Exhaust gas cleaning device, which is equipped with a combustion engine catalytic converter

Abstract

An exhaust gas cleaning device comprising: an engine (10) which generates power by burning fuel and air which flow into a combustion chamber; an exhaust pipe (20) through which the exhaust gas produced by the engine (10) flows; a first three-way catalyst (30), which is mounted on the exhaust pipe downstream of the engine (10) and converts pollutants contained in the exhaust gas, such as carbon monoxide, hydrocarbons and nitrogen oxides, into harmless substances by means of an oxidation or reduction reaction; and a combustion engine catalyst (40) which is mounted on the exhaust pipe (20) downstream of the first three-way catalyst (30) and removes pollutants from the exhaust gas which are not removed at the first three-way catalyst; wherein the internal combustion engine catalyst (40) comprises: at least one inlet channel (42) with one end through which an exhaust gas flows and another end which is blocked, at least one outlet channel (44) with one end which is blocked and another end through which the exhaust gas is discharged; and a wall (50) which defines a boundary between an inlet channel (42) and an adjacent outlet channel (44) and is adapted to supply or allow the exhaust gas from the inlet channel (42) to the outlet channel (44), and wherein the wall (50) comprises a single-layer section (52) which is formed at an end section and has a three-way catalyst layer, and a multi-layer section (54) which is the other section than the single-layer section (52) and has a three-way catalyst layer (66), a hydrocarbon trap layer (64) and an insulating layer (62), and wherein the three-way catalyst layer (66), the hydrocarbon trap layer (64) and the insulating layer (63) of the multilayer section (54) are arranged from the inlet channel (42) towards the outlet channel (44) in the order insulating layer (62), hydrocarbon trap layer (64) and three-way catalyst layer (66).

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a catalyst for an internal combustion engine and an exhaust gas purification device equipped with the same. In particular, the present invention relates to an internal combustion engine catalyst and an exhaust gas purification device equipped with the same, which are capable of effectively removing pollutants, including hydrocarbons, which are produced in large quantities during initial start-up. Description of related technology

[0002] Gasoline direct injection (GDI) engines are increasingly being used to improve fuel economy and performance. In a typical gasoline engine, fuel (gasoline) is injected into an intake manifold and mixed with intake air to create an air-fuel mixture. This mixture is then fed into a combustion chamber. In contrast, the GDI engine uses a fuel injection method in which gasoline is injected directly into the combustion chamber.

[0003] Because the GDI engine causes the air / fuel ratio to be rich around a spark plug, it has the advantage of being able to operate at a lean air / fuel ratio. However, since the fuel is injected directly into the combustion chamber, it is not fully mixed with the intake air, and an incomplete combustion region can increase in the combustion chamber, as is typical for GDI engines. Such an increase in the incomplete combustion region can result in an increase in particulate matter and pollutants contained in the exhaust gas.

[0004] Recently, technologies are being developed for mounting a particulate filter on an exhaust pipe of a vehicle equipped with a GDI engine, as well as for mounting additional catalysts alongside a three-way catalyst used in the classic gasoline engine.

[0005] Even if the additional catalyst is mounted on the exhaust pipe, in the case of a cold start, where the temperature of the exhaust gas is very low, it is very difficult to remove pollutants contained in the exhaust gas until the temperature of the exhaust gas reaches an activation temperature of the catalyst.

[0006] In particular, material such as hydrocarbons is produced in large quantities during an initial start-up, but the hydrocarbons produced in large quantities during the initial start-up cannot be cleaned by the catalyst and are emitted into the vehicle environment.

[0007] Furthermore, in most combustion engines, the exhaust gas is not cleaned during the initial start-up and is emitted into the vehicle environment or the vehicle exterior.

[0008] The information disclosed in this background section is provided solely for a better understanding of the general background of the invention and should not be construed as an endorsement or any form of suggestion that this information constitutes the prior art already known to a person skilled in the art.

[0009] For example, US 2011 / 030346A1 discloses an exhaust gas cleaning device comprising: an engine, an exhaust pipe, a first three-way catalyst, and an internal combustion engine catalyst comprising: at least one inlet channel with one end through which exhaust gas flows and another end which is blocked; at least one outlet channel with one end which is blocked and another end through which exhaust gas is discharged; and a wall which defines a boundary between an inlet channel and an adjacent outlet channel and is adapted to allow exhaust gas to pass from the inlet channel to the outlet channel.

