CN103868877B - A kind of infrared gas sensor and detection method - Google Patents

A kind of infrared gas sensor and detection method Download PDF

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CN103868877B
CN103868877B CN201410094249.3A CN201410094249A CN103868877B CN 103868877 B CN103868877 B CN 103868877B CN 201410094249 A CN201410094249 A CN 201410094249A CN 103868877 B CN103868877 B CN 103868877B
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infrared
light source
resistance
gas
temperature
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CN103868877A (en
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刘永平
刘丁鑫
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Abstract

For the deficiency existing for existing mine infrared gas sensor, the invention provides a kind of infrared gas sensor and detection method; Sensor comprises shell, Inner cylindrical shell, circuit unit, light source, infrared eye, temperature sensor, filtering membrane, wire netting, vent board; Light source is through modulation, and periodically radiation light-wave, after gas absorption to be measured, is radiated on infrared eye, through filtering, amplification, extracts and has the electric signal with modulation of source same period; This product detects the concentration of gas to be measured in measurement mode; Under calibration mode, equipment self is demarcated; The technique effect that the present invention is useful is: this product is long-term stable and reliability service in rugged surroundings, there is explosion-proof performance, it is under the heating of light source periodic radiation light wave, define respiratory air chamber, air chamber and optical system are integrated, can carry out the detection of multiple gases concentration, its measurement and calibration method is simple, reliable simultaneously.

Description

A kind of infrared gas sensor and detection method
Technical field
The invention belongs to explosion-proof detection technique field, be specifically related to the gas detection technology of underground coal mine, particularly relate to multi-component infrared gas sensor and detection method.
Background technology
Infrared gas sensor is the principle utilizing the infrared radiation of tested gas to specific wavelength to have absorption, carrys out the concentration of mensurated gas composition according to the change of some certain wave strong point absorption peak on various gaseous spectrum curve.
Adopt the multicomponent gas sensor of infrared technique, make up the deficiency of colliery detecting instrument, improve the performance of detecting instrument, for mine safety provides more effective detection means and equipment, to the safety in production improving colliery, ensure that national wealth and human life have safely extremely important realistic meaning.But, existing infrared gas sensor uses under can not being suitable for underground coal mine explosive atmosphere, rugged surroundings, temperature, steam, dust, corrosive gas, flammable explosive gas cause damage to sensor, make its hydraulic performance decline, and concrete manifestation is summarized as following several aspect:
1, existing sensor adopts traditional infrared gas detection means, does not take into full account the impact of underground coal mine rugged surroundings on sensor, adopts detection method and temperature compensation, can not ensure stability and the reliability of sensor long-term work;
2, existing sensor explosion-proof, dust-proof, damp proof, anticorrosive property, anti-tampering poor performance, affects sensor safe handling in the presence of a harsh environment and the accuracy of measurement;
3, existing sensor air chamber structure and optical system complexity, therefore, manufacturing process is complicated, cost is high, difficult in maintenance, is also difficult to realize the measurement to multicomponent gas;
4, existing sensor air chamber structure and detection method, is unfavorable for air chamber and the abundant exchanging gas of environment, and it is long to cause measuring the response time, unreliable to gas detect in environment;
5, existing sensor generally only detects a kind of gas concentration;
6, existing sensor only exports the electric signal that infrared eye transforms mostly, does not have follow-up signal process;
7, existing sensor does not provide good transducer calibration and measuring method.
For this reason, a large amount of scientific research institutions and industrial enterprise conduct extensive research and technology exploration infrared gas sensor, but still have require further improvement, perfect place.The processing of patent " a kind of non-dispersive infrared gas sensor " (CN201477043U) is simpler, but is difficult to the focusing realizing light path.Patent " double light source double sensitive element infra-red multiple gas detection sensor " (CN101105449) provides a kind of two light source sensitive element infrared gas detection sensor, its light channel structure is complicated, need focusing mirror, and the manufacture of air chamber is comparatively complicated, poor practicability, this device without self-inspection and transfer function, being limited in scope of use.Patent " has the infrared gas sensor of communication facilities and passes on the method from the control information of infrared gas sensor " (CN1886654A) and introducing the method for a kind of reception and registration from the control information of infrared gas sensor, mainly for the infrared energy of the infrared energy source in sensor outer housing, with software approach, integrated optimizing design scheme is not proposed to overall device structure.
Summary of the invention
For the above-mentioned deficiency existing for existing infrared gas sensor, the invention provides a kind of infrared gas sensor and detection method, its concrete structure and detection method are respectively:
A kind of infrared gas sensor, comprises shell 1, Inner cylindrical shell 2 and circuit unit; Wherein, there is shell 1 in the outer cover of Inner cylindrical shell 2, be connected with circuit unit in the bottom of Inner cylindrical shell 2; In addition: described shell 1 is hollow cylinder, the step 11 inwardly stretched is provided with on the top of shell 1; Described step 11 ringwise; One deck filtering membrane 12 is covered with at the main header casing of step 11; Be covered with layer of metal net 13 in the bottom of step 11, the bottom surface of wire netting 13 is connected with one piece of vent board 14; Described vent board 14 is thin sheet of metal plate-like, and vent board 14 is evenly equipped with a circle through hole 15; Namely by filtering membrane 12, wire netting 13 and vent board 14, the open top of shell 1 is covered;
Described Inner cylindrical shell 2 is the hollow cylinder of top closure, is provided with outward extending annular edge 21 in the bottom of Inner cylindrical shell 2, and the sidewall of Inner cylindrical shell 2 is provided with a light inlet 22; Annular edge 21 is provided with an accurate tri-prismoid, described accurate tri-prismoid by reflecting plate 23, light barrier 24 and arc 26 around forming, wherein, reflecting plate 23 is connected with Inner cylindrical shell 2 sidewall on the left of light inlet 22 with the corner angle limit of light barrier 24 connecting place, and the base of arc 26 and one section of edge of annular edge 21 coincide; Annular edge 21 near light barrier 24 is provided with a through hole 25;
The end face of Inner cylindrical shell 2 and the bottom surface close contact of vent board 14; The annular edge 21 of Inner cylindrical shell 2 connects with the inwall of shell 1; Annular edge 21 is filled with epoxy sealing with the junction of shell 1; The region that shell 1 and inner barrel 2 surround forms the air chamber 9 of this infrared gas sensor; Namely external environment gas spreads through after the through hole 15 of filtering membrane 12, wire netting 13 and vent board 14 air inlet chamber 9 of going forward side by side successively;
Described circuit unit comprises base plate 3, light source 4, infrared eye 5, temperature sensor 6 and signal processing circuit 7; Described base plate 3 is circular metal plate and isometric with the external diameter of annular edge 21; Base plate 3 is connected with the bottom surface of annular edge 21, is namely sealed by the opening below Inner cylindrical shell 2 by base plate 3;
Infrared eye 5 is provided with in the central authorities of base plate 3 end face; Base plate 3 end face near infrared eye 5 is provided with temperature sensor 6; Light source 4 is arranged on air chamber 9 end near light barrier 24 side, and the bottom of light source 4 is connected with base plate 3 through after through hole 25; Signal processing circuit 7 is placed on base plate 3, and infrared eye 5, temperature sensor 6 is connected with signal processing circuit 7 respectively with light source 4 by wire;
The control end of described signal processing circuit 7 is connected with light source 4, to the voltage of light source 4 transport cycle; The signal input part of signal processing circuit 7 is connected with the signal output part of infrared eye 5 and temperature sensor 6 respectively;
Described light source 4 produces periodic radiation light-wave under the driving of periodic voltage; The periodic radiation light wave that light source 4 produces also is radiated on infrared eye 5 through light inlet 22 through air chamber 9 multiple reflections; The periodic radiation light wave that light source 4 produces is used as the infrared radiation light wave detected on the one hand, on the other hand the gas in air chamber 9 is periodically heated, impel the gases cycle ground dilation in air chamber 9, thus the environmental gas of the gas realized in air chamber 9 and shell 1 outside carries out gas exchanges rapidly, define " respiratory air chamber ";
The periodic radiation light wave that infrared eye 5 will receive, be converted into the electric signal of radiation light-wave same period after be passed to signal processing circuit 7; Temperature sensor 6 detects the temperature near infrared eye 5 in real time and is passed to signal processing circuit 7, and the electric signal passed back for signal processing circuit 7 pairs of infrared eyes 5 does temperature compensation.
