Exhaust system of an internal combustion engine

Abstract

Exhaust system (1) of an internal combustion engine in the state before the first heating of the exhaust system (1), at least with a particle filter (2) and an exhaust line (3) upstream of the particle filter (2), wherein a carrier element (11) for forming ash-forming components or ash is provided upstream of the particle filter (2), characterized in that the carrier element (11) consists of paper, cardboard or plastic, wherein the carrier element (11) is provided with the ash-forming components or with the ash, wherein the carrier element (11) is applied to the particle filter (2) on its side facing the exhaust line (3) or to a catalyst (4) arranged upstream of the particle filter (2), wherein the ash-forming components or the ash are or are in powder form.

Description

[0001] The invention relates to an exhaust system of an internal combustion engine in the state before the first heating of the exhaust system, with a particle filter and an exhaust line upstream of the particle filter, wherein a carrier element for forming ash-forming components or ash is provided upstream of the particle filter.

[0002] Such exhaust systems are widely known from motor vehicles in practical use. These exhaust systems typically also feature a catalyst for treating the exhaust gases, which is located upstream or downstream of the particulate filter.

[0003] The ongoing legal requirement to reduce fuel consumption and the simultaneous tightening of particulate limits (mass and number) pose an increasing challenge for the development of combustion engines. Compliance with future particulate limits under the required conditions will hinder fuel consumption reduction in the future. This will result in almost all combustion engines having to be equipped with a particulate filter in the future, as is already the case with diesel engines.

[0004] In the particulate filter, the soot from combustion is separated and converted back into gaseous components through targeted regeneration of the filter. Furthermore, ash components originating from the engine oil and / or oil additives permanently remain in the filter. Today, the soot load in the filter is recorded using backpressure measurement and redundantly via a calculation module. Active soot regeneration measures are initiated depending on the soot fill level. However, the backpressure measurement (Δp = f (soot load)) exhibits strong hysteresis, which is why a clear correlation between the soot load in the particulate filter and the backpressure is not possible. Due to the strong fuel influence, calculation-model-based regeneration is usually much too early, particularly because the particle number / mass can vary by a factor of 5 between fuels.The goal must be to reduce the backpressure hysteresis in order to obtain a clear control variable for the regeneration of the particulate filter. At the same time, in a case without hysteresis behavior, more stable component protection can be ensured, since specifically highly loaded peripheral zones can be better detected using backpressure measurement.

[0005] Today's particulate filters have two filter functions: deep filtration and surface filtration. Soot deposition leads to deep filtration with a high pressure increase in the first step and surface filtration with a lower pressure increase in the second step.

[0006] With depth filtration, the particles are separated in the wall of the particulate filter. With surface filtration, filtration takes place on the surface of the filter. Over its service life, the particulate filter gradually transforms from a depth filter into a surface filter. Depth filtration is associated with a sharp increase in pressure, as this particularly negatively affects the permeability of the exhaust gas. If the cavities in the wall are largely covered with soot, the soot will subsequently be deposited primarily on the wall. This surface filtration leads to a moderate increase in pressure, less than with depth filtration. If the soot in the filter is regenerated, the pressure dissipates with hysteresis behavior, i.e. initially with a large pressure drop, followed by a moderate pressure drop.

[0007] Unlike soot, ash in the particulate filter always deposits on the wall, not in it. This fundamentally and irreversibly prevents the soot from penetrating the ash layer, preventing it from penetrating the ash layer. This means that the pressure increase with increasing soot deposits exhibits a linear relationship across the entire range, without hysteresis. This significantly improves the accuracy of determining soot loading through backpressure measurement, allowing for more targeted and fuel-efficient soot regeneration strategies.

[0008] In order to solve the problem described above, a layer of ash would have to be applied as a filter cake to the surface of the channel walls of the particulate filter in its new state.

[0009] WO 2014 / 183 998 A1 discloses a method for determining soot loads in a particulate filter in gasoline engines. The determination of the recorded soot load involves taking into account predetermined soot fractions from soot-relevant events in a standardized driving cycle.

[0010] The generic Japanese publication JP 2004-150 330 A discloses the provision of a combustible carrier element that, upon combustion, generates an ash layer for the particulate filter. Furthermore, the subsequently published publications DE 10 2017 219 940 A1 and DE 10 2018 203 225 A1 disclose exhaust systems in which the carrier element is additionally made of paper, cardboard, or plastic, wherein the carrier element is provided with the ash-forming components or with the ash.