[0010] Furthermore, a layer arrangement in a catalyst is known, for example, from KR 10 0 610 424 B1. BRIEF SUMMARY / BRIEF DESCRIPTION OF THE INVENTION

[0011] The present invention provides a catalyst for an internal combustion engine (hereinafter referred to as internal combustion engine catalyst) and an exhaust gas cleaning device equipped with it, which have the advantage of effectively removing pollutants, such as hydrocarbons, during initial start-up as a consequence of an insulating layer delaying / inhibiting / retaining / slowing down the temperature rise of a hydrocarbon trap layer until a temperature of a three-way catalyst layer reaches an activation temperature.

[0012] That is, according to the invention, an exhaust gas cleaning device with the features according to claim 1 is provided. Further embodiments of the exhaust gas cleaning device are described in the dependent claims.

[0013] This means that an internal combustion engine catalyst can have: at least one inlet channel with one end (e.g., first / left end, e.g., inflow end, e.g., an end facing the engine) through which exhaust gas flows, and another end (e.g., second / right end, e.g., outflow end, e.g., an end facing away from the engine) which is blocked; at least one outlet channel with one end (e.g., first end, e.g., inflow end, e.g., an end facing the engine) which is blocked, and another end (e.g., second end, e.g., outflow end, e.g., an end facing away from the engine) through which the exhaust gas is expelled; and a wall which defines a boundary between an inlet channel and an adjacent outlet channel and is adapted to direct the exhaust gas from the inlet channel to the outlet channel; wherein the wall comprises a single-layer section (orsingle-layer section), which is formed at an end section (e.g. at a first / left (end) section in the longitudinal direction) and which has a three-way catalyst layer (e.g. consists of this), as well as a multi-layer section (or multi-layer section), which is the other (e.g. the remaining / longitudinal) section than the single-layer section and which has a three-way catalyst layer, a hydrocarbon trap layer and an insulating layer (e.g. consists of these).

[0014] Furthermore, an exhaust gas cleaning device according to the invention comprises: an engine which generates power by burning fuel and air which flow into a combustion chamber; an exhaust pipe (e.g., exhaust pipe) through which the exhaust gas generated by the engine flows; a first three-way catalyst which is mounted on the exhaust pipe downstream of the engine and which converts pollutants contained in the exhaust gas, such as carbon monoxide, hydrocarbons, and nitrogen oxides, into harmless substances by means of an oxidation-reduction reaction; and a catalyst which is mounted on the exhaust pipe downstream of the first three-way catalyst and which removes pollutants from the exhaust gas that are not removed by the first three-way catalyst;wherein the catalyst comprises at least one inlet channel with one end through which exhaust gas flows in and another end which is blocked, at least one outlet channel with one end which is blocked and another end through which the exhaust gas is discharged; and a wall which defines a boundary between an inlet channel and an adjacent outlet channel and is adapted to allow the exhaust gas to flow from the inlet channel to the outlet channel, and wherein the wall comprises a single-layer section which is formed at one end section and has a three-way catalyst layer, and a multi-layer section which is the other section than the single-layer section and has a three-way catalyst layer, a hydrocarbon trap layer and an insulating layer.

[0015] The three-way catalyst layer, the hydrocarbon trap layer and the insulating layer of the multilayer section are arranged from the inlet channel towards the outlet channel in the order insulating layer, hydrocarbon trap layer and three-way catalyst layer.

[0016] For example, the insulating layer can prevent heat from being transferred from the exhaust gas to the hydrocarbon trap layer through moisture adsorption.

[0017] The length of a single-layer section can be, for example, 10% - 50% of the length of the wall, while the length of a multi-layer section can be 50% - 90% of the length of the wall.

[0018] The catalyst can be, for example, a catalytic particulate filter in which a catalyst is provided in the form of a coating.

[0019] The devices of the present invention have advantages which are evident from or are shown in detail in the attached drawing, which is included herein, as well as in the following detailed description, which together serve to explain certain principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic view of an exhaust gas cleaning system of the present invention, serving as an example. Fig. Figure 2 is a partial sectional view of an exemplary catalyst according to the present invention. Fig. Figure 3 is a sectional view of a single-layer section in an exemplary catalyst according to the present invention. Fig. Figure 4 is a sectional view of a multilayer section in an exemplary catalyst according to the present invention. Fig. Figure 5 is a diagram illustrating the temperatures of a three-way catalyst layer and a hydrocarbon trap layer over time, in an exemplary multilayer section according to the present invention. DETAILED DESCRIPTION

[0020] Fig. Figure 1 is a schematic view of an exhaust gas cleaning device according to the present invention.