Say further, the spectral range of the radiation light-wave that light source 4 sends is that visible ray is to infrared band.The preferred wavelength band of infrared radiation is 2 ~ 5 μm, 8 ~ 12 μm, 2 ~ 12 μm and 2 ~ 20 μm; Infrared eye 5 is made up of 2 to 16 infrared sensors, wherein 1 infrared sensor receives the infrared radiation that wavelength is 3.9 μm, the sensitive area of remaining infrared sensor is all provided with spike interference filter, receives the infrared radiation of wavelength corresponding with spike interference filter; The radiation light-wave that light source 4 sends is after the multiple reflections of air chamber 9, and the hot spot direct irradiation of formation, on the whole sensitive area of infrared eye 5, whole light path does not add the optical device of any convergence or light splitting.
Say further, described signal processing circuit 7 is made up of arrowband bandpass filtering amplifying circuit 71, analog to digital conversion circuit 72, microprocessor 73, modulation of source driving circuit 74 and interface 75; The signal output part of each infrared sensor of infrared eye 5 is all connected with an arrowband bandpass filtering amplifying circuit 71; The signal output part of each arrowband bandpass filtering amplifying circuit 71 is connected with the multi-analog input end of analog to digital conversion circuit 72 jointly; The electric signal that infrared eye 5 exports by arrowband bandpass filtering amplifying circuit 71 transfers to analog to digital conversion circuit 72 after carrying out filtering, amplification, and the voltage signal after filtering, amplification has the identical cycle with the signal of the driving light source modulation drive circuit 74 of microprocessor 73; The signal output part of temperature sensor 6 is connected with the analog input end of analog to digital conversion circuit 72; The digital output end of analog to digital conversion circuit 72 is connected with the signal input part of microprocessor 73, and namely analog to digital conversion circuit 72 inputs to microprocessor 73 again after all transferring the electric signal of the temperature signal received and each infrared sensor to digital signal and processes; Microprocessor 73, according to the digital quantity received, carries out analyzing and processing, temperature compensation, calculates the concentration of gas to be measured; The signal output part of microprocessor 73 is connected with the signal input part of modulation of source driving circuit 74; Microprocessor 73 is responsible for producing periodic control signal, and described periodic control signal is square wave; The cyclic control signal received is converted to the voltage-drop loading of same period on light source 4 by modulation of source driving circuit 74, light source 4 is made to produce periodic radiation light-wave, this radiation light-wave is after gas absorption to be measured in air chamber 9 sidewall reflects and air chamber 9, be radiated on the photosurface of infrared eye 5, convert electric signal to; Microprocessor 73 is connected with interface 75, is realized the connection of microprocessor 73 and long-range host computer by interface 75.
Say further, in infrared eye 5, each infrared sensor is all connected with an arrowband bandpass filtering amplifying circuit 71; Each arrowband bandpass filtering amplifying circuit 71 is connected with an analog to digital conversion circuit 72 multi-analog input end jointly; Arrowband bandpass filtering amplifying circuit 71 is made up of the first resistance R1, the second resistance R2, the first electric capacity C1, the second electric capacity C2 and operational amplifier OP; Wherein, between the output terminal and negative input end of operational amplifier OP, the first resistance R1 and the first electric capacity C1 is parallel with; The negative input end of operational amplifier OP is connected with one end of the second resistance R2, and the other end of the second resistance R2 is connected with one end of the second electric capacity C2; The other end of the second electric capacity C2 is connected with the power supply negative terminal of infrared eye 5; The positive input terminal of operational amplifier OP is connected with the output terminal of infrared sensor; The output terminal of operational amplifier OP is connected with analog to digital conversion circuit 72; The transition function of arrowband bandpass filtering amplifying circuit 71 is:
By regulating the parameter of resistance R1, R2, electric capacity C1, C2, realize arrowband bandpass filtering amplifying circuit 71 centre frequency f 0, bandwidth f w, enlargement factor A 0, quality factor q control.
Say further, the wick of light source 4 is tungsten filament or thermal resistance film; In the energized state, light source 4 generates heat and produces infrared radiation; Modulation of source driving circuit 74 is made up of light source 4, the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, triode VT1 and field effect transistor VT2; Wherein, the source electrode of field effect transistor VT2 connects power supply ground, the source electrode of field effect transistor VT2 is connected by the 6th resistance R6 with the drain electrode of field effect transistor VT2, the drain electrode of field effect transistor VT2 connects the 5th resistance R5, the gate pole of field effect transistor VT2 is connected with one end of the 4th resistance R4, the emitter of triode VT1 respectively, the other end of the 4th resistance R4 connects power supply VCC, triode VT1 collector is connected with the source electrode of field effect transistor VT2, the base stage of triode VT1 is connected with one end of the 3rd resistance R3, and the other end of the 3rd resistance R3 is connected with microprocessor 73; Light source 4 is in series with between the other end and the other end of the 5th resistance R5 of the 4th resistance R4; Namely the electric current that power supply VCC provides flows through light source 4, the 5th resistance R5, the 6th resistance R6 and field effect transistor VT2 successively, realize the power supply to light source 4, the cyclic control signal that microprocessor 73 produces is successively through the 3rd resistance R3, triode VT1 and field effect transistor VT2, and driving light source 4 periodically sends radiation light-wave; Tungsten filament passes into current flow heats, temperature raise, along with the rising of temperature, tungsten filament resistance value increase, do not have electric current by time resistance be called cold resistance, when have electric current by time, resistance will raise, and be called thermal resistance; Tungsten filament cold resistance is very little, if light source 4 is lighted from cold resistance state, this process can produce very large dash current; Modulation of source driving circuit 74, by loading certain electric current on light source 4, avoids light source 4 and lights from cold resistance state;
During field effect transistor VT2 cut-off, power supply VCC arrives power supply ground through light source 4, resistance R5, R6, can set by light source 4 current value by regulating resistance R6, determine light source 4 depth of modulation, when namely scene effect pipe VT2 ends, electric current is passed into, when avoiding light source 4 cold resistance state to light, to the impact of power supply VCC in light source 4;
Field effect transistor VT2 is the N-channel MOS FET of a low on-resistance, and conducting resistance is zero point several ohm only; During field effect transistor VT2 conducting, power supply VCC is through light source 4, resistance R5, field effect transistor VT2 and the leakage, the source resistance R6 arrival power supply ground that are parallel to field effect transistor VT2, set by light source 4 current value by regulating resistance R5, determine the radiant light wave intensity that light source 4 produces;
Triode VT1 mono-is for the protection of field effect transistor VT2, prevents field effect transistor VT2 from damaging, and two is that the control signal that exported by microprocessor 73 and light source 4 power supply VCC isolate, and prevents mutual interference.
The detection method of infrared gas sensor provided by the present invention; Measure as follows:
Measuring process one, initialization; Microprocessor 73 exports cyclic control signal, described cyclic control signal is square wave, light source 4 just periodically sends radiation light-wave, the heat that radiation light-wave produces periodically heats gas indoor gas, gas indoor gas is impelled to carry out the circulation of " expansion-contraction ", carry out sufficient gas exchanges with environment, air chamber 9 is carried out drying, cleaned;
Measuring process two, signals collecting; Microprocessor 73 exports channel coding and the instruction of sampled signal, gathers and is converted to digital signal respectively to temperature, each point voltage, infrared eye 5 output signal; Export through amplifying to each sensitive element of infrared eye 5, filtered sine wave, after cyclic control signal to make in light source 4 electric current from large to small, carry out 128 ~ 1024 samplings;
Measuring process three, calculates; Temperature, each point voltage, infrared eye 5 are exported, calculates when signals collecting is idle, particularly at cyclic control signal, electric current in light source 4 is calculated after changing from small to big;
Wherein, in infrared eye 5, the output signal of each sensitive element is sinusoidal wave after the process of arrowband bandpass filtering amplifying circuit 71, samples, and calculate by following formula in a sine wave:
In formula, u mfor the analog sine measured value after gas absorption infrared energy to be measured, u rfor all gas to be measured does not all absorb the analog sine reference value after infrared energy, U mfor measured value u mpeak value, U rfor reference value u rpeak value, u m/ u rrepresent the numerical value of a certain gas concentration to be measured, be the peakedness ratio of measured value and reference value sine function waveform, n is sampling number in one-period, and the value of n is between 128 ~ 1024;
Measuring process four, self-inspection; Compared with the regime values store the numerical value such as calculate gained temperature, each point voltage, infrared eye 5 export and microprocessor 73, judge whether to there is fault, during fault, output fault type code;
Measuring process five, temperature compensation; Zero temperature compensation and range temperature compensation two steps are comprised to the temperature compensation that the concentration parameter calculating gas carries out, gas concentration value after acquisition temperature compensation subsequently;
Wherein, at real time temperature T ttime, the formula of zero temperature compensation is:
In formula, k 0be zero temperature compensation coefficient, a is temperature T 0time be stored in value in microprocessor 73 memory, a treal time temperature T ttime offset;
At real time temperature T ttime, the formula of range temperature compensation is:
In formula, k srange temperature compensation coefficient, a treal time temperature T ttime offset, b is temperature T 0time be stored in value in microprocessor 73 memory, u m/ u rreal time temperature T ttime measured value, c be temperature compensated after the concentration value of gas to be measured that will calculate;
Measuring process six, converts the gas concentration value after the temperature compensation of step 5 to analog quantity or digital quantity signal, and transmits through interface 75.
