CN212514244U - Permeation diffusion type gas concentration measuring sensor - Google Patents
Permeation diffusion type gas concentration measuring sensor Download PDFInfo
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- CN212514244U CN212514244U CN202021692684.3U CN202021692684U CN212514244U CN 212514244 U CN212514244 U CN 212514244U CN 202021692684 U CN202021692684 U CN 202021692684U CN 212514244 U CN212514244 U CN 212514244U
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Abstract
The invention relates to a permeation diffusion type gas concentration measuring sensor, and belongs to the field of gas concentration measuring sensors. Comprises an air chamber component, a light source, a lens component, a microphone and a circuit board; the air chamber component is provided with a waterproof breathable film and a concave lens wall. By diffusion effect, the gas is contained in the gas chamber in a permeation mode, so that the gas flow disorder generated when the gas is pumped into the common gas sensor can be avoided, the noise caused by the gas flow disorder is eliminated, and the measurement precision is improved; the full light area can be formed in the air chamber, the utilization rate of light energy is improved, the active number of air molecules in the air chamber can be increased, and the intensity of an acoustic signal generated by a photoacoustic effect is improved; the temperature compensation can be realized by the arrangement of the temperature sensor; the concentration of different gases can be measured by selecting different wavelengths of light through different filters.
Description
Technical Field
The invention relates to a permeation diffusion type gas concentration measuring sensor, in particular to a method for measuring the concentration of specific gas by utilizing a photoacoustic spectroscopy technology, and belongs to the field of gas concentration measuring sensors.
Background
The photoacoustic spectroscopy gas detection is realized by utilizing the principle of photoacoustic conversion effect and weak signal detection technology, and the main principle is as follows: when a specific monochromatic light beam is emitted into a container through which gas to be measured is introduced at a fixed frequency f, if the wavelength of the incident light beam is within the absorption range of the gas to be measured, the incident light beam is absorbed by the gas to be measured, and a sound wave having the same period as the modulation frequency is generated, namely, the photoacoustic effect. The detected sound wave signal is converted into an electric signal which can be processed by a microphone, and the concentration of the detected gas can be calculated by analyzing the detected electric signal.
Common methods for detecting the concentration of the gas include a non-optical method and an optical method, and the non-optical method mainly includes an electrochemical method, a thermocatalysis method and the like; the optical method mainly includes absorption spectroscopy, photoacoustic spectroscopy, and the like. In recent years, with the increasing sensitivity of microphones, photoacoustic spectroscopy technology has been developed rapidly, and the detection of gas concentration by photoacoustic spectroscopy is becoming a mainstream trend. When the photoacoustic spectrometry is used for detecting the gas concentration, the gas concentration can be determined directly through the measured acoustic signal without preprocessing the gas to be detected, and compared with the traditional non-optical detection method, the method has the advantages of high detection speed, good real-time performance and the like.
However, the current method for measuring the concentration of a specific gas by using the photoacoustic spectroscopy has certain disadvantages. Firstly, the light ray emission and the air chamber structure are unreasonable, so that the light ray energy utilization rate is low; secondly, the breather pump entry structural design is unreasonable, and gas business turn over into the air chamber can cause the gas to flow, also can produce the noise signal, need wait for longer time just can resume stable, can influence the detection precision, and it is long when increasing the detection.
Disclosure of Invention
The invention provides a gas concentration sensor, aiming at the problems that the light energy utilization rate is low and gas flows when gas enters and exits a gas chamber.
The invention is realized by the following technical scheme: the gas concentration measuring sensor comprises a gas chamber component, a light source, a lens component, a microphone and a circuit board; the air chamber component is provided with a waterproof breathable film and a concave lens wall.
The air chamber part has air chamber main part, waterproof ventilated membrane and concave lens wall, the bottom surface wall of air chamber main part is installed on the circuit board, installs waterproof ventilated membrane on the front and back two sides of air chamber main part and the top surface, and the position that does not have waterproof ventilated membrane on the top surface of air chamber main part runs through and installs the microphone, and the microphone probe is in the air chamber that the air chamber main part formed, and the inboard of a lateral wall of air chamber main part is concave lens wall, and concave lens wall is concave lens structure.
