Post-processing assembly and vehicle

Abstract

The invention relates to the technical field of vehicles, and particularly discloses an aftertreatment assembly and a vehicle. The aftertreatment assembly comprises a first tail gas treatment device, an HC injection system, a second tail gas treatment device and a third tail gas treatment device; tail gas sequentially flows through the first tail gas treatment device, the HC injection system, the second tail gas treatment device and the third tail gas treatment device, CO, HC and part of PM in the tail gas are converted into carbon dioxide and water through the oxidation catalyst, and particulate matter in the tail gas is captured through the particulate matter catcher. The first-stage selective catalytic reduction device and the second-stage selective catalytic reduction device cooperate to convert oxynitride NOx, and the second-stage ammoxidation catalyst device absorbs residual ammonia gas in the first-stage selective catalytic reduction device and the second-stage selective catalytic reduction device. According to the treatment assembly, the first tail gas treatment device and the HC injection system are additionally arranged on the basis of a tail gas treatment assembly of the national sixth standard, and the requirement for low cost is met while the higher emission standard is met.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and in particular to a post-processing assembly and a vehicle. Background Art

[0002] As environmental protection is increasingly valued, countries are increasingly stringent in their requirements for motor vehicle emission standards. As one of the most stringent emission regulations in the world, the National VI Emission Standard places extremely high demands on vehicle exhaust treatment devices. In order to meet these requirements, modern vehicles are usually equipped with a complex exhaust after-treatment system, which includes but is not limited to diesel oxidation catalyst (DOC), selective catalytic reduction device (SCR), ammonia slip catalyst (ASC) and particulate filter (DPF or GPF) and other components.

[0003] In practical applications, these devices work together to reduce emissions of harmful substances such as nitrogen oxides (NOx), unburned hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM).

[0004] However, with the advancement of technology and social development, even if the National VI standard is met, it is not enough to meet the more stringent environmental protection requirements in the future. Therefore, how to upgrade and transform the existing post-processing assembly on the basis of the existing National VI and meet the requirements of the future National VII in a low-cost form has become an urgent problem that R&D personnel need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a post-processing assembly and a vehicle to solve the problem in the related technology of meeting higher emission standards, that is, how to upgrade the existing post-processing assembly at low cost on the basis of the existing National VI to meet the requirements of the future National VII.

[0006] In one aspect, the present invention provides an aftertreatment assembly, the aftertreatment assembly comprising:

[0007] The first exhaust gas treatment device comprises a primary selective catalytic reducer, wherein the air intake chamber of the primary selective catalytic reducer is respectively used to communicate with the exhaust port of the diesel engine and the urea supply device;

[0008] an HC injection system, the HC injection system comprising an HC mixer and an HC nozzle, the air inlet end of the HC mixer being in communication with the air outlet end of the primary selective catalytic reducer, the HC nozzle being capable of injecting oil into the HC mixer;

[0009] A second exhaust gas treatment device comprises an oxidation catalyst and a particulate trap connected in series, wherein an air inlet end of the oxidation catalyst is connected to an air outlet end of the HC mixer;

[0010] The third exhaust gas treatment device comprises a secondary selective catalytic reducer and a secondary ammonia oxidation catalyst connected in series in sequence, wherein the air inlet end of the secondary selective catalytic reducer is communicated with the air outlet end of the particulate trap and the urea supply device respectively.

[0011] As a preferred technical solution of the after-treatment assembly, the first exhaust gas treatment device also includes a primary ammonia oxidation catalyst, the air inlet end of the primary ammonia oxidation catalyst is connected to the air outlet end of the primary selective catalytic reducer, and the air outlet end of the primary ammonia oxidation catalyst is connected to the air inlet end of the HC mixer.

[0012] As a preferred technical solution of the after-treatment assembly, the HC mixer is provided with a first mixing chamber, and a first air inlet hole and a first air outlet hole connected to the first mixing chamber are respectively provided on one side wall of the HC mixer along a first direction, the air outlet end of the first-stage ammonia oxidation catalyst is connected to the first air inlet hole, the air inlet end of the oxidation catalyst is connected to the first air outlet hole, the first exhaust gas treatment device and the second exhaust gas treatment device are arranged along a second direction, and the first direction is perpendicular to the second direction.

