Infrared gas analyzer

Abstract

The invention provides an infrared gas analyzer, and relates to the field of gas analyzers. The infrared gas analyzer comprises a product shell, and a light source, a light filter and a diaphragm receiver which are arranged in the product shell, and further comprises a self-rotating light chopper which is arranged between the light source and the light filter, and further comprises a detection chamber and a reference chamber which are arranged in the product shell, and the air inlet and outlet assembly is arranged in the product shell and is connected with the detection chamber. According to the infrared gas analyzer, vortex dispersion of entering gas flow can be realized by utilizing the detection chamber, so that the light absorption condition of different gases can be more easily tested during light irradiation, the problem of large error of a test structure caused by non-uniform gas concentration is avoided, and the interior of the detection chamber can be emptied by the negative pressure pump after gas inlet detection is stopped, so that the detection efficiency is improved. Therefore, the detection chamber is directly maintained, and the problem of inaccurate test structure caused by pollution in the later period is avoided.

Description

Technical Field

[0001] The present invention relates to the field of gas analyzers, and more particularly to an infrared gas analyzer. Background Art

[0002] An infrared gas analyzer uses infrared rays for gas analysis. Based on the different concentrations of the components to be analyzed, the absorbed radiant energy is different, and the remaining radiant energy causes different temperature increases in the detector. The pressures on both sides of the moving film are different, thus generating an electrical signal of a capacitance detector. In this way, the concentration of the component to be analyzed can be indirectly measured.

[0003] However, the current infrared gas analyzers still have the following disadvantages: First, there is cross-interference between gases. For the gases flowing in the detection chamber, if there is cross-interference, the absorption of light will fluctuate, so there will be small errors in the measurement data. Second, the detection chamber cannot be kept pure when there is no detection, so the machine needs to be frequently maintained. Once precise cleaning is not done before detection, the measurement results will not be accurate enough.

[0004] Third, the power sources of the light-shielding plates are generally installed unreasonably, so the light source cannot be evenly distributed in the reference chamber and the detection chamber. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides an infrared gas analyzer, which solves the problems raised in the above background art.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: An infrared gas analyzer includes a product housing and a light source, a filter, and a diaphragm receiver installed inside the product housing. It also includes a self-rotating light-shielding device disposed between the light source and the filter, and a detection chamber and a reference chamber installed in the product housing, disposed between the filter and the diaphragm receiver. It further includes an air inlet and outlet assembly installed in the product housing, which is connected to the detection chamber and is used for filtering and pressurizing the incoming air, evacuating the internal gas of the detection chamber under negative pressure when the air intake stops, and stopping the negative pressure when actively admitting air. The gas entering the detection chamber can maintain a low-speed spin from the inlet to the outlet.

[0007] Preferably, the detection chamber includes a reflection tube and window plates installed at both ends of the reflection tube. It also includes two intake pipes, which are obliquely installed on the reflection tube and are inclined towards the direction of gas flow. At the positions corresponding to the intake pipes on the inner wall of the reflection tube, two eddy current plates are installed, and the eddy current plates are on the side of the air outlet of the intake pipe. A circle of distributed air outlets is provided on the outer wall at the other end of the reflection tube, and the air outlets and the intake pipes are used to connect the air inlet and outlet assembly to realize the gas path circulation.

[0008] Preferably, an air sleeve is fixedly sleeved on the outer wall of the reflection tube corresponding to the position of the air outlet. The air outlets are all communicated with the inner cavity of the air sleeve, and the air sleeve is connected to the air inlet and outlet assembly.

[0009] Preferably, the air inlet and outlet assembly includes an air inlet passage, a constant pressure member, an electronically controlled three-way air outlet, and a negative pressure pump. One end of the air inlet passage is installed on the product housing and communicated with the outside, and the other end is connected to the constant pressure member. The air outlet end of the constant pressure member is further divided into two air passages and respectively connected to two air inlet pipes; One end of the electronically controlled three-way air outlet is connected to the air sleeve, the other end is connected to the outside of the product housing and communicated with the outside, and a negative pressure pipe is installed at the last end. The negative pressure pipe is connected to the negative pressure pump. The electronically controlled three-way air outlet is used to control the air sleeve to disconnect the negative pressure pipe and directly communicate with the outside of the product housing, and is also used to control the air sleeve to disconnect the connection with the outside and directly communicate with the negative pressure pipe. At this time, the negative pressure pump starts to operate; When the air inlet passage operates, the constant pressure member can control the negative pressure pump to stop pumping air from the negative pressure pipe.

