CN109798168B

CN109798168B - Can dismantle post processor structure of integrated urea nozzle

Info

Publication number: CN109798168B
Application number: CN201811507577.6A
Authority: CN
Inventors: 黄凯; 王科星; 邢喜春; 朱宏志; 朱光贞; 李会; 龙远; 刘守顺
Original assignee: FAW Jiefang Automotive Co Ltd
Current assignee: FAW Jiefang Automotive Co Ltd
Priority date: 2018-12-11
Filing date: 2018-12-11
Publication date: 2021-07-09
Anticipated expiration: 2038-12-11
Also published as: CN109798168A

Abstract

The invention relates to a post-processor structure of a detachable integrated urea nozzle, wherein a mixing cavity is arranged in a shell of the post-processor structure; the air inlet unit is fixed on the front end cover of the postprocessor shell, and the opening part of the air inlet unit extends into the postprocessor shell; the mixing unit is arranged on the side surface of the postprocessor shell, and a urea nozzle seat welding assembly of the mixing unit is connected with an external urea nozzle and is connected with a liquid path assembly through a V-shaped clamp assembly; the liquid path assembly is connected with the urea mixer assembly, and the urea mixer assembly is positioned in the mixing cavity; the SCR unit is positioned in the postprocessor shell, the front end of the SCR unit is connected with the mixing cavity, and the rear end of the SCR unit is close to the rear end cover of the postprocessor shell; the silencing unit is arranged at the periphery of the SCR unit; the air outlet unit is arranged close to the rear end cover of the postprocessor shell. The invention has high integration level, can be detached at any time to check whether urea crystals are generated in the post-processor and the mixer, and can be detached at any time to clean the urea crystals generated in the post-processor and the mixer.

Description

Can dismantle post processor structure of integrated urea nozzle

Technical Field

The invention relates to a square post-processor structure of a detachable integrated urea nozzle, which is suitable for diesel commercial vehicles meeting national IV, V and VI regulations.

Background

The limit of the exhaust pollutants (mainly particles and nitrogen oxides NOx) in the emission regulations of the state IV, the state V and the state VI of the diesel engines is greatly reduced compared with the emission regulations of the state III. The two exhaust pollutants are difficult to be reduced simultaneously in the engine, and the SCR (selective catalytic reduction) system can effectively reduce the content of nitrogen oxide in the exhaust pollutants, so that the exhaust pollutants of the engine meet the emission regulation requirements.

With the great application of the SCR technology, an aqueous urea solution as a reducing agent needs to be injected into an exhaust pipe through a urea nozzle in advance to be sufficiently and uniformly mixed with exhaust gas so as to be subjected to an oxidation-reduction reaction with NOx on an aftertreatment carrier. However, the arrangement requirement of the urea nozzle is relatively strict, and the existing urea nozzle arrangement mode has the following technical problems:

1. the urea nozzle is arranged on the pipeline and has the arrangement requirements of the included angle between the urea nozzle and the axis of the pipeline, the welding height of the nozzle seat, the offset between the urea nozzle and the pipeline and the like. The bent pipe and the pipeline welding process of the existing pipeline arrangement scheme are difficult to meet the requirements;

2. the urea nozzle is arranged on the pipeline, and the urea is corrosive, so that all pipelines in contact with the urea are required to be made of stainless steel materials, and the cost is high;

3. urea aqueous solution may generate urea crystals, and the urea crystals of the pipeline of the existing pipeline arrangement scheme may generate leakage and corrosion, thereby greatly affecting the aesthetic property;

4. urea aqueous solution may generate urea crystals, and the urea crystals in the existing pipeline arrangement scheme may be generated and accumulated in the pipeline and the post-processor, so that the backpressure of an exhaust system is influenced, and even the pipeline and the post-processor are blocked;

5. urea crystallization may be generated in the urea aqueous solution, if the urea crystallization occurs, the urea can not be used as reducing agent ammonia gas for SCR reaction to participate in selective catalytic reduction reaction, nitrogen oxide standard exceeding fault of the whole vehicle can be caused, and even the output torque of the whole vehicle is limited;

6. urea aqueous solution may generate urea crystals, and the existing pipeline arrangement scheme cannot observe whether crystals are generated in the postprocessor at any time;