[0013] As a preferred technical solution of the after-treatment assembly, it also includes a first urea mixer, the first urea mixer is provided with a second mixing chamber, a side wall of the first urea mixer is respectively provided with a second air inlet hole and a second air outlet hole along the first direction, the air outlet end of the particulate collector is connected with the second air inlet hole, the second air outlet hole is connected with the air inlet end of the secondary selective catalytic reduction device, the third exhaust gas treatment device is arranged on a side of the second exhaust gas treatment device away from the first exhaust gas treatment device along the second direction, and the second mixing chamber is connected with the urea supply device.

[0014] As a preferred technical solution of the aftertreatment assembly, it also includes a second urea mixer, which includes a connecting pipe and a mixing piece. A urea hole is provided on the peripheral wall of the connecting pipe, and the urea hole is used to communicate with the urea supply device. The air inlet end of the connecting pipe is used to communicate with the exhaust port of the engine, and the air outlet end of the connecting pipe is communicated with the air inlet cavity of the primary selective catalytic reducer. Along the air flow direction in the connecting pipe, the urea hole is located upstream of the mixing piece. The mixing piece is provided in the connecting pipe and is used to mix the exhaust gas and urea in the connecting pipe.

[0015] As a preferred technical solution of the aftertreatment assembly, the mixing element includes a tapered tube and a plurality of guide plates, the tapered tube is arranged in the connecting tube, and along the axial direction of the connecting tube, the tapered tube is located between the gas outlet end of the connecting tube and the urea hole, the large diameter end of the tapered tube is fixedly connected to the gas outlet end of the connecting tube, a plurality of through holes are arranged on the peripheral wall of the tapered tube, and the plurality of through holes are arranged at intervals along the circumference of the tapered tube, and the plurality of guide plates are arranged on the peripheral wall of the tapered tube and correspond one-to-one to the plurality of through holes.

[0016] As a preferred technical solution of the post-processing assembly, the mixing element further comprises a cylindrical tube, the large diameter end of the tapered tube is coaxially fixedly connected to the cylindrical tube, and the cylindrical tube is fitted and fixedly connected to the inner wall of the connecting tube.

[0017] As a preferred technical solution for the post-processing assembly, the mixing element is an integrally formed element.

[0018] As a preferred technical solution of the after-treatment assembly, the second exhaust gas treatment device further includes a pressure difference sensor, and the pressure difference sensor is used to monitor the pressure difference between the intake end and the exhaust end of the particulate trap.

[0019] On the other hand, the present invention provides a vehicle, comprising a cab, a truck bed and the after-treatment assembly of any of the above schemes, wherein the after-treatment assembly is arranged between the cab and the truck bed along the front-rear direction of the vehicle.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides an aftertreatment assembly and a vehicle. The aftertreatment assembly includes a first exhaust gas treatment device, an HC injection system, a second exhaust gas treatment device and a third exhaust gas treatment device. When the vehicle equipped with the aftertreatment assembly is driving, the exhaust gas generated by the engine flows through the first exhaust gas treatment device, the HC injection system, the second exhaust gas treatment device and the third exhaust gas treatment device in sequence. During this process, the oxidation catalyst is used to convert carbon monoxide CO, hydrocarbons HC and part of particulate matter PM in the exhaust gas into harmless carbon dioxide and water, and the particle trap is used to capture the particulate matter therein; the primary selective catalytic reduction device and the secondary selective catalytic reduction device cooperate to complete the reduction of nitrogen oxides (NO x ), and the secondary ammonia oxidation catalyst is used to absorb the remaining ammonia in the primary selective catalytic reducer and the secondary selective catalytic reducer. This treatment assembly adds a first exhaust gas treatment device and an HC injection system on the basis of the exhaust gas treatment assembly of the National VI standard. It does not need to dismantle and change the original exhaust gas treatment device, but only needs to install the first exhaust gas treatment device and the HC injection system on the original exhaust gas treatment device, which meets the higher emission standards while achieving low cost requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a post-processing assembly in an embodiment of the present invention;