[0010] Preferably, the constant pressure member includes a sleeve, a core shaft, a piston, a stopper, and a spring. The stopper is arranged in the sleeve, dividing the sleeve into two cavities with different sizes. The piston is connected to the core shaft and is inside the large cavity of the sleeve. The piston seals the sleeve. The spring is outside the core shaft and connects the piston to the inner bottom wall of the sleeve. The air inlet passage is communicated with the small cavity of the sleeve, and the air inlet pipe is communicated with the large cavity of the sleeve. When air enters the air inlet passage, the piston moves to compress the spring and makes the core shaft extend out of the sleeve until the piston moves to the air inlet pipe to exhaust air; When the core shaft extends out of the sleeve, it can close the negative pressure pump.

[0011] Preferably, the two eddy current plates and the two air inlet pipes are distributed relatively at 180 degrees. The expansion angle of the eddy current plate is 90 degrees, and it is a spiral structure.

[0012] Preferably, the rotary light shutter includes a housing and a light shielding sheet. The housing is a ring-shaped structure and is installed on the light source. The light shielding sheet is inside the housing. A motor is installed outside the housing, and the motor uses gears to engage the outer ring of the light shielding sheet to control the rotation of the light shielding sheet.

[0013] Preferably, annular grooves are provided on the outer circles of both sides of the light shielding sheet. The corresponding positions of the housing have the same structure as it, and a number of rollers are provided in the grooves of the two.

[0014] Preferably, a moisture absorber and an air pump are respectively installed on the air inlet passage.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The infrared gas analyzer can achieve the vortex dispersion of the incoming air flow by using the detection chamber. The air flow gradually enters and then disperses out after dispersion. Thus, when the light is irradiated, it is easier to measure the absorption of different gases by the light, avoiding the problem of large errors in the test results caused by uneven gas concentration.

[0016] 2. When the infrared gas analyzer intakes air, it can first use a negative pressure pump to evacuate the gas inside the detection chamber. As the air gradually intakes, the air pressure inside the detection chamber is then balanced. Thus, during detection, the initial gas is purer, the test results are more accurate, and once the air intake for detection stops, the negative pressure pump will evacuate the inside of the detection chamber again, directly maintaining the detection chamber and avoiding inaccurate test results caused by pollution problems later.

[0017] 3. For the infrared gas analyzer, the power source of the light shield is not concentrated at the center of the circle, thus avoiding the power source from blocking the infrared light source. Using the form of outer ring meshing drive, while increasing the rotation speed, it does not affect the irradiation of the light source, thus avoiding complex position designs and improving the test accuracy.

[0018] 4. If the pressure of the incoming gas fluctuates, the piston moves under the reaction force of the spring, and the negative pressure pump starts in time to quickly evacuate the gas to be detected inside. Therefore, the gas that enters again after the fluctuation is not affected by the previous gas, and the detection result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is an internal structural diagram of the product shell of the present invention; Figure 3 is a top view of the structure of the product shell of the present invention; Figure 4 is a partial structural diagram of the present invention; Figure 5 is a structural diagram of the self-rotating light shield of the present invention; Figure 6 is a structural diagram of the air inlet / outlet assembly and the reflection tube of the present invention; Figure 7 is the present invention Figure 6 is an enlarged view of the structure at A in; Figure 8 is a structural diagram of the detection chamber of the present invention; Figure 9 is an internal structural diagram of the reflection tube of the present invention.

[0020] In the figure: 1. Rotary light shifter; 101. Sheath; 102. Light-shielding piece; 103. Motor; 2. Detection chamber; 201. Reflection tube; 202. Window piece; 203. Air inlet pipe; 204. Vortex piece; 205. Air outlet; 206. Air jacket; 3. Reference chamber; 4. Air inlet and outlet assembly; 401. Air inlet path; 402. Constant pressure part; 4022. Sleeve; 4023. Core shaft; 4024. Piston; 4025. Limiter; 4026. Spring; 403. Electrically controlled three-way air outlet; 404. Negative pressure pump; 405. Negative pressure pipe; 406. Moisture absorber; 407. Air pump. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0022] It should be noted that all the directional indications in the embodiments of the present application are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If this specific posture changes, the directional indications will also change accordingly.