For the constant a and range constant b, zero temperature compensation coefficient k at zero point in this product sensor measuring method 0with range temperature compensation coefficient k sby demarcating sensor and after calculating, stored in microprocessor 73 memory, transferring time to be measured and use.
useful technique effect
1, light source is periodically to air chamber heating, and " expansion-contraction " of gas in air chamber, forms respiratory air chamber, on a sensor after electricity, drying is carried out to air chamber, " expansion-contraction " of gas in air chamber, eliminate steam, dust to the impact of light path, optical system and air chamber;
Respiratory air chamber can exchanging gas abundant with environment, shortens the response time of sensor, improves the reliability detected environmental gas;
Air chamber heating is integrated with both light sources, with common by well heater air chamber to be heated compared with, sensor construction is compact, power consumption reduces greatly, also improves the explosion-proof performance of sensor;
Described modulation of source control circuit makes light source periodically light on and off, in the half period that light source is not lighted, load certain electric current on light source, to expose ratio from cold resistance state point with common light source, avoid light source lights generation dash current from cold resistance state, thus meet the requirement that underground coal mine essential safety source powers; Meanwhile, described modulation of source control circuit, limits the energy of light source and controls, and makes its type of protection [of an electrical apparatus for explosive atmospheres be essential safe type;
2, for ensureing sensor long-term Stability and dependability run in underground coal mine rugged surroundings, this patent takes following technical measures:
(1) adopt ripe measurement and with reference to sensitive element testing compensation technique, light path and optical system compensated, eliminating light intensity in light source fluctuation, light path and be disturbed the impact caused;
(2) temperature compensation described in, eliminates the impact caused by temperature variation;
(3) wire netting described in and filtering membrane can intercept steam, dust enters air chamber; Described air chamber heating, on a sensor after electricity, carries out drying to air chamber, and " expansion-contraction " of gas in air chamber, eliminates steam, dust to the impact of light path, optical system and air chamber;
(4) the air chamber inwall described in covers reflective membrane (gold-plated), except the reflection efficiency that improve light, also prevents the corrosion of corrosive gas;
3, from circuit and structure, technical measures to the explosion-proof performance of sensor is taked: described modulation of source control circuit, limits the energy of light source and control, its type of protection [of an electrical apparatus for explosive atmospheres is essential safe type, even if light sources fail or damage, also do not affect explosion-proof performance; If described modulation of source control circuit also breaks down or damages, described wire netting can play flame proof effect, makes to be transferred to energy in external environment and is restricted;
4, air chamber is the space that described shell and described Inner cylindrical shell surround, outer casing inner wall and Inner cylinder body outer wall constitute camber reflection optical system, light defines the light path detecting gas through multiple reflections, air chamber and optical system are integrated, there is no optical concentration, beam splitting system, air chamber structure is simple, volume is little, lightweight, processing, assemble easy, according to light source, the device installing spaces such as infrared eye, and detect the quantity of gas composition, resolution, the requirement of precision, change described shell and described Inner barrel diameter and height, just increase or reduce air chamber capacity and light path light path, meet the various requirement to gas detect, optimize structure and the volume of sensor,
The centre frequency of 5, described arrowband bandpass filtering amplifying circuit is consistent with the frequency of modulation of source, narrow-band filtering is carried out to this frequency signal, export infrared sensor institute receive infrared radiation generation electric signal, thus, eliminate the interference of background and other noises, even if this signal is submerged in noise, arrowband bandpass filtering amplifying circuit also can export this frequency signal, has processing power and the antijamming capability of very strong signal; Form arrowband bandpass filtering amplifying circuit by the operational amplifier of a low noise, filtering, amplification, the function such as anti-interference are completed by stage circuit, circuit is simple, reliable, debugging is convenient, cost is low, antijamming capability is strong;
6, each parts are through suitable cooperation, realize the detection that sensor carries out multiple gases concentration simultaneously:
(1) infra red radiation band of described light source contains 2 ~ 5 μm, 8 ~ 12 μm, 2 ~ 12 μm and 2 ~ 20 μm, comprise the characteristic wavelength of all gas absorption infrared radiations to be measured, the radiation spectrum of light source has the characteristic wavelength of the gas absorption infrared radiation simultaneously carrying out multiple gases Concentration Testing;
(2) infrared eye described in is polynary pyroelectric infrared detector, be made up of multiple infrared sensor, the sensitive area of each infrared sensor reception infrared radiation is provided with spike interference filter, spike interference filter plays optical filtering, the infrared radiation of the characteristic wavelength only allowing corresponding gas to be measured absorb passes through, only have the infrared radiation of gas characteristic absorbing wavelength to be measured to arrive infrared sensor, therefore, can select all kinds gasmetry;
(3) inner barrel described in is used for the space of installation infrared detector, can adjust according to the volume of infrared eye with to gasmetry precision, is convenient to the installation of the multielement infrared detector of multiple infrared sensor composition;
(4) optical system of described air chamber formation, light path reflects through gas chamber sidewall, infrared eye described in the hot spot direct irradiation formed, send light without the need to optical device to described light source to converge or light splitting, only just arrive described infrared eye through reflection, the infrared eye being applicable to multiple sensitive area, to the detection of infrared radiation, can detect multiple gases light path simultaneously;
7, described calibration mode, demarcates zero point of sensor, range, zero temperature compensation coefficient and range temperature compensation coefficient, ensure that sensor detects accuracy and the precision of gas; The all parameters of calibration process automatically complete and calculate and storage, easy and simple to handle, are a kind of transducer calibration patterns of novelty;
8, described signals collecting, calculating are the characteristic of foundation sine function and the principle of Lambert-Beer's law detection gas concentration, export through amplification, filtered sine wave, carry out n time and sample in one-period each sensitive element of described infrared eye; Compared with once sampling with usual one-period, feature of the present invention carries out n sampling in one-period, be equivalent in time sample to n cycle, be all equivalent to select at peak value place in the sampling of the arbitrfary point of sine function waveform, thus, improve the fiduciary level of signals collecting, add antijamming capability, reduce the sampling time, eliminate the time of microprocessor time delay, wait, improve program operational efficiency, shorten the sensor response time;
9, described zero temperature compensation and range temperature compensation, all temperature compensation has been carried out to the arbitrary concentration value detecting gas, avoid existing sensor and there is no temperature compensation, or only to the temperature compensation of zero point or several sampling spot, be a kind of Sensor Temperature Compensation method of novelty.
Accompanying drawing explanation
Fig. 1 is the longitudinal sectional view of this product.
Fig. 2 is the A-A cut-open view of Fig. 1.
Fig. 3 is the assembly drawing of Fig. 1.
Fig. 4 is the B-B cut-open view of Fig. 1.
Fig. 5 is the structured flowchart of this product signal treatment circuit.
Fig. 6 is the circuit diagram of modulation of source driving circuit 74.
Fig. 7 is that in Fig. 6, modulation of source driving circuit 74 is carried in electric current on light source 4 and voltage waveform view.
The circuit diagram of Fig. 8 arrowband bandpass filtering amplifying circuit 71.
Fig. 9 is the process flow diagram under this product measurement pattern.
Figure 10 is the process flow diagram under this product calibration mode.
concrete embodiment
Now be described with reference to the accompanying drawings the technical characterstic of this patent.
