Pollution abatement device for an internal combustion engine and pollution abatement system comprising the device

Abstract

An apparatus (ATS1) for abatement of pollutants of an internal combustion engine, comprising: a casing (CN) in which a DOC and a bypass duct (BP) of the DOC are housed to define a bifurcation for the exhaust gases passing through the apparatus, so that a first flow (F1) is intended to pass through the DOC and a second flow (F2) is intended to bypass the DOC; an injector (J) of urea-based reducing agent arranged at the bifurcation or immediately downstream of the bifurcation; and an electric heater (H) arranged annularly with respect to the bypass duct and configured to heat the bypass duct and be passed through by the first exhaust gas flow (F1).

Description

Technical Field

[0001] This invention relates to the field of emission reduction systems (ATS) for internal combustion engines and internal combustion engines including such emission reduction systems. Background Technology

[0002] Regulations related to harmful emissions from land vehicles are becoming increasingly stringent, making it imperative to find individual devices or interconnected groups of devices to reduce pollutant emissions.

[0003] Common components in diesel cycle internal combustion engines include: DPF = Particulate Filter DOC = Diesel engine oxidation catalyst SCR stands for Selective Catalyst, which uses the presence of ammonia to reduce NOx contained in exhaust gas. SCRoF is a selective SCR catalyst manufactured on a filter matrix similar to DPF. CUC = Ammonia Reduction Unit. It is usually used as the last component of ATS to prevent the release of ammonia into the environment, which would contribute to an increase in the amount of pollutants released into the environment.

[0004] They are well known to those skilled in the art, and their respective acronyms are acronyms of the equally well known Anglo-Saxon expressions.

[0005] One of the fundamental problems in NOx reduction is the proper hydrolysis of urea-based reducing agents.

[0006] The latest regulations stipulate that, taking into account the pollutants emitted during ATS heating, ATS must be efficient as quickly as possible.

[0007] Devices that facilitate hydrolysis are known. The use of electric heaters is known. For example, EP2826973 shows the use of an electric coil arranged in the cone of a urea-based reducing agent sprayer.

[0008] Unless explicitly excluded in the detailed description below, the contents described in this chapter shall be considered part of the detailed description. Summary of the Invention

[0009] The object of this invention is to improve pollutant emission reduction equipment, and in particular, to improve the hydrolysis of urea-based reducing agents sprayed to reduce NOx content.

[0010] The basic idea of ​​this invention is to propose an exhaust gas emission reduction device, which includes at least one DOC (Diesel Oxide Container) and an exhaust gas bypass duct to define the bifurcation of the exhaust gas, such that a first flow is intended to pass through the DOC matrix, and a second flow bypasses the DOC matrix. A urea-based reducing agent injector is arranged at or immediately downstream of the bifurcation.

[0011] In addition, a bypass duct is inserted into an electric heater designed to heat the bypass duct and allow the first waste gas flow through it.

[0012] The first and second waste gas streams mix in the terminal section of the equipment before leaving the equipment.

[0013] The object of the present invention is a first device that satisfies the exhaust gas generated by an internal combustion engine for an ATS (Automatic Test System).

[0014] The fact that the urea-based reducing agent is injected into the second stream, which comes directly from the internal combustion engine and bypasses the DOC, ensures maximum heat content because the DOC matrix does not need to be heated when the stream is colder.

[0015] The heater is preferably arranged to primarily heat the bypass duct, and secondarily heat the first waste gas flow.

[0016] It is worth emphasizing that in a typical diesel engine exhaust aftertreatment system composed of diesel oxidation catalyst (DOC), besides oxidizing CO to CO2, the primary purpose of DOC is to oxidize NO to NO2. The conversion from NO to NO2 is a significant contribution to the downstream SCR system because the rapid reaction of SCR provides the highest conversion rates of NOx to H2O and N2. This rapid reaction works well only when the concentrations of NO and NO2 are approximately equal.

[0017] If the DOC does not reach a sufficient operating temperature, it cannot balance the concentrations of NO and NO2, which will impair the function of the SCR even in the presence of sufficient ammonia.