[0023] In the present application, unless otherwise clearly specified and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0024] In addition, in the present application, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0025] Such as Figures 1-9As shown, an infrared gas analyzer includes a product housing and a light source, a filter and a diaphragm receiver installed inside the product housing, and also includes a self-rotating shade 1, which is arranged between the light source and the filter, and also includes a detection chamber 2 and a reference chamber 3 installed in the product housing, which are arranged between the filter and the diaphragm receiver, and also includes an air inlet and outlet assembly 4 installed in the product housing, the air inlet and outlet assembly 4 is connected to the detection chamber 2, and is used for filtering pressurized incoming air, emptying the internal gas of the detection chamber 2 with negative pressure when the air intake is stopped, and stopping the negative pressure when the air intake is active, so that the gas entering the detection chamber 2 can maintain low-speed rotation from entry to exit.

[0026] The infrared gas analyzer is a new type of intelligent analyzer developed by combining the NDIR and GFC principles with new microcomputer technology. It adopts the principle of non-dispersive infrared absorption spectroscopy. When infrared light of a specific wavelength passes through the gas to be measured, the gas absorbs the light energy, and the concentration of the corresponding gas can be detected. At the same time, the module adds a related round filter, which can effectively reduce the cross-interference of the background gas, and can be used to continuously analyze the concentration of one or several gas components to be measured in the mixed gas. The product shell can be customized according to the actual usage scenario, and can be embedded or placed horizontally.

[0027] The product shell is equipped with a TFT true color display screen, which can simultaneously display the measured value, historical curve, range, status, and various parameter setting interfaces; the configuration, calibration, and test of various instrument parameters can be carried out in the form of a full Chinese touch menu, and historical records and curves can be set according to time and other quick operations, and the Chinese and English menus can be switched with one key; it has a built-in voltage and current stabilizing device; control contact output, over-limit self-alarm (buzzer), and the control mode can be set at will; and it is equipped with standard 4~20mA current output, RS-232 or RS-485 (either one can be selected) and other external ports; Ethernet port, etc.

[0028] The light source can be a single beam: simple structure, low cost, but susceptible to light source fluctuations, or a double beam: the reference beam compensates for light source fluctuations and has high stability.

[0029] The filter uses multi-layer dielectric films such as ZnS / MgF2 alternating coating, up to 50 layers. It is a key optical component in the infrared gas analyzer. Its performance directly affects the detection selectivity and sensitivity, and is used to filter out interference bands.

[0030] The structure of the reference chamber 3 is basically the same as that of the detection chamber 2, and the interior of the reference chamber 3 is filled with nitrogen that does not absorb infrared light.

[0031] In an optional embodiment, the detection chamber 2 includes a reflection tube 201 and window plates 202 installed at both ends of the reflection tube 201. It further includes two intake pipes 203, which are obliquely installed on the reflection tube 201 and inclined towards the direction of gas flow. At the positions of the reflection tube 201's inner wall corresponding to the intake pipes 203, two eddy current plates 204 are installed. The eddy current plates 204 are on the side where the intake pipes 203 discharge air. On the outer wall of the other end of the reflection tube 201, there is a circle of distributed air outlets 205. The air outlets 205 and the intake pipes 203 are used to connect to the air inlet and outlet assembly 4 to realize the air circuit circulation.

[0032] In this embodiment, the detection chamber adopts the White cell optical structure, which can provide an actual optical path of 6m, greatly increasing the optical path within a limited gas chamber size range, thereby improving the instrument resolution. The inner wall of the reflection tube 201 is gold-plated or polished aluminum, with a reflectivity > 95%. The eddy current plates 204 are welded inside the reflection tube 201 without blocking the window plates 202. The window plate material is CaF2 (2 - 10μm, ZnSe 0.5 - 20μm or sapphire UV - IR).

[0033] In an optional embodiment, a gas sleeve 206 is fixedly sleeved on the outer wall of the reflection tube 201 at the position corresponding to the air outlets 205. The air outlets 205 are all communicated with the internal cavity of the gas sleeve 206, and the gas sleeve 206 is connected to the air inlet and outlet assembly 4.