See Fig. 1, a kind of infrared gas sensor, comprises shell 1, Inner cylindrical shell 2 and circuit unit; Wherein, there is shell 1 in the outer cover of Inner cylindrical shell 2, be connected with circuit unit in the bottom of Inner cylindrical shell 2;
See Fig. 1 and Fig. 3, described shell 1 is hollow cylinder, is provided with the step 11 inwardly stretched on the top of shell 1; Described step 11 ringwise; One deck filtering membrane 12 is covered with at the main header casing of step 11; Described filtering membrane 12 is waterproof and the hydrophobic film of ventilation; Be covered with layer of metal net 13 in the bottom of step 11, described wire netting 13 is 60 ~ 80 orders and thickness is greater than the circular stainless steel wire mesh of 1mm for aperture, is provided with vent board 14 in the bottom surface of wire netting 13; Described vent board 14 is thin sheet of metal plate-like, and be evenly equipped with through hole 15 at the edge of vent board 14, the quantity of through hole 15 is between 10 to 30; Namely covered by filtering membrane 12, wire netting 13 and vent board 14 opening by shell 1 top, as shown in Figure 4;
See Fig. 2 and Fig. 3, described Inner cylindrical shell 2 is the hollow cylinder of top closure, be provided with outward extending annular edge 21 in the bottom of Inner cylindrical shell 2, the sidewall of Inner cylindrical shell 2 is provided with a light inlet 22, the opening angle α of described light inlet 22 is contour with Inner cylindrical shell 2 between 60 ~ 80 °; Annular edge 21 is provided with an accurate tri-prismoid, described accurate tri-prismoid by reflecting plate 23, light barrier 24 and arc 26 around forming, wherein, reflecting plate 23 is connected with Inner cylindrical shell 2 sidewall on the left of light inlet 22 with the corner angle limit of light barrier 24 connecting place, and the base of arc 26 and one section of edge of annular edge 21 coincide; Annular edge 21 near light barrier 24 is provided with a through hole 25;
See the end face of Fig. 1, Inner cylindrical shell 2 and the bottom surface close contact of vent board 14; The annular edge 21 of Inner cylindrical shell 2 connects with the inwall of shell 1; Annular edge 21 is filled with epoxy sealing with the junction of shell 1; The region that shell 1 and inner barrel 2 surround forms the air chamber 9 of this infrared gas sensor; Namely external environment gas spreads through after the through hole 15 of filtering membrane 12, wire netting 13 and vent board 14 air inlet chamber 9 of going forward side by side successively;
Described circuit unit comprises base plate 3, light source 4, infrared eye 5, temperature sensor 6 and signal processing circuit 7; Described base plate 3 is circular metal plate and isometric with the external diameter of annular edge 21; The end face of base plate 3 is connected with the bottom surface of annular edge 21, is namely sealed by the opening below Inner cylindrical shell 2 by base plate 3, as shown in figures 1 and 3;
See Fig. 1 and Fig. 2, the central authorities of base plate 3 end face surrounded at Inner cylindrical shell 2 are provided with infrared eye 5; Base plate 3 end face near infrared eye 5 is provided with temperature sensor 6; Light source 4 is arranged on air chamber 9 end near light barrier 24 side, and the bottom of light source 4 is connected with base plate 3 through after through hole 25, and namely light source 4 via through holes 25 extends in air chamber 9; Signal processing circuit 7 is placed on base plate 3, and the infrared eye 5 of base plate 3 end face, temperature sensor 6 is connected with signal processing circuit 7 respectively with light source 4 by wire;
The control end of described signal processing circuit 7 is connected with light source 4, to the voltage of light source 4 transport cycle; The signal input part of signal processing circuit 7 is connected with the signal output part of infrared eye 5 and temperature sensor 6 respectively;
See Fig. 5, described light source 4 produces periodic radiation light-wave under the driving of periodic voltage; The periodic radiation light wave that light source 4 produces also is radiated on infrared eye 5 through light inlet 22 through air chamber 9 multiple reflections; The periodic radiation light wave that light source 4 produces is used as the infrared radiation light wave detected on the one hand, on the other hand the gas in air chamber 9 is periodically heated, impel the gases cycle ground dilation in air chamber 9, thus the environmental gas of the gas realized in air chamber 9 and shell 1 outside carries out gas exchanges rapidly, define " respiratory air chamber ";
Described infrared eye 5 by receive by light source 4 produce periodic radiation light wave, be converted into the electric signal of radiation light-wave same period after be passed to signal processing circuit 7;
Described temperature sensor 6 detects the temperature near infrared eye 5 in real time and is passed to signal processing circuit 7, and the electric signal passed back for signal processing circuit 7 pairs of infrared eyes 5 does temperature compensation.
Say further, the spectral range of the radiation light-wave that light source 4 sends is that visible ray is to infrared band.Wherein, the preferred wavelength band of infrared radiation is 2 ~ 5 μm, 8 ~ 12 μm, 2 ~ 12 μm and 2 ~ 20 μm; Infrared eye 5 is made up of 2 to 16 infrared sensors, wherein 1 infrared sensor receives the infrared radiation that wavelength is 3.9 μm, the sensitive area of remaining infrared sensor is all provided with spike interference filter, receives the infrared radiation of wavelength corresponding with spike interference filter; The radiation light-wave that light source 4 sends is after the multiple reflections of air chamber 9, and the hot spot direct irradiation of formation, on the whole sensitive area of infrared eye 5, whole light path does not add the optical device of any convergence or light splitting.
See Fig. 5, described signal processing circuit 7 is made up of arrowband bandpass filtering amplifying circuit 71, analog to digital conversion circuit 72, microprocessor 73, modulation of source driving circuit 74 and interface 75; The signal output part of each infrared sensor of infrared eye 5 is all connected with an arrowband bandpass filtering amplifying circuit 71; The signal output part of each arrowband bandpass filtering amplifying circuit 71 is connected with the multi-analog input end of analog to digital conversion circuit 72 jointly; The electric signal that infrared eye 5 exports by arrowband bandpass filtering amplifying circuit 71 transfers to analog to digital conversion circuit 72 after carrying out filtering, amplification, and the voltage signal after filtering, amplification has the identical cycle with the signal of the driving light source modulation drive circuit 74 of microprocessor 73; The signal output part of temperature sensor 6 is connected with the analog input end of analog to digital conversion circuit 72; The digital output end of analog to digital conversion circuit 72 is connected with the signal input part of microprocessor 73, and namely analog to digital conversion circuit 72 inputs to microprocessor 73 again after all transferring the electric signal of the temperature signal received and each infrared sensor to digital signal and processes; Microprocessor 73, according to the digital quantity received, carries out analyzing and processing, temperature compensation, calculates the concentration of gas to be measured; The signal output part of microprocessor 73 is connected with the signal input part of modulation of source driving circuit 74; Microprocessor 73 is responsible for producing periodic control signal, and described periodic control signal is square wave; Modulation of source driving circuit 74 converts the cyclic control signal received to voltage-drop loading on light source 4, light source 4 is made to produce periodic radiation light-wave, this radiation light-wave is after gas absorption to be measured in air chamber 9 sidewall reflects and air chamber 9, be radiated on the photosurface of infrared eye 5, convert electric signal to; Microprocessor 73 is connected with interface 75, is realized the connection of microprocessor 73 and long-range host computer by interface 75.
Say further, in infrared eye 5, each infrared sensor is all connected with an arrowband bandpass filtering amplifying circuit 71; Each arrowband bandpass filtering amplifying circuit 71 is connected with an analog to digital conversion circuit 72 multi-analog input end jointly; See Fig. 8, arrowband bandpass filtering amplifying circuit 71 is made up of the first resistance R1, the second resistance R2, the first electric capacity C1, the second electric capacity C2 and operational amplifier OP; Wherein, between the output terminal and negative input end of operational amplifier OP, the first resistance R1 and the first electric capacity C1 is parallel with; The negative input end of operational amplifier OP is connected with one end of the second resistance R2, and the other end of the second resistance R2 is connected with one end of the second electric capacity C2; The other end of the second electric capacity C2 is connected with the power supply negative terminal of infrared eye; The positive input terminal of operational amplifier OP is connected with the output terminal of infrared sensor; The output terminal of operational amplifier OP is connected with analog to digital conversion circuit 72; The transition function of arrowband bandpass filtering amplifying circuit 71 is:
（I）
By regulating the parameter of resistance R1, R2, electric capacity C1, C2 in formula (I), realize arrowband bandpass filtering amplifying circuit 71 centre frequency f 0, bandwidth f w, enlargement factor A 0, quality factor q control.
