High-precision double-range infrared gas sensor and high-precision double-range infrared gas analysis method

Abstract

A high-precision double-range infrared gas sensor and a high-precision double-range infrared gas analysis method. The sensor comprises a chamber (10); the outer frame of the chamber (10) is of an enclosed structure; the inner wall of the chamber (10) is provided with a reflective part in an enclosed structure; and a first light source (7), a second light source (8), and an infrared detector (9) are arranged in the cavity of the chamber (10). During measurement, light emitted by the first light source and the second light source (8) is controlled, in a time-sharing manner, to be reflected in the chamber (10) to form a long measurement optical path length and a short measurement optical path length, thereby implementing the measurement of a gas to be measured having a low-range concentration and a high-range concentration. The high-precision double-range infrared gas sensor and the high-precision double-range infrared gas analysis method can simultaneously perform high-precision measurement on a low-range concentration and a high-range concentration, can simultaneously meet uses in HVAC air quality monitoring and heat pump CO2 safety and leakage monitoring, and have low cost and high reliability.

Description

A high-precision dual-range infrared gas sensor and gas analysis method Technical Field

[0001] The present invention relates to the field of infrared gas sensors, and in particular to a high-precision dual-range infrared gas sensor and a gas analysis method. Background Art

[0002] In recent years, people have become increasingly concerned about the air quality in indoor and public places. Carbon dioxide, for example, is a key indicator for indoor air quality monitoring. In the field of heating, ventilation and air conditioning (HVAC), carbon dioxide sensors are used to monitor the carbon dioxide content in indoor spaces or vehicles. When the carbon dioxide content exceeds the set limit, fresh air is introduced through the ventilation system in the HVAC system, which can effectively improve energy efficiency and is of great significance for energy conservation and environmental protection.

[0003] In addition, carbon dioxide, as an important component of the new refrigerant R744, will be an ideal refrigerant for future air-conditioning technology because it does not damage the atmospheric ozone layer, has an ODP value of zero and a very low GWP value. The document "Application Research of Carbon Dioxide Refrigerants" states: In the early 1990s, Norway's NTH-SINTEF developed a prototype automotive air-conditioning unit using a carbon dioxide critical refrigeration cycle. Since 1994, famous European companies such as BMW, DALMLERENZ, VOLVO, and Volkswagen have launched a cooperative project called "RACE", jointly developing carbon dioxide automotive air-conditioning systems with famous European universities and automotive air-conditioning manufacturers. It has been used as a long-term substitute for automotive air-conditioning refrigerants in many countries. In actual application, once carbon dioxide is used as an air-conditioning refrigerant, once it leaks, it will directly affect the refrigeration efficiency. Therefore, a carbon dioxide gas sensor is required to monitor refrigerant leakage. Therefore, the use of carbon dioxide sensors for R744 refrigerant gas leak detection has huge market prospects.

[0004] In actual application, once R744 leaks, it will not only directly affect the refrigeration efficiency, but may also cause suffocation. Therefore, a carbon dioxide gas sensor is required to monitor refrigerant leakage and issue an alarm in time.

[0005] Different sensor application scenarios often require different gas measurement ranges. For precise monitoring of carbon dioxide levels indoors or in vehicles, low-range sensors are typically used. However, monitoring refrigerant leaks (R744) in heat pump air conditioners requires high-range sensors, as a leak can result in high carbon dioxide concentrations and pose a safety risk. To meet these requirements, two sensors with different concentration ranges must be deployed simultaneously in different locations. This is costly and unsuitable for mass deployment. Furthermore, since both sensors are constantly operating, the probability of simultaneous failure is high. Therefore, a high-precision, dual-range, and low-cost CO2 sensor is urgently needed.

