CN211500765U

CN211500765U - Tail gas treatment assembly

Info

Publication number: CN211500765U
Application number: CN202020178893.XU
Authority: CN
Inventors: 丁宁宁; C·多林
Original assignee: Robert Bosch GmbH
Current assignee: Bosch Automotive System Wuxi Co Ltd
Priority date: 2020-02-18
Filing date: 2020-02-18
Publication date: 2020-09-15
Anticipated expiration: 2030-02-18

Abstract

The application provides a tail gas treatment subassembly, DOC, DPF, blender and SCR that loops through including tail gas, be provided with the tail gas entry on the DOC, be provided with the tail gas export on the SCR, tail gas passes through the tail gas entry gets into the DOC flows through the tail gas export SCR, spout into urea aqueous solution and tail gas mixture in the blender, DPF with set up the separator that can nevertheless not pass through the urea crystallization through tail gas between the blender.

Description

Tail gas treatment assembly

Technical Field

The present application relates to the field of diesel internal combustion engines, and more particularly to an exhaust treatment assembly using a reductant for selective catalytic reduction.

Background

Due to the need for environmental protection, the legislation on the exhaust emissions of diesel internal combustion engines is increasingly demanding. In the treatment of exhaust gas from a diesel engine, both DOC (diesel oxidation catalyst) and DPF (diesel particulate filter) are components that must be used at present. In addition, it is also a commonly used technique to sufficiently mix the reducing agent with the exhaust gas using a mixer before SCR (selective catalytic reduction) is performed.

Since the temperature of the exhaust gas in the mixer has been reduced, a crystallization phenomenon of a portion of the reducing agent occurs when the reducing agent is injected into the mixer through the injector. The crystallized crystal particles or powder enter the DOC or DPF, thereby affecting the function of the DOC or DPF. In particular, when the exhaust treatment assembly is arranged vertically, the crystals will eventually fall on the base of the DPF due to the effect of gravity, which negatively affects the operating efficiency of the DPF.

There is a need for an exhaust treatment assembly that reduces the above-mentioned negative effects.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the not enough of prior art, provide a tail gas treatment component that reduces reductant crystallization and to DPF function influence.

For accomplishing above-mentioned application purpose, this application provides a tail gas treatment component, DOC, DPF, blender and SCR that loops through including tail gas, be provided with the tail gas entry on the DOC, be provided with the tail gas export on the SCR, tail gas passes through the tail gas entry gets into the DOC flows through the tail gas export SCR, spout into urea aqueous solution and tail gas mixture in the blender, DPF with set up the separator that can nevertheless not pass through the urea crystallization through tail gas between the blender.

The present application also features the isolator including an outer ring extending a thickness in a direction of exhaust gas flow through the DPF toward the mixer and a breather plate coupled to the outer ring substantially perpendicular to the flow direction.

The present application also features the vent plate having a plurality of vents penetrating the vent plate.

The present application also has a feature that the ventilation holes penetrate the ventilation plate obliquely.

The present application is also characterized in that the size of the air-permeable holes is smaller than the size of crystals of the urea aqueous solution, and more preferably the air-permeable holes are circular holes having a diameter of 6 to 10 mm.

The present application also features the gas permeable plate intermediate portion being convex in the flow direction relative to a portion proximate the outer ring.

The present application also features the outer ring having a front face formed upstream and a rear face formed downstream in the direction of flow, and the breather plate being connected to the front face of the outer ring.

The present application also has the feature that the mixer is located vertically above the DPF, in the vertical direction, the partition is provided between the DPF and the mixer.

The present application also features an injector disposed within the mixer that injects the reductant.

The present application also features the outer ring conforming to an outer peripheral edge of the DPF.

By using the technical scheme provided by the application, the setting of the isolating piece can enable crystals to less enter the DPF area, so that the function of the DPF is influenced.

Drawings

Exemplary embodiments of the present application will be described in detail below with reference to the attached drawings, it being understood that the following description of the embodiments is only for the purpose of explanation and not limitation of the scope of the present application, and in the accompanying drawings:

FIG. 1 is a structural view of one embodiment of an exhaust treatment assembly of the present application;

FIG. 2 is a block diagram of one embodiment of a partition in the exhaust treatment assembly of the present application;

fig. 3 is a cross-sectional view of the spacer shown in fig. 2 taken along the direction a-a.

List of reference numerals:

DOC 11

DPF 12

mixer 13

Ejector 131

Tail gas inlet 14

SCR 16

Exhaust gas outlet 17

Spacer 20

Outer ring 21

Front end face 211

Rear end face 212

Ventilation plate 22

Air hole 221

Detailed Description

It should be understood that the drawings are for purposes of illustration only and that the dimensions, proportions and number of parts are not to be construed as limiting the application.