[0018] Preferably, the device is designed as a rotational solid, wherein the bypass conduit is arranged away from the peripheral wall of the outer casing (often referred to as "canning"), and preferably arranged axially.

[0019] More preferably, the device includes an exhaust gas inlet duct arranged to introduce exhaust gas incidentally relative to the aforementioned axial direction, and a reducing agent injector arranged coaxially relative to the bypass duct at the bifurcation point.

[0020] According to a preferred variant of the invention, downstream of the device containing DOC, there is at least one additional device comprising an SCR having CUC and further downstream platinum or platinum and palladium catalyzed DOC and DPF.

[0021] According to another variation of the invention, downstream of the DPF there is another SCR with a CUC having an additional urea-based reducing agent dispenser (doser), which is activated when the ATS is sufficiently hot. When the ATS is sufficiently hot, it is advantageous to deactivate the first urea-based reducing agent dispenser to promote spontaneous regeneration in the DPF.

[0022] According to another preferred variant of the invention, at least one additional device comprising a component referred to as SCRof (an acronym for SCR on Filter) is arranged downstream of the device comprising DOC (i.e., an SCR capable of filtering particles contained in the exhaust gas). Preferably, another SCR having CUC is arranged downstream of SCRof (as described with respect to the relevant dispensing device for the urea-based reducing agent to be activated and for the aforementioned benefits).

[0023] The dependent claims describe preferred variations of the invention, which form part of this specification. Attached Figure Description

[0024] Further objectives and advantages of the invention will become clear from the following detailed description of examples of embodiments (and variations thereof) of the invention and from the accompanying drawings, which are given only by way of non-limiting interpretation, in which: Figure 1 A first illustration shows an internal combustion engine and an exhaust emission reduction device according to a first variant of the invention; Figure 2 Another preferred variant of the invention is shown; Figure 3 Another preferred variant of the invention is shown; Figures 4 to 7 It shows according to Figures 1 to 3 The structural details of the components of the device.

[0025] The same reference numerals and letters in the accompanying drawings identify the same elements, components, or functions.

[0026] It should also be noted that this document may use the terms “first,” “second,” “third,” “upper,” “lower,” etc., to distinguish various elements. These terms do not imply the spatial, sequential, or hierarchical order of the modified elements unless specifically indicated or inferred from the text.

[0027] As described below, the elements and features shown in the various preferred embodiments, including the accompanying drawings, can be combined with each other without departing from the scope of this application. Detailed Implementation

[0028] Figure 1 An example of a diesel cycle internal combustion engine E (hereinafter referred to as "engine E") is shown, which includes an intake manifold IP and an exhaust manifold OP.

[0029] Preferably, the engine E is boosted by a turbocharger T, which includes a turbine connected to the exhaust manifold and a compressor arranged on the intake manifold and driven by the rotation of the turbine.

[0030] The engine can be equipped with an EGR valve for exhaust gas recirculation.

[0031] According to the present invention, the exhaust emission reduction system includes a first device, designated as ATS1, which is arranged as a first component of an ATS, which exhaust gases encounter during their normal outflow from the engine E to the external environment.

[0032] The first device ATS1 includes at least one DOC and an exhaust bypass duct BP to define the bifurcation of exhaust gases such that a first flow F1 is intended to pass through the DOC matrix, while a second flow F2 bypasses the DOC matrix.

[0033] The first and second streams mix together in the terminal section of the device before leaving the first device ATS1 and entering a possible second device ATS2, and so on.

[0034] The urea-based reducing agent injector J is located at the bifurcation point or immediately downstream of the bifurcation. Furthermore, a bypass duct is inserted into an electric heater H, which is configured to heat the bypass duct and is passed through by the first flow of exhaust gas F1.

[0035] In this way, the heater performs the dual function of heating the bypass pipe and indirectly heating the second waste gas flow F2, as well as directly heating the first waste gas flow F1.

[0036] The first device ATS1 is preferably designed as a rotating body, wherein the BP bypass pipe is arranged away from the periphery of the housing and is preferably arranged coaxially with respect to the rotation axis of the entire device.

