Ambient air condensate water sampler

Abstract

The invention relates to the technical field of environment monitoring equipment, and discloses an ambient air condensate water sampler which comprises a support, a protective cover is arranged on the support, an observation window is arranged on the outer side of the protective cover, a conical top plate is fixed to the top end of the protective cover, a sliding rod is arranged in the support in a sliding mode, and the sliding rod is arranged in the support. A limiting ring is fixed at the end part of the sliding rod; the air inlet assembly is arranged on the protective cover and used for guiding air into the device; the exhaust assembly is arranged at the bottom of the outer side of the protective cover and used for exhausting the condensed and dewatered air; and the condensation assembly is arranged on the limiting ring, the condensation assembly comprises a condensation bottle, and the outer wall of the condensation bottle is attached to the inner side of the limiting ring. Through cooperation of internal structures of the condensation assembly, continuous and stable refrigeration of the condensation bottle is achieved, the effective low-temperature working time is prolonged, and the effect of rapid replacement of the condensation core is achieved through a magnetic attraction structure.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring equipment, in particular to an environmental air condensate sampler. Background Art

[0002] The atmospheric environment is extremely complex, containing a large number of suspended aerosols, soluble ions, and various pollutants. Atmospheric condensate sampling, as a technique that can directly enrich these water-soluble substances, is of great significance for environmental monitoring and pollution source tracing. By analyzing the composition of condensate, we can effectively obtain first-hand data on the atmospheric quality of a specific area, providing a basis for scientific research and decision-making on environmental governance.

[0003] Existing atmospheric condensate sampling technology has many limitations. A common method is to use a pre-frozen container as a condensation surface. The core limitation of this method is that the cold source is consumable. The ice will continue to melt during the sampling process, causing the temperature of the condensation surface to continue to rise, which directly weakens the temperature difference between it and the air, causing the condensation efficiency to drop significantly over time. Therefore, stable, long-term continuous sampling cannot be achieved. More importantly, the current equipment has a very simple way to collect condensed water, usually by introducing it into a simple collection bottle. All liquids condensed at different time points are mixed together, which causes the sample to lose resolution in the time dimension. Researchers cannot know whether there are peaks and valleys in pollutant concentrations at dawn or dusk or at noon, and the valuable information in the time series is completely lost after averaging.

[0004] Furthermore, many passive sampling devices have inherent flaws in their aerodynamic design. They rely on weak natural temperature convection to guide airflow, which is not only slow but also easily disturbed by external winds, resulting in low sampling efficiency. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides an ambient air condensate sampler, which solves the problem that the traditional single frozen bottle sampling method has poor low-temperature endurance and cannot perform long-term continuous sampling due to the melting of ice cubes.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: an ambient air condensation water sampler, comprising: a bracket, a protective cover is provided on the bracket, an observation window is provided on the outer side of the protective cover, a conical top plate is fixed on the top of the protective cover, a sliding rod is slid inside the bracket, and a limiting ring is fixed on the end of the sliding rod; an air intake assembly is provided on the protective cover for introducing air into the interior of the device; an exhaust assembly is provided at the outer bottom of the protective cover for discharging the air after condensation and dehydration; a condensation assembly is provided on the limiting ring, the condensation assembly includes a condensation bottle, the outer wall of the condensation bottle is attached to the inner side of the limiting ring, a heat conduction plate is fixed on the outer wall of the condensation bottle, a plurality of magnet blocks are fixed on the outer side of the heat conduction plate, a cooling plate is passed through the outer side of the protective cover, a magnet ring is fixed on the outer wall of the cooling plate, and the cooling surface of the cooling plate and the outer wall of the heat conduction plate are attached through the magnet ring and the magnet block; a collecting assembly is provided on the bracket for collecting water droplets generated after condensation.

[0007] Preferably, the internal thread of the limiting ring is connected with a fixing bolt, and the end of the fixing bolt is fitted on the outer wall of the condensation bottle.

[0008] Preferably, a plurality of heat sinks are fixed to the heating surface of the refrigeration fin, and a fan is fixed to the outer wall of the heat sink.