[0034] In this embodiment, the gas sleeve 206 seals the outer wall of the reflection tube 201. At the same time, an electromagnetic valve is provided inside the gas sleeve 206, which can be controlled to open and close using an electrical signal.

[0035] In an optional embodiment, the air inlet and outlet assembly 4 includes an air inlet path 401, a constant pressure component 402, an electronically controlled gas outlet three-way valve 403, and a negative pressure pump 404. One end of the air inlet path 401 is installed on the product housing and communicated with the outside, and the other end is connected to the constant pressure component 402. The air outlet end of the constant pressure component 402 branches out two gas paths and is respectively connected to the two intake pipes 203; One end of the electronically controlled gas outlet three-way valve 403 is connected to the gas sleeve 206, the other end is connected outside the product housing and communicated with the outside, and the last end is equipped with a negative pressure pipe 405. The negative pressure pipe 405 is connected to the negative pressure pump 404. The electronically controlled gas outlet three-way valve 403 is used to control the gas sleeve 206 to disconnect the negative pressure pipe 405 and directly communicate with the outside of the product housing, and is also used to control the gas sleeve 206 to disconnect the connection with the outside and directly communicate with the negative pressure pipe 405. At this time, the negative pressure pump 404 starts to operate; When the air inlet path 401 is operating, the constant pressure component 402 can control the negative pressure pump 404 to stop pumping air from the negative pressure pipe 405.

[0036] In this embodiment, the air inlet path 401 is responsible for connecting to the pipeline of the outside detection gas. The air inlet path 401 has an interface outside the product housing for realizing the quick connection of the detection gas pipeline.

[0037] The electronically controlled three-way air outlet 403 is composed of multiple solenoid valves, and one of the paths can be individually closed during use.

[0038] In an alternative embodiment, the constant pressure member 402 includes a sleeve 4022, a mandrel 4023, a piston 4024, a stopper 4025, and a spring 4026. The stopper 4025 is disposed in the sleeve 4022, dividing the sleeve 4022 into two cavities of different sizes. The piston 4024 is connected to the mandrel 4023 and is located inside the large cavity of the sleeve 4022. The piston 4024 seals the sleeve 4022. The spring 4026 is outside the mandrel 4023 and connects the piston 4024 to the inner bottom wall of the sleeve 4022. The air inlet passage 401 communicates with the small cavity of the sleeve 4022, and the intake pipe 203 communicates with the large cavity of the sleeve 4022. When air enters through the air inlet passage 401, the piston 4024 moves to compress the spring 4026 and causes the mandrel 4023 to extend out of the sleeve 4022 until the piston 4024 moves to the exhaust of the intake pipe 203. The mandrel 4023 extending out of the sleeve 4022 can close the negative pressure pump 404.

[0039] In this embodiment, a position sensor is installed on the switch of the negative pressure pump 404, and a sensor kit is attached to the mandrel 4023. When the mandrel 4023 extends out of the sleeve 4022, the negative pressure pump 404 is controlled to close by the position sensor.

[0040] The stopper 4025 inside the sleeve 4022 can prevent the problem that the piston 4024 moves excessively, resulting in difficulty in pushing the piston 4024 by the later air pressure.

[0041] In an alternative embodiment, the two eddy current plates 204 and the two intake pipes 203 are distributed 180 degrees opposite to each other. The expansion angle of the eddy current plate 204 is 90 degrees, and it has a spiral structure.

[0042] In this embodiment, the eddy current plate 204 has a certain pitch, which can make the incoming air flow in a rotating state, and the blowing direction of the intake pipe 203 just corresponds to the eddy current plate 204.

[0043] In an alternative embodiment, the self-rotating light shutter 1 includes a housing 101 and a light-shielding sheet 102. The housing 101 has an annular structure and is installed on the light source. The light-shielding sheet 102 is inside the housing 101. A motor 103 is installed outside the housing 101, and the motor 103 controls the rotation of the light-shielding sheet 102 by engaging with the outer ring of the light-shielding sheet 102 through gears.

