Tail gas after-treatment device and method

Abstract

The tail gas post-treatment device comprises a nitrogen and oxygen detection device fixed to the inner wall of a post-treatment gas outlet pipe, the nitrogen and oxygen detection device comprises a nitrogen and oxygen sensing device and a perforated plate, and the nitrogen and oxygen sensing device is located on the gas inlet side of the perforated plate; the distance between the nitrogen and oxygen sensing device and the perforated plate is smaller than or equal to 5 mm. Wherein the nitrogen-oxygen sensing device comprises a nitrogen-oxygen sensor and a plurality of gas circulating pipes, the plurality of gas circulating pipes are fixedly connected with the inner wall of the post-treatment gas outlet pipe, the extending direction is along the radial direction of the post-treatment gas outlet pipe, the gas inlet side of each gas circulating pipe is provided with a gas inlet hole, and the gas outlet side of each gas circulating pipe is provided with a gas outlet hole. The perforated plate comprises a through hole in the gas circulation direction of the post-treatment gas outlet pipe, and the through hole is used for allowing gas exhausted from the nitrogen-oxygen sensing device to pass through, so that the gas exhausted from the nitrogen-oxygen sensing device is decelerated through the perforated plate, Karman vortexes behind the nitrogen-oxygen sensing device are shielded, high-frequency noise in exhaust noise is reduced, and the comfort of the whole vehicle is improved.

Description

Technical Field

[0001] The present invention relates to the field of vehicles, and in particular to an exhaust gas post-processing device and method. Background Art

[0002] In order to measure the NOx density in the exhaust gas, a nitrogen oxide sensor is set at the position of the post-processing exhaust pipe, such as a cylindrical cross-shaped nitrogen oxide sensor. However, in actual operation, the nitrogen oxide sensor is prone to noise problems and cannot achieve a silencing effect. Summary of the invention

[0003] In order to solve the above technical problems, the embodiments of the present application provide an exhaust gas after-treatment device and method to reduce high-frequency noise in exhaust noise.

[0004] The embodiment of the present application provides an exhaust gas post-treatment device, comprising:

[0005] A nitrogen and oxygen detection device fixed to the inner wall of the post-processing outlet pipe;

[0006] The nitrogen oxide detection device comprises a nitrogen oxide sensor device and a perforated plate, wherein the nitrogen oxide sensor device is located on the air intake side of the perforated plate, and the distance between the nitrogen oxide sensor device and the perforated plate is less than or equal to 5 mm;

[0007] The nitrogen oxide sensor device comprises a nitrogen oxide sensor and a plurality of gas flow pipes, wherein the plurality of gas flow pipes are fixedly connected to the inner wall of the post-processing gas outlet pipe and extend in a radial direction along the post-processing gas outlet pipe, and the gas flow pipe has an air inlet hole on the air inlet side and an air outlet hole on the air outlet side;

[0008] The perforated plate comprises through holes along the gas flow direction of the post-processing gas outlet pipe, and the through holes are used for passing the gas exhausted from the nitrogen oxide sensor device.

[0009] Optionally, the nitrogen oxygen sensor device is fixedly connected to the perforated plate, and the air outlet hole is arranged opposite to at least one of the through holes.

[0010] Optionally, the nitrogen oxygen sensor device and the perforated plate are fixed together, or connected by solder ball welding.

[0011] Optionally, the perforated plate has a groove on one side facing the nitrogen oxide sensor device, and at least one through hole is located in the groove, the nitrogen oxide sensor device is embedded in the groove, and the air outlet is arranged opposite to the through hole in the groove.

[0012] Optionally, the size of the perforated plate along the gas flow direction of the post-processing gas outlet pipe ranges from 10 to 15 cm.

[0013] Optionally, the radial dimension of the through hole ranges from 10 to 15 mm.

[0014] Optionally, the multiple gas circulation tubes form a cross-shaped structure.

[0015] Optionally, the length of the post-processing air outlet pipe is greater than 20 cm.