7. aqueous urea solutions may produce urea crystals. Once crystals are generated, the existing pipeline arrangement scheme cannot clean the crystals generated in the post processor;

8. the hydrolysis of the urea aqueous solution needs continuous high temperature (140 ℃), the temperature of the inner wall of the pipeline of the existing single-layer pipeline arrangement scheme is reduced quickly, the heat utilization rate of a system is low, and the continuous high temperature cannot be ensured;

9. the liquid drops of the urea aqueous solution are required to be fully contacted, impacted and crushed with the air flow to ensure the evaporation rate of the ammonia gas, and the existing arrangement scheme without a mixer can not ensure the full mixing of the liquid drops and the air flow to ensure the mixing uniformity of the urea and the evaporation rate of the ammonia gas;

10. the mixing and hydrolysis of the urea aqueous solution requires a certain reaction time, and the existing pipeline arrangement scheme needs to arrange longer pipelines (more than or equal to 500mm) to ensure the mixing and hydrolysis time, which is not beneficial to saving space;

11. the whole vehicle urea tank is arranged behind the exhaust system, and a urea supply pipeline is required to be connected between the urea nozzle and the urea tank. The distance between the urea nozzle and the urea tank is longer in the existing pipeline arrangement scheme, and the supply pipeline is also longer, so that the weight and cost are not reduced;

12. the whole vehicle has various vehicle types (carrying, traction, self-unloading, dangerous chemicals and the like), and the product diversity is ensured by generalization, integration and modularization as much as possible. The existing pipeline arrangement scheme is not beneficial to generalization, integration and modularization.

In order to solve the above problems, an exhaust system is required to reduce the risk of urea crystallization while ensuring the uniformity of urea mixing. It is also desirable to have a structure that allows for the observed cleaning of the crystals once they have actually occurred.

Therefore, there is an urgent need for a simple and low-cost urea nozzle arrangement method that can solve the above problems, integrate with the post-processor, be modular, ensure sealing, have a mixer, have strong urea crystallization resistance, high heat utilization rate, can be disassembled for cleaning and inspection, and can reduce the arrangement difficulty and realize uniform mixing of urea and strong urea crystallization resistance.

Disclosure of Invention

The invention aims to solve the technical problem of providing an integrated modular after-treatment device structure with a detachable integrated urea nozzle, which can be detached at any time to check whether urea crystals are generated inside the after-treatment device and a mixer or not and can be detached at any time to clean the urea crystals generated inside the after-treatment device.

In order to solve the technical problem, the post-processor structure of the detachable integrated urea nozzle comprises a post-processor shell, an air inlet unit, a mixing unit, an SCR unit, a silencing unit and an air outlet unit; the post-processor shell is internally provided with a cylindrical mixing cavity, and the rear end of the mixing cavity is provided with a porous end cover; the air inlet unit is fixed on the front end cover of the postprocessor shell, the part of the air inlet unit with the opening extends into the postprocessor shell, and the axis of the part of the air inlet unit extending into the postprocessor shell is parallel to the axis of the mixing cavity; the mixing unit is arranged on the side surface of the postprocessor shell and comprises a urea nozzle seat welding assembly, a liquid path assembly and a urea mixer assembly; the urea nozzle seat welding assembly is connected with an external urea nozzle through a bolt and a sealing gasket and is connected with the liquid path assembly through a V-shaped hoop assembly; the liquid path assembly is connected with the urea mixer assembly, and the urea mixer assembly is positioned in the mixing cavity; the SCR unit is positioned in the postprocessor shell, the front end of the SCR unit is connected with the mixing cavity, and the rear end of the SCR unit is close to the rear end cover of the postprocessor shell; the silencing unit is arranged at the periphery of the SCR unit; the air outlet unit is arranged on the side surface of the postprocessor shell and is close to the rear end cover of the postprocessor shell.

The mixing cavity comprises a mixing cavity end cover, a mixing cavity shell, a mixing cavity porous end cover and a fixing cone; the mixing cavity end cover is fixed on the front end cover; the mixing cavity shell is positioned in the postprocessor shell, the front end of the mixing cavity shell is connected with the mixing cavity end cover, and the tail end of the mixing cavity shell is connected with the porous end cover of the mixing cavity and the small-diameter end of the fixed cone.