[0023] Figure 2 The structure of the second urea mixer in the embodiment of the present invention is shown in FIG. Figure 1 ;

[0024] Figure 3 The structure of the second urea mixer in the embodiment of the present invention is shown in FIG. Figure 2 ;

[0025] Figure 4 It is a cross-sectional view of the second urea mixer in the embodiment of the present invention.

[0026] In the figure:

[0027] 1. First tail gas treatment device; 11. First-stage selective catalytic reduction device; 12. First-stage ammonia oxidation catalyst;

[0028] 2. Second exhaust gas treatment device; 21. Oxidation catalyst; 22. Particulate filter;

[0029] 3. The third tail gas treatment device; 31. The secondary selective catalytic reduction device; 32. The secondary ammonia oxidation catalyst;

[0030] 4. HC injection system; 41. HC mixer; 42. HC nozzle;

[0031] 5. The first urea mixer;

[0032] 6. The second urea mixer; 61. The connecting pipe; 611. The urea hole; 62. The mixing element; 621. The conical tube; 6211. The through hole; 622. The guide plate; 623. The cylindrical tube. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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 creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0037] In the existing technology, the post-treatment assembly required by National VI usually includes an oxidation catalyst (DOC), a particulate filter (DPF or GPF), a selective catalytic reduction device (SCR) and an ammonia slip catalyst (ASC) connected in series. These devices work together to reduce the emission of harmful substances such as nitrogen oxides (NOx), unburned hydrocarbons (HC), carbon monoxide (CO) and particulate matter (PM). For example, the diesel oxidation catalyst is mainly used to convert unburned carbon monoxide and hydrocarbons into carbon dioxide and water; the selective catalytic reduction device generates ammonia by injecting urea solution to react with nitrogen oxides in the exhaust gas, thereby converting them into harmless nitrogen and water vapor; and the particulate filter is responsible for capturing and storing solid particulate matter in the exhaust flow. In order to meet the more demanding emission standards, how to upgrade the existing post-treatment assembly at a low cost based on the existing National VI to meet the requirements of the future National VII. To solve this problem, such as Figure 1 to Figure 4 As shown, the present embodiment provides an after-treatment assembly, which includes a first exhaust gas treatment device 1, an HC injection system 4, a second exhaust gas treatment device 2 and a third exhaust gas treatment device 3. The first exhaust gas treatment device 1 includes a primary selective catalytic reducer 11, and the air intake chamber of the primary selective catalytic reducer 11 is used to communicate with the exhaust port of the diesel engine and the urea supply device respectively; the HC injection system 4 includes an HC mixer 41 and an HC nozzle 42, the air intake end of the HC mixer 41 is communicated with the air outlet end of the primary selective catalytic reducer 11, and the HC nozzle 42 can spray oil into the HC mixer 41; the second exhaust gas treatment device 2 includes an oxidation catalyst 21 and a particulate trap 22 connected in series in sequence, and the air intake end of the oxidation catalyst 21 is connected with the air outlet end of the HC mixer 41; the third exhaust gas treatment device 3 includes a secondary selective catalytic reducer 31 and a secondary ammonia oxidation catalyst 32 connected in series in sequence, and the air intake end of the secondary selective catalytic reducer 31 is respectively connected with the air outlet end of the particulate trap 22 and the urea supply device. When the vehicle equipped with the after-treatment assembly is driving, the exhaust gas generated by the engine flows through the first exhaust gas treatment device 1, the HC injection system 4, the second exhaust gas treatment device 2 and the third exhaust gas treatment device 3 in sequence. During this process, the oxidation catalyst 21 is used to convert carbon monoxide CO, hydrocarbons HC and part of the particulate matter PM in the exhaust gas into harmless carbon dioxide and water, and the particle trap 22 is used to capture the particulate matter therein; the primary selective catalytic reduction device 11 and the secondary selective catalytic reduction device 31 cooperate to complete the reduction of nitrogen oxides (NO x), and the secondary ammonia oxidation catalyst 32 is used to absorb the remaining ammonia in the primary selective catalytic reducer 11 and the secondary selective catalytic reducer 31. The post-treatment assembly adds a first exhaust gas treatment device 1 and an HC injection system 4 on the basis of the exhaust gas treatment assembly of the National VI standard. It does not need to dismantle and modify the original exhaust gas treatment device, but only needs to install the first exhaust gas treatment device 1 and the HC injection system 4 on the original exhaust gas treatment device, thereby meeting the higher emission standards and achieving the low cost requirement.

