wherein the method comprises the following steps: reading a point detection value of the standard sensor, and taking the point detection value of the standard sensor as a reference concentration value of the target gas in the sensor calibration tool; reading the initial concentration value of the target gas and the real-time concentration value of the target gas of the main sampling point, and selecting different gas distribution strategies according to different calibration types to perform automatic gas distribution; after the gas distribution is finished, judging whether the real-time concentration value of the target gas is equal to the reference concentration value of the target gas or not; if the real-time concentration value of the target gas is equal to the reference concentration value of the target gas, judging whether the uniformity of the target gas in the sensor calibration tool is qualified or not based on the consistency of the real-time concentration values of the target gas of all the sampling points; and if the uniformity of the target gas in the sensor calibration tool is qualified, calibrating the sensor to be calibrated. The invention has the functions of automatic temperature compensation, automatic point inspection, automatic gas distribution and automatic calibration.
Description
Technical Field
The invention relates to the technical field of sensor calibration, in particular to an automatic calibration method and device for a gas sensor.
Background
Calibration mainly refers to the detection of whether the accuracy (precision) of a used instrument meets a standard by using a standard measuring instrument, and is generally used for instruments with higher precision. At present, the gas sensor calibration process is complex, the calibration process control difficulty is high, the man-made interference factors are excessive, the mass production efficiency is low, and the consistency of product performance and the production efficiency are influenced to a certain extent.
The existing calibration device has the following problems and disadvantages: (1) in the prior art, a mass flow controller is used for proportioning a required concentration value according to a mass flow proportioning mode, and the dependence degree on the precision of the mass flow controller is high; (2) the gas obtained by proportioning has no feedback, or the feedback mechanism is imperfect, so that the proportioning concentration and the actual concentration have deviation; (3) the existing gas distribution mode distributes gas to a sensor calibration tool in a replacement mode, is slow in speed and is not suitable for batch production; (4) after the concentration is stable, the requirement on the air tightness of the sensor calibration tool is high due to the need of keeping the gas concentration; (5) monitoring feedback is not carried out on a plurality of positions of the sensor calibration tool, and the uniformity of the large-volume sensor calibration box cannot be guaranteed; (6) the number of temperature points and the temperature points at which customization is not provided for the sensor are not set.
In order to solve the above problems, people are always seeking an ideal technical solution.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides an automatic calibration method and device for a gas sensor.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides an automatic calibration method of a gas sensor, which comprises the following steps:
reading a point detection value of the standard sensor, and taking the point detection value of the standard sensor as a reference concentration value of the target gas in the sensor calibration tool;
reading the initial concentration value and the real-time concentration value of the target gas of the main sampling point, and selecting different gas distribution strategies according to different calibration types to perform automatic gas distribution:
if the calibration type is range calibration, roughly adjusting the transmission flow of the target gas when the difference value between the reference concentration value of the target gas and the initial concentration value of the target gas is greater than a first preset concentration threshold value, finely adjusting the transmission flow of the target gas when the difference value between the reference concentration value of the target gas and the real-time concentration value of the target gas is less than or equal to the first preset concentration threshold value, and finely adjusting the transmission flow of nitrogen when the real-time concentration value of the target gas is greater than the reference concentration value of the target gas;
if the calibration type is zero calibration, performing coarse adjustment on the transmission flow of the nitrogen when the difference value between the target gas reference concentration value and the target gas initial concentration value is greater than a second preset concentration threshold value, performing fine adjustment on the transmission flow of the nitrogen when the difference value between the target gas reference concentration value and the target gas real-time concentration value is less than or equal to the second preset concentration threshold value, and performing fine adjustment on the transmission flow of the target gas when the target gas real-time concentration value is less than the target gas reference concentration value;
after the gas distribution is finished, judging whether the real-time concentration value of the target gas is equal to the reference concentration value of the target gas or not; if the real-time concentration value of the target gas is equal to the reference concentration value of the target gas, acquiring the real-time concentration value of the target gas of each sampling point in the sensor calibration tool, and judging whether the uniformity of the target gas in the sensor calibration tool is qualified or not based on the consistency of the real-time concentration values of the target gas of each sampling point; and if the uniformity of the target gas in the sensor calibration tool is qualified, calibrating the sensor to be calibrated.