For light source 4 glow frequency for 4Hz, the realization of parameter described in arrowband bandpass filtering amplifying circuit 71 is described:
Corresponding with light source 4 modulating frequency, arrowband bandpass filtering amplifying circuit 71 centre frequency f 0=4Hz; Bandwidth is as far as possible narrow, is not the undesired signal of 4Hz, selects bandwidth f with filtering as much as possible w=8Hz; For preventing the self-oscillatory generation of amplifying circuit and the amplitude versus frequency characte below bandwidth sharply declined, the quality factor q <1 of wave filter;
Calculate according to described transition function H (s), can obtain resistance R1, R2, electric capacity C1, C2 parameter to meet the parameter request of arrowband bandpass filtering amplifying circuit 71, shown in table 1, be give several groups of typical parameter values:
The parameter of table 1 arrowband bandpass filtering amplifying circuit 71 regulates
At centre frequency f 0, bandwidth f w, quality factor q constant under, adjustable resistor R1, R2 reach the requirement of arrowband bandpass filtering amplifying circuit 71 enlargement factor.
Say further, light source 4 is low frequency electrical modulation broadband IR source, and infra red radiation band contains 2 ~ 5 μm, 8 ~ 12 μm, 2 ~ 12 μm and 2 ~ 20 μm, and wick is tungsten filament or thermal resistance film, heating after energising, the infrared radiation of generation;
See Fig. 6, modulation of source driving circuit 74 is made up of light source 4, the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, triode VT1 and field effect transistor VT2; Wherein, the source electrode of field effect transistor VT2 connects power supply ground, the source electrode of field effect transistor VT2 is connected by the 6th resistance R6 with the drain electrode of field effect transistor VT2, the drain electrode of field effect transistor VT2 connects the 5th resistance R5, the gate pole of field effect transistor VT2 is connected with one end of the 4th resistance R4, the emitter of triode VT1 respectively, the other end of the 4th resistance R4 connects power supply VCC, triode VT1 collector is connected with the source electrode of field effect transistor VT2, the base stage of triode VT1 is connected with one end of the 3rd resistance R3, and the other end of the 3rd resistance R3 is connected with microprocessor 73; Light source 4 is in series with between the other end and the other end of the 5th resistance R5 of the 4th resistance R4; Namely the electric current that power supply VCC provides flows through light source 4, the 5th resistance R5, the 6th resistance R6 and field effect transistor VT2 successively, realize the power supply to light source 4, the cyclic control signal that microprocessor 73 produces is successively through the 3rd resistance R3, triode VT1 and field effect transistor VT2, and driving light source 4 periodically sends radiation light-wave; Tungsten filament passes into current flow heats, temperature raise, along with the rising of temperature, tungsten filament resistance value increase, do not have electric current by time resistance be called cold resistance, when have electric current by time, resistance will raise, and be called thermal resistance; Tungsten filament cold resistance is very little, if light source 4 is lighted from cold resistance state, this process can produce very large dash current; Modulation of source driving circuit 74, by loading certain electric current on light source 4, avoids light source 4 and lights from cold resistance state;
During field effect transistor VT2 cut-off, power supply VCC arrives power supply ground through light source 4, resistance R5, R6, can set by light source 4 current value by regulating resistance R6, determine light source 4 depth of modulation, when namely scene effect pipe VT2 ends, electric current is passed into, when avoiding light source 4 cold resistance state to light, to the impact of power supply VCC in light source 4;
Field effect transistor VT2 is the N-channel MOS FET of a low on-resistance, and conducting resistance is zero point several ohm only; During field effect transistor VT2 conducting, power supply VCC is through light source 4, resistance R5, field effect transistor VT2 and the leakage, the source resistance R6 arrival power supply ground that are parallel to field effect transistor VT2, set by light source 4 current value by regulating resistance R5, determine the radiant light wave intensity that light source 4 produces.
See Fig. 7, light source 4 modulating frequency is 4Hz(cycle 0.25s); During field effect transistor VT2 cut-off, by regulating resistance R6, light source 4 electric current is 10mA, and now light source 4 is not lighted; During field effect transistor VT2 conducting, by regulating resistance R5, light source 4 electric current is 60mA, and now light source 4 is lighted; The modulation of source driving circuit of usual employing, when light source is not lighted, the electric current that modulation of source driving circuit loads is 0, like this, light source is just lighted under cold resistance state, produce very large dash current to power supply, this powers for underground coal mine essential safety source and causes adverse effect, makes sensor can not power on or work abnormal.
Triode VT1 mono-is for the protection of field effect transistor VT2, prevents field effect transistor VT2 from damaging, and two is that the control signal that exported by microprocessor 73 and light source 4 power supply VCC isolate, and prevents mutual interference.
In addition, sensor explosion-proof performance is realized by modulation of source driving circuit 74 and wire netting 13;
Modulation of source driving circuit 74 controls the electric current or the restriction energy that are supplied to light source 4, makes light source 4 and signal processing circuit 7 meet the requirement of GB3836.4 essential safety; When modulation of source driving circuit 74 safeguard protection was lost efficacy, wire netting 13 should ensure to reach back-fire relief, explosion-proof functional requirement, thus realized sensor explosion prevention function, can be used for the concentration of explosion hazard environment measuring gas to be measured; In addition, filtering membrane 12 ensures air chamber and extraneous exchanging gas, does not allow steam enter air chamber, realizes the water-proof function of sensor, can use having in steam, high humidity environment.
See Fig. 9, infrared gas sensor provided by the present invention is adopted to carry out the measurement of gas as follows:
Measuring process one, initialization; Microprocessor 73 exports cyclic control signal, described cyclic control signal is square wave, light source 4 just periodically sends radiation light-wave, the heat that radiation light-wave produces periodically heats gas indoor gas, gas indoor gas is impelled to carry out the circulation of " expansion-contraction ", carry out sufficient gas exchanges with external environment, air chamber 9 is carried out drying, cleaned; After sensor powers on, field effect transistor VT2 ends, and light source 4 flows through small electric stream through resistance R6, when being powered on by cold resistance to avoid light source 4, occurs heavy current impact; After about 5 seconds, microprocessor 73 exports cyclic control signal, light source 4 just periodically sends radiation light-wave, its heat carries out periodic heat to air chamber 9 simultaneously, gas indoor gas is made to carry out " expansion-contraction " circulation, carry out sufficient gas exchanges with external environment, also serve the function of dehumidifying, dedusting, heat about 1 minute; In microprocessor 73 pairs of memories, each calibrating parameters is read and write and checks;
Measuring process two, signals collecting; Microprocessor 73 exports channel coding and the instruction of sampled signal, and analog to digital conversion circuit 72 receives instruction, opens corresponding passage, gathers and is converted to digital signal respectively to temperature, each point voltage, infrared eye 5 output signal; Export through amplifying to each sensitive element of infrared eye 5, filtered sine wave, after cyclic control signal to make in light source 4 electric current from large to small, carry out 128 ~ 1024 samplings;
Measuring process three, calculates; Temperature, each point voltage, infrared eye 5 are exported, calculates when signals collecting is idle, particularly at cyclic control signal, electric current in light source 4 is calculated after changing from small to big;
Temperature, voltage are direct current signals, after multiple repairing weld, calculate just can through arithmetic mean;
In infrared eye 5, the output signal of each sensitive element is sine wave after arrowband bandpass filtering amplifying circuit 71, common way is once sampled at one-period, and at the peak value place of this sine wave, although the amplitude of this sampled value is large, but owing to only having carried out once sampling, reliability and the antijamming capability of actual acquisition signal are poor; The characteristic of patent of the present invention according to sine function and the principle of Lambert-Beer's law detection gas concentration, after cyclic control signal to make in light source 4 electric current from large to small, carry out multiple repairing weld (samplings of 128 ~ 1024 times) and calculate by formula (II):
(II)
In formula (II): u mfor the analog sine measured value after a certain gas absorption infrared energy to be measured, u rfor all gas to be measured does not all absorb the analog sine reference value after infrared energy, U mfor measured value u mpeak value, U rfor reference value u rpeak value, u m/ u rrepresenting the numerical value of gas concentration to be measured, is the peakedness ratio of measured value and reference value sine function waveform, and n is that one-period carries out sampling number, and the span of n is between 128 ~ 1024; Compared with once sampling with usual one-period, feature of the present invention carries out n sampling in one-period, be equivalent in time sample to n cycle, be all equivalent to select at peak value place in the sampling of the arbitrfary point of sine function waveform, thus, improve the fiduciary level of signals collecting, add antijamming capability, reduce the sampling time, eliminate the time of microprocessor 73 time delay, wait, improve program operational efficiency, shorten the sensor response time; u m/ u rlambert-Beer's law is followed with the relation of gas concentration c to be measured:
(III)
In formula (III): a and b is constant, be stored in the memory of microprocessor 73, gas concentration c to be measured can be calculated thus;
Measuring process four, self-inspection; Compared with the regime values that the detected value such as temperature, each point voltage, infrared eye 5 output and microprocessor 73 store, judge whether to there is fault, during fault, export fault type code;