[0021] As in Fig. Figure 1 shows an exhaust gas cleaning device according to the present invention comprising an engine (for example, an internal combustion engine) 10, an exhaust gas line (for example, an exhaust pipe) 20, a first three-way catalyst 30 and a catalyst 40.

[0022] The engine 10 burns fuel and air to convert chemical energy into mechanical energy. The engine 10 can have multiple combustion chambers 11 into which the fuel and air flow, and an ignition device that ignites the fuel and air flowing into the combustion chamber 11. The engine 10 is connected to an intake manifold 15 (e.g., intake manifold) to draw air into the combustion chamber 11 and is connected to an exhaust manifold 17 (e.g., exhaust manifold). Exhaust gas produced during the combustion process is collected in the exhaust manifold 17 and then expelled to an external outlet of the engine 10. An injector 13 can be mounted in the combustion chamber 11 to inject fuel directly into the combustion chamber 11.

[0023] A gasoline direct injection (GDI) engine is described by way of example in this description, but various embodiments of the present invention are not limited to the GDI engine. It is understood that various types of gasoline engines other than the GDI engine can be used. In this case, the injector is mounted on the intake manifold 15 or an intake pipe and injects the fuel there.

[0024] Alternatively, a diesel engine can be used. In this case, no ignition device is installed in combustion chamber 11.

[0025] The exhaust pipe 20 is connected to the exhaust manifold 17 and expels the exhaust gas to the outside of the vehicle. The first three-way catalytic converter 30 and the catalytic converter 40 are mounted on the exhaust pipe 20 and remove hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas.

[0026] The first three-way catalyst 30 is mounted downstream of the engine 10 on the exhaust pipe 20 and removes pollutants contained in the exhaust gas emitted by the engine 10 by means of an oxidation-reduction reaction. In general, the first three-way catalyst 30 converts three pollutants (CO, HC, NO). x The oxygen-containing gases in the exhaust gas are converted into harmless gases (CO2, H2O, N2) via an oxidation-reduction reaction. The first three-way catalyst 30 is equipped with an oxygen storage material, such as cerium oxide, an oxidation catalyst, such as palladium and / or platinum, and a reduction catalyst, such as rhodium, which is coated on it. Since the three-way catalyst is well known to those skilled in the art, a detailed description is omitted.

[0027] The catalyst 40 is mounted downstream of the first three-way catalyst 30 on the exhaust pipe 20. The catalyst 40 is configured to remove hydrocarbons, carbon monoxide, and nitrogen oxides remaining in the exhaust gas that has flowed through the first three-way catalyst 30. In addition, the catalyst 40 can be a catalytic particulate filter with a catalyst applied as a coating. In this case, the catalyst 40 can capture particulate material contained in the exhaust gas.

[0028] The catalyst 40 is described in detail below.

[0029] Fig. Figure 2 is a partial sectional view of a catalyst according to the present invention; Fig. 3 is a sectional view of a single-layer section in a catalyst according to the present invention; and Fig. Figure 4 is a sectional view of a multilayer section in a catalyst according to the present invention.

[0030] As in Fig. As shown in Figure 2, the catalyst 40 according to the present invention has a plurality of channels 42 and 44 formed therein. The channels 42 and 44 comprise inlet channels 42 and outlet channels 44.

[0031] The inlet channel 42 is a channel into which exhaust gas, which has flowed through the first three-way catalyst 30, enters. For this purpose, one end (a left end in the drawing) of the inlet channel 42 is open, and the other end (a right end in the drawing) of the inlet channel 42 is blocked by a channel plug or channel closure.

[0032] The outlet channel 44 is a channel through which the exhaust gas flows within the catalyst 40 to the exhaust pipe 20. For this purpose, one end (a left end in the drawing) of the outlet channel is blocked by means of a channel plug or channel closure, and the other end (a right end in the drawing) of the outlet channel 44 is open.

[0033] The inlet channel 42 and the outlet channel 44 are essentially parallel to each other. A wall 50, formed between two adjacent inlet channels 42 and 44, defines a boundary or interface between the inlet channel 42 and the outlet channel 44. Since the wall 50 is made of porous material, the exhaust gas can pass through the wall 50, but the particulate matter contained in the exhaust gas cannot. Therefore, the exhaust gas flows through the inlet channel 42 into the catalyst 40 and, after passing through the wall 50, is discharged from the catalyst 40 through the outlet channel 44. At this time, the particulate matter is trapped at the other end of the inlet channel 44.

[0034] As in Fig. As shown in Figure 2, wall 50 has a single-layer section 52 and a multi-layer section 54.