[0006] Non-dispersive infrared (NDIR) spectroscopy is an important gas analysis method commonly used for quantitative gas analysis. The principle of using NDIR to analyze gases is as follows: infrared light is irradiated on the gas being measured, and the gas being measured absorbs light of a specific wavelength. According to the Lambert-Beer absorption law, under ideal conditions, given the effective absorption pathlength of light and the absorption coefficient of the molecule at a specific wavelength, the concentration of the gas being measured can be calculated using the ratio of the light signal before and after absorption by the gas being measured. Gas sensors that utilize the NDIR principle offer advantages such as fast response, high sensitivity, good stability, and long lifespan. Consequently, infrared gas sensors have experienced rapid development in recent years.

[0007] Patent document WO02077619A2 discloses an infrared gas sensor that uses a single light source, a single detector, and a single gas chamber structure to achieve gas concentration detection function. This gas sensor has a simple structure and low cost, but its disadvantages are low detection accuracy and a small range, making it impossible to achieve high-precision measurement of a large range of carbon dioxide concentrations.

[0008] Patent document CN2554623Y discloses a gas concentration detector that uses a single light source or dual light sources, dual detectors, and an independent dual-chamber structure. During actual operation, a certain concentration of nitrogen is sealed in the reference chamber, and the measuring chamber is filled with the gas to be measured. An infrared light source illuminates the measuring chamber and the reference chamber, and the concentration of the gas to be measured is obtained based on the ratio of the electrical signals output by the two detectors. This solution can overcome the drift problem of the gas sensor caused by temperature, light source, and aging of the gas chamber. The disadvantages are low detection accuracy and small range, and it is impossible to achieve high-precision measurement of a large range of carbon dioxide concentration. The use of dual detectors is costly, which is not conducive to the miniaturization and low cost of the gas sensor structure.

[0009] Patent document DE19925196C2 discloses an NDIR gas sensor with a dual-light source and single detector. The two light sources are symmetrically positioned around the measurement chamber, with the same path length from the two light sources to the detector. The first light source is used for long-term detection, while the second light source serves as a reference. After the first light source reaches a predetermined service life, the second light source switches to operation. The two light sources operate with different pulse intervals, and the second light source serves only as a backup light source. This solution cannot achieve high-precision detection of CO2 concentrations across different ranges to meet complex application scenarios.

[0010] Patent document CN104122223B discloses a dual-path multi-gas infrared gas sensor, in which the lower half of the infrared light emitted by the infrared light source is reflected by a plane mirror and reaches the lower half of the dual-channel detector, forming a short optical path. The upper half of the infrared light emitted by the infrared light source is reflected multiple times by the inner surface of the annular cavity and reaches the upper half of the dual-channel detector, forming a long optical path. This achieves both long and short optical paths within a single chamber. This can meet the requirements for simultaneous detection of gases with different infrared absorptivity, while also meeting the requirements for different detection accuracies for the same gas. However, this solution requires the light source to operate for a long time, significantly reducing its operating life. Furthermore, the use of a dual-channel infrared detector results in a high cost.

[0011] Patent document CN114136911A discloses a gas sensor that takes both range and resolution into account and its implementation method. The light beam emitted by the light source assembly is split by a spectrometer. The split light beams are incident on different detectors respectively, forming optical paths with different optical path lengths. Each detector receives the light signal of the corresponding optical path and calculates the gas concentration measurement results corresponding to the optical paths with different optical path lengths. The detector corresponding to the long optical path achieves high-sensitivity detection of gas concentration, and the detector corresponding to the short optical path achieves large-scale detection of gas concentration, which can realize the detection of high and low concentrations of CO2. The disadvantage of this solution is that the life of a single light source is not as good as that of a dual light source, and the cost of dual detectors is high.

[0012] In summary, existing NDIR infrared gas sensors have limitations in detection accuracy and range. They are unable to simultaneously measure CO2 concentrations with high accuracy across different ranges while maintaining low cost and a long lifespan. They must use two sensors to measure low and high ranges, respectively. Therefore, there is an urgent need to develop a low-cost, long-life infrared gas sensor that can achieve high accuracy across both ranges.

[0013] Summary of the Invention

[0014] In order to solve the defects of existing NDIR infrared gas sensors in detection accuracy, range and manufacturing cost, the present invention proposes a dual-range NDIR infrared gas sensor using dual light sources and a single detector and a corresponding gas analysis method.