The air inlet unit comprises an air inlet flange, an air inlet connecting pipe and a half-opening porous pipe; the air inlet connecting pipe extends into the air inlet flange and is welded together along the circumferential direction; the air inlet connecting pipe extends into the shell of the aftertreatment device and is welded with the semi-open perforated pipe.

The semi-open porous pipe comprises a porous section and a semi-open section.

In the mixing unit, a flange with a step opening, a urea nozzle seat welding base and a transition base are sequentially welded together to form a detachable urea nozzle seat welding assembly; the flange with the step of the boss port, the liquid path inlet base and the outer mixing pipe are welded together in sequence to form a liquid path assembly; the flange with the step of the boss opening is fixed on the side surface of the shell of the post processor; an inner mixing pipe and a porous end cover are welded in the liquid path assembly to form a urea mixer assembly; the opening of the stepped flange with the opening is matched with the step of the stepped flange with the lug boss opening to form circumferential positioning, and the circumferential positioning is hermetically connected by adopting a sealing gasket and a V-shaped clamp assembly; the urea mixer assembly is welded with the opening on the side surface of the mixing cavity.

The SCR unit comprises an SCR front carrier, an SCR rear carrier and an SCR packaging shell; the SCR front carrier and the SCR rear carrier are plugged into the SCR packaging shell through carrier gaskets in a front-back sequence and are fixed in the SCR packaging shell to form an SCR assembly; and welding the SCR front carrier side of the SCR assembly and the circumference of the fixed cone to form an SCR unit.

The silencing unit comprises a first baffle plate and a second silencing baffle plate; the first partition plate is welded with the large-diameter end of the fixed cone and the front end of the SCR packaging shell; the second silencing partition plate is welded in the middle of the outer side of the SCR packaging shell.

The air outlet unit comprises an air outlet flange and an air outlet pipe; the air outlet pipe is welded and fixed on the side surface of the postprocessor shell, and the air outlet flange is welded on the outer end surface of the air outlet pipe.

The urea nozzle seat is directly integrated and arranged on the post-processor and is matched with the urea mixer assembly for use, so that the problems of difficult arrangement of pipelines and urea nozzles, difficult guarantee of urea mixing uniformity, insufficient urea crystallization resistance and the like can be well solved.

The connection position of the urea nozzle seat and the postprocessor is changed from a traditional welding mode of the nozzle seat and a pipeline to a flange sealing gasket connection mode, and the urea nozzle seat is guaranteed to be detachable and observable while sealing is guaranteed. The internal part of the post-processor and the mixer can be disassembled at any time to check whether urea crystals are generated. The urea crystal generated in the device can be detached and cleaned at any time. The invention has high integration level, simplicity and low cost.

The most key technology of the invention is a detachable urea nozzle seat structure for ensuring the sealing property. The structure is a sealing structure of a concave-convex step flange, a sealing gasket and a V-shaped clamp assembly. Can well ensure the sealing performance, does not generate gas and urea leakage, and can be repeatedly used for many times. This technique ensures that once urea crystallization and plugging actually occur, it can be observed by opening the detachable urea nozzle holder structure. Meanwhile, the urea mixing pipe can be observed and cleaned completely after the structure is opened, the size of the opening is guaranteed to be more than 80mm, and a small amount of urea crystals can be cleaned simply by using tools conveniently. Failure of the entire aftertreatment assembly due to urea crystallization is avoided.

The post-processor adopts an integrated urea nozzle scheme, so that the system integration can be greatly improved, and the system difference is reduced. The cost of the original stainless steel pipeline can be reduced to non-stainless steel while the pipeline arrangement difficulty is greatly reduced. The urea supply line and the like may be shortened. The influence of pipeline manufacturing errors on urea crystallization is completely eliminated. The modularized assembly is more reliable and more beneficial to generalization.

The urea mixer is additionally arranged in the post-processor, and the original structure of the inner and outer spinning disks and the mixing cavity is adopted, so that the uniformity of gas supplied by the gas circuit entering the mixing pipe is greatly improved. The design of the inner mixing pipe and the outer mixing pipe can greatly improve the impact effect of gas and liquid. The uniformly entering gas fully impacts the urea sprayed into the liquid path, so that urea liquid drops are fully crushed and hydrolyzed. Meanwhile, the hydrolysis process is in the mixing pipe, the temperature of the mixing pipe is greatly increased by external gas, and the hydrolysis rate is greatly improved.