Compared with the regime values that the voltage of voltage and each monitoring point that supply voltage, light source 4 detected and microprocessor 73 are stored, can judge supply voltage superelevation or ultralow, light source 4 open a way or short circuit or damage, circuit trouble spot; During fault, the fault type code of interface 75 out-put supply or light source or circuit;
Diagnosis temperature whether in normal range, thus judges that temperature sensor 6 is opened a way or short circuit or damage; During fault, the fault type code of interface 75 output temperature;
Detect measuring-signal that infrared eye 5 transmission comes whether in the normal range of gas to be measured, thus judge that whether work whether normal, optical system and light path of infrared eye 5 be normal, during fault, interface 75 exports the fault type code of infrared eye and light path; Close to normal range by the abnormal value of infrared eye 5 being detected, to judge the process just carrying out the pollutions such as steam in air chamber 9, interface 75 exports air chamber and cleans code, air chamber 9 is through heating and having carried out sufficient gas exchanges with environment, after air chamber drying, dedusting, just normal operating conditions can be entered;
In the trouble-free situation of sensor self-inspection, automatically enter measurement pattern;
Measuring process five, temperature compensation; Zero temperature compensation and range temperature compensation two steps are comprised to the temperature compensation that the concentration parameter calculating gas carries out, gas concentration value after acquisition temperature compensation subsequently;
Calculating concentration c described in step 3 Chinese style (III) is that temperature is T within the scope of senor operating temperature (as: senor operating temperature is 0 ~ 40 DEG C) 0(as: T 0=13 DEG C) when carries out, due to measured value and reference value u m, u rtemperature influence, obtains real-time temperature by temperature sensor 6, carries out temperature compensation, can measure the concentration of gas to be measured exactly; Temperature compensation has zero temperature compensation and range temperature compensation; At real time temperature T t(as: T t=33 DEG C) time, be exactly zero temperature compensation to the compensation of a value in formula (III):
(IV)
In formula (IV): k 0be zero temperature compensation coefficient, a is temperature T 0time be stored in value in microprocessor 73 memory, a treal time temperature T ttime offset;
At real time temperature T t(as: T t=33 DEG C) time, to u in formula (III) m/ u rthe compensation of value is exactly range temperature compensation:
(V)
In formula (V): k srange temperature compensation coefficient, a treal time temperature T ttime offset, b is temperature T 0time be stored in value in microprocessor 73 memory, u m/ u rreal time temperature T ttime measured value, c be temperature compensated after the concentration value of gas to be measured that will calculate;
Measuring process six, converts the gas concentration value after the temperature compensation of step 5 to analog quantity or digital quantity signal, transmits through interface 75.
The concentration c calculated by formula (V), be temperature compensated after measured gas concentration to be measured; Gas concentration, according to corresponding standard or standard, converts analog quantity or digital quantity signal to, carries out wired or wireless transmission through interface 75.
See Figure 10, in this sensor measurement, the temperature T of the Zero calibration constant a in microprocessor 73 memory, range designation constant b, timing signal 0, zero temperature compensation coefficient k 0, range temperature compensation coefficient k svalue calculated under calibration mode by this product sensor, the method that its calibration mode carries out demarcating is carried out as follows:
Demarcating steps one, Zero calibration;
Infrared gas sensor is at demarcation temperature T 0under condition, in air chamber 9, pass into nitrogen (i.e. gas concentration c=0 to be measured), until air chamber 9 is full of nitrogen completely, measure the analog sine measured value u after the gas absorption infrared energy to be measured of each infrared sensor mthe analog sine reference value u after infrared energy is not all absorbed with gas to be measured r, and the value of constant a at zero point is calculated by formula (III), and stored in microprocessor 73 memory, the temperature T that temperature sensor 6 measures 0value is also stored in microprocessor 73 memory;
Demarcating steps two, range designation;
At the temperature T that demarcating steps one is same 0time, the Standard Gases sample that concentration is the gas to be measured of maximum range value is passed in air chamber 9, until air chamber 9 is full of the Standard Gases sample of this gas to be measured completely, measure the analog sine measured value u after the absorption infrared energy of each infrared sensor under the Standard Gases sample of this gas to be measured mwith under the Standard Gases sample of this gas to be measured do not absorb infrared energy after analog sine reference value u rvalue, calculate the value of b by formula (III), stored in microprocessor (73) memory;
Demarcating steps three, zero temperature compensation coefficient is demarcated;
The environment temperature of temperature sensor 6 is made to rise or drop to T t, again in air chamber 9, pass into nitrogen (i.e. gas concentration c=0 to be measured), until air chamber 9 is full of nitrogen completely, survey calculation draws u m/ u rvalue, namely temperature is T ttime constant a at zero point tvalue, by the zero temperature compensation formula (IV) in measuring process five, calculates k 0value, stored in microprocessor 73 memory;
Demarcating steps four, range temperature compensation coefficient is demarcated;
The environment temperature of temperature sensor 6 is continued to remain on T tunder state, in air chamber 9, pass into temperature is T t, concentration is the Standard Gases sample of the gas to be measured of maximum range value, survey calculation draws u m/ u rvalue, calculate k by the range temperature compensation formula (V) in measuring process five svalue and stored in microprocessor 73 memory, call time to be measured; After transducer calibration completes, return measurement pattern.

Claims (8)

1. an infrared gas sensor, comprises shell (1), Inner cylindrical shell (2) and circuit unit; Wherein, there is shell (1) in the outer cover of Inner cylindrical shell (2), be connected with circuit unit in the bottom of Inner cylindrical shell (2); It is characterized in that: described shell (1) is hollow cylinder, be provided with the step (11) inwardly stretched on the top of shell (1); Described step (11) ringwise; One deck filtering membrane (12) is coated with at the top of step (11); Be covered with layer of metal net (13) in the bottom of step (11), the bottom surface of wire netting (13) is connected with vent board (14); Described vent board (14) is thin sheet of metal plate-like, and vent board (14) is evenly equipped with a circle through hole (15); Namely by filtering membrane (12), wire netting (13) and vent board (14), the open top of shell (1) is covered; The hollow cylinder that described Inner cylindrical shell (2) is top closure, be provided with outward extending annular edge (21) in the bottom of Inner cylindrical shell (2), the sidewall of Inner cylindrical shell (2) is provided with a light inlet (22); Annular edge (21) is provided with an accurate tri-prismoid, described accurate tri-prismoid by reflecting plate (23), light barrier (24) and arc (26) around forming, wherein reflecting plate (23) is connected with Inner cylindrical shell (2) sidewall in light inlet (22) left side with the corner angle limit of light barrier (24) connecting place, and the base of arc (26) and one section of edge of annular edge (21) coincide; Annular edge (21) near light barrier (24) is provided with a through hole (25);
The end face of Inner cylindrical shell (2) and the bottom surface close contact of vent board (14); The annular edge (21) of Inner cylindrical shell (2) connects with the inwall of shell (1); Epoxy sealing is filled with in annular edge (21) and the junction of shell (1); The region that shell (1) and inner barrel (2) surround forms the air chamber (9) of this infrared gas sensor; Namely external environment gas spreads air inlet chamber (9) of going forward side by side afterwards through the through hole (15) of filtering membrane (12), wire netting (13) and vent board (14) successively;
Described circuit unit comprises base plate (3), light source (4), infrared eye (5), temperature sensor (6) and signal processing circuit (7); Described base plate (3) is with the external diameter of annular edge (21) isometric for circular metal plate; Base plate (3) is connected with the bottom surface of annular edge (21), is namely sealed by the opening of base plate (3) by Inner cylindrical shell (2) below;
Infrared eye (5) is provided with in the central authorities of base plate (3) end face; Base plate (3) end face near infrared eye (5) is provided with temperature sensor (6); Light source (4) is arranged on air chamber (9) end near light barrier (24) side, and the bottom of light source (4) is connected with base plate (3) afterwards through through hole (25); Signal processing circuit (7) is placed on base plate (3), and infrared eye (5), temperature sensor (6) is connected with signal processing circuit (7) respectively with light source (4) by wire;
The control end of described signal processing circuit (7) is connected with light source (4), to the voltage of light source (4) transport cycle; The signal input part of signal processing circuit (7) is connected with the signal output part of infrared eye (5) and temperature sensor (6) respectively;
Described light source (4) produces periodic radiation light-wave under the driving of periodic voltage; The periodic radiation light wave that light source (4) produces also is radiated on infrared eye (5) through light inlet (22) after air chamber (9) reflection; The periodic radiation light wave that light source (4) produces periodically heats the gas in air chamber (9), impel the gases cycle ground dilation in air chamber (9), thus the environmental gas of the gas realized in air chamber (9) and shell (1) outside carries out gas exchanges rapidly, defines " respiratory air chamber ";
The periodic radiation light wave that infrared eye (5) will receive, be converted into the electric signal of radiation light-wave same period after be passed to signal processing circuit (7);
Temperature sensor (6) detects the temperature near infrared eye (5) in real time and is passed to signal processing circuit (7), does temperature compensation for signal processing circuit (7) to the electric signal that infrared eye (5) is passed back.