[0038] Specifically, the full name of the primary selective catalytic reduction device 11 and the secondary selective catalytic reduction device 31 is Selective Cataly tic Reductiong, referred to as SCR. The working principle is that urea aqueous solution (commonly known as AdBlue) is injected into the exhaust pipe, and urea is decomposed at high temperature to generate ammonia (NH3). Subsequently, ammonia reacts with nitrogen oxides in the exhaust gas under the action of a catalyst to convert harmful nitrogen oxides into harmless nitrogen (N 2 ) and water (H 2 O), thus greatly reducing the pollution to the environment.

[0039] The full name of the oxidation catalyst 21 is Diesel Oxidation Catalyst (DOC), which is one of the key components in the exhaust aftertreatment system of diesel engines. Its main function is to convert harmful substances in exhaust gas (such as carbon monoxide CO, hydrocarbons HC and some particulate matter PM) into harmless carbon dioxide (CO) through catalytic reaction. 2 ) and water (H 2 O). The DOC is usually installed in the engine exhaust line, after the turbocharger and before the DPF (particulate filter 22).

[0040] The full name of the particle trap 22 is Diesel Particulate Filter, or DPF for short. It is a key post-treatment device used to reduce the emission of particulate matter (PM) in diesel engine exhaust. DPF captures particulate matter in exhaust gas by filtering, but as the use time increases, particulate matter will gradually accumulate inside the DPF, causing increased back pressure and affecting engine performance. Therefore, the DPF needs to be regenerated regularly to remove accumulated particulate matter.

[0041] The full name of the secondary ammonia oxidation catalyst 32 is Ammonia Slip Catalyst, referred to as ASC, which is an important component in the exhaust aftertreatment assembly of diesel engines. Its main function is to reduce the unreacted ammonia (NH 3 ) released into the atmosphere.

[0042] In this embodiment, the HC nozzle 42 injects diesel into the HC mixer 41, and the atomized diesel is mixed with the exhaust gas in the mixer and enters the oxidation catalyst 21. During this process, the diesel in the oxidation catalyst 21 undergoes an oxidation reaction with oxygen to generate heat (such as raising the temperature to above 600°C), which in turn provides heat to the particulate filter 22, reaching the temperature range required for the regeneration of the particulate filter 22 (above 600°C) to promote the active regeneration of the particulate filter 22.

[0043] Optionally, the first exhaust gas treatment device 1 further includes a primary ammonia oxidation catalyst 12, the air inlet end of the primary ammonia oxidation catalyst 12 is connected to the air outlet end of the primary selective catalytic reducer 11, and the air outlet end of the primary ammonia oxidation catalyst 12 is connected to the air inlet end of the HC mixer 41. In this embodiment, after the reaction inside the primary selective catalytic reducer 11, part of the ammonia gas still remains. After the part of the ammonia gas enters the second exhaust gas treatment device 2, it reacts with sulfur oxides (SO 3 ) will form a viscous ammonium bisulfate (NH 4 HSO 4 ). This substance is easy to adhere to the surface of the particle collector at low temperature (<280℃), causing the particle collector 22. At the same time, ammonium bisulfate (NH 4 HSO 4 ) is easily decomposed into NH 3 and H 2 SO 4 The released acidic gas will aggravate internal corrosion and affect the stable operation of the after-treatment assembly. Therefore, it is necessary to capture the remaining ammonia in the primary selective catalytic reducer 11 as much as possible, so the primary ammonia oxidation catalyst 12 is used to capture and remove the remaining ammonia in the primary selective catalytic reducer 11.