[0009] Preferably, a fixing frame is fixed to the outer wall of the bracket, a funnel is placed on the fixing frame, the outer wall of the funnel is arranged directly below the heat conduction plate and the condensation bottle, and a hose is fixed to the bottom end of the funnel.

[0010] Preferably, the collecting assembly includes a collecting bottle, the lower surface of which is arranged on a bracket, the top of the collecting bottle is threadedly connected to a top cover, the top of the top cover is slidably provided with a sealing plug, and the inner wall of the sealing plug fits the outer wall of the hose.

[0011] Preferably, a fixing plate is fixed to the inner wall of the collecting bottle, and a chamber one is fixed to the outer wall of the fixing plate, the outer wall of the chamber one is arranged above the interior of the collecting bottle, one end of the hose is arranged inside the chamber one, a guide tube one is passed through above the outer side of the chamber one, a chamber two is arranged above the inner wall of the collecting bottle, the end of the guide tube one is arranged inside the chamber two, the chamber two is arranged on one side of the chamber one, a chamber three is arranged below the inner wall of the collecting bottle, a guide tube two is passed through the outer side of the chamber two, the end of the guide tube two is fixed inside the chamber three, the outer wall of the chamber three is arranged on the other side of the chamber one, and the tops of the chamber three and chamber two are both provided with sealing plates, and the outer wall of the guide tube one slides inside the sealing plate.

[0012] Preferably, the air intake assembly includes an air intake pipe, and an end portion of the air intake pipe passes through the outside of the protective cover.

[0013] Preferably, a rubber sleeve is slidably provided on the air inlet end of the air inlet pipe, a filter is fixed inside the rubber sleeve, the outer wall of the filter is arranged below the air inlet end of the air inlet pipe, and a plurality of anti-slip strips are provided on the outer wall of the rubber sleeve.

[0014] Preferably, the exhaust assembly includes an exhaust pipe, and an end portion of the exhaust pipe passes through the outer side and below the protective cover.

[0015] Preferably, a plurality of connection blocks are fixed to the end of the exhaust pipe, an exhaust fan is fixed to the outer wall of the connection block, the outer wall of the exhaust fan is arranged at the air outlet end of the exhaust pipe, and a thermal gas flow meter is arranged inside the exhaust pipe.

[0016] The present invention provides an ambient air condensate sampler. It has the following beneficial effects:

[0017] 1. The present invention achieves continuous and stable refrigeration of the condensation bottle and extended effective low-temperature working time through the coordination between the internal structures of the condensation components, and realizes the rapid removal and replacement of the condensation core through the magnetic attraction structure, thereby solving the problem of poor low-temperature endurance and inability to perform long-term continuous sampling in the traditional single frozen bottle sampling method due to the melting of ice cubes.

[0018] 2. The present invention achieves the function of automatically separating condensed water samples collected in different time periods and sequentially injecting them into different chambers for independent storage by utilizing the coordination between the internal structures of the collection components without human intervention through the principle of gravity overflow. This solves the problems of the traditional single-bottle collection method that can only obtain mixed average samples and cannot analyze the dynamic changes of indicators such as pollutant concentration or water vapor isotopes over time, and that relies on manual timed replacement of sample bottles, which is cumbersome, labor-intensive, and prone to operational errors.

[0019] 3. The present invention achieves the effect of actively, uniformly and measurably guiding the external air to flow through the condensation system and physically filtering and purifying the incoming gas through the cooperation between the air intake component and the exhaust component, thereby solving the problems of passive sampling method relying on natural temperature difference convection, slow and uncontrollable air flow speed, low sampling efficiency, and difficulty in accurately quantifying the analysis results due to the inability to accurately calculate the total volume of the sampled air. At the same time, the design of the inverted air inlet effectively avoids direct contamination of the sample by vertical dust. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A perspective view of the present invention;

[0021] Figure 2 It is a schematic diagram of the structure of the protective cover of the present invention;

[0022] Figure 3It is a structural schematic diagram of the sliding rod portion of the present invention;

[0023] Figure 4 This is a schematic diagram of the structure of the bracket part of the present invention;

[0024] Figure 5 This is a partial structural diagram of the condensation bottle of the present invention;

[0025] Figure 6 It is a schematic diagram of the structure of the refrigeration plate of the present invention;

[0026] Figure 7 This is a schematic diagram of the internal structure of the collecting bottle of the present invention;

[0027] Figure 8 Schematic diagram of the structure of the chamber of the present invention.

