A kind of infrared gas detector based on micro-air-flow
Technical field
The invention belongs to field of gas detection, be specifically related to a kind of infrared gas detector based on micro-air-flow.
Background technology
Infrared spectrum is a kind of common method that current gas detects. It is traditional that to pass through the detector that infrared spectrum absorption pattern carries out gas detection be all to adopt pyroelectric infrared sensor, pyroelectric infrared sensor is mainly the material by a kind of high Seebeck coefficient, as lead zirconate titanate system pottery, lithium tantalate, triglycine sulfate etc. are made the detecting element that is of a size of 2*1mm. The major defect of pyroelectric sensor is too wide to infrared wavelength sensitizing range, and the spectrum of nearly all infrared region has impact to pyroelectric sensor. Therefore in order to improve the interference free performance of pyroelectric sensor, traditional mode all needs to do a large amount of anti-interference process work on light path and circuit, and complicated structure and circuit have reduced the reliability of equipment, has also limited the precision that INFRARED ABSORPTION is surveyed. The detector of infrared spectrum is generally to adopt pyroelectric sensor at present. This sensor has the temperature humidity of being subject to be affected greatly, the impact of the too wide grade of induction light spectral limit, and therefore detection sensitivity is lower, in order to address this problem, propose a kind of new infrared acquisition method, adopted the detection method of micro-air-flow, well avoided the problems referred to above.
Summary of the invention
The technical problem to be solved in the present invention is, detects above shortcomings for existing gas, and a kind of new infrared gas detector based on micro-air-flow is provided, and adopts micro-air-flow to detect, and avoids being subject to temperature humidity to affect, and infrared detection technology is improved to an order of magnitude.
The present invention for solving the problems of the technologies described above adopted technical scheme is:
A kind of infrared gas detector based on micro-air-flow, comprise the first temperature-controlling chamber, devitrified glass air chamber, glass capillary, the second temperature-controlling chamber, glass capillary spirals, accurate flow probe, signal processing unit and check valve, devitrified glass air chamber is arranged in the first temperature-controlling chamber, the glass capillary that spirals is arranged in the second temperature-controlling chamber, one end of devitrified glass air chamber is connected with one end of the glass capillary that spirals by glass capillary, the spiral other end of glass capillary and the input of accurate flow probe is connected, the output of accurate flow probe is connected with signal processing unit, also be connected with the other end of devitrified glass air chamber by check valve simultaneously, it is Ta that the first temperature-controlling chamber is used for controlling whole devitrified glass air chamber initial temperature, and it is Tb that the second temperature-controlling chamber is used for controlling the whole glass capillary initial temperature of spiraling, and Ta > Tb.
Press such scheme, described the first temperature-controlling chamber and the second temperature-controlling chamber all adopt TEC cooling piece.
Press such scheme, the detection air chamber that described devitrified glass air chamber is devitrified glass, the relative two sides of surveying air chamber is coated with reflectance coating (by reflectance coating, make IR interreflection in devitrified glass air chamber increase light path, guarantee that incident ray is all absorbed).
Press such scheme, the third generation MEMS flow sensor that described accurate flow sensor adopts Sensirion company of Switzerland to release.
Operation principle of the present invention: devitrified glass air chamber, glass capillary, the glass capillary that spirals are the entirety of UNICOM's one, and be full of 100% gas to be measured, accurate flow probe, for the micrometeor digitized measurement to gas, accurately records the flow spiraling in glass capillary, and signal processing unit is converted into concentration signal for the flow signal that accurate flow probe is recorded. when original state, first temperature-controlling chamber's control devitrified glass air chamber temperature is Ta, and it is Tb that the second temperature-controlling chamber controls the glass capillary temperature of spiraling, Ta > Tb. because the air chamber in the pass microcrystalline glass in series air chamber of the temperature difference will flow, the flow detecting by accurate flow probe is initial flow La, when Infrared irradiation is on devitrified glass air chamber time, because contain tested calibrating gas in devitrified glass air chamber, the wave band responding with tested gas in infrared light is just by GAS ABSORPTION, GAS ABSORPTION after infrared light energy increase temperature rise, a temperature Δ T rises on the basis of the former Ta of temperature of gas in devitrified glass air chamber, because the rising of temperature will cause the variation of flow, therefore the flow Δ L that also can rise, wherein the variation of flow will be reacted the content of concentration in air chamber, the known content that can infer thus devitrified glass air chamber incident intensity of content of concentration.
