Gas taking structure for reducing measurement deviation of NOx sensor

Abstract

The utility model discloses a gas taking structure capable of reducing measurement deviation of a NOx sensor, which comprises an SCR (selective catalytic reduction) catalyst and a rear NOx sensor arranged at a gas outlet of the SCR catalyst, a gas taking structure is further arranged at the gas outlet and comprises at least three gas taking pipes formed by branching of the gas taking structure, and the rear NOx sensor is arranged at the gas outlet of the SCR catalyst. The end parts of the at least three gas taking pipes extend to the circular inner wall close to the gas outlet, and the end part of one gas taking pipe is in threaded connection with a rear NOx sensor; and a gas taking hole is formed in the gas taking pipe in the length direction of the gas taking pipe. According to the utility model, the gas taking structure of the NOx sensor at the outlet of the catalyst is optimized, so that the problem of large measurement deviation of the NOx sensor caused by non-uniformity of a flow field of the catalyst is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of engines, in particular to an air intake structure for reducing measurement deviation of a NOx sensor. Background Art

[0002] To meet the National VI diesel engine emission control requirements, the SCR (Selective Catalytic Reduction) control technology route is: a NOx measuring sensor is installed at the inlet and outlet of the catalyst. The NOx sensor at the catalyst inlet measures the NOx discharged from the engine body, and the software algorithm calculates the urea injection amount that meets the emission requirements through this measurement value; the NOx sensor at the catalyst outlet measures the NOx after purification by the catalyst. If the standard is not met, an on-board diagnostic alarm will be issued to remind the driver that the vehicle needs maintenance and inspection.

[0003] Some suppliers lack R&D capabilities, resulting in catalysts with poor flow field uniformity. This makes it difficult to ensure accurate measurement at all exhaust flow rates. This results in significant variations in measurement accuracy at the catalyst outlet under varying exhaust flow rates, a phenomenon particularly pronounced on specialized vehicles. The same catalyst performs differently on vehicles with different application segments. Benchmark measurement analysis has shown that the NOx sensor at the catalyst outlet exhibits significant deviations from true values above a certain exhaust flow rate.

[0004] The information disclosed in the above background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art. Utility Model Content

[0005] In response to the above-mentioned existing defects, the purpose of the present invention is to provide an air intake structure that reduces the measurement deviation of the NOx sensor, optimize the air intake structure of the NOx sensor at the catalyst outlet, and solve the problem of large measurement deviation of the NOx sensor due to the uneven flow field of the catalyst.

[0006] The technical solution of the utility model is as follows:

[0007] An air intake structure for reducing NOx sensor measurement deviation includes: an SCR catalyst, and a post-NOx sensor arranged at the air outlet of the SCR catalyst. An air intake structure is also provided at the air outlet, wherein the air intake structure includes at least three air intake pipes formed by partial forks, the ends of at least three of the air intake pipes extending to a circular inner wall near the air outlet, and the end of one of the air intake pipes is connected to the post-NOx sensor by a thread; and air intake holes are opened on the air intake pipe along its length.

[0008] Specifically, the angles between two adjacent air extraction pipes are the same.

[0009] Specifically, the aperture of the air extraction pipe is 3cm-5cm.

[0010] Specifically, the diameter of the air extraction hole is 0.3-0.8 cm.

[0011] Beneficial effects of the utility model:

[0012] The utility model provides an air intake structure specifically for connecting to the rear NOx sensor at the outlet of the SCR catalyst. The air intake structure optimizes the air intake range, reduces the measurement deviation of the sensor, and reduces false alarms related to the catalyst system, thereby improving the competitiveness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of an air intake structure for reducing NOx sensor measurement deviation in the present invention.

[0014] Figure 2 This is a structural diagram of the gas intake structure of the utility model.

[0015] In the figure: 1-SCR catalyst, 2-air inlet, 3-air outlet, 4-rear NOx sensor, 5-air intake structure, 6-air intake pipe, 7-air intake hole. DETAILED DESCRIPTION

[0016] To explain the technical content, objectives, and effects of the present invention in detail, the following embodiments are described in conjunction with the accompanying drawings. In the description of the embodiments, it should be understood that the terms indicating orientation or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the embodiments and simplify the description. They do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Example

[0017] like Figure 1 As shown, according to a specific embodiment of the present invention, an air intake structure for reducing the measurement deviation of a NOx sensor comprises: an SCR catalyst (1), and a rear NOx sensor (4) arranged at an air outlet (3) of the SCR catalyst (1), characterized in that: an air intake structure (5) is further provided at the air outlet (3), the air intake structure (5) comprising at least three air intake pipes (6) formed by partial forks thereof, the ends of at least three of the air intake pipes (6) extending to a circular inner wall close to the air outlet (3), the end of one of the air intake pipes (6) being connected to the rear NOx sensor (4) by a thread; and an air intake hole (7) is provided on the air intake pipe (6) along its length direction.