[0028] Figure 9 It is a schematic diagram of the structure of the air intake pipe of the present invention;

[0029] Figure 10 It is a partial structural schematic diagram of the exhaust pipe of the present invention.

[0030] Among them, 1. Bracket; 2. Protective cover; 3. Conical top plate; 4. Inlet assembly; 401. Inlet pipe; 402. Rubber sleeve; 403. Filter; 404. Anti-slip strip; 5. Exhaust assembly; 501. Exhaust pipe; 502. Connecting block; 503. Exhaust fan; 504. Thermosensitive gas flow meter; 6. Condensation assembly; 601. Condensation bottle; 602. Heat conduction plate; 603. Magnet block; 604. Refrigeration plate; 605. Magnet ring; 606, heat sink; 607, fan; 7, funnel; 8, hose; 9, collection assembly; 901, collection bottle; 902, sealing plug; 903, fixing plate; 904, chamber one; 905, guide tube one; 906, chamber two; 907, sealing plate; 908, guide tube two; 909, chamber three; 910, top cover; 10, observation window; 11, sliding rod; 12, limiting ring; 13, fixing bolt; 14, fixing bracket. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Please see the attached Figure 1 -Attached Figure 6, an embodiment of the present invention provides an ambient air condensation water sampler, comprising: a bracket 1, a protective cover 2 is provided on the bracket 1, an observation window 10 is provided on the outer side of the protective cover 2, a conical top plate 3 is fixed to the top of the protective cover 2, a sliding rod 11 is slid inside the bracket 1, and a limiting ring 12 is fixed to the end of the sliding rod 11; an air intake component 4, which is provided on the protective cover 2 and is used to introduce air into the interior of the device; an exhaust component 5, which is provided on the outer bottom of the protective cover 2 and is used to discharge the air after condensation and dehydration; a condensation component 6, which is provided on the limiting ring 12, and the condensation component 6 includes a condensation bottle 601, the outer wall of the condensation bottle 601 is attached to the inner side of the limiting ring 12, and the condensation bottle 60 1 is fixed with a heat conducting plate 602 on the outer wall, and a plurality of magnet blocks 603 are fixed on the outer side of the heat conducting plate 602. A cooling fin 604 is passed through the outer side of the protective cover 2, and a magnet ring 605 is fixed to the outer wall of the cooling fin 604. The cooling surface of the cooling fin 604 and the outer wall of the heat conducting plate 602 are fitted together through the magnet ring 605 and the magnet block 603; a collecting component 9 is arranged on the bracket 1 and is used to collect water droplets generated after condensation. The internal thread of the limiting ring 12 is connected with a fixing bolt 13, and the end of the fixing bolt 13 is fitted on the outer wall of the condensation bottle 601. A plurality of heat sinks 606 are fixed to the heating surface of the cooling fin 604, and a fan 607 is fixed to the outer wall of the heat sink 606.

[0033] Specifically, a stable working cavity is constructed by the bracket 1 and the protective cover 2, and the direct interference of the external environment is effectively avoided through the conical top plate 3. The device works in conjunction with a set of precise condensation components 6 to achieve efficient and sustainable atmospheric moisture capture. When working, the pre-frozen condensation bottle 601 is placed as the core cold source, and is accurately positioned horizontally and vertically by adjusting the sliding rod 11, and then the fixing bolt 13 is tightened to provide a stable mechanical lock. During the sampling process, the refrigeration plate 604 starts to work continuously, and the cold energy is continuously compensated to the condensation bottle 601 through the heat conduction plate 602, which greatly delays the melting rate of the ice inside it. degree, ensuring the temperature constancy of the condensation surface throughout the sampling process, and the heat of the refrigeration plate 604 is quickly taken away by the forced air cooling system composed of the heat sink 606 and the fan 607, avoiding the backflow of heat to affect the cooling efficiency. The significant beneficial effect of this design is that it not only solves the problems of short sampling time and rapid efficiency decay of the traditional method, but also realizes the tool-free rapid replacement of the condensation bottle 601 through the magnetic adsorption function of the magnet block 603 and the magnet ring 605, which greatly improves the convenience and continuity of on-site operations. The user can also monitor the condensation status in real time through the observation window 10, ensuring the high controllability and sample representativeness of the entire sampling process.