The light source and the lens component are provided with a light source, a light source mounting shell, a lens and an optical filter, the optical filter is arranged in the other side wall of the non-concave lens wall of the air chamber main body in a penetrating mode, the thick part of the light source mounting shell is connected to the outer side of the side wall provided with the optical filter, the light source is arranged on the thin part of the light source mounting shell, the lens is arranged inside the light source mounting shell and located between the light source and the optical filter, and the light source, the lens and the optical filter are on the same straight line with the surface.
The lenses include, but are not limited to, convex lenses and fresnel lenses.
The waterproof and breathable film comprises but is not limited to a PTFE film and an ultrafine fiber fabric.
The inner surface of the air chamber main body and the inner surface of the concave lens wall are made of mirror materials and/or plated with mirror coatings and/or subjected to mirror polishing, the mirror materials include but are not limited to mirror aluminum alloy and mirror stainless steel, the mirror coatings include but are not limited to chemical nickel-plating layers, and the mirror polishing means that the surface roughness value Ra is less than or equal to Ra0.2; and a full light area can be formed in the closed air chamber by combining the concave lens structure of the concave lens wall.
The circuit board is provided with a power supply circuit, a calculation control circuit, a light source driving circuit and a signal processing circuit, wherein the signal processing circuit comprises a differential amplification circuit and a frequency selection amplification circuit; the power supply circuit is connected with a battery and supplies power to the light source, the microphone, the electromagnet, the calculation control circuit, the light source driving circuit, the acquisition circuit and the signal processing circuit; the calculation control circuit is provided with a singlechip; the light source driving circuit is provided with a high-speed optical coupler and an enhanced field effect transistor and can be matched with PWM (pulse width modulation) waves to drive a light source; the differential amplification circuit is connected with the microphone, is provided with an amplifier and can properly amplify the weak signal output by the microphone; the frequency-selecting amplifying circuit is provided with a multiplier and a low-pass filter and can filter high-frequency signals.
The circuit board is provided with a temperature measuring module, and measured environment temperature data are transmitted to the single chip microcomputer.
The invention has the advantages that through the diffusion effect, the gas is contained in the gas chamber in a permeation mode, the gas flow disorder generated when the gas is pumped into the common gas sensor can be avoided, the noise caused by the gas flow disorder is eliminated, and the measurement precision is improved; the full light area can be formed in the air chamber, the utilization rate of light energy is improved, the active number of air molecules in the air chamber can be increased, and the intensity of an acoustic signal generated by a photoacoustic effect is improved; the temperature compensation can be realized by the arrangement of the temperature sensor; the concentration of different gases can be measured by selecting different wavelengths of light through different filters.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is an isometric view of the present invention;
FIG. 3 is a schematic structural view of the present invention;
FIG. 4 is a front view of the present invention;
FIG. 5 is a power supply circuit diagram;
FIG. 6 is a circuit diagram of a calculation control circuit;
FIG. 7 is a circuit diagram of a light source driving circuit;
FIG. 8 is a differential amplifier circuit diagram;
fig. 9 is a frequency-selective amplifier circuit diagram.
In the figure, 1, a gas chamber component, 101, a gas chamber body, 102, a waterproof breathable film, 103, a concave lens wall, 2, a light source and lens component, 201, a light source, 202, a light source mounting shell, 203, a lens, 204, a filter, 3, a microphone, 301, a microphone probe, 4 and a circuit board.
Detailed Description
The gas concentration measuring sensor of the permeation diffusion type, including the part 1 of the air cell, light source and lens part 2, microphone 3 and circuit board 4; the air chamber component 1 is provided with a waterproof breathable film 102 and a concave lens wall 103.
The air chamber component 1 is provided with an air chamber main body 101, a waterproof breathable film 102 and a concave lens wall 103, the bottom wall of the air chamber main body 101 is installed on a circuit board 4, the waterproof breathable film 102 is installed on the front surface, the rear surface and the top surface of the air chamber main body, a microphone 3 is installed on the top surface of the air chamber main body in a penetrating mode at a position without the waterproof breathable film, a microphone probe 301 is arranged in an air chamber formed by the air chamber main body, the inner side of one side wall of the air chamber main body is the concave lens wall 103, and the concave lens wall is of a concave lens structure.