[0011] The object of the present invention is to develop an exhaust system of the type mentioned at the outset in such a way that, with its simple structural design, a sufficient layer of ash can be quickly and easily applied to the particle filter, in particular as a filter cake on the surface of the channel walls of the particle filter.

[0012] The problem is solved by an exhaust system having the features of patent claim 1.

[0013] In this exhaust system, it is thus provided that the carrier element consists of paper, cardboard or plastic, wherein the carrier element is provided with the ash-forming components or with the ash, wherein the carrier element is applied to the particle filter on its side facing the exhaust line, a carrier element or to a catalyst arranged upstream of the particle filter, wherein the ash-forming components or the ash are or are in powder form.

[0014] If the carrier element containing the ash-forming components or ash is applied to the particulate filter or catalytic converter, the carrier element combusts when the exhaust system initially heats up, releasing the ash-forming components or ash and depositing them on the particulate filter. Paper, cardboard, or plastic, which can combust under the conditions prevailing in an exhaust system, can be used as the carrier element material. The only requirement is that it contains the ash-forming components or ash, and that these are released when the exhaust system heats up and carried to the particulate filter by the exhaust stream. The position only needs to be selected upstream of the particulate filter.

[0015] It is particularly advantageous if the carrier element is mounted directly on the particulate filter, on the side facing the exhaust line. This ensures that the ash-forming components or the ash itself, when released, only affect the particulate filter, leaving other engine components unaffected. Another advantage is that the particulate filter reaches its full filtration rate after the exhaust system has been heated up for the first time.

[0016] In particular, a carrier element made of paper, cardboard, or plastic containing the ash-forming components or the ash is provided. These materials are particularly well suited for absorbing the ash-forming components or the ash.

[0017] The ash-forming components, or the ash layer applied to the particulate filter, consist primarily of elements that cannot be removed during subsequent operation through oxidation or general detachment. Furthermore, it must be ensured that the ash layer is only applied to the wall and not into it. Such elements include Ca, Mg, P, and Zn for ash-forming components, and MgO and Al2O3 for ash.

[0018] If the exhaust system includes a catalytic converter, it is particularly provided that the carrier element is applied to the catalytic converter on the side of the catalytic converter facing the particulate filter or on the side of the catalytic converter facing away from the particulate filter. In each of these described preferred arrangements, which are located downstream of the particulate filter, it is ensured that when the carrier element is burned, the ash-forming components or the ash are released during the initial heating of the exhaust system and deposited on the particulate filter.

[0019] A particularly simple arrangement of the carrier element on the particulate filter or the catalyst is possible if the carrier element is glued to the particulate filter or the catalyst.

[0020] The carrier element is designed, in particular, as a circular disk in the form of a wafer. Such a carrier disk can be particularly easily connected, in particular glued, to an annular flange in the inflow area of ​​the particulate filter or to an annular flange in the inflow or outflow area of ​​the catalyst.

[0021] The combustion engine is typically a gasoline engine or a diesel engine. Accordingly, a gasoline particulate filter or a diesel particulate filter is used.

[0022] The exhaust system according to the invention and its further developments include various advantages: - This makes it possible to apply the ash precisely to the surface of the particulate filter. - The thickness and composition of the ash layer can be precisely adjusted if the support element is appropriately equipped with ash-forming components or ash. - The deep filtration is specifically prevented and thus a clear correlation between back pressure and deposited soot can be established. - The back pressure of the parts remains relatively constant over their running time and the pressure increase is linear. - The filtration rate of today's particulate filters only reaches the desired value after a certain period of operation. The exhaust system allows for very precise adjustment of the filtration rate, and it reaches the required value immediately after the exhaust system has initially warmed up. - The particulate filter can be made extremely porous and thus have an extremely low back pressure because the exhaust system allows precise adjustment of the filtration rate.

[0023] Further features of the invention emerge from the subclaims, the attached drawings and the description of the embodiments shown in the drawings, without being limited thereto.