The second aspect of the invention provides an automatic calibration device for a gas sensor, which comprises an upper computer, a sensor calibration tool and an automatic calibration control cabinet, wherein the automatic calibration control cabinet is connected with the sensor calibration tool, the automatic calibration control cabinet executes the steps of the automatic calibration method for the gas sensor, and a calibration environment which accords with the reference concentration value of the target gas is prepared in the sensor calibration tool;
the upper computer is respectively connected with the automatic calibration control cabinet and the sensor calibration tool and is used for issuing a gas distribution instruction to the automatic calibration control cabinet and acquiring an output signal of a sensor to be calibrated.
Compared with the prior art, the invention has prominent substantive characteristics and remarkable progress, particularly:
1) the invention provides an automatic calibration method and device for a gas sensor, which are characterized in that a point detection value of a standard sensor is read and is used as a reference concentration value of a target gas in a sensor calibration tool; reading the initial concentration value and the real-time concentration value of the target gas of the main sampling point, and selecting different gas distribution strategies according to different calibration types to perform automatic gas distribution, so that the dependence of the calibration result of the gas sensor on the precision of the standard sensor is eliminated, the influence of the self-drifting of the standard sensor on the gas distribution precision is weakened, and the calibration accuracy of the sensor is improved;
2) the consistency of the real-time concentration values of the target gas of each sampling point is compared and the stirring device is driven to act, so that the uniformity of the gas in the sensor calibration tool is ensured, the gas tightness dependence on the sensor calibration tool is reduced, and the consistency of batch calibration is improved;
3) reading the initial concentration value and the real-time concentration value of the target gas of the main sampling point, and selecting different gas distribution strategies according to different calibration types to perform automatic gas distribution, so that the aims of rapid and stable gas distribution and high gas distribution precision are fulfilled;
4) the automatic calibration method and the device for the gas sensor have the functions of automatic temperature compensation, automatic point inspection, automatic gas distribution and automatic calibration, so that the calibration process is simplified, the influence of human factors is reduced, the automation degree of sensor production is improved, and the purposes of controllability in the calibration process and improvement of product performance are achieved.
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FIG. 1 is a flow chart of a method for automatic calibration of a gas sensor of the present invention;
FIG. 2 is a schematic structural diagram of an automatic calibration device for a gas sensor according to the present invention;
FIG. 3 is a schematic structural diagram of the automatic calibration control cabinet of the present invention;
fig. 4 is a schematic structural view of a sensor calibration stand of the present invention.
Detailed Description
The technical solution of the present invention is further described in detail by the following embodiments.
Example 1
As shown in fig. 1, the automatic calibration method for the gas sensor comprises the following steps:
reading a point detection value of the standard sensor, and taking the point detection value of the standard sensor as a reference concentration value of the target gas in the sensor calibration tool;
reading the initial concentration value and the real-time concentration value of the target gas of the main sampling point, and selecting different gas distribution strategies according to different calibration types to perform automatic gas distribution:
if the calibration type is range calibration, roughly adjusting the transmission flow of the target gas when the difference value between the reference concentration value of the target gas and the initial concentration value of the target gas is greater than a first preset concentration threshold value, finely adjusting the transmission flow of the target gas when the difference value between the reference concentration value of the target gas and the real-time concentration value of the target gas is less than or equal to the first preset concentration threshold value, and finely adjusting the transmission flow of nitrogen when the real-time concentration value of the target gas is greater than the reference concentration value of the target gas;
if the calibration type is zero calibration, performing coarse adjustment on the transmission flow of the nitrogen when the difference value between the target gas reference concentration value and the target gas initial concentration value is greater than a second preset concentration threshold value, performing fine adjustment on the transmission flow of the nitrogen when the difference value between the target gas reference concentration value and the target gas real-time concentration value is less than or equal to the second preset concentration threshold value, and performing fine adjustment on the transmission flow of the target gas when the target gas real-time concentration value is less than the target gas reference concentration value;
after the gas distribution is finished, judging whether the real-time concentration value of the target gas is equal to the reference concentration value of the target gas or not; if the real-time concentration value of the target gas is equal to the reference concentration value of the target gas, acquiring the real-time concentration value of the target gas of each sampling point in the sensor calibration tool, and judging whether the uniformity of the target gas in the sensor calibration tool is qualified or not based on the consistency of the real-time concentration values of the target gas of each sampling point; and if the uniformity of the target gas in the sensor calibration tool is qualified, calibrating the sensor to be calibrated.