[0016] Optionally, the post-processing air outlet pipe is also used to connect to a muffler, and the muffler is connected to the air inlet end of the post-processing air outlet pipe.

[0017] The present application provides an exhaust gas post-treatment method, comprising:

[0018] If it is determined that the vehicle has a need for silencing, the exhaust gas after-treatment device is provided for the vehicle.

[0019] The embodiment of the present application provides an exhaust gas post-treatment device and method, the exhaust gas post-treatment device includes a nitrogen oxygen detection device fixed to the inner wall of the post-treatment outlet pipe, the nitrogen oxygen detection device includes a nitrogen oxygen sensor device and a perforated plate, the nitrogen oxygen sensor device is located on the air intake side of the perforated plate, and the distance between the nitrogen oxygen sensor device and the perforated plate is less than or equal to 5mm. The nitrogen oxygen sensor device includes a nitrogen oxygen sensor and a plurality of gas flow pipes, the plurality of gas flow pipes are fixedly connected to the inner wall of the post-treatment outlet pipe, and the extension direction is along the radial direction of the post-treatment outlet pipe, the gas flow pipe has an air intake hole on the air intake side, and has an air outlet hole on the air outlet side. The perforated plate includes through holes along the gas flow direction of the after-treatment exhaust pipe, and the through holes are used for passing the gas discharged from the nitrogen oxide sensor device, so that the gas discharged from the nitrogen oxide sensor device is decelerated after passing through the perforated plate, shielding the Karman vortex after the nitrogen oxide detection device, reducing the high-frequency noise in the exhaust noise, solving the problem of excessive exhaust noise caused by insufficient silencer capacity, ensuring the measurement accuracy of the NOx sensor while taking into account the engine exhaust noise requirements, and having a very obvious noise reduction effect on the exhaust noise of the engine in the full speed range, especially high speed conditions, so that the after-treatment muffler plays its due exhaust noise silencing role, improves the silencing level of the after-treatment device in full speed conditions, and improves the comfort of the whole vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0021] Figure 1 and Figure 2 A schematic diagram of the structure of an exhaust gas post-treatment device provided in an embodiment of the present application;

[0022] Figure 3 A flow chart of an exhaust gas post-treatment method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0025] The specific implementation of the embodiments of the present application will be described in detail below through examples in conjunction with the accompanying drawings.

[0026] refer to Figure 1 and Figure 2 FIG. 1 is a schematic diagram of the structure of the exhaust gas post-treatment device provided in an embodiment of the present application, wherein Figure 1 It is a schematic diagram of the exhaust gas after-treatment device in the after-treatment outlet pipe. Figure 2 It is a schematic diagram of the exhaust gas after-treatment device in a plane perpendicular to the gas flow direction. The exhaust gas after-treatment device may include a nitrogen oxygen detection device 2 fixed to the inner wall of the after-treatment outlet pipe 1, and the nitrogen oxygen detection device 2 includes a nitrogen oxygen sensor device 4 and a perforated plate 3. The nitrogen oxygen sensor device 4 is located on the air intake side of the perforated plate 3.

[0027] The nitrogen oxygen sensing device 4 includes a nitrogen oxygen sensor and a plurality of gas flow pipes 41, wherein the plurality of gas flow pipes 41 are fixedly connected to the inner wall of the post-treatment outlet pipe 1, and the extension direction is along the radial direction of the post-treatment outlet pipe 1, and the gas flow pipe 41 has an air inlet hole 42 on the air inlet side and an air outlet hole on the air outlet side, wherein the nitrogen oxygen sensor can be arranged on the air outlet side of the gas flow pipe 41 to detect the nitrogen oxygen content in the gas.

[0028] The multiple gas flow pipes 41 can form a cross-shaped structure in the radial plane of the post-processing gas outlet pipe, or other structures. The gas flow pipe 41 has a starting end and an end, wherein the starting end is located at the center of the post-processing gas outlet pipe 1, and the end is connected to the inner wall of the post-processing gas outlet pipe 1, wherein the air inlet holes 31 can be evenly distributed on the side wall of the gas flow pipe 41, and the air outlet holes can be set at the end. The gas flow pipe 41 is cylindrical, and the structure composed of the multiple gas flow pipes 41 is circular in the radial direction of the post-processing gas outlet pipe 1, and is cylindrical as a whole.