[0034] Please see the attached Figure 6 -Attached Figure 8, the outer wall of the bracket 1 is fixed with a fixing bracket 14, a funnel 7 is placed on the fixing bracket 14, the outer wall of the funnel 7 is arranged just below the heat conducting plate 602 and the condensation bottle 601, a hose 8 is fixed to the bottom end of the funnel 7, the collecting assembly 9 includes a collecting bottle 901, the lower surface of the collecting bottle 901 is arranged on the bracket 1, the top of the collecting bottle 901 is threadedly connected with a top cover 910, a sealing plug 902 is slid on the top of the top cover 910, the inner wall of the sealing plug 902 is fitted with the outer wall of the hose 8, the inner wall of the collecting bottle 901 is fixed with a fixing plate 903, the outer wall of the fixing plate 903 is fixed with a chamber 904, the outer wall of the chamber 904 is arranged above the interior of the collecting bottle 901, and one end of the hose 8 is arranged in the cavity Inside chamber 1 904, a flow guide tube 1 905 passes through the upper outer side of chamber 1 904, chamber 2 906 is arranged above the inner wall of the collecting bottle 901, the end of flow guide tube 1 905 is arranged inside chamber 2 906, chamber 2 906 is arranged on one side of chamber 1 904, chamber 3 909 is arranged below the inner wall of the collecting bottle 901, a flow guide tube 2 908 passes through the outer side of chamber 2 906, the end of flow guide tube 2 908 is fixed inside chamber 3 909, the outer wall of chamber 3 909 is arranged on the other side of chamber 1 904, and sealing plates 907 are provided at the top of chamber 3 909 and chamber 2 906, and the outer wall of flow guide tube 1 905 slides inside the sealing plate 907.

[0035] Specifically, the condensed water dripping from the surface of the condensation bottle 601 and the heat conducting plate 602 is accurately captured by the funnel 7 supported by the fixed frame 14, and passes through the slidable sealing plug 902 on the top cover 910 through the hose 8, and enters the interior of the collection bottle 901 without pollution. Here, the water sample is not simply collected, but first injected into the initial chamber 1 904 supported by the fixed plate 903. When the liquid level of this chamber reaches a preset height, the subsequent water sample will pass through an ingeniously designed guide tube 1 905 and automatically transfer to the independent chamber 2 9 using the gravity overflow principle. 06. Similarly, when chamber two 906 is full, the water sample will overflow into chamber three 909 again through diversion tube two 908, thereby completing the automatic separation and sealing of samples from different time periods without human intervention. The design of sealing plate 907 ensures the isolation of the full chamber from the internal environment of the device. The extraordinary benefit of this design is that it decomposes a continuous sampling process into multiple discrete time slices, allowing researchers to capture instantaneous pollution events or daily changes in atmospheric composition that would be completely ignored by traditional mixed sampling methods.

[0036] Please see the attached Figure 8 -Attached Figure 10The air intake assembly 4 includes an air intake pipe 401, the end of the air intake pipe 401 passes through the outside of the protective cover 2, a rubber sleeve 402 is slidably provided on the air intake end of the air intake pipe 401, a filter screen 403 is fixed inside the rubber sleeve 402, the outer wall of the filter screen 403 is arranged below the air intake end of the air intake pipe 401, and a plurality of anti-slip strips 404 are provided on the outer wall of the rubber sleeve 402. The exhaust assembly 5 includes an exhaust pipe 501, the end of the exhaust pipe 501 passes through the outside and below of the protective cover 2, a plurality of connecting blocks 502 are fixed on the end of the exhaust pipe 501, an exhaust fan 503 is fixed on the outer wall of the connecting block 502, the outer wall of the exhaust fan 503 is arranged at the air outlet end of the exhaust pipe 501, and a thermal gas flow meter 504 is provided inside the exhaust pipe 501.