Beneficial effect of the present invention:
1, detect with micro-air-flow, avoid being subject to temperature humidity to affect, well solve the precision problem of detector in current infrared detection, infrared detection technology is improved to an order of magnitude, avoid the problem of the poor anti-interference that traditional pyroelectric detector brings, improve the accuracy of detection of Infrared Detectors, adopted this detector accuracy of detection can reach the precision of 0.1ppm;
2, the flow sensor chip integrated level of the accurate flow sensor of MEMS is high, volume only has a mung bean size, this sensor can probing medium flow, accuracy is low to moderate 1nL/min, possesses very high accuracy repeatedly simultaneously, its actuation time, in measuring process, the accurate flow sensor of MEMS and medium did not need to come in contact, and can measure rate-of flow in it across glass capillary wall within the scope of millisecond.
Brief description of the drawings
Fig. 1 is the structural representation that the present invention is based on the infrared gas detector of micro-air-flow;
Fig. 2 is the structural representation of devitrified glass air chamber of the present invention;
In figure, 1-the first temperature-controlling chamber, 2-devitrified glass air chamber, 3-glass capillary, 4-the second temperature-controlling chamber, the 5-glass capillary that spirals, the accurate flow probe of 6-, 7-signal processing unit, 8-check valve, 21-reflectance coating.
Detailed description of the invention
Below by embodiment and accompanying drawing, the present invention is further elaborated.
As shown in Figure 1, infrared gas detector based on micro-air-flow of the present invention, comprise the first temperature-controlling chamber 1, devitrified glass air chamber 2, glass capillary 3, the second temperature-controlling chamber 4, glass capillary 5 spirals, accurate flow probe 6, signal processing unit 7 and check valve 8, devitrified glass air chamber 2 is arranged in the first temperature-controlling chamber 1, the glass capillary 5 that spirals is arranged in the second temperature-controlling chamber 4, one end of devitrified glass air chamber 2 is connected with one end of the glass capillary 5 that spirals by glass capillary 3, the other end of glass capillary 5 of spiraling is connected with the input of accurate flow probe 6, the output of accurate flow probe 6 is connected with signal processing unit 7, also be connected with the other end of devitrified glass air chamber 2 by check valve 8 simultaneously. the Main Function of check valve 8 is that guarantee the to spiral gas of glass capillary 5 can not be back to devitrified glass air chamber 2, and gas only flows into through glass capillary 3 glass capillary 5 that spirals from devitrified glass air chamber 2, the first temperature-controlling chamber 1 is Ta for controlling whole devitrified glass air chamber 2 initial temperatures, and the second temperature-controlling chamber 4 is Tb for controlling whole glass capillary 5 initial temperatures of spiraling, and Ta > Tb.
The first temperature-controlling chamber 1 and the second temperature-controlling chamber 4 all adopt TEC cooling piece.
As shown in Figure 2, the detection air chamber that devitrified glass air chamber 2 is devitrified glass, the relative two sides of surveying air chamber is coated with reflectance coating 21, makes IR interreflection in devitrified glass air chamber 2 increase light path by reflectance coating 21, guarantees that incident ray is all absorbed.
The third generation MEMS flow sensor that accurate flow sensor adopts Sensirion company of Switzerland to release, chip integration is high, volume only has a mung bean size, this sensor can probing medium flow, accuracy is low to moderate receives liter, minute, possesses very high accuracy repeatedly simultaneously, and its actuation time is within the scope of millisecond, in measuring process, the accurate flow sensor of MEMS and medium do not need to come in contact, and can measure rate-of flow in it across glass capillary wall.
When work, the entirety that devitrified glass air chamber 2, glass capillary 3, the glass capillary 5 that spirals are UNICOM's one, and be full of 100% gas to be measured, the accurate flow probe 6 of MEMS, for the micrometeor digitized measurement to gas, accurately records the flow spiraling in glass capillary 5, and signal processing unit 7 is converted into concentration signal for the flow signal that accurate MEMS flow probe 6 is recorded. when original state the first temperature-controlling chamber 1 to control devitrified glass air chamber 2 temperature be Ta, it is Tb that the second temperature-controlling chamber 4 controls glass capillary 5 temperature of spiraling, Ta > Tb. because the air chamber in the pass microcrystalline glass in series air chamber 2 of the temperature difference will flow, the flow detecting by the accurate flow probe 6 of MEMS is initial flow La, when Infrared irradiation is on devitrified glass air chamber 2 time, because contain tested calibrating gas in devitrified glass air chamber 2, the wave band responding with tested gas in infrared light is just by GAS ABSORPTION, GAS ABSORPTION after infrared light energy increase temperature rise, a temperature Δ T rises on the basis of the former Ta of temperature of gas in devitrified glass air chamber 2, because the rising of temperature will cause the variation of flow, therefore the flow Δ L that also can rise, wherein the variation of flow will be reacted the content of concentration in air chamber, the known content that can infer thus devitrified glass air chamber 2 incident intensities of content of concentration.
Obviously, above-described embodiment is only for example of the present invention is clearly described, and is not the restriction to embodiments of the present invention. The apparent variation of being extended out according to spirit of the present invention for those of ordinary skill in the field, or variation are still among protection scope of the present invention.