2. a kind of infrared gas sensor according to claim 1, is characterized in that, the spectral range of the radiation light-wave that light source (4) sends is that visible ray is to infrared band; Infrared eye (5) is made up of 2 to 16 infrared sensors, wherein 1 infrared sensor receives the infrared radiation that wavelength is 3.9 μm, the sensitive area of remaining infrared sensor is all provided with spike interference filter and the infrared radiation of reception wavelength corresponding with spike interference filter; The hot spot direct irradiation that the radiation light-wave that light source (4) sends is formed after the multiple reflections of air chamber (9), on the whole sensitive area of infrared eye (5), whole light path does not add the optical device of any convergence or light splitting.
3. a kind of infrared gas sensor as claimed in claim 1, it is characterized in that, described signal processing circuit (7) is made up of arrowband bandpass filtering amplifying circuit (71), analog to digital conversion circuit (72), microprocessor (73), modulation of source driving circuit (74) and interface (75);
The signal output part of each infrared sensor of infrared eye (5) is all connected with arrowband bandpass filtering amplifying circuit (71); The signal output part of each arrowband bandpass filtering amplifying circuit (71) is connected with the multi-analog input end of analog to digital conversion circuit (72) jointly; Arrowband bandpass filtering amplifying circuit (71) transfers to analog to digital conversion circuit (72) after the electric signal that infrared eye (5) exports being carried out filtering, amplification, and the voltage signal after filtering, amplification has the identical cycle with the signal of the driving light source modulation drive circuit (74) of microprocessor (73);
The signal output part of temperature sensor (6) is connected with the analog input end of analog to digital conversion circuit (72); The digital output end of analog to digital conversion circuit (72) is connected with the signal input part of microprocessor (73), and namely analog to digital conversion circuit (72) inputs to microprocessor (73) again after all transferring the electric signal of the temperature signal received and each infrared sensor to digital signal and processes; Microprocessor (73), according to the digital quantity that receives, carries out analyzing and processing, temperature compensation, calculates the concentration of gas to be measured;
The signal output part of microprocessor (73) is connected with the signal input part of modulation of source driving circuit (74); Microprocessor (73) is responsible for producing periodic control signal, and described periodic control signal is square wave; The cyclic control signal received is converted to synperiodic driving voltage and is carried on light source (4) by modulation of source driving circuit (74), light source (4) is made to produce periodic radiation light-wave, this radiation light-wave is after gas absorption to be measured in air chamber (9) sidewall reflects and air chamber (9), be radiated on the photosurface of infrared eye (5), convert electric signal to;
Microprocessor (73) is connected with interface (75), is realized the connection of microprocessor (73) and long-range host computer by interface (75).
4. a kind of infrared gas sensor according to claim 1, is characterized in that, in infrared eye (5), each infrared sensor is all connected with arrowband bandpass filtering amplifying circuit (71); Each arrowband bandpass filtering amplifying circuit (71) is connected with the multi-analog input end of an analog to digital conversion circuit (72) jointly;
Arrowband bandpass filtering amplifying circuit (71) is made up of the first resistance R1, the second resistance R2, the first electric capacity C1, the second electric capacity C2 and operational amplifier OP; Wherein, between the output terminal and negative input end of operational amplifier OP, the first resistance R1 and the first electric capacity C1 is parallel with; The negative input end of operational amplifier OP is connected with one end of the second resistance R2, and the other end of the second resistance R2 is connected with one end of the second electric capacity C2; The other end of the second electric capacity C2 is connected with the power supply negative terminal of infrared eye (5); The positive input terminal of operational amplifier OP is connected with the output terminal of infrared sensor; The output terminal of operational amplifier OP is connected with analog to digital conversion circuit (72); The transition function of arrowband bandpass filtering amplifying circuit (71) is:
H ( s ) = 1 + s 1 R 2 C 1 s 2 + s ( 1 R 1 C 1 + 1 R 2 C 2 ) + 1 R 1 R 2 C 1 C 2
By regulating the parameter of resistance R1, R2, electric capacity C1, C2, realize arrowband bandpass filtering amplifying circuit (71) centre frequency f 0, bandwidth f w, enlargement factor A 0, quality factor q control.
5. a kind of infrared gas sensor according to claim 3, is characterized in that, the wick of light source (4) is tungsten filament or thermal resistance film; In the energized state, light source (4) generates heat and produces infrared radiation;
Modulation of source driving circuit (74) is made up of light source (4), the 3rd resistance R3, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, triode VT1 and field effect transistor VT2, wherein, the source electrode of field effect transistor VT2 connects power supply ground, the source electrode of field effect transistor VT2 is connected by the 6th resistance R6 with the drain electrode of field effect transistor VT2, the drain electrode of field effect transistor VT2 connects the 5th resistance R5, the gate pole of field effect transistor VT2 respectively with one end of the 4th resistance R4, the emitter of triode VT1 is connected, the other end of the 4th resistance R4 connects power supply VCC, triode VT1 collector is connected with the source electrode of field effect transistor VT2, the base stage of triode VT1 is connected with one end of the 3rd resistance R3, the other end of the 3rd resistance R3 is connected with microprocessor (73), light source (4) is in series with between the other end and the other end of the 5th resistance R5 of the 4th resistance R4, namely the electric current that power supply VCC provides flows through light source (4), the 5th resistance R5, the 6th resistance R6 and field effect transistor VT2 successively, realize the power supply to light source (4), the cyclic control signal that microprocessor (73) produces is successively through the 3rd resistance R3, triode VT1 and field effect transistor VT2, and driving light source (4) periodically sends radiation light-wave,
Tungsten filament passes into current flow heats, temperature raise, along with the rising of temperature, tungsten filament resistance value increase, do not have electric current by time resistance be called cold resistance, when have electric current by time, resistance will raise, and be called thermal resistance; Tungsten filament cold resistance is very little, if light source (4) is lighted from cold resistance state, this process can produce very large dash current; Modulation of source driving circuit (74), by loading certain electric current on light source (4), avoids light source (4) and lights from cold resistance state;
During field effect transistor VT2 cut-off, power supply VCC arrives power supply ground through light source (4), resistance R5, R6, can set by light source (4) current value by regulating resistance R6, determine light source (4) depth of modulation, when namely scene effect pipe VT2 ends, light source passes into electric current in (4), when avoiding light source (4) cold resistance state to light, to the impact of power supply VCC;
Field effect transistor VT2 is the N-channel MOS FET of a low on-resistance, and conducting resistance is zero point several ohm only; During field effect transistor VT2 conducting, power supply VCC is through light source (4), resistance R5, field effect transistor VT2 and the leakage, the source resistance R6 arrival power supply ground that are parallel to field effect transistor VT2, set by light source (4) current value by regulating resistance R5, determine the radiant light wave intensity that light source (4) produces;
Triode VT1 mono-is for the protection of field effect transistor VT2, prevents field effect transistor VT2 from damaging, and two is that the control signal that exported by microprocessor (73) and light source (4) power supply VCC isolate, and prevents mutual interference.
6. a kind of infrared gas sensor according to claim 2, is characterized in that, the wavelength coverage of infrared radiation is 2 ~ 5 μm, 8 ~ 12 μm, 2 ~ 12 μm and 2 ~ 20 μm.