The light source and lens component 2 is provided with a light source 201, a light source mounting shell 202, a lens 203 and a filter 204, the filter is arranged in the other side wall of the non-concave lens wall 103 of the air chamber main body 101 in a penetrating way, the thick part of the light source mounting shell 202 is connected to the outer side of the side wall provided with the filter 204, the light source 201 is arranged on the thin part of the light source mounting shell, the lens 203 is arranged in the light source mounting shell and is positioned between the light source and the filter, and the light source, the lens and the filter are positioned on the same straight line with the surface center of the cross section.
The lens 203 includes, but is not limited to, a convex lens and a fresnel lens.
The waterproof and breathable membrane 102 includes, but is not limited to, a PTFE membrane and an ultrafine fiber fabric.
The inner surfaces of the air chamber main body 101 and the concave lens wall 103 are made of mirror materials and/or plated with mirror coatings and/or subjected to mirror polishing, the mirror materials include but are not limited to mirror aluminum alloy and mirror stainless steel, the mirror coatings include but are not limited to chemical nickel-plating layers, and the mirror polishing means that the surface roughness value Ra is less than or equal to Ra0.2; in combination with the concave lens structure of the concave lens wall 103, a full light zone can be formed within the closed gas chamber.
The circuit board 4 is provided with a power supply circuit, a calculation control circuit, a light source driving circuit and a signal processing circuit, wherein the signal processing circuit comprises a differential amplification circuit and a frequency selection amplification circuit; the power supply circuit is connected with a battery and supplies power to the light source, the microphone, the electromagnet, the calculation control circuit, the light source driving circuit, the acquisition circuit and the signal processing circuit; the calculation control circuit is provided with a singlechip; the light source driving circuit is provided with a high-speed optical coupler and an enhanced field effect transistor and can be matched with PWM (pulse width modulation) waves to drive a light source; the differential amplification circuit is connected with the microphone, is provided with an amplifier and can properly amplify the weak signal output by the microphone; the frequency-selecting amplifying circuit is provided with a multiplier and a low-pass filter and can filter high-frequency signals.
The circuit board 4 is provided with a temperature measuring module, and measured environment temperature data are transmitted to the single chip microcomputer.
The temperature change can cause measurement error, and the singlechip corrects the measured gas concentration data by combining the temperature data measured by the temperature measurement module, so that the measurement error caused by the temperature change is compensated.
The working process of the gas detection device comprises the following steps that a singlechip of a control circuit outputs PWM (pulse-width modulation) waves with specific duration and specific frequency to control the frequency of light emitted by a light source, then a lens is used for refracting the light to obtain parallel light, and then the wavelength of incident light is selected through an optical filter, so that the central wavelength of the incident light can completely scan an absorption line of gas to be detected in a gas chamber; incident light penetrates through the gas to be detected after entering the gas chamber, is reflected by the convex mirror and is reflected by the inner side surface of the wall of the gas chamber, and finally a uniform light field is formed in the gas chamber, so that the gas to be detected in the gas chamber can fully absorb light energy; the gas molecule to be detected absorbs light energy and then undergoes transition, thermal motion is intensified to generate an acoustic signal, the acoustic signal is collected and converted into an electric signal by the microphone, the collected electric signal is subjected to differential amplification, frequency-selective amplification and noise signal filtering by the signal processing circuit and then is transmitted to the single chip microcomputer, the single chip microcomputer analyzes and calculates the signal according to a preset program, and the gas concentration value is output by referring to prestored reference data.
To measure NH3For example, the gas concentration is selected by selecting a filter to transmit light with wavelength of about 1531.6nm, and generating the light by a single chip microcomputerPWM signal to control the frequency of 1160Hz light source modulation signal, and measuring NH according to the parameter3The gas concentration.
Because the waterproof breathable film is used, the situations of light leakage, gas exchange and the like are avoided, errors are generated in acoustic signal detection, the single chip can analyze and calculate acoustic signals measured by the microphone for multiple times within specific time to obtain the calculation effective value of the acoustic signals, and corresponding concentration values are obtained through calculation and retrieval of early experimental data. During research and development, the acoustic signal amplitudes detected by the corresponding microphones of the plurality of concentration values are obtained through a large number of experiments, and a data corresponding fitting curve is obtained through a genetic algorithm. The single chip microcomputer processes the detected acoustic signals by using the data obtained in advance, and then searches and calculates to obtain the corresponding concentration value.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
It will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in the embodiments described above without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims.