[0037] The first device ATS1 includes an exhaust gas inlet pipe IN, which is arranged to allow exhaust gas to enter in an incident manner relative to the aforementioned axial direction, and a reducing agent injector is arranged coaxially relative to the bypass pipe at the bifurcation.

[0038] As can be seen from the attached drawings, the first device ATS1 includes a bell-shaped component that encloses the base of the rotating body, and an injector J for a urea-based reducing agent is located at the top of the bell-shaped component, while an exhaust gas inlet pipe IN is formed at the lateral position of the bell-shaped component.

[0039] The injector end is arranged so that the urea-based reducing agent spray is completely injected into the second stream F2 of the exhaust gas.

[0040] The bypass conduit includes a first proximal section near the injector J and a second proximal section with the terminal section OUT of the device ATS1.

[0041] The first section of the bypass duct is inserted into and in contact with the electric heater H. This arrangement is primarily for heating the bypass duct, and secondarily for heating the first waste gas flow.

[0042] Figures 4 to 7 A cross-sectional view of heater H, according to different embodiments, is shown.

[0043] For example, Figure 4 and Figure 5 A matrix heater is shown, while solutions 6 and 7 show finned heaters, particularly... Figure 6 In the middle, the straight fins are radial, while... Figure 7 In the middle, the fins are folded, and each fin forms an S-shape.

[0044] Figure 1 The additional ATS2 and ATS3 components are shown arranged sequentially downstream of the first device ATS1.

[0045] The second device ATS2, located immediately downstream of the first device ATS1, includes an SCR and a CUC to utilize a preheated gas mixture containing appropriate proportions of NH3, NO, and NO2 to maximize the conversion efficiency of the SCR itself during the first stage of engine start-up.

[0046] Downstream of SCR and CUC, there are DOC / DPF loaded with platinum and / or palladium that are able to retain solid particles known in themselves.

[0047] According to the statement Figure 1 The variant of the illustration Figure 2 Downstream of the third device ATS3 is a fourth device ATS4, which includes an SCR and a subsequent CUC, and immediately upstream of the fourth device ATS4 is a second injector J2 for a urea-based reducing agent.

[0048] Preferably, the second injector J2 and thus the fourth device ATS4 are activated after the same fourth component ATS4 has been sufficiently heated.

[0049] Preferably, when the fourth component is fully operational, the first injector J of the urea-based reducing agent is deactivated so as to facilitate the spontaneous regeneration of the DPF contained in the third ATS3 device due to the NO2 effect.

[0050] Figure 3 Another preferred variant of the invention is shown, wherein additional ATS23 and ATS4 components are arranged sequentially downstream of the first device ATS1. The second device ATS23 differs from the second device ATS2 in the preceding figures, although it is arranged close to the first device ATS1, just like ATS2. The ATS23 device includes a component called SCRof (an acronym for “SCR on Filter”), which is an SCR capable of filtering particles contained in exhaust gases.

[0051] In this way, the same components can be used to maximize the conversion efficiency of SCR by passing through and containing a mixture of preheated gases in appropriate proportions of NH3, NO and NO2, and to filter out solid particles of particulate matter.

[0052] There is a third device downstream of SCRoF, which corresponds to Figure 2 The fourth ATS4 in this system. This third device includes an SCR and a CUC (and is also equipped with a second injector J2 containing a urea-based reducing agent). Similarly, in this case, the second injector is expected to activate when the temperature of the ATS4 is sufficient.

[0053] In the same situation, it is advantageous to deactivate the first injector when the ATS4 component is fully effective, so as to facilitate the spontaneous regeneration of carbon residue in the SCRoF filter by NO2.

[0054] This means that conditions for simultaneous operation of both injectors can be anticipated.

[0055] Therefore, the first injector J of the urea-based reducing agent is configured to activate during cold start and remain activated until the temperature of the fourth device ATS4 is below a first predetermined temperature threshold, and wherein the second injector J2 of the urea-based reducing agent is configured to activate when the temperature of the fourth device ATS4 exceeds a second predetermined temperature threshold below the first temperature threshold.