It should be noted that when the consistency of the real-time concentration value of the target gas in the sensor calibration tool is not qualified, the stirring device is driven to act; after the stirring device acts, whether the real-time concentration value of the target gas at the main sampling point is equal to the reference concentration value of the target gas or not is judged, and when the real-time concentration value of the target gas at the main sampling point is equal to the reference concentration value of the target gas, whether the uniformity of the target gas in the sensor calibration tool is qualified or not is judged again, so that the real-time concentration value of the target gas in the sensor calibration tool is dynamically balanced.
It can be understood that when the range calibration is carried out, different solenoid valves are switched to transmit different standard gases to the standard sensor according to different range ranges so as to obtain different target gas reference concentration values.
When the gas sensor is calibrated, the standard sensor and the sensor to be calibrated are usually placed in the same calibration environment, a gas distribution concentration value is preset, and the target gas concentration is adjusted according to the detection value of the standard sensor and the set gas distribution concentration value until the detection value of the standard sensor is equal to the set gas distribution concentration value; once the error generated by the drift of the standard sensor affects the actual target gas concentration value in the calibration environment, the calibration accuracy of the calibration sensor is further reduced. The standard sensor and the sensor to be calibrated are placed in different environments, the standard sensor of each sampling point is subjected to zero point and SPAN point detection by adopting standard gas, point detection data is recorded, the point detection value of the standard sensor is used as the target gas reference concentration value in the sensor calibration tool, and gas distribution is carried out based on the target gas reference concentration value, so that the dependence of the calibration result of the gas sensor on the precision of the standard sensor is eliminated, the influence of the drift of the standard sensor on the gas distribution precision is weakened, the precision of the target gas reference concentration value in the sensor calibration tool is improved, and the calibration accuracy of the sensor is improved.
For example, 5000ppm target gas, namely 5000ppm standard gas and a standard sensor are required to be prepared in a sensor calibration tool; 5000ppm of standard gas is firstly applied to the standard sensor, the reaction concentration of the standard sensor is 5050ppm, and 5050ppm of the reaction of the standard sensor is generally judged to be 5000ppm of the standard gas. Therefore, the target gas in the sensor calibration tool is proportioned to the reaction value of a standard sensor of 5050ppm (target gas reference concentration value), namely the effect of proportioning the gas with the standard concentration of 5000ppm is achieved; therefore, the inaccuracy of the concentration value of the target gas which is proportioned due to the error of the standard sensor is avoided, and the fact that the higher standard is directly transmitted into the sensor calibration tool which needs proportioning through the standard sensor is equivalent.
It should be noted that, the existing gas distribution method is slow in speed and is not suitable for mass production by distributing gas to the sensor calibration tool in a replacement manner. In order to improve the calibration efficiency, the invention automatically calibrates the sensors to be calibrated in batches, and when calibrating in batches, if the consistency of the real-time concentration value of the target gas in the sensor calibration tool is unqualified, the consistency of the batch calibration is influenced, at the moment, the invention ensures the uniformity of the gas in the sensor calibration tool by driving the stirring device to act and automatically supplying air, thereby improving the consistency of the batch calibration.
The gas concentration needs to be maintained after the target gas concentration is stable, so that the gas tightness requirement of the sensor calibration tool is generally higher, and the sensor calibration tool with high gas tightness has high requirements on the manufacturing process and needs to invest higher equipment cost.
The multi-path standard sensor monitors the real-time concentration value of the target gas of each sampling point in the sensor calibration tool in real time, and judges whether the uniformity of the target gas in the sensor calibration tool is qualified or not according to the real-time concentration value of the target gas of each sampling point; if the uniformity of the target gas in the sensor calibration tool is unqualified, supplying gas into the sensor calibration tool in real time to adjust the concentration ratio, and changing the state of a stirring device to ensure that the real-time concentration value of the target gas in the sensor calibration tool reaches dynamic balance, thereby ensuring the uniformity of the gas in the large-volume sensor calibration tool; therefore, the calibration process does not need to depend on the sensor calibration tool with high air tightness, the air tightness requirement on the sensor calibration tool is reduced, and meanwhile, the calibration accuracy of the sensor is ensured.
Example 2
The embodiment provides specific implementation manners of different air distribution strategies.