[0015] Specifically, the present invention provides a high-precision dual-range infrared gas sensor, comprising:

[0016] The outer frame of the chamber is an enclosing structure; correspondingly, the inner wall of the chamber is provided with a reflective portion in an enclosing structure;

[0017] A first light source, a second light source, and an infrared detector are provided in the cavity of the chamber;

[0018] The light emitted by the first light source is reflected by the reflecting part and captured by the infrared detector, forming a long optical path gas chamber L1 to detect the first concentration gas;

[0019] The light emitted by the second light source is reflected by the reflecting part and captured by the infrared detector, forming a short optical path gas chamber L2 to detect the second concentration gas;

[0020] The first light source and the second light source are controlled by a control module; the control module includes: a light source driving unit, a control unit and an operational amplifier unit;

[0021] The detection signal of the infrared detector is amplified by the operational amplifier unit and then transmitted to the control unit;

[0022] The control unit generates a control signal using time-sharing control, and the control signal is transmitted to the first light source and the second light source through the light source driving unit;

[0023] The first concentration gas concentration is lower than the second concentration gas concentration.

[0024] A high-precision dual-range infrared gas analysis method is applied to the high-precision dual-range infrared gas sensor. The method is as follows:

[0025] S1. The control unit sends an initial control signal to control the first light source and the second light source to flash alternately;

[0026] S2, the operational amplifier circuit samples the signal value C1 of the long optical path gas chamber L1 and the signal value C2 of the short optical path gas chamber L2 from the infrared detector;

[0027] S3. Fitting the linear formula D1=f(C1) based on the calibration data of the long optical path gas cell L1 to calculate the gas concentration D1; fitting the linear formula D2=f(C2) based on the calibration data of the short optical path gas cell L2 to calculate the gas concentration D2;

[0028] S4. Determine whether the current concentration is in the low-range interval, high-range interval, or mid-range interval. If it is in the low-range interval, output the gas concentration D1; if it is in the high-range interval, output the gas concentration D2; otherwise, output the comprehensive calculated value k*D1+(1-k)*D2.

[0029] The beneficial effects provided by the present invention are:

[0030] 1. Solved the technical problem of being unable to measure low-range concentration and high-range concentration simultaneously with high precision;

[0031] 2. Achieve low cost: By simply adding a low-cost light source, the technical problem of using two infrared gas sensors, which is high cost and not conducive to large-scale batch application, is solved;

[0032] 3. Long life and high reliability: Since the infrared gas sensor uses two light sources to work alternately, it can effectively shorten the working time of each light source. Compared with the single light source and single detector sensor, it is equivalent to extending the working life and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic structural diagram of the device of the present invention;

[0034] FIG2 is a control principle diagram of the first light source 7 and the second light source 8;

[0035] FIG3 is a perspective view of the internal structure of the chamber 10 from two different angles;

[0036] FIG4 is a schematic diagram of two optical paths of a long optical path gas cell;

[0037] FIG5 is a schematic diagram of the optical path of a short optical path gas cell;

[0038] Figure 6 is a schematic diagram of a control signal;

[0039] FIG7 is a schematic diagram of test data of the first light source 7 and the second light source 8 passing through the long optical path gas cell L1 and the short optical path gas cell L2 at different concentrations;

[0040] FIG8 is a fitting curve of the calibration data of the long optical path gas cell L1 at low concentration;

[0041] FIG9 is a fitting curve of the calibration data of the long optical path gas cell L1 at high concentration;

[0042] FIG10 is a fitting curve of the calibration data of the short optical path gas cell L2 at low concentration;

[0043] FIG11 is a fitting curve of the calibration data of the short optical path gas cell L2 at high concentration;

[0044] FIG12 is a fitting curve of the calibration data of the long optical path gas chamber L1 of the sensor embodiment at low concentrations;

[0045] FIG13 is a fitting curve of the calibration data of the short optical path gas chamber L2 of the sensor according to the embodiment at high concentration. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0047] Please refer to FIG1 , which is a schematic structural diagram of an infrared sensor according to the present invention.