[0035] The single-layer section 52 is arranged at the end section of the catalyst 40. As in Fig. As shown in Figure 3, the single-layer section 52 has a three-way catalyst layer. This means that a three-way catalyst is provided on the single-layer section 52 in the form of a coating. Similar to the first three-way catalyst 30, the three-way catalyst layer converts three pollutants (CO, HC, NO). x The three-way catalyst layer converts the oxygen-containing gases in the exhaust gas into harmless gases (CO2, H2O, N2) through an oxidation-reduction reaction. The catalyst layer consists of an oxygen storage material, such as cerium oxide, an oxidation catalyst, such as palladium and / or platinum, and a reduction catalyst, such as rhodium coated on it. Since the three-way catalyst is well known to those skilled in the art, a detailed description is omitted.

[0036] The multi-shift section 54 is the other section compared to the single-shift section 52, and as in Fig. As shown in Figure 4, in the multilayer section 54 an insulating layer 62, a hydrocarbon trap layer 64 and a three-way catalyst layer 66 are formed in succession or sequentially.

[0037] The insulating layer 62 is located close to / adjacent to the inlet channel 42 and, through moisture adsorption, prevents heat from the exhaust gas from being transferred to the hydrocarbon trap layer 64. This means that moisture is adsorbed / absorbed in the insulating layer 62 and evaporates using the heat from the exhaust gas when the vehicle starts and the exhaust gas temperature rises. Therefore, a temperature increase in the hydrocarbon trap layer 64 is suppressed. A catalyst / material capable of performing an insulating function through moisture adsorption, for example, a catalyst / material containing zeolite material that enables moisture adsorption, can be coated / applied to the insulating layer 62.

[0038] The hydrocarbon trap layer 64 is made of beta-zeolite, type A zeolite, type X zeolite, ZSM-5, USY, and so on. The hydrocarbon trap layer 64 absorbs hydrocarbons contained in the exhaust gas when the exhaust gas temperature is low (less than or equal to approximately 150°C) and releases the absorbed hydrocarbons when the exhaust gas temperature is high. That is, the hydrocarbon trap layer 64 captures hydrocarbons contained in the exhaust gas in cases where the exhaust gas temperature is low (for example, during initial start-up) and the three-way catalyst layer of the single-layer section 52 and the three-way catalyst layer 66 of the multi-layer section 54 are not activated. Therefore, it prevents hydrocarbons that cannot be cleaned during initial start-up from being emitted to the outside of the vehicle.The hydrocarbon trap layer 64 is arranged between the insulating layer 62 and the three-way catalyst layer 66.

[0039] The three-way catalyst layer 66 is arranged close to / adjacent to the outlet channel 44. Similar to the first three-way catalyst 30, the three-way catalyst layer converts three pollutants (CO, HC, NO). x The oxygen molecules contained in the exhaust gas are converted into harmless gases (CO2, H2O, N2) via an oxidation-reduction reaction. The three-way catalyst layer 66 is provided with oxygen storage material, such as cerium oxide, an oxidation catalyst, such as palladium and / or platinum, and a reduction catalyst, such as rhodium, which is coated on top. Since the three-way catalyst is well known to those skilled in the art, a detailed description is omitted.

[0040] Meanwhile, since the bulk density of the zeolite material is lower than that of the three-way catalyst, the length of the single-layer section 52 can be 10% to 50% of the length of the wall 50, while the length of the multi-layer section 54 can be 50% to 90% of the length of the wall 50. In this case, since the zeolite material and the three-way catalyst, which have almost the same mass (or nearly the same mass), are coated on the wall 50, the functions of the insulating layer 62 and the hydrocarbon trap layer 64 can be maximized.

[0041] Furthermore, since the single-layer section 52 is arranged without the insulating layer near the exhaust gas flowing into the catalyst 40, it is avoided that a temperature rise of the three-way catalyst layer (in the single-layer section 52) to the activation temperature is hindered or delayed.

[0042] The operation of the catalyst according to the present invention is described in detail below.

[0043] When the vehicle is started, the engine 10 expels the exhaust gas, which flows through the first three-way catalyst 30 into the catalyst 40. The exhaust gas flowing into the catalyst 40 raises the temperature of the three-way catalyst layer in the single-layer section 52 and flows through the wall 50 to the outlet channel 44. Furthermore, the exhaust gas raises the temperature of the three-way catalyst layer 66 in the multi-layer section 54 as it flows through the outlet channel 44. At this time, the exhaust gas flowing through the inlet channel 42 near the multi-layer section 54 evaporates the moisture adsorbed in the insulating layer 62. This process reduces the temperature of the exhaust gas. The exhaust gas with the reduced temperature flows through the wall 50 into the outlet channel 44, but cannot quickly raise the temperature of the hydrocarbon trap layer 64.Therefore, hydrocarbons contained in the exhaust gas are absorbed in the hydrocarbon trap layer 64.