Please refer to fig. 1, which is a block diagram of an embodiment of an exhaust gas treatment assembly according to the present application. The exhaust gas treatment assembly of the diesel engine in this embodiment is mounted on a vehicle in a vertical direction, and includes a DOC11, a DPF12, a mixer 13, and an SCR16 stacked in this order in the vertical direction, wherein there is an exhaust gas inlet 14 before the DOC, and an exhaust gas outlet 17 is provided on the SCR. The mixer 13 is mixed with an aqueous urea solution as a reducing agent, and a reduction reaction is generated in the SCR 16. The exhaust from the vehicle enters the exhaust treatment assembly of the present application from exhaust inlet 14 and is discharged from exhaust outlet 17. There is a spacer 20 between the DPF12 and the mixer 13. For the purposes of this application, it is understood that the partition 20 must be permeable to air, i.e., allow the exhaust gases to flow from the DPF12 to the mixer 13, but not allow the urea crystals to pass through. An injector 131 is provided on the mixer 13, and the injector 131 can inject the reducing agent into the mixer 13. In this application, the exhaust entering the mixer 13 from the DPF12 is defined as the flow direction from upstream to downstream.

Referring to fig. 2 and 3, the separator 20 includes an outer ring 21 extending in a flowing direction of the exhaust gas to the mixer 13 through the DPF12 to have a certain thickness, and a vent plate 22 connected to the outer ring 21 substantially perpendicular to the flowing direction. The outer ring 21 has a front end surface 211 formed on the upstream side and a rear end surface 212 formed on the downstream side in the flow direction, and the air-permeable plate 22 is connected to the front end surface 211 of the outer ring 21. The ventilation plate 22 has a plurality of ventilation holes 221 penetrating through the ventilation plate 22, and preferably, the ventilation holes 221 penetrate through the ventilation plate 22 in an inclined manner. The breather 221 in some embodiments, including this embodiment, has a size smaller than the size of crystals of the urea aqueous solution structure, so that it cannot fall from the mixer 13 into the DPF 12. Preferably, the airing hole 221 is a circular hole with a diameter of 6-10 mm. The intermediate portion of the gas permeation plate 22 is convex in the flow direction with respect to the portion close to the outer ring 21.

In use, the injector 131 injects reductant into the mixer 13 and encounters exhaust gas entering from upstream to cause a reduction reaction, thereby reducing nitrogen oxides in the exhaust gas to nitrogen. However, since the gas temperature is not already at the optimum temperature in the mixer 13, part of the reducing agent crystallizes to form particles or powder of crystals. The crystals settle downward under the force of gravity and fall onto gas permeable plate 22. The crystals are blown upward by the exhaust gas from the ventilation holes 221 of the ventilation plate 22. Since the middle of the gas permeation plate 22 is convex and connected to the front end surface 211 of the outer ring 21, a housing space is formed between the outer ring 21 and the gas permeation plate 22 near the outer ring 21, and crystals can accumulate there. Preferably, if the ventilation holes 221 are obliquely penetrated through the ventilation plate 22, even if a part of the crystals enter the ventilation holes, they may stay only in the ventilation holes and do not enter the DPF. In addition, during DPF regeneration, the crystals may again participate in the reduction reaction due to the increase in temperature.

In some embodiments, including this embodiment, the exhaust treatment assembly is vertically disposed. Of course, in other embodiments, the spacing member may not be vertically disposed, and the spacing member may prevent the crystal from entering the DPF under the driving of the vortex.

Claims

1. The utility model provides an exhaust treatment assembly, characterized in that, DOC (11), DPF (12), blender (13) and SCR (16) that loop through including tail gas, be provided with tail gas entry (14) on DOC (11), be provided with tail gas export (17) on SCR (16), tail gas passes through tail gas entry (14) get into DOC (11) flows through tail gas export (17) SCR (16), spout into urea aqueous solution and tail gas mixture in blender (13), DPF (12) with set up between blender (13) and can pass through tail gas but not through isolator (20) of urea crystallization.

2. An exhaust gas treatment assembly according to claim 1, wherein the partition (20) comprises an outer ring (21) having a thickness extending in a flow direction of the exhaust gas through the DPF (12) towards the mixer (13), and a gas permeable plate (22) connected to the outer ring (21) substantially perpendicular to the flow direction.

3. The exhaust treatment assembly according to claim 2, wherein the gas permeable plate (22) has a plurality of gas permeable holes (221) penetrating the gas permeable plate (22).

4. The exhaust gas treatment assembly according to claim 3, wherein the ventilation holes (221) penetrate the ventilation plate (22) obliquely.

5. An exhaust gas treatment assembly according to claim 3, wherein the size of the venting holes (221) is smaller than the size of the crystals of the aqueous urea solution, more preferably the venting holes (221) are circular holes with a diameter of 6-10 mm.

6. The exhaust gas treatment assembly according to claim 2, wherein the intermediate portion of the gas permeable plate (22) is convex in the flow direction with respect to a portion close to the outer ring (21).

7. The exhaust gas treatment assembly according to claim 2, wherein the outer ring (21) forms a front end face (211) upstream and a rear end face (212) downstream in the flow direction, and the gas-permeable plate (22) is connected to the front end face (211) of the outer ring (21).

8. An exhaust gas treatment assembly according to any of claims 1 to 7, characterized in that the mixer (13) is vertically above the DPF, and in the vertical direction the partition (20) is arranged between the DPF (12) and the mixer (13).

9. An exhaust gas treatment assembly according to claim 8, characterized in that an injector for injecting a reducing agent is arranged in the mixer (13).

10. The exhaust gas treatment assembly according to claim 2, wherein the outer ring (21) is fitted to an outer periphery of the DPF (12).