[0029] Exhaust noise contains complex noise components: exhaust noise with the number of exhaust times per unit time as the fundamental frequency, air column resonance noise in the pipeline, Karman vortex street noise, and turbulent noise inside the exhaust system, etc. At present, the integrated SCR catalytic conversion silencer integrates the catalytic reduction of NOx in the engine exhaust and the silencer of the engine exhaust, which can effectively reduce the nitrogen and oxygen content in the exhaust gas and the emission noise. However, when the nitrogen oxide sensor device 4 is set in the post-processing outlet pipe 1, when the airflow blows through the cylindrical gas flow pipe 41 in the nitrogen oxide sensor device 4, a cylindrical flow occurs, and a Karman vortex street is formed at the rear end, and a Karman vortex sound appears. At this time, the attenuation effect of the post-processing silencer on the exhaust noise is greatly reduced, resulting in a serious weakening of the silencer ability of the SCR silencer, which is mainly manifested in that the silencer fails to effectively silence the high-frequency airflow noise, resulting in the inability to take into account the exhaust noise problem in the exhaust passage.

[0030] Among them, flow around a cylinder refers to the movement of a fluid around a cylinder; Karman vortex street refers to the situation when a steady flow under certain conditions passes around certain objects, and double rows of line vortices with opposite rotation directions and regular arrangement will periodically fall off on both sides of the object. After nonlinear action, a Karman vortex street is formed; Karman vortex sound refers to the sound radiated when the airflow encounters an obstacle and a Karman vortex is generated behind the obstacle.

[0031] Specifically, the Karman vortex sound generated by the airflow blowing through the cylindrical cross structure is mainly affected by the Reynolds number of the fluid: Re = рνD / μ. The Reynolds number is a dimensionless number used to characterize the flow of the fluid. When the Reynolds number is large, the fluid changes from a laminar state to a turbulent state. For the engine exhaust, after the post-treatment is determined, the kinematic viscosity μ of the fluid is determined. The engine is running at high speed, the flow rate is large (pressure p is large), the flow velocity ν is high, and the Reynolds number increases; the diameter D of the cylindrical cross structure increases, and the Reynolds number also increases. At this time, the airflow passing through the cylinder is more likely to separate from the boundary layer behind the cylinder, and the resulting Karman vortex sound bandwidth increases, resulting in an increase in exhaust noise. If the Reynolds number continues to increase, the cylinder wake becomes turbulent, further increasing the exhaust noise. In other words, the airflow blows through the cylindrical cross structure, and a cylindrical flow occurs, forming a Karman vortex street at the rear end. The larger the diameter of the cylinder, the higher the bandwidth of the Karman vortex sound formed after the exhaust airflow passes through this place, and the greater the radiation noise.

[0032] Based on this, in the embodiment of the present application, a perforated plate 3 is further provided, and the nitrogen oxide sensor device 4 is located on the air intake side of the perforated plate 3, and the distance between the nitrogen oxide sensor device 4 and the perforated plate 3 is less than or equal to 5 mm. The perforated plate 3 includes a through hole 31 along the gas flow direction of the post-processing outlet pipe 1, and the through hole 31 is used to pass the gas discharged from the nitrogen oxide sensor device 4, so that the gas discharged from the nitrogen oxide sensor device 4 is decelerated through the perforated plate 3, shielding the Karman vortex after the nitrogen oxide detection device 2, reducing the high-frequency noise in the exhaust noise, solving the problem of excessive exhaust noise caused by insufficient muffler silencing capacity, ensuring the measurement accuracy of the NOx sensor while taking into account the engine exhaust noise requirements, and having a very obvious noise reduction effect on the exhaust noise of the engine in the full speed range, especially the high speed working condition, so that the post-processing muffler plays the due exhaust noise silencing role, improving the silencing level of the post-processing device in the full speed working condition, and improving the comfort of the whole vehicle.