[0044] Subsequently, when / as the exhaust gas flows continuously, the temperature of the first three-way catalyst 30 reaches the activation temperature. At this time, the temperature of the exhaust gas rises rapidly due to the catalytic reaction. The exhaust gas with the increased temperature raises the temperature of the three-way catalyst layer in the single-layer section 52 to the activation temperature. At this time, the temperature of the exhaust gas is further increased by the catalytic reaction in the single-layer section 52.

[0045] At this time, the temperature of the hydrocarbon trap 64 in the multilayer section 54 is gradually increased via the insulating layer 62.

[0046] Then, when the temperature of hydrocarbon trap 64 reaches a release temperature (for example, 150°C), the release of the hydrocarbon absorbed in hydrocarbon trap 64 begins. At this time, as in Fig. As shown in Figure 5, the temperature of the three-way catalyst layer 66 reaches the activation temperature (for example, 350°C). Therefore, the three-way catalyst layer 66 oxidizes the released hydrocarbon and removes carbon monoxide and nitrogen oxide.

[0047] As described above, the insulating layer 62 prevents the temperature of the hydrocarbon trap layer 64 from rising to the release temperature until the temperature of the three-way catalyst layer 66 reaches its activation temperature. Therefore, when the hydrocarbon trap layer 64 begins to release hydrocarbons, the three-way catalyst layer 66 reaches its activation temperature and can oxidize the released hydrocarbons. This improves exhaust gas purification efficiency.

[0048] Since the insulating layer delays or postpones the temperature rise of the hydrocarbon trap layer until the three-way catalyst layer reaches its activation temperature, pollutants, including hydrocarbons, can be effectively purified upon initial start-up according to various embodiments of the present invention.

[0049] Furthermore, since the three-way catalyst layer, the insulating layer and the hydrocarbon trap layer are coated / applied to the particulate filter, pollutant cleaning efficiency can be further improved and the emission of particulate material reduced.

[0050] For easier description and precise definition in the attached claims, the terms left or right etc. are used to describe features of the exemplary embodiments with reference to their position in the figures.

Claims

[1] An exhaust gas cleaning device comprising: an engine (10) which generates power by burning fuel and air which flow into a combustion chamber; an exhaust pipe (20) through which the exhaust gas produced by the engine (10) flows; a first three-way catalyst (30), which is mounted on the exhaust pipe downstream of the engine (10) and converts pollutants contained in the exhaust gas, such as carbon monoxide, hydrocarbons and nitrogen oxides, into harmless substances by means of an oxidation or reduction reaction; and a combustion engine catalyst (40) which is mounted on the exhaust pipe (20) downstream of the first three-way catalyst (30) and removes pollutants from the exhaust gas which are not removed at the first three-way catalyst; wherein the internal combustion engine catalyst (40) comprises: at least one inlet channel (42) with one end through which an exhaust gas flows and another end which is blocked, at least one outlet channel (44) with one end which is blocked and another end through which the exhaust gas is discharged; and a wall (50) which defines a boundary between an inlet channel (42) and an adjacent outlet channel (44) and is adapted to supply or allow the exhaust gas from the inlet channel (42) to the outlet channel (44), and wherein the wall (50) comprises a single-layer section (52) which is formed at an end section and has a three-way catalyst layer, and a multi-layer section (54) which is the other section than the single-layer section (52) and has a three-way catalyst layer (66), a hydrocarbon trap layer (64) and an insulating layer (62), and wherein the three-way catalyst layer (66), the hydrocarbon trap layer (64) and the insulating layer (63) of the multilayer section (54) are arranged from the inlet channel (42) towards the outlet channel (44) in the order insulating layer (62), hydrocarbon trap layer (64) and three-way catalyst layer (66). [2] The exhaust gas cleaning device according to claim 1, wherein the insulating layer (62) prevents heat from being transferred from the exhaust gas to the hydrocarbon trap layer (64) by moisture adsorption. [3] The exhaust gas cleaning device according to claim 1 or 2, wherein a length of the single-layer section (52) is 10% - 50% of a length of the wall (50), and wherein a length of the multi-layer section (54) is 50% - 90% of the length of the wall (50). [4] The exhaust gas cleaning device according to one of claims 1 to 3, wherein the combustion engine catalyst (40) is a catalytic particulate filter in which a catalyst is provided in the form of a coating.

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