It should be noted that, a mass flow controller is usually used to match a required set gas distribution concentration value according to a mass flow matching method, so that the degree of dependence on the precision of the mass flow controller is high; and because there is no feedback or feedback mechanism is imperfect to the real-time concentration value of the target gas obtained by proportioning, the real-time concentration value of the proportioned target gas has deviation with the required set gas distribution concentration value. The invention selects different gas distribution strategies to automatically distribute gas according to different calibration types; in different gas distribution strategies, different mass flow controllers are configured at different stages to output different transmission flows according to the relation among the target gas reference concentration value, the target gas initial concentration value, the target gas real-time concentration value and the first preset concentration threshold (or the second preset concentration threshold), so that the gas distribution precision is ensured, and the gas distribution process is ensured to be rapid and stable.
Specifically, when the target gas in the sensor calibration tool is matched from low concentration to high concentration, the target gas is used for rough adjustment and fine adjustment, and when the target gas exceeds a target gas reference concentration value, the nitrogen is used for fine adjustment; when the target gas in the sensor calibration tool is proportioned from high concentration to low concentration, nitrogen is used for coarse adjustment and fine adjustment, and the target gas is used for fine adjustment when the target gas is lower than the reference concentration value of the target gas.
Further, when the transmission flow rate of the target gas is coarsely adjusted, the following steps are performed: when the initial concentration value of the target gas is less than or equal to a preset concentration value A1, starting a mass flow controller I, and adjusting the real-time flow of the mass flow controller I to be B1; when the real-time concentration value of the target gas is greater than a preset concentration value A1 and less than or equal to a preset concentration value A2, adjusting the real-time flow of the mass flow controller I to be B2; when the real-time concentration value of the target gas is greater than a preset concentration value A2 and less than or equal to a preset concentration value A3, adjusting the real-time flow of the mass flow controller I to be B3; the preset concentration value A1 is less than the preset concentration value A2 is less than the preset concentration value A3, and the real-time flow rate B1 is greater than the real-time flow rate B2 is greater than the real-time flow rate B3.
Further, the transmission flow rate of the target gas is finely adjusted, and the following steps are carried out: when the real-time concentration value of the target gas is greater than or equal to the preset concentration threshold value A3 and less than or equal to a preset concentration value A4, closing the mass flow controller I, opening the mass flow controller II, and adjusting the real-time flow of the mass flow controller II to be C1; when the real-time concentration value of the target gas is greater than a preset concentration value A4 and is less than or equal to the reference concentration value of the target gas, adjusting the real-time flow of the mass flow controller II to be C2; wherein the preset concentration value A3 is less than the preset concentration value A4 is less than the reference concentration value, and the real-time flow rate C1 is greater than the real-time flow rate B2.
Further, when the transmission flow of the nitrogen is roughly adjusted, the following steps are executed: when the initial concentration value of the target gas is greater than or equal to a preset concentration value A1 ', starting a mass flow controller I', and adjusting the real-time flow of the mass flow controller I 'to be B1'; when the real-time concentration value of the target gas is smaller than a preset concentration value A1 'and is larger than or equal to a preset concentration value A2', adjusting the real-time flow of the mass flow controller I 'to be B2'; when the real-time concentration value of the target gas is smaller than a preset concentration value A2 'and is larger than or equal to a preset concentration value A3', adjusting the real-time flow of the mass flow controller I 'to be B3'; wherein, the preset concentration value A1 '> the preset concentration value A2' > the preset concentration value A3 ', and the real-time flow B1' > the real-time flow B2 '> the real-time flow B3'.
Further, the transmission flow of the nitrogen is finely adjusted, and the following steps are carried out: when the real-time concentration value of the target gas is smaller than the preset concentration threshold value A3 'and is larger than or equal to a preset concentration value A4', closing the mass flow controller I ', opening the mass flow controller II', and adjusting the real-time flow of the mass flow controller II 'to be C1'; when the real-time concentration value of the target gas is smaller than a preset concentration value A4 ' and is larger than or equal to the reference concentration value of the target gas, adjusting the real-time flow of the mass flow controller II ' to be C2 '; wherein the preset concentration value A3 '> the preset concentration value A4' > the reference concentration value, and the real-time flow C1 '> the real-time flow B2'.
The mass flow controller I is a wide-range mass flow controller and is arranged between a target gas cylinder and a sensor calibration tool so as to roughly adjust the transmission flow of the target gas; and the mass flow controller II is a small-range mass flow controller and is arranged between the target gas cylinder and the sensor calibration tool so as to finely adjust the transmission flow of the target gas. The mass flow controller I' is a wide-range mass flow controller and is arranged between the nitrogen gas cylinder and the sensor calibration tool to roughly adjust the transmission flow of nitrogen; and the mass flow controller II' is a small-range mass flow controller and is arranged between the nitrogen gas cylinder and the sensor calibration tool so as to finely adjust the transmission flow of the nitrogen gas. Through the two sets of mass flow controllers MFC of coarse adjustment and fine adjustment, the mass flow controller MFC of coarse adjustment can realize that the gas distribution is close to the reference concentration value of the target gas quickly; after the gas reaches the vicinity of the target gas reference concentration value, the gas concentration is quickly stabilized by using the fine tuning mass flow controller MFC, so that the gas distribution precision can be ensured while the gas concentration is quickly stabilized.