[0044] Optionally, the HC mixer 41 is provided with a first mixing chamber, and a first air inlet and a first air outlet are provided on one side wall of the HC mixer 41 along a first direction, respectively, and are connected to the first mixing chamber. The outlet end of the primary ammonia oxidation catalyst 12 is connected to the first air inlet, and the air inlet end of the oxidation catalyst 21 is connected to the first air outlet. The first exhaust gas treatment device 1 and the second exhaust gas treatment device 2 are arranged along the second direction, and the first direction and the second direction are perpendicular. In this embodiment, compared with the first exhaust gas treatment device 1, the second exhaust gas treatment device 2 and the third exhaust gas treatment device 3 being arranged in sequence along the first direction, the first exhaust gas treatment device 1 and the second exhaust gas treatment device 2 are arranged in sequence along the second direction, thereby reducing the occupied space of the post-treatment assembly along the first direction. In addition, the HC mixer 41, as a connecting component, connects the primary ammonia oxidation catalyst 12 and the oxidation catalyst 21, which eliminates the need for connecting pipes, thereby reducing the overall volume and reducing the manufacturing cost.

[0045] Optionally, the post-treatment assembly further includes a first urea mixer 5, the first urea mixer 5 is provided with a second mixing chamber, a side wall of the first urea mixer 5 is respectively provided with a second air inlet and a second air outlet along the first direction, the air outlet end of the particulate trap 22 is connected to the second air inlet, the second air outlet is connected to the air inlet end of the secondary selective catalytic reducer 31, the third exhaust gas treatment device 3 is arranged on the side of the second exhaust gas treatment device 2 away from the first exhaust gas treatment device 1 along the second direction, and the second mixing chamber is connected to the urea supply device. In this embodiment, compared with the first exhaust gas treatment device 1, the second exhaust gas treatment device 2 and the third exhaust gas treatment device 3 being arranged in sequence along the first direction, this arrangement makes the exhaust gas in the post-treatment assembly flow in a serpentine shape, further improving the occupied space of the post-treatment assembly along the first direction. In addition, the first urea mixer 5 is used as a connecting component to connect the particulate trap 22 and the secondary selective catalytic reducer 31, which eliminates the connection pipe fittings, thereby reducing the overall volume and reducing the manufacturing cost. Since the second mixing chamber is connected to the urea supply device, after the urea is injected into the second mixing chamber, the urea is converted into ammonia under the high temperature of the exhaust gas in the second mixing chamber, and then the ammonia enters the secondary selective catalytic reducer 31 .

[0046] like Figure 2-Figure 4 As shown, optionally, the post-treatment assembly further includes a second urea mixer 6, which includes a connecting pipe 61 and a mixing element 62. A urea hole 611 is provided on the peripheral wall of the connecting pipe 61. The urea hole 611 is used to communicate with the urea supply device. The air inlet end of the connecting pipe 61 is used to communicate with the exhaust port of the engine. The air outlet end of the connecting pipe 61 is communicated with the air inlet cavity of the primary selective catalytic reducer 11. Along the air flow direction in the connecting pipe 61, the urea hole 611 is located upstream of the mixing element 62. The mixing element 62 is provided in the connecting pipe 61 and is used to mix the exhaust gas and urea in the connecting pipe 61. In this embodiment, the exhaust gas and urea are mixed by the mixing element 62 in the connecting pipe 61 and then enter the air inlet cavity of the primary selective catalytic reducer 11 to improve the reaction efficiency of the primary selective catalytic reducer 11.