[0033] Specifically, the nitrogen oxide sensor device 4 is fixedly connected to the perforated plate 3, and the outlet hole is arranged opposite to at least one of the through holes 31. Of course, the nitrogen oxide sensor device 4 and the perforated plate 3 can be connected to the inner wall of the post-treatment outlet pipe 1 respectively and arranged independently of each other.

[0034] Specifically, the nitrogen oxide sensor device 4 and the perforated plate 3 are fixed together or connected by soldering balls. Alternatively, the perforated plate 3 has a groove on one side facing the nitrogen oxide sensor device 4, and at least one through hole 31 is located in the groove, the nitrogen oxide sensor device 4 is embedded in the groove, and the air outlet is arranged opposite to the through hole 31 in the groove.

[0035] In the post-treatment outlet pipe 1, the exhaust gas flow is divided into two parts, one part passes through the channel between the gas flow pipe 41 and is ejected through the through hole 31 of the perforated plate 3, and the other part is captured by the sensor and discharged into the through hole 31 in the perforated plate 3. The perforated plate 3 is long enough to shield the Karman vortex originally formed after blowing through the cylinder, reducing the high-frequency noise in the exhaust noise; at the same time, the through-hole structure of the perforated plate 3 plays a "throttling and silencing" role. When the airflow flows in the through hole, due to the damping and friction on the hole wall, part of the sound energy is consumed and converted into heat energy, mainly reducing the medium and low frequency noise; a straight pipe is required after the nitrogen oxide detection device 2, so that the flow rate of the airflow through the expansion is reduced and the formation of the sound source is weakened. After shielding the Karman vortex sound caused by the cylindrical cross structure, the high-frequency broadband noise at 1000Hz to 16000Hz is significantly reduced, and the exhaust noise is finally reduced by 7.1dBA, greatly reducing the exhaust noise.

[0036] In a specific implementation, the size of the perforated plate 3 along the gas flow direction of the post-processing outlet pipe 1 is in the range of 10 to 15 cm, and the spacing between adjacent through holes is in the range of 1 to 5 mm. The radial size of the through holes is in the range of 10 to 15 mm. The post-processing outlet pipe 1 is cylindrical in shape, and its length is greater than 20 cm.

[0037] The post-processing outlet pipe 1 is also used to connect a muffler, and the muffler is connected to the air inlet end of the post-processing outlet pipe 1. The muffler can be an integrated SCR catalytic conversion muffler, and the frequency range of its muffler is 500-9000 Hz.

[0038] The embodiment of the present application provides an exhaust gas aftertreatment device, including a nitrogen oxygen detection device fixed to the inner wall of the aftertreatment outlet pipe, the nitrogen oxygen detection device includes a nitrogen oxygen sensor device and a perforated plate, the nitrogen oxygen sensor device is located on the air intake side of the perforated plate, and the distance between the nitrogen oxygen sensor device and the perforated plate is less than or equal to 5mm. The nitrogen oxygen sensor device includes a nitrogen oxygen sensor and a plurality of gas flow pipes, the plurality of gas flow pipes are fixedly connected to the inner wall of the aftertreatment outlet pipe, and the extension direction is along the radial direction of the aftertreatment outlet pipe, the gas flow pipe has an air intake hole on the air intake side, and has an air outlet hole on the air outlet side. The perforated plate includes through holes along the gas flow direction of the after-treatment exhaust pipe, and the through holes are used for passing the gas discharged from the nitrogen oxide sensor device, so that the gas discharged from the nitrogen oxide sensor device is decelerated after passing through the perforated plate, shielding the Karman vortex after the nitrogen oxide detection device, reducing the high-frequency noise in the exhaust noise, solving the problem of excessive exhaust noise caused by insufficient silencer capacity, ensuring the measurement accuracy of the NOx sensor while taking into account the engine exhaust noise requirements, and having a very obvious noise reduction effect on the exhaust noise of the engine in the full speed range, especially high speed conditions, so that the after-treatment muffler plays its due exhaust noise silencing role, improves the silencing level of the after-treatment device in full speed conditions, and improves the comfort of the whole vehicle.