[0044] In this embodiment, the light-shielding sheet 102 is a key modulation component in the infrared gas analyzer, which converts the continuous optical signal into an alternating signal by periodically blocking the optical path. The outer ring of the light-shielding sheet 102 is provided with tooth grooves, which are engaged with the gear. The motor 103 can be rotated externally to drive the light-shielding sheet 102 to rotate.

[0045] In an alternative embodiment, annular grooves are provided at the outer rings of both sides of the light-shielding sheet 102, and the corresponding positions of the housing 101 have the same structure as it. A number of rollers are provided in the grooves of both of them.

[0046] In this embodiment, it is easier to break through the speed limit of the light-shielding sheet 102 by using the rollers, and it can be used for a long time without wear.

[0047] In an alternative embodiment, a moisture absorber 406 and an air pump 407 are respectively installed on the air inlet path 401.

[0048] In this embodiment, in the infrared gas analyzer, the moisture absorber 406 is used to eliminate the interference of water vapor in the sample gas on the detection. Especially when measuring gases such as CO2, CO, and SO2, the infrared absorption peaks of water (such as 2.7 μm and 6.2 μm) will overlap with the absorption peaks of the target gas, resulting in measurement errors. Molecular sieve or silica gel can be used.

[0049] During use, turn on the power supply, the electronically controlled three-way gas outlet 403 operates, and the communication between the closed gas jacket 206 and the outside is blocked. At this time, the negative pressure pump 404 starts to operate. The negative pressure pump 404 evacuates the inside of the reflection tube 201 by using the negative pressure tube 405. The light source emits infrared light, which passes through the rotary light-shielding device 1, and then is filtered by the filter, and is respectively irradiated onto the detection chamber 2 and the reference chamber 3. The rotary light-shielding device 1 can freely control the rotation speed as the motor 103 operates, and the motor 103 is arranged above the light source without affecting the irradiation of the light source. Subsequently, the air inlet path 401 is opened, and the air pump 407 starts to pump the gas to be detected. The gas enters and is first dehumidified, and then enters the constant pressure member 402. The gas entering the constant pressure member 402 uses the pressure to push the piston 4024 until the spring 4026 is compressed and the core shaft 4023 moves out of the sleeve 4022. After the core shaft 4023 moves out of the sleeve 4022, the operation of the negative pressure pump 404 can be controlled by detecting the position of the sensor or the change of the electrical signal. If the air pressure index extracted by the negative pressure meets the requirements at this time, then the negative pressure pump 404 stops automatically.

[0050] After the gas passes through the sleeve 4022 and enters the reflection tube 201, the gas enters from the direction of the two intake pipes 203. After entering, the gas blows towards the eddy current piece 204 and then rotates. Since the air outlet 205 is distributed annularly along the reflection tube 201, the gas can be discharged all around. Therefore, the gas passing through the reflection tube is in a state of low-speed rotation, so that the infrared rays can be well absorbed by the gas to be detected when passing through. Once the pressure of the incoming gas fluctuates, the piston 4024 moves under the reaction force of the spring 4026, and the negative pressure pump 404 starts in time and can quickly evacuate the gas to be detected inside. Therefore, the gas entering again after the fluctuation is not affected by the previous gas, and the detection result is more accurate.

[0051] After the subsequent detection is completed, once the intake of the detection is stopped, the negative pressure pump 404 will evacuate the inside of the detection chamber 2 again, thereby directly maintaining the detection chamber 2 and avoiding inaccurate test results caused by pollution problems in the later stage.

[0052] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0053] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions conflicts with each other or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0054] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An infrared gas analyzer, comprising a product housing, a light source, a filter, and a diaphragm receiver installed inside the product housing, characterized in that: It also includes a rotary shutter (1) provided between the light source and the filter, a detection chamber (2) and a reference chamber (3) installed in the product housing, provided between the filter and the diaphragm receiver, and an air inlet and outlet assembly (4) installed in the product housing. The air inlet and outlet assembly (4) is connected to the detection chamber (2) and is used for filtering and pressurizing the incoming air, evacuating the internal gas of the detection chamber (2) under negative pressure when the incoming air stops, and stopping the negative pressure during active air intake. The gas entering the detection chamber (2) can maintain a low-speed spin from inlet to outlet.