[0047] As for the specific structure of the mixing element 62, optionally, the mixing element 62 includes a tapered tube 621 and a plurality of guide plates 622, the tapered tube 621 is arranged in the connecting tube 61, and along the axial direction of the connecting tube 61, the tapered tube 621 is located between the gas outlet end of the connecting tube 61 and the urea hole 611, the large diameter end of the tapered tube 621 is fixedly connected to the gas outlet end of the connecting tube 61, a plurality of through holes 6211 are arranged on the peripheral wall of the tapered tube 621, and the plurality of through holes 6211 are arranged at intervals along the circumference of the tapered tube 621, and a plurality of guide plates 622 are arranged on the peripheral wall of the tapered tube 621 and correspond one-to-one to the plurality of through holes 6211. In this embodiment, the urea supply device sprays urea to the small diameter end of the conical tube 621 through the urea hole 611, and the exhaust gas opposite to the small diameter end of the conical tube 621 blows the atomized urea into the conical tube 621. The exhaust gas opposite to the peripheral wall of the conical tube 621 passes through the through hole 6211 under the action of the guide plate 622 and rotates around the circumference of the conical tube 621, and is fully mixed with the urea in the conical tube 621 in the process.

[0048] Optionally, the mixing element 62 is an integrally formed element. In this embodiment, this arrangement can reduce the processing cost of the mixing element 62 and improve the processing accuracy of the mixing element 62.

[0049] Optionally, the mixing element 62 further includes a cylindrical tube 623, the large diameter end of the tapered tube 621 is coaxially fixedly connected to the cylindrical tube 623, and the cylindrical tube 623 is fitted and fixedly connected to the inner wall of the connecting tube 61. In this embodiment, this arrangement is conducive to the coaxial arrangement between the tapered tube 621 and the connecting tube 61, and is conducive to the fixation between the tapered tube 621 and the connecting tube 61.

[0050] Optionally, the second exhaust treatment device 2 further includes a differential pressure sensor, which is used to monitor the differential pressure between the intake end and the exhaust end of the particulate trap 22. In this embodiment, the blockage state of the particulate trap 22 at this time is determined by monitoring the differential pressure change of the differential pressure sensor, and the ECU determines the working state of the HC injection system 4 based on this information.

[0051] In the prior art, if only one selective catalytic reduction device is provided, and the selective catalytic reduction device is provided at the rear of the post-treatment assembly, when the vehicle is cold started, the temperature of the exhaust gas discharged by the engine is low and the selective catalytic reduction device is far away from the exhaust port of the engine, so the catalyst (such as V 2 O 5 / TiO 2 or V 2 O 5 -WO 3 / TiO 2 ) effectively promotes the production of nitrogen oxides (NO x) Chemical reactions with reducing agents (such as ammonia or urea). Furthermore, during cold start, there is a problem of low conversion efficiency of the selective catalytic reduction converter for nitrogen oxides (NO x ).

[0052] To solve this problem, adjust the engine intake throttle valve and the exhaust throttle valve to raise the exhaust temperature at the engine exhaust port to the urea injection start temperature of the primary selective catalytic reduction converter 11. Also, since the primary selective catalytic reduction converter 11 is directly connected to the engine exhaust port, the primary selective catalytic reduction converter 11 will reach the urea injection start temperature point first. At this time, start the urea injection of the primary selective catalytic reduction converter 11, and the injection amount is equal to 100% of the demand; when the secondary selective catalytic reduction converter 31 reaches the injection start temperature, at this time, both the primary selective catalytic reduction converter 11 and the secondary selective catalytic reduction converter 31 perform urea injection, and the injection amount is 50% of the demand; and before the temperature of the secondary selective catalytic reduction converter 31 reaches the preset value T 预 , T 预 is greater than the urea injection start temperature of the secondary selective catalytic reduction converter 31, and dynamically adjust the urea injection ratio of the primary selective catalytic reduction converter 11 and the secondary selective catalytic reduction converter 31 according to the urea injection amount map; when the temperature of the secondary selective catalytic reduction converter 31 is greater than the preset value T 预 , turn off the urea injection of the primary selective catalytic reduction converter 11, and the urea injection amount of the secondary selective catalytic reduction converter 31 is equal to 100% of the demand. This setting can well solve the problem of low conversion efficiency of nitrogen oxides (NO x ) during cold start due to low temperature.