[0037] Specifically, the exhaust fan 503 fixed by the connecting block 502 rotates at a high speed, forming a stable negative pressure inside the device, thereby forcibly and evenly drawing in the outside air through the air inlet pipe 401. Before entering the main cavity, the air must first pass through a replaceable filter 403 fixed by a rubber sleeve 402. This design can not only effectively filter out solid particles, pollen and large aerosols entrained in the air, ensuring the purity of the subsequent condensed water sample, but also its structure with anti-slip strips 404 greatly simplifies the on-site maintenance and replacement of the filter 403. The air after condensation and dehumidification will eventually flow through the device. The thermal-sensitive gas flowmeter 504 placed inside the exhaust pipe 501 can accurately measure and accumulate the total volume of air flowing through the device in real time. The core benefit of this design is that it solves the fundamental defects of passive sampling devices that rely on uncontrollable natural convection, resulting in low sampling efficiency and instability. More importantly, by introducing precise measurement of gas flow, the final analysis results can leap from the traditional qualitative or semi-quantitative level to the precise quantitative scientific level that can calculate the absolute concentration of pollutants in unit volume of air, greatly improving the scientific value and comparability of the data.

[0038] Working principle: First, place the pre-frozen condensation bottle 601 in the limiting ring 12 and secure it by tightening the fixing bolts 13. The user can adjust the position of the condensation bottle 601 by adjusting the sliding rod 11. Then start the exhaust assembly 5, and the exhaust fan 503 starts to operate through the fixing of the connecting block 502, generating negative pressure inside the protective cover 2, and the outside air is actively sucked in by the intake pipe 401 of the air intake assembly 4. Before entering, the air passes through the filter 403 fixed in the rubber sleeve 402 to filter out foreign particles. The anti-slip strip 404 facilitates the disassembly and assembly of the rubber sleeve 402. The clean air entering the device flows through the outer wall of the condensation bottle 601 to condense. In order to ensure long-term and efficient condensation, the refrigeration plate 604 of the condensation assembly 6 is energized and its cooling surface is in close contact with the heat conducting plate 602, and is tightly attracted by the magnetic force generated by the magnet block 603 on the heat conducting plate 602 and the magnet ring 605 on the refrigeration plate 604, continuously providing cooling for the condensation bottle 601, and the refrigeration plate 604 makes The heat generated by the hot surface is quickly discharged by the heat sink 606 and the fan 607. The whole process can be monitored through the observation window 10. The water droplets generated by condensation slide along the bottle wall and the surface of the heat conducting plate 602, and are collected by the funnel 7 supported by the fixing frame 14. Then, they pass through the sealing plug 902 on the top cover 910 of the collection bottle 901 through the hose 8 and first drip into the chamber 1 904 supported by the fixing plate 903. When the chamber 1 904 is filled, the subsequent water samples will pass through the guide tube 1 905 It automatically overflows into chamber two 906 covered by the sealing plate 907. After chamber two 906 is also filled, the water sample continues to overflow into chamber three 909 through the guide tube two 908, and finally completes the automatic sampling and collection without human intervention. The dehumidified air flows to the exhaust pipe 501 and is accurately measured by the thermal gas flow meter 504 before being discharged. Finally, under the protection of the conical top plate 3, a complete, quantitative, and time-divided atmospheric condensate sampling operation is completed.

[0039] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Ambient air condensate sampler, characterized in that, include: A bracket (1), wherein a protective cover (2) is provided on the bracket (1), an observation window (10) is provided on the outer side of the protective cover (2), a conical top plate (3) is fixed to the top end of the protective cover (2), a sliding rod (11) is slidably provided inside the bracket (1), and a limiting ring (12) is fixed to the end of the sliding rod (11); An air intake assembly (4), which is arranged on the protective cover (2) and is used to introduce air into the interior of the device; An exhaust assembly (5) is arranged at the outer bottom of the protective cover (2) and is used to discharge the air after condensation and dehydration; A condensation assembly (6) is arranged on a limiting ring (12), the condensation assembly (6) comprising a condensation bottle (601), the outer wall of the condensation bottle (601) being fitted on the inner side of the limiting ring (12), a heat conducting plate (602) being fixed to the outer wall of the condensation bottle (601), a plurality of magnet blocks (603) being fixed to the outer side of the heat conducting plate (602), a cooling plate (604) passing through the outer side of the protective cover (2), a magnet ring (605) being fixed to the outer wall of the cooling plate (604), and a cooling surface of the cooling plate (604) and the outer wall of the heat conducting plate (602) being fitted together via the magnet ring (605) and the magnet blocks (603); A collecting component (9) is arranged on the bracket (1) and is used to collect water droplets generated after condensation.