Example 3
The present embodiment is different from the foregoing embodiments in that, before calibrating the sensor to be calibrated, the following steps are further performed: configuring a temperature curve, and customizing the number of temperature compensation points and the temperature points based on the temperature curve;
and reading the number of the self-defined temperature compensation points and the temperature points, adjusting the ambient temperature in the sensor calibration tool, and performing temperature compensation on the sensor to be calibrated.
It should be noted that, the existing calibration method does not consider temperature compensation, and cannot provide customized number of temperature points and temperature point setting for the sensor, and the temperature will affect the detection accuracy of the sensor in practical application. The invention compensates the temperature of the sensor in the calibration process according to the set temperature curve, so that the invention has the functions of automatic point inspection, automatic gas distribution and automatic calibration and also has the function of automatic temperature compensation, thereby further improving the accuracy of the calibration of the sensor.
Example 4
The embodiment provides a specific implementation manner of an automatic calibration device of a gas sensor, the automatic calibration device of the gas sensor comprises an upper computer, a sensor calibration tool and an automatic calibration control cabinet, the automatic calibration control cabinet is connected with the sensor calibration tool, the automatic calibration control cabinet executes the steps of the automatic calibration method of the gas sensor, and a calibration environment which meets the reference concentration value of the target gas is prepared in the sensor calibration tool;
the upper computer is respectively connected with the automatic calibration control cabinet and the sensor calibration tool and is used for issuing a gas distribution instruction to the automatic calibration control cabinet and acquiring an output signal of a sensor to be calibrated.
As shown in fig. 3, the automatic calibration control cabinet comprises a cabinet body, a standard gas transmission channel, a target gas transmission channel and a nitrogen transmission channel which are arranged in the cabinet body, and further comprises a gas distribution controller, a standard sensor group and a gas pump;
the gas inlet end of the standard gas transmission channel is hermetically communicated with a standard gas cylinder, and the gas outlet end of the standard gas transmission channel is hermetically communicated with the standard sensor group; the gas inlet end of the target gas transmission channel is communicated with a target gas cylinder in a sealing manner, and the gas outlet end of the target gas transmission channel is communicated with the sensor calibration tool in a sealing manner; the gas inlet end of the nitrogen transmission channel is hermetically communicated with a nitrogen gas bottle, and the gas outlet end of the nitrogen transmission channel is hermetically communicated with the sensor calibration tool;
a point detection electromagnetic valve is arranged between the air inlet end and the air outlet end of the standard gas transmission channel, a target gas distribution valve, a mass flow controller I and a mass flow controller II are arranged between the air inlet end and the air outlet end of the target gas transmission channel, and a nitrogen gas distribution valve, a mass flow controller I 'and a mass flow controller II' are arranged between the air inlet end and the air outlet end of the nitrogen gas transmission channel;
the gas inlet end of the gas pump is communicated with each sampling point in the sensor calibration tool in a sealing manner, and the gas outlet end of the gas pump is communicated with the standard sensor group in a sealing manner so as to detect the real-time concentration value of the target gas at each sampling point;
the distribution controller is respectively connected with the standard sensor group and the point inspection electromagnetic valve so as to carry out point inspection on the standard sensor by adopting standard gas and obtain a point inspection value of the standard sensor;
the gas distribution controller is also respectively connected with the gas pump, the target gas distribution valve, the mass flow controller I, the mass flow controller II, the nitrogen gas distribution valve, the mass flow controller I 'and the mass flow controller II' so as to input nitrogen and target gas into the sensor calibration tool and obtain the real-time concentration value of the target gas at each sampling point.
It is understood that the automatic calibration control cabinet comprises 4 MFCs, the mass flow controller i and the mass flow controller i 'are used for coarse tuning, and the mass flow controller ii' are used for fine tuning. When the initial concentration value of the target gas is far away from the reference concentration value of the target gas, the initial concentration value of the target gas quickly reaches the vicinity of the reference concentration value of the target gas by coarse adjustment; when the real-time concentration value of the target gas reaches the vicinity of the reference concentration value of the target gas, the MFC (mass flow controller) is started for fine adjustment, so that the gas distribution speed and the gas distribution precision can be ensured.