[0048] The present invention provides a high-precision dual-range infrared gas sensor, comprising: a chamber 10;

[0049] The outer frame of the chamber 10 is an enclosing structure; correspondingly, the inner wall of the chamber 10 is provided with a reflecting portion in an enclosing structure; it should be noted that, in this embodiment, the enclosing structure is rectangular, and in other embodiments, it can also be other types of enclosing structures, such as square, polygonal, etc.

[0050] A first light source 7, a second light source 8, and an infrared detector 9 are provided in the cavity 10;

[0051] The light emitted by the first light source 7 is reflected by the reflecting part and captured by the infrared detector 9, forming a long optical path gas chamber L1 to detect the first concentration gas;

[0052] The light emitted by the second light source 8 is reflected by the reflecting part and captured by the infrared detector 9, forming a short optical path gas chamber L2 to detect the second concentration gas;

[0053] The first light source 7 and the second light source 8 are controlled by a control module; the control module includes: a light source driving unit, a control unit and an operational amplifier unit;

[0054] Please refer to FIG2 , which is a control principle diagram of the first light source 7 and the second light source 8;

[0055] The first light source 7 and the second light source 8 are controlled by a control module; the control module includes: a light source driving unit, a control unit and an operational amplifier unit;

[0056] The detection signal of the infrared detector 9 is amplified by the operational amplifier unit and then transmitted to the control unit;

[0057] The control unit generates a control signal using time-sharing control, and the control signal is transmitted to the first light source 7 and the second light source 8 through the light source driving unit;

[0058] The first concentration gas concentration is lower than the second concentration gas concentration.

[0059] As an embodiment, the light source driving unit adopts a TPS79301 chip; the control unit adopts an STM32F031F6 chip; and the operational amplifier circuit adopts an OPA2365 module or chip.

[0060] Please refer to FIG3 ; FIG3 is a three-dimensional view of the internal structure of the chamber 10 from two different angles;

[0061] The reflecting portion provided in the chamber 10 includes a first reflecting surface 1 , a second reflecting surface 2 , a third reflecting surface 3 , a fourth reflecting surface 4 , a fifth reflecting surface 5 and a sixth reflecting surface 6 .

[0062] In this embodiment, the outer frame of the chamber 10 is rectangular, and the first reflecting surface 1 is arranged at the upper left corner of the chamber 10 and partially surrounds the first light source 7; the second reflecting surface 2 is arranged at the upper right corner of the chamber 10; the third reflecting surface 3 is arranged in the middle part of the right end of the chamber 10; the fourth reflecting surface 4 is arranged at the lower right corner of the chamber 10; the fifth reflecting surface 5 is arranged at the bottom part of the chamber 10 and partially surrounds the second light source 8; the sixth reflecting surface 6 is arranged at the lower left corner of the chamber 10, and the infrared detector 9 is arranged opposite to the sixth reflecting surface 6.

[0063] It should be noted that the positions of the first light source 7 , the second light source 8 and the infrared detector 9 are fixed by opening holes in the cover plate to reserve positions. When in use, the cover plate can be used to cover the chamber 10 .

[0064] The first reflecting surface 1 is used to gather the light emitted by the first light source 7 and reflect it to the third reflecting surface 3 or the fourth reflecting surface 4 , and the first reflecting surface 1 is a parabolic reflecting surface or an elliptical reflecting surface.

[0065] Preferably, the first light source 7 is an incandescent lamp or a point light source;

[0066] The second reflecting surface 2 , the third reflecting surface 3 , and the fourth reflecting surface 4 are arc reflecting surfaces or plane reflecting surfaces.

[0067] The fifth reflecting surface 5 is used to gather the light emitted by the second light source 8 and reflect it to the sixth reflecting surface 6 .

[0068] Preferably, the second light source 8 is the same as the first light source 7 and is an incandescent lamp or a point light source;

[0069] It should be noted that the second reflecting surface 2 , the third reflecting surface 3 , and the fourth reflecting surface 4 adopt arc reflection or plane reflection.