2. The infrared gas analyzer according to claim 1, characterized in that: The detection chamber (2) includes a reflection tube (201) and window panes (202) installed at both ends of the reflection tube (201). It also includes two intake pipes (203) which are obliquely installed on the reflection tube (201) and inclined towards the direction of gas flow. At the position of the reflection tube (201) corresponding to the intake pipes (203), two eddy current plates (204) are installed on the inner wall of the reflection tube (201). The eddy current plates (204) are on the side where the intake pipes (203) discharge air. A circle of distributed air outlets (205) is provided on the outer wall of the other end of the reflection tube (201). The air outlets (205) and the intake pipes (203) are used to connect to the air inlet and outlet assembly (4) to realize the air path circulation.

3. The infrared gas analyzer according to claim 2, wherein: A gas sleeve (206) is fixedly sleeved on the outer wall of the reflection tube (201) corresponding to the position of the air outlets (205). The air outlets (205) are all communicated with the internal cavity of the gas sleeve (206), and the gas sleeve (206) is connected to the air inlet and outlet assembly (4).

4. The infrared gas analyzer according to claim 3, characterized in that: The air inlet and outlet assembly (4) includes an intake air path (401), a constant pressure component (402), an electronically controlled gas outlet tee (403), and a negative pressure pump (404). One end of the intake air path (401) is installed on the product housing and communicated with the outside, and the other end is connected to the constant pressure component (402). The gas outlet end of the constant pressure component (402) branches out into two gas paths and is respectively connected to the two intake pipes (203). One end of the electronically controlled gas outlet tee (403) is connected to the gas sleeve (206), the other end is connected outside the product housing and communicated with the outside, and a negative pressure pipe (405) is installed at the last end. The negative pressure pipe (405) is connected to the negative pressure pump (404). The electronically controlled gas outlet tee (403) is used to control the gas sleeve (206) to disconnect the negative pressure pipe (405) and directly communicate with the outside of the product housing, and is also used to control the gas sleeve (206) to disconnect the connection with the outside and directly communicate with the negative pressure pipe (405). At this time, the negative pressure pump (404) starts to operate. When the intake air path (401) operates, the constant pressure component (402) can control the negative pressure pump (404) to stop pumping air from the negative pressure pipe (405).

5. The infrared gas analyzer according to claim 4, wherein: The constant pressure member (402) includes a sleeve (4022), a mandrel (4023), a piston (4024), a stopper (4025) and a spring (4026). The stopper (4025) is arranged in the sleeve (4022) and divides the sleeve (4022) into two cavities with different sizes. The piston (4024) is connected to the mandrel (4023) and is located inside the large cavity of the sleeve (4022). The piston (4024) seals the sleeve (4022). The spring (4026) is located outside the mandrel (4023) and connects the piston (4024) to the inner bottom wall of the sleeve (4022). The air inlet passage (401) is communicated with the small cavity of the sleeve (4022), and the air inlet pipe (203) is communicated with the large cavity of the sleeve (4022). When air enters through the air inlet passage (401), the piston (4024) moves to compress the spring (4026) and makes the mandrel (4023) extend out of the sleeve (4022) until the piston (4024) moves to the exhaust port of the air inlet pipe (203). The mandrel (4023) extending out of the sleeve (4022) can close the negative pressure pump (404).

6. The infrared gas analyzer according to claim 5, wherein: The two eddy current plates (204) and the two air inlet pipes (203) are distributed relatively at 180 degrees. The expansion angle of the eddy current plate (204) is 90 degrees, and it has a spiral structure.

7. The infrared gas analyzer according to claim 6, wherein: The rotary light shutter (1) includes a housing (101) and a light shielding sheet (102). The housing (101) has an annular structure and is installed on the light source. The light shielding sheet (102) is located inside the housing (101). A motor (103) is installed outside the housing (101). The motor (103) controls the rotation of the light shielding sheet (102) by meshing with the outer ring of the light shielding sheet (102).

8. The infrared gas analyzer according to claim 7, characterized in that: Annular grooves are provided at the outer circles on both sides of the light shielding sheet (102). The housing (101) has the same structure at the corresponding position. A number of rollers are provided in the grooves of both of them.

9. The infrared gas analyzer according to claim 4, characterized in that: A water absorber (406) and an air pump (407) are respectively installed on the air inlet passage (401).

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