The standard sensor is used as a feedback controller in the calibration process, the air pump pumps out and samples the gases at different sampling points and sends the gases to the feedback sensor so as to monitor the real-time concentration value of the target gas at each sampling point, the real-time concentration value of the target gas at the main sampling point provides a reference for automatic gas distribution, and the real-time concentration value of the target gas at each sampling point provides a reference basis for judging the uniformity of the target gas; and when the calibration is carried out in different measuring range ranges, the point inspection electromagnetic valve controls the standard gas cylinders with different concentrations to supply gas.
It should be noted that, the automatic calibration control cabinet performs zero point and SPAN point detection on the standard sensor of each sampling point and records point detection data through an automatic point detection function, eliminates errors caused by drift of the standard sensor, and issues a gas distribution command according to a point detection value, so as to realize automatic gas distribution in the sensor calibration tool.
The invention is provided with a main standard gas cylinder and a standby standard gas cylinder, wherein the main standard gas cylinder and the standby standard gas cylinder are respectively communicated with a mass flow controller I/a mass flow controller II through gas distribution electromagnetic valves to realize automatic switching between main and standby; the target gas cylinder (pure gas cylinder) is used for preparing gas with required concentration, and the main target gas cylinder and the standby target gas cylinder are respectively communicated with the mass flow controller I '/the mass flow controller II' through gas distribution electromagnetic valves, so that automatic main-standby switching is realized. The target gas distribution valve and the nitrogen gas distribution valve are used for controlling gas distribution, and corresponding gas cylinders are controlled to supply gas by controlling corresponding electromagnetic valves; specifically, the main standard gas cylinder, the standby standard gas cylinder, the main target gas cylinder and the standby target gas cylinder correspond to one electromagnetic valve respectively.
Specifically, the gas distribution controller can set parameters through a touch liquid crystal screen, and perform data monitoring, curve display and gas distribution/calibration command issuing of flow/concentration/and the like.
The upper computer has the main functions of realizing the control of the whole automatic calibration process and monitoring the data of each system in real time; the sensor calibration tool is communicated with an automatic calibration control cabinet through an RS232 interface, a gas distribution instruction is issued, the real-time transmission flow of each mass flow controller is monitored, and the real-time concentration value of the target gas of each sampling point in the sensor calibration tool is monitored; communicating with the sensor calibration tool in a 485 communication mode, issuing a calibration/calibration command, and collecting and processing data of the sensor mounted on the calibration tool; and carrying out temperature control/acquisition on the sensor calibration tool through the Ethernet port.
Specifically, the upper computer sets three levels of authority: the primary authority is the authority of the production personnel, only one key is operated, the operation is simple, and the error probability is reduced; the middle-level authority is the operator authority, and calibration information of the sensor to be calibrated and process customization can be set; the high-level authority is the administrator authority, and the parameters of the automatic calibration system can be modified.
Further, the sensor calibration tool is a high-low temperature box with a temperature adjusting function, and a sensor calibration frame is arranged in the high-low temperature box, as shown in fig. 4; the sensor calibration frame is configured with a sensor concentration unit to be calibrated, and the sensor concentration unit to be calibrated communicates with an upper computer through the sensor calibration frame to read information of the sensor to be calibrated and distribute a calibration command. Specifically, the sensor to be calibrated centralized unit is used for centralizing the communication of a plurality of sensors to be calibrated, each centralized unit has an address, and the centralized unit is connected with the sensor calibration frame in an RS485 communication mode; the sensors are installed on the sensor calibration frame after being concentrated by the sensor concentration units to be calibrated, the sensor calibration frame is communicated with each concentration unit by adopting an MODBUS protocol, data of each sensor to be calibrated are collected and uploaded to an upper computer, and commands of the upper computer are distributed to each sensor to be calibrated.
It should be noted that the automatic calibration device for the gas sensor also has fault self-diagnosis, different fault prompting sounds exist in the running process of the system, fault points are quickly located according to the prompting sounds, and faults are eliminated.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.