The harm of urea crystallization is huge, and the scheme that the original urea nozzle is arranged on the pipeline is not beneficial to avoiding urea crystallization. The main influencing factors of crystallization are temperature, flow rate, droplet breaking condition, whether continuous spraying is carried out or not, and the like. The integrated urea nozzle solution with the added mixer has the porous mixing pipe completely surrounded by the high-temperature exhaust gas, so the temperature is higher. The inner mixing pipe is circumferentially provided with holes, so that the flow velocity is uniform, and no flow dead zone exists. The urea in the liquid path is impacted by the uniform airflow, so that the urea can be crushed and hydrolyzed. If the continuous spraying condition of the urea nozzle is found, the detachable structure is opened for observation and cleaning.

Drawings

FIG. 1 is a perspective view of an aftertreatment device with a square removable integrated urea nozzle according to the invention.

FIG. 2 is a sectional view of an aftertreatment device with a square removable integrated urea nozzle according to the invention.

FIG. 3 is a schematic diagram of the gas circuit and liquid circuit of the post-processor structure of the square detachable integrated urea nozzle of the present invention.

FIG. 4 is a cross-sectional view of the integrated intake unit.

Fig. 5 is a perspective view of a half-open perforated pipe.

Fig. 6 is a partial perspective view of the present invention.

Fig. 7a is a partial sectional view of the mixing unit, and fig. 7b is a partial enlarged view of fig. 5.

Fig. 8 is a cross-sectional view of an SCR unit.

Fig. 9 is a sectional view of the muffler unit.

Fig. 10 is a sectional view of the gas outlet cell.

1. A post-processor outer housing; 101. a front end cover; 102. an outer shell, 103, a rear end cover; 104. a mixing chamber end cap; 105. a mixing chamber housing; 106. a mixing chamber porous end cap; 107. a fixed cone; 2. an air inlet unit; 201. an air inlet flange; 202. an air inlet connecting pipe; 203. a semi-open porous tube; 2031. a porous section; 2032. a semi-open section; 3. a mixing unit; 303. a porous end cap; 304. an inner mixing tube; 305. an outer mixing tube; 306. a liquid path inlet base; 307. a flange with a step of a boss opening; 308. a transition base; 309. a urea nozzle seat is welded with the base; 310. a urea nozzle holder; 311. a stepped flange with a notch; 312. a V-shaped clamp assembly; 4. an SCR unit; 401. an SCR pre-carrier; 402. SCR rear carrier; 403. an SCR package housing; 501. a first separator; 502. a second sound-deadening partition plate; 6. an air outlet unit; 601. an air outlet flange; 602. an air outlet pipe; 701. a temperature sensor seat; 702. the nitrogen oxygen sensor seat.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments and accompanying drawings.

As shown in fig. 1, 2 and 3, the post-processor structure of the detachable integrated urea nozzle of the present invention is a series structure, and includes a post-processor housing 1, an air inlet unit 2, a mixing unit 3, an SCR unit 4, a muffler unit 5 and an air outlet unit 6;

as shown in fig. 1, 2 and 4, the aftertreatment device casing 1 includes a front end cover 101, an outer casing 102 and a rear end cover 103 welded together; the post-processor shell 1 is internally provided with a cylindrical mixing cavity; the mixing cavity comprises a mixing cavity end cover 104, a mixing cavity outer shell 105, a mixing cavity porous end cover 106 and a fixed cone 107 which are welded and fixed together; the mixing cavity end cover 104 is fixed at the front end of the mixing cavity shell 105 and is arranged on the front end cover 101; a mixing chamber housing 105 is located within the aftertreatment housing 1 and terminates in a mixing chamber porous end cap 106 and a small diameter end of a fixed cone 107.