2. The ambient air condensate sampler according to claim 1, characterized in that: The internal thread of the limiting ring (12) is connected to a fixing bolt (13), and the end of the fixing bolt (13) is fitted on the outer wall of the condensation bottle (601).

3. The ambient air condensate sampler according to claim 1, characterized in that: A plurality of heat sinks (606) are fixed to the heating surface of the refrigeration fin (604), and a fan (607) is fixed to the outer wall of the heat sink (606).

4. The ambient air condensate sampler according to claim 1, characterized in that: A fixing frame (14) is fixed to the outer wall of the bracket (1), a funnel (7) is placed on the fixing frame (14), the outer wall of the funnel (7) is arranged directly below the heat conducting plate (602) and the condensation bottle (601), and a hose (8) is fixed to the bottom end of the funnel (7).

5. The ambient air condensate sampler according to claim 1, characterized in that: The collecting assembly (9) comprises a collecting bottle (901), the lower surface of the collecting bottle (901) is arranged on the bracket (1), the top end of the collecting bottle (901) is threadedly connected to a top cover (910), the top end of the top cover (910) is slidably provided with a sealing plug (902), and the inner wall of the sealing plug (902) is in contact with the outer wall of the hose (8).

6. The ambient air condensate sampler according to claim 5, characterized in that: A fixing plate (903) is fixed to the inner wall of the collecting bottle (901), and a chamber 1 (904) is fixed to the outer wall of the fixing plate (903). The outer wall of the chamber 1 (904) is arranged above the interior of the collecting bottle (901), and one end of the hose (8) is arranged inside the chamber 1 (904). A flow guide tube 1 (905) passes through the outer side of the chamber 1 (904). A chamber 2 (906) is arranged above the inner wall of the collecting bottle (901), and the end of the flow guide tube 1 (905) is arranged inside the chamber 2 (906). (906) is arranged on one side of chamber one (904), chamber three (909) is arranged below the inner wall of the collecting bottle (901), a guide tube two (908) passes through the outer side of chamber two (906), the end of the guide tube two (908) is fixed inside chamber three (909), the outer wall of chamber three (909) is arranged on the other side of chamber one (904), the top of chamber three (909) and chamber two (906) are both provided with a sealing plate (907), and the outer wall of the guide tube one (905) slides inside the sealing plate (907).

7. The ambient air condensate sampler according to claim 1, characterized in that: The air intake assembly (4) comprises an air intake pipe (401), and the end of the air intake pipe (401) passes through the outside of the protective cover (2).

8. The ambient air condensate sampler according to claim 7, characterized in that: A rubber sleeve (402) is slidably mounted on the air inlet end of the air inlet pipe (401), a filter screen (403) is fixed inside the rubber sleeve (402), an outer wall of the filter screen (403) is arranged below the air inlet end of the air inlet pipe (401), and a plurality of anti-slip strips (404) are arranged on the outer wall of the rubber sleeve (402).

9. The ambient air condensate sampler according to claim 1, characterized in that: The exhaust assembly (5) comprises an exhaust pipe (501), and the end of the exhaust pipe (501) passes through the lower outer side of the protective cover (2).

10. The ambient air condensate sampler according to claim 9, characterized in that: A plurality of connection blocks (502) are fixed to the end of the exhaust pipe (501), an exhaust fan (503) is fixed to the outer wall of the connection block (502), the outer wall of the exhaust fan (503) is arranged at the gas outlet end of the exhaust pipe (501), and a thermal-sensitive gas flow meter (504) is arranged inside the exhaust pipe (501).

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