Claims (10)
1. An automatic calibration method for a gas sensor is characterized by comprising the following steps:
reading a point detection value of the standard sensor, and taking the point detection value of the standard sensor as a reference concentration value of the target gas in the sensor calibration tool;
reading the initial concentration value and the real-time concentration value of the target gas of the main sampling point, and selecting different gas distribution strategies according to different calibration types to perform automatic gas distribution:
if the calibration type is range calibration, roughly adjusting the transmission flow of the target gas when the difference value between the reference concentration value of the target gas and the initial concentration value of the target gas is greater than a first preset concentration threshold value, finely adjusting the transmission flow of the target gas when the difference value between the reference concentration value of the target gas and the real-time concentration value of the target gas is less than or equal to the first preset concentration threshold value, and finely adjusting the transmission flow of nitrogen when the real-time concentration value of the target gas is greater than the reference concentration value of the target gas;
if the calibration type is zero calibration, performing coarse adjustment on the transmission flow of the nitrogen when the difference value between the target gas reference concentration value and the target gas initial concentration value is greater than a second preset concentration threshold value, performing fine adjustment on the transmission flow of the nitrogen when the difference value between the target gas reference concentration value and the target gas real-time concentration value is less than or equal to the second preset concentration threshold value, and performing fine adjustment on the transmission flow of the target gas when the target gas real-time concentration value is less than the target gas reference concentration value;
after the gas distribution is finished, judging whether the real-time concentration value of the target gas is equal to the reference concentration value of the target gas or not; if the real-time concentration value of the target gas is equal to the reference concentration value of the target gas, acquiring the real-time concentration value of the target gas of each sampling point in the sensor calibration tool, and judging whether the uniformity of the target gas in the sensor calibration tool is qualified or not based on the consistency of the real-time concentration values of the target gas of each sampling point; and if the uniformity of the target gas in the sensor calibration tool is qualified, calibrating the sensor to be calibrated.
2. The automatic calibration method of the gas sensor according to claim 1, wherein when the transmission flow rate of the target gas is coarsely adjusted, the following steps are performed:
when the initial concentration value of the target gas is less than or equal to a preset concentration value A1, starting a mass flow controller I, and adjusting the real-time flow of the mass flow controller I to be B1; when the real-time concentration value of the target gas is greater than a preset concentration value A1 and less than or equal to a preset concentration value A2, adjusting the real-time flow of the mass flow controller I to be B2; when the real-time concentration value of the target gas is greater than a preset concentration value A2 and less than or equal to a preset concentration value A3, adjusting the real-time flow of the mass flow controller I to be B3;
the preset concentration value A1 is less than the preset concentration value A2 is less than the preset concentration value A3, and the real-time flow rate B1 is greater than the real-time flow rate B2 is greater than the real-time flow rate B3.
3. The automatic calibration method of the gas sensor according to claim 2, wherein the fine adjustment of the transmission flow rate of the target gas is performed by:
when the real-time concentration value of the target gas is greater than or equal to the preset concentration threshold value A3 and less than or equal to a preset concentration value A4, closing the mass flow controller I, opening the mass flow controller II, and adjusting the real-time flow of the mass flow controller II to be C1; when the real-time concentration value of the target gas is greater than a preset concentration value A4 and is less than or equal to the reference concentration value of the target gas, adjusting the real-time flow of the mass flow controller II to be C2;
wherein the preset concentration value A3 is less than the preset concentration value A4 is less than the reference concentration value, and the real-time flow rate C1 is greater than the real-time flow rate B2.
4. The automatic calibration method of the gas sensor according to claim 1, characterized in that: when the transmission flow of the nitrogen is roughly adjusted, the following steps are carried out:
when the initial concentration value of the target gas is greater than or equal to a preset concentration value A1 ', starting a mass flow controller I', and adjusting the real-time flow of the mass flow controller I 'to be B1'; when the real-time concentration value of the target gas is smaller than a preset concentration value A1 'and is larger than or equal to a preset concentration value A2', adjusting the real-time flow of the mass flow controller I 'to be B2'; when the real-time concentration value of the target gas is smaller than a preset concentration value A2 'and is larger than or equal to a preset concentration value A3', adjusting the real-time flow of the mass flow controller I 'to be B3';
wherein, the preset concentration value A1 '> the preset concentration value A2' > the preset concentration value A3 ', and the real-time flow B1' > the real-time flow B2 '> the real-time flow B3'.