The air inlet unit 2 comprises an air inlet flange 201, an air inlet connecting pipe 202 and a semi-open porous pipe 203; the air inlet connecting pipe 202 extends into the air inlet flange 201 and is welded together along the circumferential direction; the air inlet connecting pipe 202 extends into the front end cover 101 and is welded with the semi-open perforated pipe 203 to form a front end cover welding assembly; the semi-open perforated tube 203 is comprised of a forward perforated section 2031 and a rearward semi-open section 2032; the axis of the inlet connection 202 is parallel to the axis of the mixing chamber housing 105.

As shown in fig. 2, 7a and 7b, the mixing unit 3 includes a urea nozzle holder welding assembly, a liquid path assembly and a urea mixer assembly; the flange 311 with the step of the opening, the urea nozzle holder 310, the urea nozzle holder welding base 309 and the transition base 308 are welded together in sequence to form a detachable urea nozzle holder welding assembly; a stepped flange 307 with a boss opening is fixed on the side surface of the postprocessor shell 1; the flange 307 with the step of the boss port, the liquid path inlet base 306 and the outer mixing pipe 305 are welded together in sequence to form a liquid path assembly; an inner mixing pipe 304 and a porous end cover 303 are welded in the liquid path assembly to form a urea mixer assembly; wherein the opening of the stepped flange 311 with the opening is matched with the step of the stepped flange 307 with the boss opening to form circumferential positioning and is connected in a sealing way by adopting a sealing gasket and a V-shaped hoop assembly 312; the urea mixer assembly is welded to an opening in the side of the mixing chamber housing 105.

As shown in fig. 8, the SCR unit 4 includes an SCR front carrier 401, an SCR rear carrier 402, and an SCR package housing 403; the SCR front carrier 401 and the SCR rear carrier 402 are plugged into the SCR package shell 403 through carrier gaskets in a front-to-back sequence and are fixed in the SCR package shell 403 to form an SCR assembly; the SCR front carrier 401 side of the SCR assembly is circumferentially welded to the stationary cone 107.

As shown in fig. 9, the sound-deadening unit 5 includes a first partition plate 501 and a second partition plate 502; the first partition plate 501 is welded with the large-diameter end of the fixed cone 106 and the front end of the SCR package shell 403; a second sound damping spacer 502 is welded to the outside of the middle of the SCR package housing 403.

As shown in fig. 10, the outlet unit 6 includes an outlet flange 601 and an outlet pipe 602; the outlet pipe 602 is welded and fixed on the side surface of the outer shell 102, and the outlet flange 601 is welded on the outer end surface of the outlet pipe 602.

As shown in fig. 10, a temperature sensor seat 701 and a nitrogen-oxygen sensor seat 702 are further fixed to the outer shell 102.

The high-temperature exhaust gas of the engine sequentially enters the interior of the aftertreatment housing 1 through the air inlet flange 201, the air inlet adapter 202 and the half-open porous pipe 203 of the air inlet unit 2. The air channel flow guide cavity formed by the front end cover 101, the outer shell 102, the mixing cavity outer shell 105, the fixed cone 107, the first partition 501 and the outer mixing pipe 305 is entered from the opening side of the semi-open porous pipe 203 and is guided to the periphery of the open fan blades of the outer mixing pipe 305 through the air channel flow guide cavity. And providing an impact airflow which is vertical to the spraying direction of the urea aqueous solution sprayed from the liquid path.

The urea aqueous solution is introduced into the outer mixing pipe 305 from the liquid path diversion cavity of the mixing unit 3 through the V-shaped hoop assembly 312, the flange 311 with the notch step, the urea nozzle holder 310, the urea nozzle holder welding base 309, the transition base 308, the flange 307 with the boss step and the liquid path inlet base 306 in sequence, and is mixed with the high-temperature waste gas provided by the gas path in the gas inlet unit 2 in an impact manner. And then the urea aqueous solution in the liquid path and the high-temperature waste gas in the gas path are fully mixed and hydrolyzed by the inner mixing pipe 304 and the porous end cover 303 to generate ammonia gas, thereby providing a reducing agent for the selective catalytic reduction reaction of the SCR unit.