7. adopt the detection method of infrared gas sensor as claimed in claim 3; It is characterized in that,
Measuring process one, initialization; Microprocessor (73) exports cyclic control signal, described cyclic control signal is square wave, light source (4) just periodically sends radiation light-wave, the heat that radiation light-wave produces periodically heats gas indoor gas, gas indoor gas is impelled to carry out the circulation of " expansion-contraction ", carry out sufficient gas exchanges with environment, air chamber (9) is carried out drying, cleaned;
Measuring process two, signals collecting; Microprocessor (73) exports channel coding and the instruction of sampled signal, gathers and is converted to digital signal respectively to temperature, each point voltage, infrared eye (5) output signal; Export through amplification, filtered sine wave to each sensitive element of infrared eye (5), after cyclic control signal makes the middle electric current of light source (4) from large to small, carry out 128 ~ 1024 samplings;
Measuring process three, calculates; Export temperature, each point voltage, infrared eye (5), calculate when signals collecting is idle, particularly in cyclic control signal makes light source (4), electric current calculates after changing from small to big; Wherein, in infrared eye (5), the output signal of each sensitive element is sinusoidal wave after arrowband bandpass filtering amplifying circuit (71) process, samples, and calculate by following formula in a sine wave:
u m / u r = &Sigma; i = 1 n U m sin&omega;t n &Sigma; i = 1 n U r sin&omega;t n = U m U r
In formula, u mfor the analog sine measured value after gas absorption infrared energy to be measured, u rfor all gas to be measured does not all absorb the analog sine reference value after infrared energy, U mfor measured value u mpeak value, U rfor reference value u rpeak value, u m/ u rrepresent the numerical value of a certain gas concentration to be measured, be the peakedness ratio of measured value and reference value sine function waveform, n is sampling number in one-period, and the value of n is between 128 ~ 1024;
Measuring process four, self-inspection; To calculate compared with regime values that the numerical value such as gained temperature, each point voltage, infrared eye (5) output and microprocessor (73) store, and judge whether to there is fault, during fault, export fault type code;
Measuring process five, temperature compensation; Zero temperature compensation and range temperature compensation two steps are comprised to the temperature compensation that the concentration parameter calculating gas carries out, gas concentration value after acquisition temperature compensation subsequently;
Wherein, at real time temperature T ttime, the formula of zero temperature compensation is:
A t=a+k 0(T t-T 0), in formula, k 0be zero temperature compensation coefficient, a is temperature T 0time be stored in value in microprocessor (73) memory, a treal time temperature T ttime offset;
At real time temperature T ttime, the formula of range temperature compensation is:
in formula, k srange temperature compensation coefficient, a treal time temperature T ttime offset, b is temperature T 0time be stored in value in microprocessor (73) memory, u m/ u rreal time temperature T ttime measured value, c be temperature compensated after the concentration value of gas to be measured that will calculate;
Measuring process six, converts the gas concentration value after the temperature compensation of step 5 to analog quantity or digital quantity signal, and transmits through interface (75).
8. adopt the detection method of infrared gas sensor as claimed in claim 7; It is characterized in that, before testing, to the constant a and range constant b, zero temperature compensation coefficient k at zero point of infrared gas sensor 0with range temperature compensation coefficient k scarry out demarcating and stored in microprocessor (73) memory, transfer time to be measured and use; The method of concrete demarcation is carried out as follows:
Demarcating steps one, Zero calibration;
Infrared gas sensor is at demarcation temperature T 0under condition, in air chamber (9), pass into nitrogen, until air chamber (9) is full of nitrogen completely, measure the analog sine measured value u after the gas absorption infrared energy to be measured of each infrared sensor mthe analog sine reference value u after infrared energy is not all absorbed with gas to be measured r, and press formula
U m/ u r=ae -bccalculate the value of constant a at zero point, stored in microprocessor (73) memory, the temperature T that temperature sensor (6) measures 0value is also stored in microprocessor (73) memory;
Demarcating steps two, range designation;
At the temperature T that demarcating steps one is same 0time, the Standard Gases sample that concentration is the gas to be measured of maximum range value is passed in air chamber (9), until air chamber (9) is full of the Standard Gases sample of this gas to be measured completely, measure the analog sine measured value u after the absorption infrared energy of each infrared sensor under the Standard Gases sample of this gas to be measured mwith under the Standard Gases sample of this gas to be measured do not absorb infrared energy after analog sine reference value u rvalue, obtain the value of b by the formulae discovery of demarcating steps one, stored in microprocessor (73) memory;
Demarcating steps three, zero temperature compensation coefficient is demarcated;
The environment temperature of temperature sensor (6) is made to rise or drop to T t, again in air chamber (9), pass into nitrogen, until air chamber (9) is full of nitrogen completely, survey calculation draws u m/ u rvalue, namely temperature is T ttime constant a at zero point tvalue, by the zero temperature compensation formula a in measuring process five t=a+k 0(T t-T 0), calculate k 0value, stored in microprocessor (73) memory;
Demarcating steps four, range temperature compensation coefficient is demarcated;
The environment temperature of temperature sensor (6) is continued to remain on T tunder state, in air chamber (9), pass into temperature is T t, concentration is the Standard Gases sample of the gas to be measured of maximum range value, survey calculation draws u m/ u rvalue, by the range temperature compensation formula in measuring process five calculate k svalue and stored in microprocessor (73) memory, call time to be measured.
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CN116879215B (en) * 2023-07-18 2024-04-09 上海苏萨电子科技有限公司 Non-dispersive infrared gas sensor
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63113346A (en) * 1986-10-30 1988-05-18 Fujitsu Ltd Gas sensor
JPS63182550A (en) * 1987-01-23 1988-07-27 Fujitsu Ltd Gas sensor
EP0287929B1 (en) * 1987-04-24 1994-02-16 Miles Inc. Remote sensing gas analyzer
EP0681179A1 (en) * 1994-05-05 1995-11-08 Santa Barbara Research Center IR-based nitric oxide sensor having water vapor compensation
CN201222035Y (en) * 2008-06-18 2009-04-15 上海安誉智能科技有限公司 Detection sensor for infrared gas
CN100510713C (en) * 2007-02-01 2009-07-08 方剑德 Intelligent type infrared gas sensor
CN201909754U (en) * 2010-11-19 2011-07-27 上海翼捷工业安防技术有限公司 Optical gas sensor
WO2012059744A1 (en) * 2010-11-01 2012-05-10 Gas Sensing Solutions Ltd. Apparatus and method for generating light pulses from leds in optical absorption gas sensors
CN102495018A (en) * 2011-11-14 2012-06-13 济南火哨安全科技有限公司 Temperature compensation integrated infrared absorption gas sensor and detecting device

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63113346A (en) * 1986-10-30 1988-05-18 Fujitsu Ltd Gas sensor
JPS63182550A (en) * 1987-01-23 1988-07-27 Fujitsu Ltd Gas sensor
EP0287929B1 (en) * 1987-04-24 1994-02-16 Miles Inc. Remote sensing gas analyzer
EP0681179A1 (en) * 1994-05-05 1995-11-08 Santa Barbara Research Center IR-based nitric oxide sensor having water vapor compensation
CN100510713C (en) * 2007-02-01 2009-07-08 方剑德 Intelligent type infrared gas sensor
CN201222035Y (en) * 2008-06-18 2009-04-15 上海安誉智能科技有限公司 Detection sensor for infrared gas
WO2012059744A1 (en) * 2010-11-01 2012-05-10 Gas Sensing Solutions Ltd. Apparatus and method for generating light pulses from leds in optical absorption gas sensors
CN201909754U (en) * 2010-11-19 2011-07-27 上海翼捷工业安防技术有限公司 Optical gas sensor
CN102495018A (en) * 2011-11-14 2012-06-13 济南火哨安全科技有限公司 Temperature compensation integrated infrared absorption gas sensor and detecting device

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
"A miniaturized carbon dioxide gas sensor based on infrared absorption";Guangjun Zhang 等;《Optics and Lasers in Engineering》;20100711;第48卷;第1206-1212页 *
"Research on coal mine gas sensor systems based on near infrared spectrum";Haiqing Zhang 等;《Procedia Engineering》;20101231;第7卷;第399-403页 *
"法国防爆型红外CO2检测仪的剖析";程文楷 等;《煤炭科学技术》;19970331;第25卷(第3期);第7-10页 *
"矿用红外气体传感器的结构及光学系统的设计与实现";刘永平 等;《硅酸盐通报》;20090430;第28卷(第2期);第400-405页 *
"矿用红外甲烷传感器的研制";刘永平 等;《煤矿现代化》;20091231(第93期);第67-70页 *

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