Claims (6)
1. The gas concentration measuring sensor comprises a gas chamber component, a light source, a lens component, a microphone and a circuit board; the method is characterized in that: the air chamber component is provided with a waterproof breathable film and a concave lens wall, the air chamber component is provided with an air chamber main body, the waterproof breathable film and a concave lens wall, the bottom wall of the air chamber main body is arranged on the circuit board, the front surface, the rear surface and the top surface of the air chamber main body are provided with the waterproof breathable films, a microphone is arranged on the top surface of the air chamber main body in a penetrating way at a position without the waterproof breathable film, a microphone probe is arranged in an air chamber formed by the air chamber main body, the inner side of one side wall of the air chamber main body is the concave lens wall, and the concave lens wall is of; the light source and the lens component are provided with a light source, a light source mounting shell, a lens and an optical filter, the optical filter is arranged in the other side wall of the non-concave lens wall of the air chamber main body in a penetrating mode, the thick part of the light source mounting shell is connected to the outer side of the side wall provided with the optical filter, the light source is arranged on the thin part of the light source mounting shell, the lens is arranged inside the light source mounting shell and located between the light source and the optical filter, and the light source, the lens and the optical filter are on the same straight line with the surface.
2. The pervaporation gas concentration measurement sensor according to claim 1, wherein: the lenses include, but are not limited to, convex lenses and fresnel lenses.
3. The pervaporation gas concentration measurement sensor according to claim 1, wherein: the waterproof and breathable film comprises but is not limited to a PTFE film and an ultrafine fiber fabric.
4. The pervaporation gas concentration measurement sensor according to claim 1, wherein: the inner surface of the air chamber main body and the inner surface of the concave lens wall are made of mirror materials and/or plated with mirror coatings and/or subjected to mirror polishing, the mirror materials include but are not limited to mirror aluminum alloy and mirror stainless steel, the mirror coatings include but are not limited to chemical nickel-plating layers, and the mirror polishing means that the surface roughness value Ra is less than or equal to Ra0.2; and a full light area can be formed in the closed air chamber by combining the concave lens structure of the concave lens wall.
5. The pervaporation gas concentration measurement sensor according to claim 1, wherein: the circuit board is provided with a power supply circuit, a calculation control circuit, a light source driving circuit and a signal processing circuit, wherein the signal processing circuit comprises a differential amplification circuit and a frequency selection amplification circuit; the power supply circuit is connected with a battery and supplies power to the light source, the microphone, the electromagnet, the calculation control circuit, the light source driving circuit, the acquisition circuit and the signal processing circuit; the calculation control circuit is provided with a singlechip; the light source driving circuit is provided with a high-speed optical coupler and an enhanced field effect transistor and can be matched with PWM (pulse width modulation) waves to drive a light source; the differential amplification circuit is connected with the microphone, is provided with an amplifier and can properly amplify the weak signal output by the microphone; the frequency-selecting amplifying circuit is provided with a multiplier and a low-pass filter and can filter high-frequency signals.
6. The pervaporation gas concentration measurement sensor according to claim 1, wherein: the circuit board is provided with a temperature measuring module, and measured environment temperature data are transmitted to the single chip microcomputer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202021692684.3U CN212514244U (en) | 2020-08-14 | 2020-08-14 | Permeation diffusion type gas concentration measuring sensor |
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| CN202021692684.3U CN212514244U (en) | 2020-08-14 | 2020-08-14 | Permeation diffusion type gas concentration measuring sensor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116202961A (en) * | 2022-12-29 | 2023-06-02 | 江苏舒茨测控设备股份有限公司 | Air inlet structure of photoacoustic gas sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116202961A (en) * | 2022-12-29 | 2023-06-02 | 江苏舒茨测控设备股份有限公司 | Air inlet structure of photoacoustic gas sensor |
| CN116202961B (en) * | 2022-12-29 | 2023-09-29 | 江苏舒茨测控设备股份有限公司 | Air inlet structure of photoacoustic gas sensor |
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