The detachable urea nozzle connecting structure V-shaped clamp assembly 312, the flange 311 with the notch step, the urea nozzle seat 310, the urea nozzle seat welding base 309, the transition base 308 and the flange 307 with the boss step of the mixing unit 3 can ensure that the high-temperature waste gas in the gas path and the urea aqueous solution in the liquid path are sealed and have no leakage. Meanwhile, the V-shaped clamp assembly 312 can be detached at any time, and the flange 311 with the notch and the flange 307 with the boss opening are separated. Whether urea crystals were generated inside the mixer was observed through the observation hole. If urea crystals are generated, the inner crystal blocks can be cleaned through the observation holes.

In order to ensure the maximum SCR conversion efficiency, the ammonia gas, which is the reducing agent introduced by the mixing unit 3, is required to uniformly flow into the SCR front carrier 401. The mixture rectified by the porous end cover 303 uniformly flows into the SCR front carrier 401 and undergoes a selective catalytic reduction reaction with nitrogen oxides in the exhaust gas under the action of a catalyst. The mixed gas rectified more uniformly by the SCR front carrier 401 flows into the SCR rear carrier 402 to continue to generate selective catalytic reduction reaction, so that the nitrogen oxide is reduced to be below the limit value of the emission regulation. The reducing agent of the SCR reaction, i.e., ammonia gas generated by hydrolysis, is also an exhaust pollutant. It is therefore necessary to oxidize the ammonia gas not participating in the SCR reaction into harmless nitrogen and water by the ammonia oxidation catalyst coated on the tail of the SCR rear carrier 402.

The main functions of the after-treatment device include reducing the emission pollutants and reducing the exhaust noise, and the exhaust gas having been treated by the SCR unit 4 needs to be further reduced by the muffler unit 5. When the exhaust gas flow of the engine flows through the mixing cavities, the flow guide cavities, the SCR carrier and other structures in the mixing unit 3 and the SCR unit 4 when the exhaust gas flow flows in the aftertreatment equipment provided by the embodiment of the invention, the overall energy and the high-frequency noise are greatly reduced. And then the energy is reduced by the second silencing partition plate 502 of the silencing unit 5, and the sound enters a silencing cavity formed by the first partition plate 501, the second silencing partition plate 502 and the rear end cover 103 together to perform reactive silencing.

The air outlet unit 6 discharges the mixture gas which is reduced in emission by the SCR unit 4 and reduced in noise by the muffler unit 5 and meets the emission and noise regulations to the outside of the assembly. The gas flows through the gas outlet pipe 602 and the gas outlet flange 601 in sequence. Meanwhile, a nitrogen-oxygen sensor seat 505 and a temperature sensor seat 504 are arranged on the outer shell 102 to monitor the temperature of the exhaust gas and whether the nitrogen oxides are qualified or not and perform feedback control.

The post-processor structure adopts a flange sealing connection structure with a concave-convex step surface for positioning, a detachable urea nozzle seat structure is formed while the sealing performance is ensured, and the internal crystal of the post-processor mixer is convenient to observe and clean. The connecting piece adopts the V-shaped clamp assembly, is simple and reliable, is far convenient to assemble in a flange bolt connecting structure, and has good pressing force and centering correction.

The invention has the following characteristics: aiming at the problem that the urea nozzle pipeline arrangement bent pipe and the pipeline welding process are difficult to meet, the urea nozzle seat welding assembly is integrated on the post processor, the bent pipe and the pipeline can be welded into a stamping part welding structure, the machining difficulty can be reduced, and the machining precision and the assembly welding precision can be ensured;

1. aiming at the problem that the pipeline is made of stainless steel and is high in cost, the integrated urea nozzle scheme is adopted, so that all pipelines in front of the post-processor can be reduced to be made of non-stainless steel;

2. aiming at the problem that the appearance is influenced by the leakage and corrosion of urea crystals in the existing pipeline arrangement scheme, the flange, the sealing gasket and the clamp are adopted to form sealing, so that the two-phase sealing of gas and urea aqueous solution can be ensured;

aiming at the problem that internal crystallization accumulation influences backpressure, a urea mixer is adopted to ensure strong convection impact of high-temperature gas and urea aqueous solution, improve local gas flow velocity and improve anti-crystallization capacity.

3. Aiming at the problem that the discharge is influenced by crystallization, a urea mixer is adopted to ensure that urea is uniformly mixed, so that the hydrolysis is improved, the urea crystallization risk is reduced, and the utilization rate of an SCR carrier is improved.