[0039] Based on the exhaust gas after-treatment device provided in the above embodiments, an embodiment of the present application further provides an exhaust gas after-treatment method, comprising: if it is determined that the vehicle has a nitrogen oxide detection requirement, then the exhaust gas after-treatment device is provided for the vehicle.

[0040] refer to Figure 3As shown, a flow chart of an exhaust gas aftertreatment method provided by an embodiment of the present application can obtain the application market information of the vehicle, determine whether the emission regulations have high requirements for nitrogen oxides (such as the National VI Standard and above), and if so, determine that nitrogen oxide detection is required, that is, the vehicle has a nitrogen oxide detection requirement, and then an exhaust gas aftertreatment device can be set. In this way, if the engine is running in medium, high speed and rapid acceleration conditions, the exhaust flow rate is large, and the high-speed airflow noise plays a leading role in the exhaust noise. The exhaust gas aftertreatment device is used, the large pipe diameter is maintained, the outlet pipe is lengthened, and the outlet pipe is kept as a straight pipe to ensure smooth exhaust gas flow, reduced flow rate, reduced Karman vortex noise, and low exhaust noise.

[0041] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the device disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the device part description.

[0042] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0043] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

Claims

1. An exhaust gas post-treatment device, It is characterized in that include: A nitrogen and oxygen detection device fixed to the inner wall of the post-processing outlet pipe; The nitrogen oxide detection device comprises a nitrogen oxide sensor device and a perforated plate, wherein the nitrogen oxide sensor device is located on the air intake side of the perforated plate, and the distance between the nitrogen oxide sensor device and the perforated plate is less than or equal to 5 mm; The nitrogen oxide sensor device comprises a nitrogen oxide sensor and a plurality of gas flow pipes, wherein the plurality of gas flow pipes are fixedly connected to the inner wall of the post-processing gas outlet pipe and extend in a radial direction along the post-processing gas outlet pipe, and the gas flow pipe has an air inlet hole on the air inlet side and an air outlet hole on the air outlet side; The perforated plate comprises through holes along the gas flow direction of the post-processing gas outlet pipe, and the through holes are used for passing the gas exhausted from the nitrogen oxide sensor device.

2. The device according to claim 1, It is characterized in that The nitrogen oxygen sensor device is fixedly connected to the perforated plate, and the air outlet is arranged opposite to at least one of the through holes.

3. The device according to claim 2, It is characterized in that The nitrogen oxygen sensor device and the perforated plate are fixed together or connected by soldering balls.

4. The device according to claim 2, It is characterized in that The perforated plate has a groove on one side facing the nitrogen oxide sensor device, and at least one through hole is located in the groove. The nitrogen oxide sensor device is embedded in the groove, and the air outlet is arranged opposite to the through hole in the groove.

5. The device according to any one of claims 1 to 4, It is characterized in that The size of the perforated plate along the gas flow direction of the post-processing gas outlet pipe ranges from 10 to 15 cm.

6. The device according to any one of claims 1 to 4, It is characterized in that The radial dimension of the through hole ranges from 10 to 15 mm.

7. The device according to any one of claims 1 to 4, It is characterized in that The plurality of gas flow tubes form a cross-shaped structure.

8. The device according to any one of claims 1 to 4, It is characterized in that The length of the post-processing air outlet pipe is greater than 20 cm.

9. The device according to any one of claims 1 to 4, It is characterized in that The post-processing air outlet pipe is also used to connect to a muffler, and the muffler is connected to the air inlet end of the post-processing air outlet pipe.

10. A method for post-treatment of exhaust gas, It is characterized in that include: If it is determined that the vehicle has a noise reduction requirement, an exhaust gas after-treatment device as described in any one of claims 1 to 9 is provided for the vehicle.

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