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JP-7857155-B2 - Exhaust purifier

JP7857155B2JP 7857155 B2JP7857155 B2JP 7857155B2JP-7857155-B2

Inventors

  • 佐藤 考

Assignees

  • 株式会社SUBARU

Dates

Publication Date
20260512
Application Date
20220511

Claims (3)

  1. The first exhaust pipe connected to the engine, A first housing connected to the downstream side of the first exhaust pipe and housing a three-way catalytic converter, A second exhaust pipe connected to the downstream side of the first housing, A second housing connected to the downstream side of the second exhaust pipe and housing a nitrogen oxide storage catalyst, Equipped with, The three-way catalyst has a first region and a second region having lower OSC activity than the first region. The first region is positioned on the central axis of the gas flow sent from the first exhaust pipe into the first housing , The first housing is, A cylindrical portion housing the three-way catalyst, The first exhaust pipe and the cylindrical section are connected, and the first enlarged diameter section expands in diameter as it progresses from the upstream side to the downstream side, The second exhaust pipe and the cylindrical section are connected, and the second enlarged diameter section expands in diameter as it proceeds from the downstream side to the upstream side, It has, The degree of expansion of the first expanded portion is smaller than the degree of expansion of the second expanded portion. Exhaust gas purification device.
  2. The first region is located on the extension of the first exhaust pipe, The exhaust gas purification device according to claim 1.
  3. The OSC activity of the three-way catalyst is distributed such that it decreases as it moves away from the central axis. The exhaust gas purification device according to claim 1 or 2.

Description

This invention relates to an exhaust gas purification device. Exhaust gas purification systems, which clean exhaust gases emitted from engines, utilize various catalysts to purify harmful components in the exhaust gas. One such catalyst is a nitrogen oxide storage catalyst capable of absorbing nitrogen oxides (hereinafter also referred to as NOx) from exhaust gases. The NOx storage capacity of a nitrogen oxide storage catalyst decreases as the amount of NOx absorbed by the catalyst increases. Therefore, as disclosed in Patent Document 1, for example, a process called NOx purging is performed, which temporarily enriches the air-fuel ratio of the exhaust gas. NOx purging reduces and purifies the NOx absorbed by the nitrogen oxide storage catalyst, restoring the NOx storage capacity of the catalyst. Japanese Patent Publication No. 2012-255348 Figure 1 is a schematic diagram showing the general configuration of the intake and exhaust system of a vehicle according to an embodiment of the present invention.Figure 2 is a block diagram showing an example of the functional configuration of a control device according to an embodiment of the present invention.Figure 3 is a flowchart showing an example of the processing flow performed by a control device according to an embodiment of the present invention.Figure 4 is a schematic diagram showing how exhaust gas passes through a three-way catalytic converter under normal conditions in an exhaust gas purification device according to an embodiment of the present invention.Figure 5 is a schematic diagram showing how exhaust gas passes through a three-way catalyst during NOx purging in an exhaust gas purification device according to an embodiment of the present invention.Figure 6 shows an example of the distribution of OSC activity in a three-way catalyst according to an embodiment of the present invention.Figure 7 is a schematic diagram showing how exhaust gas passes through a three-way catalytic converter under normal conditions in an exhaust gas purification device according to a modified example.Figure 8 is a schematic diagram showing how exhaust gas passes through a three-way catalytic converter during NOx purging in an exhaust gas purification device according to a modified example. The embodiments of the present invention will be described in detail below with reference to the attached drawings. The specific dimensions, materials, numerical values, etc., shown in these embodiments are merely illustrative to facilitate understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations. <Overview of the vehicle's intake and exhaust system> Referring to Figures 1 to 3, an overview of the intake and exhaust system 2 of a vehicle 1 according to an embodiment of the present invention will be described. The exhaust purification device 3 according to an embodiment of the present invention is provided in the intake and exhaust system 2 of the vehicle 1. Figure 1 is a schematic diagram showing the general configuration of the intake and exhaust system 2 of vehicle 1. As shown in Figure 1, the intake and exhaust system 2 comprises an engine 10, an intake passage 20, and an exhaust passage 30. Engine 10 is, for example, a spark-ignition internal combustion engine. Engine 10 has one or more cylinders 11. In Figure 1, for ease of understanding, only one of the multiple cylinders 11 in engine 10 is shown. A piston 12 is slidably mounted in cylinder 11. A combustion chamber 13 is formed inside cylinder 11. The combustion chamber 13 is partitioned by the inner surface of cylinder 11 and the crown surface of piston 12. Cylinder 11 is provided with a spark plug 14 facing the combustion chamber 13. Cylinder 11 is also provided with a fuel injector 15 that injects fuel into the combustion chamber 13. A mixture containing air and fuel is formed in the combustion chamber 13. This mixture is ignited by the spark plug 14 and burns. As a result, the piston 12 in each cylinder 11 performs a linear reciprocating motion, and power is transmitted to the crankshaft connected to each piston 12. Furthermore, the fuel injector 15 is not limited to a type that directly injects fuel into the combustion chamber 13. For example, the fuel injector 15 may be installed in the intake passage 20 and inject fuel into the intake passage 20. In this case, the fuel is drawn into the combustion chamber 13 along with the intake air. Each combustion chamber 13 of the engine 10 is connected to an intake passage 20 via an intake port and to an exhaust passage 30 via an exhaust port. Each cylinder 11 is provided with an intake valve 16 capable of opening and closing the intake port, and an exhaust valve 17 capable of