[0053] Optionally, the value range of the urea injection start temperature is between 150° - 200°, preferably 180°. The value range of T 预 is between 200° - 300°, preferably 250°.

[0054] In the prior art, the urban road conditions are complex and congestion occurs frequently, and vehicles often stop and go. The combustion efficiency of the engine is low under this working condition, and the exhaust temperature of the exhaust gas treatment assembly is difficult to reach the standard. Normally, the particulate trap needs high temperature to burn and decompose the trapped particulate matter for regeneration and cleaning, but the exhaust temperature of urban vehicles is low, and the particulate matter gradually accumulates. The exhaust temperature of urban vehicles is low, and it is difficult to achieve passive regeneration, and can only rely on active regeneration, that is, the vehicle control system is used to increase the exhaust gas temperature to burn the particulate matter. Frequent active regeneration has negative effects. It consumes extra fuel, increases the operating cost, and also accelerates the aging and damage of the particulate trap, shortens the service life, and may damage the engine and other components.

[0055] To solve this problem, when the vehicle equipped with the aftertreatment assembly is working, the exhaust gas generated by the engine passes through the HC mixer 41, the oxidation catalyst 21 and the particulate trap 22 in sequence. As the working time of the aftertreatment assembly increases, the particulate matter in the particulate trap 22 gradually accumulates, which leads to changes in the carbon load. The carbon load is usually evaluated by the front and rear pressure difference C of the particulate trap 22. When the front and rear pressure difference C of the particulate trap 22 is greater than or equal to the preset value c, the particulate trap 22 can no longer work normally at this time, so active regeneration is required. When the front and rear pressure difference C of the particulate trap 22 is less than the preset value c, the particulate trap 22 can work normally. In order to reduce the active regeneration frequency of the particulate trap 22, when the particulate trap 22 reaches the regeneration condition, the HC nozzle 42 injects a preset amount of fuel Q1 into the HC mixer 41 to increase the temperature in the particulate trap 22, so that the carbon load in the particulate trap 22 is quickly reduced, and the frequency of active regeneration is reduced. This reduces the extra fuel consumption of the vehicle, lowers the operating cost, effectively improves the aging and damage of the particle trap 22, extends the service life, and avoids damage to the engine and other components.

[0056] This embodiment also provides a vehicle, including a cab, a truck bed and the post-processing assembly in the above solution, wherein the post-processing assembly is arranged between the cab and the truck bed along the front-rear direction of the vehicle. In this embodiment, there is a gap between the cab and the truck bed, and the post-processing assembly is arranged in the gap between the cab and the truck bed, thereby eliminating the need to add installation space for the post-processing assembly, and utilizing the existing installation space to arrange the post-processing device. Specifically, the vehicle may be a mining truck, an earthmoving vehicle, etc.

[0057] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A post-processing assembly, characterized in that: include: A first tail gas treatment device (1) comprises a primary selective catalytic reducer (11), wherein an air intake chamber of the primary selective catalytic reducer (11) is respectively used to communicate with an exhaust port of a diesel engine and a urea supply device; An HC injection system (4) comprises an HC mixer (41) and an HC nozzle (42), wherein an air inlet end of the HC mixer (41) is connected to an air outlet end of the primary selective catalytic reducer (11), and the HC nozzle (42) is capable of injecting oil into the HC mixer (41); A second exhaust gas treatment device (2) comprises an oxidation catalyst (21) and a particle trap (22) connected in series, wherein an air inlet end of the oxidation catalyst (21) is connected to an air outlet end of the HC mixer (41); The third exhaust gas treatment device (3) comprises a secondary selective catalytic reducer (31) and a secondary ammonia oxidation catalyst (32) which are sequentially connected in series, wherein the air inlet end of the secondary selective catalytic reducer (31) is respectively connected to the air outlet end of the particulate trap (22) and the urea supply device.