5. The automatic calibration method of the gas sensor according to claim 4, characterized in that the transmission flow of the nitrogen is finely adjusted to perform:
when the real-time concentration value of the target gas is smaller than the preset concentration threshold value A3 'and is larger than or equal to a preset concentration value A4', closing the mass flow controller I ', opening the mass flow controller II', and adjusting the real-time flow of the mass flow controller II 'to be C1'; when the real-time concentration value of the target gas is smaller than a preset concentration value A4 ' and is larger than or equal to the reference concentration value of the target gas, adjusting the real-time flow of the mass flow controller II ' to be C2 ';
wherein the preset concentration value A3 '> the preset concentration value A4' > the reference concentration value, and the real-time flow C1 '> the real-time flow B2'.
6. The automatic calibration method of the gas sensor according to claim 1, wherein when the consistency of the real-time concentration value of the target gas in the sensor calibration tool is not qualified, the stirring device is driven to act;
and after the stirring device acts, judging whether the real-time concentration value of the target gas at the main sampling point is equal to the reference concentration value of the target gas, and judging whether the uniformity of the target gas in the sensor calibration tool is qualified again when the real-time concentration value of the target gas at the main sampling point is equal to the reference concentration value of the target gas.
7. The automatic calibration method of the gas sensor according to claim 1, characterized in that: and when the measuring range calibration is carried out, different electromagnetic valves are switched to transmit different standard gases to the standard sensor according to different measuring range ranges so as to obtain different target gas reference concentration values.
8. The automatic calibration method of the gas sensor according to claim 1, characterized in that: before the sensor to be calibrated is calibrated, the following steps are also executed: configuring a temperature curve, and customizing the number of temperature compensation points and the temperature points based on the temperature curve;
and reading the number of the self-defined temperature compensation points and the temperature points, adjusting the ambient temperature in the sensor calibration tool, and performing temperature compensation on the sensor to be calibrated.
9. The utility model provides an automatic calibration device of gas sensor which characterized in that: the method comprises an upper computer, a sensor calibration tool and an automatic calibration control cabinet, wherein the automatic calibration control cabinet is connected with the sensor calibration tool, the automatic calibration control cabinet executes the steps of the automatic calibration method of the gas sensor according to any one of claims 1 to 8, and a calibration environment which accords with the reference concentration value of the target gas is prepared in the sensor calibration tool;
the upper computer is respectively connected with the automatic calibration control cabinet and the sensor calibration tool and is used for issuing a gas distribution instruction to the automatic calibration control cabinet and acquiring an output signal of a sensor to be calibrated.
10. The automatic calibration device for the gas sensor according to claim 9, wherein: the automatic calibration control cabinet comprises a cabinet body, a standard gas transmission channel, a target gas transmission channel and a nitrogen transmission channel which are arranged in the cabinet body, and further comprises a gas distribution controller, a standard sensor group and a gas pump;
the gas inlet end of the standard gas transmission channel is hermetically communicated with a standard gas cylinder, and the gas outlet end of the standard gas transmission channel is hermetically communicated with the standard sensor group; the gas inlet end of the target gas transmission channel is communicated with a target gas cylinder in a sealing manner, and the gas outlet end of the target gas transmission channel is communicated with the sensor calibration tool in a sealing manner; the gas inlet end of the nitrogen transmission channel is hermetically communicated with a nitrogen gas bottle, and the gas outlet end of the nitrogen transmission channel is hermetically communicated with the sensor calibration tool;
a point detection electromagnetic valve is arranged between the air inlet end and the air outlet end of the standard gas transmission channel, a target gas distribution valve, a mass flow controller I and a mass flow controller II are arranged between the air inlet end and the air outlet end of the target gas transmission channel, and a nitrogen gas distribution valve, a mass flow controller I 'and a mass flow controller II' are arranged between the air inlet end and the air outlet end of the nitrogen gas transmission channel;
the gas inlet end of the gas pump is communicated with each sampling point in the sensor calibration tool in a sealing manner, and the gas outlet end of the gas pump is communicated with the standard sensor group in a sealing manner so as to detect the real-time concentration value of the target gas at each sampling point;
the distribution controller is respectively connected with the standard sensor group and the point inspection electromagnetic valve so as to carry out point inspection on the standard sensor by adopting standard gas and obtain a point inspection value of the standard sensor;
the gas distribution controller is also respectively connected with the gas pump, the target gas distribution valve, the mass flow controller I, the mass flow controller II, the nitrogen gas distribution valve, the mass flow controller I 'and the mass flow controller II' so as to input nitrogen and target gas into the sensor calibration tool and obtain the real-time concentration value of the target gas at each sampling point.
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