[0070] The sixth reflecting surface 6 is used to reflect the reflected light parallel to the bottom surface of the chamber 10 into the infrared detector 9, and the sixth reflecting surface 6 forms an angle of 45° with the bottom surface of the chamber 10.

[0071] Please refer to Figures 4 and 5. Figure 4 is a schematic diagram of two optical paths of a long optical path gas cell; Figure 5 is a schematic diagram of the optical path of a short optical path gas cell;

[0072] The long optical path air chamber L1 includes two optical paths, namely the first optical path and the second optical path; the short optical path air chamber L2 adopts the third optical path; wherein:

[0073] First optical path: light is emitted from the first light source 7, passes through the first reflecting surface 1, the fourth reflecting surface 4, the second reflecting surface 2 and the sixth reflecting surface 6, and then enters the infrared detector 9;

[0074] Second optical path: light is emitted from the first light source 7, passes through the first reflecting surface 1, the third reflecting surface 3 and the sixth reflecting surface 6, and then enters the infrared detector 9;

[0075] Third optical path: the light is emitted from the second light source 8 , passes through the fifth reflecting surface 5 and the sixth reflecting surface 6 , and then enters the infrared detector 9 .

[0076] A high-precision dual-range infrared gas analysis method is applied to the high-precision dual-range infrared gas sensor. The method is as follows:

[0077] S1, the control unit sends an initial control signal to control the first light source 7 and the second light source 8 to flash alternately;

[0078] Please refer to FIG6 , which is a schematic diagram of control signals.

[0079] The light source driving mode is alternate lighting. V1 is the short light path light source driving signal, V2 is the long light path light source driving signal, U S is the short optical path signal waveform, U R It is the short optical path signal waveform.

[0080] S2, the operational amplifier circuit samples the signal value C1 of the long optical path gas chamber L1 and the signal value C2 of the short optical path gas chamber L2 from the infrared detector 9;

[0081] S3. Fitting the linear formula D1=f(C1) based on the calibration data of the long optical path gas cell L1 to calculate the gas concentration D1; fitting the linear formula D2=f(C2) based on the calibration data of the short optical path gas cell L2 to calculate the gas concentration D2;

[0082] It should be noted that f() represents the conversion relationship between data D1 and data C1, which is obtained by pre-calibration.

[0083] S4. Determine whether the current concentration is in the low-range interval, high-range interval, or mid-range interval. If it is in the low-range interval, output the gas concentration D1; if it is in the high-range interval, output the gas concentration D2; otherwise, output the comprehensive calculated value k*D1+(1-k)*D2.

[0084] It should be noted that the low range, high range and mid-range intervals are preset intervals. Specifically, when the current concentration is between 0 and Da, it is in the low range; when the current concentration is between Da and Db, it is in the mid-range; when the current concentration is above Db, it is in the high range. The range of k is 0 to 1;

[0085] It should be noted that the current concentration is first calculated using the long optical path fitting formula, that is, the current concentration is temporarily D1;

[0086] If D1 is between 0-Da, output D1; if D1 is greater than Db, output D2; if D1 is between Da and Db, output k*D1+(1-k)*D2.

[0087] As an example, please refer to the following table. Table 1 shows the test data of long optical path signals and short optical path signals at different concentrations.

[0088] Table 1 Test data of long pathlength signal and short pathlength signal at different concentrations

[0089] According to the data graph drawn in Table 1, refer to FIG7 , which is a schematic diagram of test data of the first light source 7 and the second light source 8 passing through the long optical path gas cell L1 and the short optical path gas cell L2 at different concentrations.

[0090] From Figure 7, we can see that the signal of the long optical path gas cell L1 gradually tends to saturation at concentrations above 5300 ppm, and the signal change rate is large below 5300 ppm; the signal of the short optical path gas cell L2 has a small signal change rate below 5300 ppm, and a large signal change rate above 5300 ppm.