[0024] It shows in schematic representation: Fig. 1 shows a first embodiment of the region relevant to the invention of an exhaust system of an internal combustion engine, Fig. 2 a second embodiment of the area relevant to the invention of an exhaust system of an internal combustion engine, Fig. 3 a third embodiment of the region relevant to the invention of an exhaust system of an internal combustion engine. Character description

[0025] Fig. 1 shows an exhaust system 1 of an internal combustion engine, which is a diesel engine or a gasoline engine, in the state before the exhaust system 1 is first heated up. The exhaust system 1 has a particulate filter 2 and an exhaust line 3 upstream of the particulate filter 2. Immediately upstream of the particulate filter 2, the exhaust system 1 has a catalytic converter 4 - oxidation catalyst. In this exemplary embodiment, the particulate filter 2 and the catalytic converter 4 are arranged in a common housing 5. A person skilled in the art will of course understand that the particulate filter 2 and the catalytic converter 4 can also be arranged in separate housings. Upstream of this housing 5 is the exhaust line 3 and downstream is an exhaust line 6 leading away from the particulate filter 2. The inflow of the exhaust gas into the catalytic converter 4 is illustrated by the arrow 7 and the outflow of the exhaust gas from the particulate filter 2 is illustrated by the arrow 8.The flow length of the catalyst 4 is illustrated by the reference number 9 and the flow length of the particle filter 2 by the reference number 10.

[0026] A carrier element 11, which contains ash-forming components or ash, is applied to the particulate filter 2, on the side facing the exhaust line 3. This carrier element 11 is made of paper, cardboard or plastic and is provided with the ash-forming components or directly with the ash. The ash-forming components are in particular Ca, Mg, P or Zn. The ash is in particular MgO. The ash-forming components or the ash are in powder form. The carrier element 11 is adhesively bonded to the particulate filter 2 in the region of its end face facing the catalytic converter 4. The carrier element 11 is designed as a disc and, due to its material composition, is flowed through by exhaust gas when the exhaust system is first heated up, whereby a layer of ash is applied to the particulate filter 2, in particular as a filter cake, to the surface of the channel walls of the particulate filter 2.

[0027] The embodiment according to the Fig. 2 corresponds to that after the Fig. 1, with the difference that the carrier element 11, which contains the ash-forming components or the ash, is not applied to the particulate filter 2, but rather to the catalytic converter 4 on the side facing the particulate filter 2. When the exhaust system is first heated up, the exhaust gas flows through the carrier element 11 connected to the catalytic converter 4, and the ash-forming components or the ash are released and deposited on the particulate filter 2.

[0028] The embodiment according to the Fig. 3 corresponds to that after the Fig.1, with the difference that the carrier element 11, which contains the ash-forming components or the ash, is not applied to the particulate filter 2, but rather to the catalytic converter 4 on the side facing away from the particulate filter 2. When the exhaust system is first heated up, the exhaust gas flows through the carrier element 11 connected to the catalytic converter 4, and the ash-forming components or the ash are released and deposited on the particulate filter 2. List of reference symbols 1 exhaust system 2 particle filters 3 exhaust pipe 4 Catalyst 5 housings 6 exhaust pipe 7 Arrow 8 Arrow 9 Flow length 10 Flow length 11 Support element

Claims

[1] Exhaust system (1) of an internal combustion engine in the state before the first heating of the exhaust system (1), at least with a particulate filter (2) and an exhaust pipe (3) upstream of the particulate filter (2), wherein upstream of the particulate filter (2) a support element (11) is provided for the formation of ash-forming components or ash, characterized by , that the carrier element (11) consists of paper, cardboard or plastic, wherein the carrier element (11) is provided with the ash-forming components or with the ash, wherein the carrier element (11) is applied to the particulate filter (2) on its side facing the exhaust pipe (3) or to a catalyst (4) arranged upstream of the particulate filter (2), wherein the ash-forming components or the ash are in powder form. [2] Exhaust system according to claim 1, characterized by that the ash-forming components are Ca, Mg, P and Zn and / or the ash is MgO, Al2O3. [3] Exhaust system according to claim 1 or 2, characterized by , that the catalyst (4) is arranged upstream of the particulate filter (2), wherein the support element (11) is applied to the catalyst (4) on the side of the catalyst (4) facing the particulate filter (2) or on the side of the catalyst (4) facing away from the particulate filter (2). [4] Exhaust system according to claim 3, characterized by , that the carrier element (11) is glued onto the particulate filter (2) or the catalyst (4). [5] Exhaust system according to claim 3 or 4, characterized by , that the catalyst (4) and the particulate filter (2) are arranged at a distance of no more than 20 mm, in particular no more than 10 mm, from each other. [6] Exhaust system according to any one of claims 1 to 5, characterized by that the internal combustion engine is a gasoline engine or a diesel engine.

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