JP-2026074687-A - Exhaust structure of an internal combustion engine

JP2026074687AJP 2026074687 AJP2026074687 AJP 2026074687AJP-2026074687-A

Abstract

[Problem] To provide an exhaust structure for an internal combustion engine that can improve exhaust purification performance and pressure loss while ensuring sufficient detection accuracy of the air-fuel ratio sensor. [Solution] The exhaust structure of the internal combustion engine comprises a turbine and a catalytic converter provided in the exhaust passage, a bypass passage that merges with the exhaust passage via a substantially circular port, and an air-fuel ratio sensor. The exhaust passage between the catalytic converter and the port is provided with an elliptical portion having a second elliptical cross-section that is similar to a hypothetical ellipse that encompasses the port and the substantially circular first cross-section of the exhaust passage between the turbine and the port, and whose major and minor axes are substantially aligned with the hypothetical ellipse, and a reducing portion that reduces the exhaust passage area toward the elliptical portion. The hypothetical ellipse has a center located on a straight line connecting the centers of the port and the first cross-section, and a major axis extending in the direction of the straight line. The air-fuel ratio sensor is provided in the elliptical portion at a position closer to one end of the minor axis of the second cross-section than to one end of the major axis of the second cross-section. [Selection Diagram] Figure 2

Inventors

岩田昭寿
水野勝雅

Assignees

トヨタ自動車株式会社

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (3)

A supercharger having a turbine installed in the exhaust passage of an internal combustion engine, A catalytic converter is provided in the exhaust passage downstream of the turbine, A bypass passage that branches off from the exhaust passage upstream of the turbine, bypasses the turbine, and merges with the exhaust passage upstream of the catalytic converter via a substantially circular port, The system includes an air-fuel ratio sensor that detects the air-fuel ratio from the exhaust gas in the exhaust passage, The exhaust passage between the catalytic converter and the port is provided with an elliptical portion having a second elliptical cross-section that is similar to a hypothetical ellipse shape encompassing the port and a substantially circular first cross-section of the exhaust passage between the turbine and the port, and whose major and minor axes are substantially aligned with the hypothetical ellipse shape, and a reducing portion that reduces the exhaust passage area toward the elliptical portion. The aforementioned virtual elliptical shape has a center located on a straight line connecting the centers of the port and the first cross-section, and a major axis extending in the direction of the straight line. The air-fuel ratio sensor is provided in the elliptical portion at a position closer to one end of the minor axis of the second cross-section than to one end of the major axis of the second cross-section. Exhaust structure of an internal combustion engine.
The air-fuel ratio sensor is provided at one end of the minor axis of the second cross-section in the elliptical portion. The exhaust structure for an internal combustion engine according to claim 1.
The air-fuel ratio sensor is positioned so that its tip is facing the inlet of the catalytic converter. The exhaust structure for an internal combustion engine according to claim 1 or 2.

Description

This invention relates to an exhaust structure for an internal combustion engine. Regarding the exhaust structure of an internal combustion engine, for example, Patent Document 1 describes an engine exhaust system equipped with a supercharger, an air-fuel ratio sensor, and a catalytic converter. Japanese Patent Publication No. 2014-227930 Figure 1 is a configuration diagram showing an example of a vehicle system.Figure 2 is a schematic cross-sectional view showing an example of an engine exhaust structure.Figure 3 is a cross-sectional view of the exhaust structure along the line A-A in Figure 2.Figure 4 is a schematic diagram showing an example of a hypothetical elliptical shape encompassing the cross-section of the exit port and the second passage, and the elliptical shape of the cross-section of the fifth passage. (Vehicle system configuration) Figure 1 is a configuration diagram showing an example of a vehicle system S. The vehicle system S includes a supercharger 1 including a compressor 31 and a turbine 41, an engine 2 which is an example of an internal combustion engine, an intake passage 3, an exhaust passage 4, a bypass passage 5, an air cleaner 30, and a catalytic converter 40. Air flows through the intake passage 3 toward the cylinder (combustion chamber) of the engine 2. Exhaust gas produced by the combustion of the fuel-air mixture in the combustion chamber flows through the exhaust passage 4. An air cleaner 30 is provided at the uppermost position of the intake passage 3. The air cleaner 30 removes dust and other particles from the air by filtering it. A compressor 31 is provided downstream of the air cleaner 30 in the intake passage 3. The compressor 31 has an impeller 14 and a housing 15. The impeller 14 is housed in the housing 15. The compressor 31 pumps air under pressure as the impeller 14 rotates. A throttle valve 6 is provided downstream of the compressor 31 in the intake passage 3. The opening degree of this throttle valve 6 is controlled, for example, by the ECU (Electronic Control Unit) based on the driver's accelerator input, according to the load required by the engine 2. This appropriately adjusts the amount of air supplied to the cylinder (intake volume). A turbine 41 is located at the uppermost position of the exhaust passage 4. The turbine 41 has a housing 11 and an impeller 12. The impeller 12 is housed in the housing 11. The impeller 12 rotates due to the exhaust flow. The rotation axes of the turbine 41's impeller 12 and the compressor 31's impeller 14 are integrally connected by a connecting shaft 13. As a result, the turbine 41's impeller 12 and the compressor 31's impeller 14 rotate as a single unit. In the exhaust passage 4, a catalytic converter 40 is provided downstream of the turbine 41. The catalytic converter 40 holds a catalyst support (such as palladium) for purifying the exhaust gas inside a case (not shown). The catalyst support of the catalytic converter 40 is, for example, made of porous ceramic and forms a grid of numerous passages. The exhaust gas purified by the catalytic converter 40 is discharged outside the vehicle. Another catalytic converter (not shown) may be provided downstream of the catalytic converter 40. In the exhaust passage 4, an air-fuel ratio sensor 42 is provided downstream of the turbine 41 and upstream of the catalytic converter 40. The air-fuel ratio sensor 42 detects the air-fuel ratio from the exhaust gas in the exhaust passage 4. An air-fuel ratio sensor 42 is provided for each cylinder (not shown) of the engine 2 and is used to determine the air-fuel ratio imbalance between cylinders. Furthermore, a bypass passage 5 that bypasses the turbine 41 is connected to the exhaust passage 4. A wastegate valve 43 is provided downstream of the bypass passage 5. The bypass passage 5 branches off from the exhaust passage 4 upstream of the turbine 41, bypasses the turbine 41, and merges with the exhaust passage 4 upstream of the catalytic converter 40 via the outlet port 51 of the wastegate valve 43. The cross-sectional area of the flow path of the bypass passage 5 changes depending on the opening degree of the outlet port 51 of the wastegate valve 43. The outlet port 51 is normally kept fully open. The exhaust flow Db that flows through the bypass passage 5 merges with the exhaust flow Da from the turbine 41 and flows into the catalytic converter 40. Figure 2 is a schematic cross-sectional view showing an example of the exhaust structure E of engine 2. Figure 2 shows a cross-section of the exhaust passage 4 along the exhaust flow. This cross-section also aligns with the direction in which the tip 42a of the air-fuel ratio sensor 42 protrudes into the exhaust passage 4. Furthermore, Figure 3 is a cross-sectional view of the exhaust structure E along the line A-A in Figure 2. Figure 3 shows a cross-section perpendicular to the cross-section of the exhaust passage 4 shown in Figure 2. The exhaust passage 4 includes a first passage 4a, a second passa