[0091] Therefore, in the range of 0 to 4000ppm, the long light path gas cell L1 is used to measure the concentration D1; in the range of 4000ppm to 5300ppm, the long light path gas cell L1 and the short light path gas cell L2 are used to measure the comprehensive concentration (k*D1+(1-k)*D2) as the final output concentration; above 5300ppm, the short light path is used to measure the concentration D2 as the output concentration.

[0092] Please refer to Figures 8 and 9; Figure 8 is the fitting curve of the calibration data of the long optical path gas cell L1 at low concentrations. Figure 9 is the fitting curve of the calibration data of the long optical path gas cell L1 at high concentrations.

[0093] Please refer to Figures 10 and 11; Figure 10 is a fitting curve of the calibration data of the short optical path gas chamber L2 at low concentrations; Figure 11 is a fitting curve of the calibration data of the short optical path gas chamber L2 at high concentrations;

[0094] Please refer to Figures 12 and 13. Figure 12 shows the fitted curve of calibration data for the long optical path gas cell L1 of the example sensor at low concentrations; Figure 13 shows the fitted curve of calibration data for the short optical path gas cell L2 of the example sensor at high concentrations. It should be noted that the long optical path gas cell L1 is used at low ranges, and the short optical path gas cell L2 is used at high ranges.

[0095] Please refer to Table 2, which shows the concentration error calculation results using single optical path L1 segmented fitting, single optical path L2 segmented fitting, and dual optical path L1 and L2 fitting (the error is calculated based on the original signal fluctuation test data ±4).

[0096] Table 2 Calculation results of concentration error using single optical path L1 segmented fitting, single optical path L2 segmented fitting and dual optical path L1 and L2 fitting:

[0097] The long-path L1 solution ensures an accuracy of 5% of reading in the 0-4000ppm range, and within 25% of reading in the 4000ppm-40000ppm range. The short-path L2 solution achieves an accuracy of 15% of reading + 400ppm in the 0-4000ppm range, and within 7% of reading in the 4000ppm-40000ppm range. Therefore, the dual-range solution ensures an accuracy of 5% of reading + 50ppm in the 0-40000ppm range.

[0098] The beneficial effects of the present invention are:

[0099] 1. Dual range: The two light sources correspond to the long optical path L1 and the short optical path L2 respectively. The low-range concentration D1 and the high-range concentration D2 are obtained by using the detection results C1 and C2 of the same detector at different times as intermediate variables. In the low-concentration range, the measurement result D1 of the long optical path L1 is used as the final concentration; in the high-concentration range, the measurement result D2 of the short optical path L2 is used as the final concentration; in the intermediate concentration range, k*D1+(1-k)*D2 is used as the final concentration (where the k value ranges from 0 to 1, which is the proportional coefficient of the distance from the boundary value between the high and low concentration intervals). The above method solves the technical problem of being unable to simultaneously measure low-range concentrations and high-range concentrations with high precision;

[0100] 2. Achieve low cost: By simply adding a low-cost light source, the technical problem of using two infrared gas sensors, which is high cost and not conducive to large-scale batch application, is solved;

[0101] 3. Long life and high reliability: Since the infrared gas sensor uses two light sources to work alternately, it can effectively shorten the working time of each light source. Compared with the single light source and single detector sensor, it is equivalent to extending the working life and high reliability.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-precision dual-range infrared gas sensor, characterized in that: include: Chamber (10); The outer frame of the chamber (10) is in an enclosed structure; correspondingly, the inner wall of the chamber (10) is provided with a reflective portion in an enclosed structure; A first light source (7), a second light source (8) and an infrared detector (9) are arranged in the cavity of the chamber (10); The light emitted by the first light source (7) is reflected by the reflecting part and then captured by the infrared detector (9), thereby forming a long optical path gas chamber L1 to detect the first concentration gas; The light emitted by the second light source (8) is reflected by the reflecting part and then captured by the infrared detector (9), thereby forming a short optical path gas chamber L2 to detect the second concentration gas; The first light source (7) and the second light source (8) are controlled via a control module; the control module comprises: a light source driving unit, a control unit and an operational amplifier unit; The detection signal of the infrared detector (9) is amplified by the operational amplifier unit and then transmitted to the control unit; The control unit generates a control signal by time-sharing control, and the control signal is transmitted to the first light source (7) and the second light source (8) through the light source driving unit; The first concentration gas concentration is less than the second concentration gas concentration.