[0056] Variations of the described non-limiting examples are possible, but do not depart from the scope of protection of the invention, which includes all equivalent embodiments of the claims by those skilled in the art.

[0057] Based on the above description, those skilled in the art can achieve the objectives of the present invention without introducing additional structural details.

Claims

1. An apparatus (ATS1) for reducing emissions of pollutants generated by an internal combustion engine, comprising: A housing (CN), a DOC, and a bypass duct (BP) of the DOC are housed within the housing to define a branch for exhaust gas passing through the device, such that a first stream (F1) of exhaust gas is intended to pass through the DOC, and a second stream (F2) of exhaust gas is intended to bypass the DOC; a first injector (J) of urea-based reducing agent is disposed at or immediately downstream of the branch for injecting urea-based reducing agent into the second stream (F2); And an electric heater (H), which is arranged in a ring relative to the bypass pipe and configured to heat the bypass pipe and be passed through by the first flow (F1).

2. The device according to claim 1, wherein the device defines a rotating body about a rotation axis (X), and wherein, The bypass conduit is configured to be spaced apart from the housing.

3. The device according to claim 2, wherein, The bypass pipe is positioned coaxial with the axis of rotation.

4. The apparatus of claim 1, further comprising an inlet conduit (IN) for the exhaust gas, the inlet conduit (IN) being arranged to introduce the exhaust gas incidentally relative to the direction indicated by the bypass conduit, and wherein, The first injector (J) of the urea-based reducing agent is arranged coaxially with respect to the bypass pipe at the bifurcation.

5. The device according to claim 1, wherein, The electric heater (H) is configured to primarily heat the bypass pipe, and secondarily heat the first flow (F1).

6. The device according to claim 1, wherein, Depending on the cross-section of the heater, the electric heater may include straight and radial fins or folded fins, each folded fin being S-shaped, or the electric heater may define a matrix.

7. An exhaust gas aftertreatment system (ATS) includes a first emission reduction device, the first emission reduction device being an apparatus (ATS1) for reducing pollutants generated by an internal combustion engine according to claim 1, the first emission reduction device being arranged to be encountered by the exhaust gas.

8. The system according to claim 7, further comprising: The second emission reduction device (ATS2) is placed directly downstream of the first emission reduction device and includes an SCR and a CUC. as well as The third emission reduction device (ATS3) is located immediately downstream of the second emission reduction device and includes DOC and DPF.

9. The system according to claim 8, further comprising: The fourth emission reduction device (ATS4) is arranged downstream of the third emission reduction device (ATS3) and includes a second injector (J2) for urea-based reducing agent that is arranged immediately upstream of the fourth emission reduction device (ATS4).

10. The system according to claim 7, further comprising: The second emission reduction device (ATS23) is located immediately downstream of the first emission reduction device and includes SCRoF, i.e., SCR on the filter.

11. The system of claim 10, further comprising: The fourth emission reduction device (ATS4) is arranged downstream of the second emission reduction device (ATS23) and includes a second injector (J2) of urea-based reducing agent arranged immediately upstream of the fourth emission reduction device (ATS4).

12. The system according to any one of claims 9 or 11, wherein, The first injector (J) of the urea-based reducing agent is configured to be activated during cold start and remain activated as long as the temperature of the fourth emission reduction device (ATS4) is below a first predetermined temperature threshold, wherein the second injector (J2) of the urea-based reducing agent is configured to be activated when the temperature of the fourth emission reduction device (ATS4) exceeds a second predetermined temperature threshold below the first predetermined temperature threshold.

13. A propulsion system comprising a diesel internal combustion engine (E), the diesel internal combustion engine (E) comprising an apparatus (ATS1) for reducing emissions of pollutants generated by the internal combustion engine according to claim 1 or comprising an exhaust gas aftertreatment system (ATS) according to claim 7, the apparatus (ATS1) for reducing emissions of pollutants generated by the internal combustion engine or the exhaust gas aftertreatment system (ATS) being operatively connected to an exhaust manifold (OP) of the diesel internal combustion engine.

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