4. Aiming at the problem that internal crystallization cannot be observed, observation is carried out through a detachable urea nozzle seat structure;

5. aiming at the problem that internal crystals cannot be cleaned, the urea nozzle seat structure can be disassembled to clean the urea nozzle seat;

6. aiming at the problem that the temperature of the inner wall of the pipeline arrangement cannot be guaranteed, a double-layer pipe mixer is adopted, and a middle pipe is surrounded by high-temperature gas, so that the mixing uniformity and the hydrolysis rate of the urea aqueous solution are greatly improved, and the crystallization risk is reduced.

7. Aiming at the problem that the liquid drops and the air flow cannot be fully mixed, a double-layer pipe mixer structure is adopted, and the external air flow and the internal urea liquid drop flow generate strong convection through the mixer, so that the liquid drop crushing and urea hydrolysis are facilitated;

8. aiming at the problem that the existing structure needs to ensure a longer mixing distance, a double-layer pipe mixer structure is adopted to enhance convection and increase rotating flow to shorten the mixing distance.

9. The urea feeding device aims at the problem that a urea feeding pipeline is long and is not beneficial to weight reduction and cost reduction. And the length of a supply pipeline can be greatly shortened by adopting an integrated urea nozzle structure.

10. Aiming at the problems of generalization and low integration, the post-treatment module of the integrated urea nozzle is adopted, the modularization of the post-treatment device assembly is ensured, and the generalization requirements of different vehicle types are met.

The post-processor assembly can solve the industrial problems of the arrangement of a urea nozzle of a pipeline, urea leakage crystallization of the pipeline and urea crystallization in the pipeline, and can be freely applied to a system of a tightly coupled post-processor. The system is compact in arrangement, and is particularly suitable for a system which has small arrangement space, is difficult to arrange pipelines and is closely coupled with an engine by an postprocessor. The assembly performance is reliable, the mixer unit ensures the urea mixing uniformity, and the urea crystallization resistance is greatly improved. The parts have good universality, simple processing and manufacturing process, convenient arrangement of the whole vehicle, good assembly reliability and strong market competitiveness.

By adopting the post-processor assembly, the following technical effects can be achieved:

the purposes of reducing the processing difficulty of the pipeline and improving the processing and welding precision of the assembly can be realized.

The average pipeline cost can be reduced by 150 yuan/m.

The gas-liquid double-phase sealing without leakage and external urea crystallization can be realized.

The crystallization risk of the system can be reduced, the stable back pressure of the system is ensured, and the fuel economy is improved.

The urea mixing uniformity can be improved, the hydrolysis rate is improved, the SCR carrier utilization rate is improved, and the system emission is ensured to meet the national emission standard.

Can realize dismantling urea nozzle holder, guarantee the observable purpose in the blender.

Can realize dismantling urea nozzle holder, guarantee the mesh that the inside crystallization of blender can be cleared up.

The purposes of improving the wall surface temperature of the mixing pipe, improving the heat rate, reducing the crystallization risk, reducing the oil consumption and improving the conversion rate of nitrogen oxides can be realized.

Can realize the purposes of good mixing uniformity of the urea aqueous solution and the high-temperature gas, improving the utilization rate of the SCR carrier, reducing the content of noble metal of the catalyst and the like.

The mixing distance can be reduced by 500mm, and the system arrangement space can be reduced.

The purposes of shortening the length of the urea supply pipeline by 500mm and reducing the system cost can be realized.

The post-processor assembly can be generalized and modularized, and the full-vehicle diversification requirement and the full-vehicle arrangement requirement of the post-processor assembly are greatly facilitated.