2. A high-precision dual-range infrared gas sensor as claimed in claim 1, characterized in that: The reflective portion in an enclosed structure comprises a first reflective surface (1), a second reflective surface (2), a third reflective surface (3), a fourth reflective surface (4), a fifth reflective surface (5) and a sixth reflective surface (6).

3. A high-precision dual-range infrared gas sensor as claimed in claim 2, characterized in that: The first reflection surface (1) is arranged at the upper left corner of the chamber (10) and partially surrounds the first light source (7); the second reflection surface (2) is arranged at the upper right corner of the chamber (10); the third reflection surface (3) is arranged at the middle part of the right end of the chamber (10); the fourth reflection surface (4) is arranged at the lower right corner of the chamber (10); the fifth reflection surface (5) is arranged at the bottom end part of the chamber (10) and partially surrounds the second light source (8); and the sixth reflection surface (6) is arranged at the lower left corner of the chamber (10).

4. A high-precision dual-range infrared gas sensor as claimed in claim 1, characterized in that: The infrared detector (9) is arranged opposite to the sixth reflecting surface (6).

5. A high-precision dual-range infrared gas sensor as claimed in claim 2, characterized in that: The first reflection surface (1) is used to gather the light emitted by the first light source (7) and reflect it to the third reflection surface (3) or the fourth reflection surface (4), and the first reflection surface (1) is a parabolic reflection surface or an elliptical reflection surface.

6. A high-precision dual-range infrared gas sensor as claimed in claim 2, characterized in that: The second reflection surface (2), the third reflection surface (3) and the fourth reflection surface (4) are arc reflection surfaces or plane reflection surfaces.

7. A high-precision dual-range infrared gas sensor as claimed in claim 2, characterized in that: The fifth reflecting surface (5) is used to collect the light emitted by the second light source (8) and reflect it to the sixth reflecting surface (6).

8. A high-precision dual-range infrared gas sensor as claimed in claim 2, characterized in that: The sixth reflection surface (6) is used to reflect the reflected light parallel to the bottom surface of the chamber 10 to the infrared detector (9), and the sixth reflection surface (6) forms an angle of 45° with the bottom surface of the chamber 10.

9. A high-precision dual-range infrared gas sensor as claimed in claim 2, characterized in that: The long optical path air chamber L1 includes two optical paths, namely the first optical path and the second optical path; the short optical path air chamber L2 adopts the third optical path; wherein: First optical path: light is emitted from the first light source (7), passes through the first reflection surface (1), the fourth reflection surface (4), the second reflection surface (2) and the sixth reflection surface (6), and then enters the infrared detector (9); Second optical path: light is emitted from the first light source (7), passes through the first reflection surface (1), the third reflection surface (3) and the sixth reflection surface (6), and then enters the infrared detector (9); Third optical path: light is emitted from the second light source (8), passes through the fifth reflecting surface (5) and the sixth reflecting surface (6), and then enters the infrared detector (9).

10. A high-precision dual-range infrared gas analysis method, applied to a high-precision dual-range infrared gas sensor as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following steps: S1, the control unit sends an initial control signal to control the first light source (7) and the second light source (8) to flash alternately; S2, an operational amplifier circuit samples a signal value C1 of a long optical path air chamber L1 and a signal value C2 of a short optical path air chamber L2 from an infrared detector (9); S3, fitting a linear formula D1=f(C1) according to the calibration data of the long optical path gas chamber L1, and calculating the gas concentration D1; fitting a linear formula D2=f(C2) according to the calibration data of the short optical path gas chamber L2, and calculating the gas concentration D2; S4. Determine whether the current concentration is in the low range, high range or mid range. If it is in the low range, output the gas concentration D1; if it is in the high range, output the gas concentration D2, otherwise output the comprehensive calculated value k*D1+(1-k)*D2.

Images