2. The post-processing assembly according to claim 1, characterized in that: The first exhaust gas treatment device (1) further comprises a primary ammonia oxidation catalyst (12), wherein an air inlet end of the primary ammonia oxidation catalyst (12) is connected to an air outlet end of the primary selective catalytic reducer (11), and an air outlet end of the primary ammonia oxidation catalyst (12) is connected to an air inlet end of the HC mixer (41).

3. The post-processing assembly according to claim 2, characterized in that: The HC mixer (41) is provided with a first mixing chamber, and a first air inlet and a first air outlet are respectively provided on a side wall of the HC mixer (41) along a first direction, the air outlet end of the first-stage ammonia oxidation catalyst (12) is connected to the first air inlet, and the air inlet end of the oxidation catalyst (21) is connected to the first air outlet. The first exhaust gas treatment device (1) and the second exhaust gas treatment device (2) are arranged along a second direction, and the first direction is perpendicular to the second direction.

4. The post-processing assembly according to claim 3, characterized in that: The invention also comprises a first urea mixer (5), wherein the first urea mixer (5) is provided with a second mixing chamber, a side wall of the first urea mixer (5) is provided with a second air inlet hole and a second air outlet hole respectively along the first direction, the air outlet end of the particulate collector (22) is communicated with the second air inlet hole, the second air outlet hole is communicated with the air inlet end of the secondary selective catalytic reduction device (31), the third exhaust gas treatment device (3) is arranged on a side of the second exhaust gas treatment device (2) away from the first exhaust gas treatment device (1) along the second direction, and the second mixing chamber is communicated with the urea supply device.

5. The post-processing assembly according to claim 1, characterized in that: The invention also comprises a second urea mixer (6), the second urea mixer (6) comprising a connecting pipe (61) and a mixing element (62), a urea hole (611) being arranged on the peripheral wall of the connecting pipe (61), the urea hole (611) being used to communicate with the urea supply device, an air inlet end of the connecting pipe (61) being used to communicate with the exhaust port of the engine, an air outlet end of the connecting pipe (61) being used to communicate with the air inlet cavity of the primary selective catalytic reducer (11), and along the air flow direction in the connecting pipe (61), the urea hole (611) being located upstream of the mixing element (62), the mixing element (62) being arranged in the connecting pipe (61) and being used to mix the exhaust gas and urea in the connecting pipe (61).

6. The post-processing assembly according to claim 5, characterized in that: The mixing element (62) comprises a conical tube (621) and a plurality of guide plates (622); the conical tube (621) is arranged in the connecting tube (61); along the axial direction of the connecting tube (61), the conical tube (621) is located between the gas outlet end of the connecting tube (61) and the urea hole (611); the large diameter end of the conical tube (621) is fixedly connected to the gas outlet end of the connecting tube (61); a plurality of through holes (6211) are arranged on the peripheral wall of the conical tube (621); the plurality of through holes (6211) are arranged at intervals along the circumference of the conical tube (621); and the plurality of guide plates (622) are arranged on the peripheral wall of the conical tube (621) and correspond one-to-one to the plurality of through holes (6211).

7. The post-processing assembly according to claim 6, characterized in that: The mixing element (62) further comprises a cylindrical tube (623), the large diameter end of the conical tube (621) is coaxially fixedly connected to the cylindrical tube (623), and the cylindrical tube (623) is in contact with and fixedly connected to the inner wall of the connecting tube (61).

8. The post-processing assembly according to claim 7, characterized in that: The mixing element (62) is an integrally formed element.

9. The post-processing assembly according to claim 1, characterized in that: The second exhaust gas treatment device (2) further comprises a differential pressure sensor, wherein the differential pressure sensor is used to monitor the differential pressure between the intake end and the exhaust end of the particulate trap (22).

10. A vehicle, characterized in that It comprises a cab, a truck bed and the after-treatment assembly according to any one of claims 1 to 9, wherein the after-treatment assembly is arranged between the cab and the truck bed along the front-rear direction of the vehicle.

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