Claims

1. A post-processor structure of a detachable integrated urea nozzle comprises a post-processor shell (1), an air inlet unit (2), a mixing unit (3), an SCR unit (4), a silencing unit (5) and an air outlet unit (6); the post-processor shell is characterized in that a cylindrical mixing cavity is arranged in the post-processor shell (1), and a porous end cover is arranged at the rear end of the mixing cavity; the air inlet unit (2) is fixed on a front end cover (101) of the postprocessor shell (1), a part with an opening of the air inlet unit extends into the postprocessor shell (1), and the axis of the part of the air inlet unit extending into the postprocessor shell (1) is parallel to the axis of the mixing cavity; the mixing unit (3) is arranged on the side surface of the postprocessor shell (1) and comprises a urea nozzle seat welding assembly, a liquid path assembly and a urea mixer assembly; the urea nozzle seat welding assembly is connected with an external urea nozzle through a bolt and a sealing gasket and is connected with the liquid path assembly through a V-shaped hoop assembly (312); the liquid path assembly is connected with the urea mixer assembly, and the urea mixer assembly is positioned in the mixing cavity; the SCR unit (4) is positioned in the postprocessor shell (1), the front end of the SCR unit is connected with the mixing cavity, and the rear end of the SCR unit is close to a rear end cover (103) of the postprocessor shell (1); the silencing unit (5) is arranged at the periphery of the SCR unit (4); the air outlet unit (6) is arranged on the side surface of the postprocessor shell (1) and is close to the rear end cover (103) of the postprocessor shell (1); in the mixing unit (3), a flange (311) with a step of a notch, a urea nozzle seat (310), a urea nozzle seat welding base (309) and a transition base (308) are sequentially welded together to form a detachable urea nozzle seat welding assembly; a step flange (307) with a boss port, a liquid path inlet base (306) and an outer mixing pipe (305) are welded together in sequence to form a liquid path assembly; a step flange (307) with a boss opening is fixed on the side surface of the postprocessor shell (1); an inner mixing pipe (304) and a porous end cover (303) are welded in the liquid path assembly to form a urea mixer assembly; wherein the opening of the flange (311) with the opening step is matched with the step of the flange (307) with the lug boss opening step to form circumferential positioning and is connected with the V-shaped hoop assembly (312) in a sealing way by adopting a sealing gasket; the urea mixer assembly is welded with the opening on the side surface of the mixing cavity; the mixing cavity comprises a mixing cavity end cover (104), a mixing cavity shell (105), a mixing cavity porous end cover (106) and a fixed cone (107); the mixing cavity end cover (104) is fixed on the front end cover (101); the mixing cavity shell (105) is positioned in the postprocessor shell (1), the front end of the mixing cavity shell is connected with a mixing cavity end cover (104), and the tail end of the mixing cavity shell is connected with a mixing cavity porous end cover (106) and a small-diameter end of a fixed cone (107).

2. The structure of a detachable integrated urea nozzle post-processor according to claim 1, characterized in that said air inlet unit (2) comprises an air inlet flange (201), an air inlet adapter (202), a semi-open perforated pipe (203); the air inlet connecting pipe (202) extends into the air inlet flange (201) and is welded together along the circumferential direction; the air inlet connecting pipe (202) extends into the post-processor shell (1) and is welded with the semi-open porous pipe (203).

3. The structure of a detachable integrated urea nozzle post-processor according to claim 2, characterized in that said semi-open perforated pipe (203) comprises a perforated section (2031) and a semi-open section (2032).

4. The detachable urea nozzle integrated aftertreatment structure according to claim 2, wherein the SCR unit (4) comprises a SCR front carrier (401), a SCR rear carrier (402) and a SCR package housing (403); the SCR front carrier (401) and the SCR rear carrier (402) are plugged into an SCR packaging shell (403) through carrier gaskets in a front-back sequence and are fixed in the SCR packaging shell (403) to form an SCR assembly; and welding the SCR front carrier (401) side of the SCR assembly and the circumference of the fixed cone (107) to form an SCR unit (4).

5. A detachable integrated urea nozzle post-processor structure according to claim 4, characterized in that said silencing unit (5) comprises a first baffle plate (501) and a second silencing baffle plate (502); the first clapboard (501) is welded with the large-diameter end of the fixed cone (106) and the front end of the SCR packaging shell (403); and the second silencing partition plate (502) is welded at the middle position of the outer side of the SCR packaging shell (403).

6. The structure of a detachable integrated urea nozzle post-processor according to claim 1, characterized in that said outlet unit (6) comprises an outlet flange (601) and an outlet pipe (602); an air outlet pipe (602) is welded and fixed on the side surface of the postprocessor shell (1), and an air outlet flange (601) is welded on the outer end surface of the air outlet pipe (602).