[0018] The working principle of this embodiment is:

[0019] When the engine is running, exhaust gas flows through the exhaust system, from the air intake 2 through the SCR catalyst 1, and at the outlet 3, is collected by an air intake structure 5. The air intake structure 5 comprises three air intake pipes 6, the ends of which extend to the circular inner wall near the outlet 3 of the SCR catalyst 1. As exhaust gas flows, it enters the pipes 6 through air intake holes 7 provided along their lengths. This allows the air intake structure 5 to achieve multi-point exhaust gas sampling through its multiple air intake pipes 6 and air intake holes 7. After entering the pipes 6 through the air intake holes 7, the multiple pipes 6 converge the gas, reducing measurement errors caused by uneven airflow distribution at the outlet 3. One of the air intake pipes 6 is fixedly connected to the rear NOx sensor 4 via a threaded point-to-point connection, enhancing the connection strength. The sensor's measurement results are transmitted to the engine control unit (ECU), which then makes adjustments based on NOx concentration. For example, if the measured NOx concentration exceeds the standard, the system may adjust the urea injection rate or other control parameters to reduce emissions.

[0020] In summary, due to the uniform sampling through multiple air intakes and air intake pipes, the gas received by the sensor is more uniform, thereby improving the accuracy of NOx measurement, so that the measurement results can be used to further control and optimize the emission system to ensure that the vehicle meets emission standards.

[0021] As a preferred technical solution of this embodiment, the angles between two adjacent air extraction pipes 6 are the same, both 120°. Depending on the situation, more air extraction pipes 6 can be provided to achieve a more uniform air extraction effect. Example

[0022] like Figure 2 As shown, this embodiment further optimizes the air intake structure 5 based on the embodiment 1.

[0023] As a preferred technical solution of this embodiment, the aperture of the air intake pipe 6 is 3 cm to 5 cm. This relatively large aperture ensures sufficient exhaust gas flow into the air intake pipe 6, thereby ensuring that the rear NOx sensor 4 receives sufficient sample gas for measurement. This aperture does not restrict airflow and reduces pressure loss.

[0024] As a preferred technical solution of this embodiment, the aperture of the air intake hole 7 is 0.3-0.8 cm. The smaller aperture of the air intake hole 7 can ensure that the gas enters the air intake pipe 6 simultaneously through multiple small holes. Through such a design, the small aperture can control the rate at which gas enters the air intake pipe, preventing excessive exhaust gas from instantly rushing into the sensor, resulting in inaccurate measurements. An appropriate airflow rate enables the sensor to operate at a stable flow rate, providing more reliable NOx concentration data. The small-aperture air intake can avoid errors caused by excessive airflow or local gas anomalies introduced by a single large hole, thereby improving the accuracy and consistency of sensor measurements.

[0025] In summary, by optimizing gas flow: the 3cm-5cm aperture of the air intake tube 6 is combined with the 0.3cm-0.8cm aperture of the air intake hole 7 to ensure stable and uniform gas flow when entering the air intake tube, and to avoid extreme cases of excessive or insufficient airflow. This design combination helps maintain high measurement accuracy under different operating conditions. This size combination can adapt to gas collection under different flow rates and pressures while preventing excessive or thin airflow, thus adapting to various vehicle operating conditions, especially the exhaust gas sampling needs under high and low speed conditions.

[0026] Although the present invention has been described in detail above using specific embodiments, it is readily apparent to those skilled in the art that modifications or improvements may be made to the present invention. Therefore, any such modifications or improvements that do not depart from the spirit of the present invention are intended to fall within the scope of protection claimed herein.

Claims

1. A gas extraction structure for reducing NOx sensor measurement deviation, comprising: An SCR catalyst (1), and a post-NOx sensor (4) arranged at an air outlet (3) of the SCR catalyst (1), characterized in that: an air intake structure (5) is also provided at the air outlet (3), the air intake structure (5) comprising at least three air intake pipes (6) formed by partial forks thereof, the ends of at least three of the air intake pipes (6) extending to a circular inner wall near the air outlet (3), the end of one of the air intake pipes (6) being connected to the post-NOx sensor (4) via a thread; and an air intake hole (7) is provided on the air intake pipe (6) along its length.

2. The air intake structure for reducing NOx sensor measurement deviation according to claim 1, characterized in that: The included angles between two adjacent air extraction pipes (6) are the same.

3. The air intake structure for reducing NOx sensor measurement deviation according to claim 1, characterized in that: The aperture of the air extraction pipe (6) is 3 cm to 5 cm.

4. The air intake structure for reducing NOx sensor measurement deviation according to claim 1, characterized in that: The diameter of the air extraction hole (7) is 0.3-0.8 cm.

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