Internal combustion engine

Abstract

An internal combustion engine having an exhaust supercharger (3) is provided with: a catalytic converter (13) disposed in an upstream-side exhaust pipe (8) connecting a cylinder (2) of the internal combustion engine and an exhaust turbine (7) of an exhaust supercharger (3); a bypass passage (14) bypassing the exhaust turbine (7) and releasing part of exhaust gas flowing through the catalytic converter (13) to a downstream-side exhaust pipe; and a waste gate valve (15) provided in the bypass passage (14). The waste gate valve (15) and the bypass passage (14) are arranged so that condensed water accumulated on the downstream side in the catalytic converter (13) can be guided to a downstream-side exhaust pipe (9).

Description

internal combustion engine

[0001] The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine having an exhaust gas supercharger.

[0002] In the internal combustion engine having an exhaust turbocharger described in Patent Document 1, an exhaust purification catalyst is arranged in an upstream exhaust pipe that connects the cylinders of the internal combustion engine and the exhaust turbine of the exhaust turbocharger. In other words, in the upstream exhaust pipe, the exhaust purification catalyst is arranged downstream of the cylinders, and the exhaust turbocharger is further arranged downstream of this exhaust purification catalyst.

[0003] In the internal combustion engine of Patent Document 1, the shape of the exhaust purification catalyst tends to be more complex compared to a configuration in which the positions of the exhaust purification catalyst and the exhaust turbocharger are swapped, i.e., a configuration in which the exhaust turbine of the exhaust turbocharger is disposed downstream of the cylinder and the exhaust purification catalyst is disposed downstream of this exhaust turbine. In an exhaust purification catalyst with such a complex shape, condensed water generated by condensation of moisture in the exhaust gas is likely to accumulate downstream of the exhaust purification catalyst. The accumulated condensed water causes corrosion of the exhaust purification catalyst, which may cause cracks in the material of the exhaust purification catalyst and reduce the function of the exhaust purification catalyst.

[0004] However, Patent Document 1 does not take into consideration any measures against condensed water that accumulates in the exhaust purification catalyst.

[0005] The present invention has been made in light of these problems, and one of its objects is to provide an internal combustion engine that can suppress the deterioration of the function of the exhaust purification catalyst caused by condensed water.

[0006] Japanese Patent Application Laid-Open No. 2020-118050

[0007] In an internal combustion engine having an exhaust turbocharger, in which an exhaust purification catalyst is arranged in an upstream exhaust pipe connecting the cylinder of the internal combustion engine and the exhaust turbine of the exhaust turbocharger, the wastegate valve and bypass passage are arranged so that condensed water that accumulates downstream in the exhaust purification catalyst can be guided to the downstream piping.

[0008] Therefore, by opening the wastegate valve, it becomes possible to discharge the condensed water that has accumulated on the downstream side inside the exhaust purification catalyst.

[0009] According to the present invention, it is possible to suppress the deterioration of the function of the exhaust purification catalyst caused by condensed water.

[0010] 1 is a diagram illustrating the configuration of an internal combustion engine according to a first embodiment; FIG. 2 is a diagram illustrating the internal configuration of a catalytic converter according to a second embodiment; FIG. 3 is a diagram illustrating the internal configuration of a catalytic converter according to a third embodiment;

[0011] An embodiment of the present invention will now be described with reference to the drawings.

[0012] FIG. 1 is an explanatory diagram of the configuration of an internal combustion engine of a first embodiment. This internal combustion engine is configured as a direct injection type internal combustion engine having four cylinders 2 provided in an engine body 1. The engine body 1 of the internal combustion engine is provided with a fuel injection valve (not shown) that injects fuel into each cylinder 2, and a spark plug, both not shown. The injection amount and injection timing of the fuel injection valve, as well as the ignition timing of the spark plug, are controlled by control signals from a control device (not shown). The internal combustion engine also has an exhaust supercharger 3, which is a turbocharger.

[0013] The engine body 1 has an intake passage 4 through which air drawn into each cylinder 2 flows (only the passage upstream of the compressor 5 is shown in FIG. 1), and an exhaust passage 6 through which exhaust gas discharged from each cylinder 2 flows.

[0014] A compressor 5 of the exhaust turbocharger 3 is disposed in the intake passage 4 .

[0015] The exhaust passage 6 has an upstream exhaust pipe 8 that connects each cylinder 2 of the engine body 1 of the internal combustion engine to an exhaust turbine 7 of the exhaust turbocharger 3, and a downstream exhaust pipe 9 that is connected downstream of the exhaust turbine 7 and through which exhaust gas that has passed through the exhaust turbine 7 flows. The upstream exhaust pipe 8 has exhaust ports 10 that communicate with each cylinder 2, an exhaust manifold 11 that communicates with the exhaust ports 10, and a pipe 12 that communicates with the exhaust manifold 11. The pipe 12 is connected to the exhaust manifold 11 and the exhaust turbine 7.

[0016] A catalytic converter (exhaust purification catalyst) 13 made of a three-way catalyst is disposed in pipe 12 of the upstream exhaust pipe 8, and purifies the exhaust gas passing through this pipe 12. The downstream side of the catalytic converter 13 is connected to one end of a bypass passage 14, which bypasses the exhaust turbine 7 and is connected to the downstream exhaust pipe 9 located downstream of the exhaust turbine 7. The bypass passage 14 allows a portion of the exhaust gas flowing through the catalytic converter 13 to escape to the downstream exhaust pipe 9.

[0017] Further, the bypass passage 14 is provided with an electric wastegate valve 15 that adjusts the flow rate of a portion of the exhaust gas flowing through the bypass passage 14. Generally, in a configuration in which an exhaust turbine of an exhaust turbocharger is arranged downstream of the cylinder and an exhaust purification catalyst is further arranged downstream of the exhaust turbine of this exhaust turbocharger, the wastegate valve is provided integrally with a housing that accommodates the exhaust turbine of the exhaust turbocharger, but the wastegate valve 15 of this embodiment is provided separately from a housing (not shown) that accommodates the exhaust turbine 7 of the exhaust turbocharger 3, and is arranged in the bypass passage 14. The wastegate valve 15 is controlled by a control signal generated by a control device (not shown) based on the operating state of the vehicle.

[0018] Furthermore, when the temperature of the catalytic converter 13 is relatively low, for example, when the vehicle is stopped from a driving state, moisture contained in the exhaust gas passing through the pipe 12 and the catalytic converter 13 condenses to form condensed water. This condensed water accumulates downstream within the catalytic converter 13. As described above, in this embodiment, the downstream side of the catalytic converter 13 is connected to one end of the bypass passage 14, and the bypass passage 14 is further provided with a wastegate valve 15. Therefore, the wastegate valve 15 and the bypass passage 14 are arranged so that condensed water accumulated downstream within the catalytic converter 13 can be guided to the downstream exhaust pipe 9. More specifically, when the temperature of the catalytic converter 13 is relatively low and condensed water accumulates downstream within the catalytic converter 13, the wastegate valve 15 is opened in response to a control signal from a control device (not shown), thereby discharging the condensed water through the bypass passage 14 to the downstream exhaust pipe 9. The wastegate valve 15 is controlled to open when the vehicle is stopped for a relatively long period of time, for example, during an idle stop or when the key is off and the driver is outside the vehicle. The wastegate valve 15 may also be controlled to open when the temperature of the catalytic converter 13 is relatively low during a cold start.

[0019] The exhaust turbocharger 3 has an exhaust turbine 7 and a compressor 5 connected to the exhaust turbine 7 via a shaft (not shown). In such an internal combustion engine, exhaust air from a pipe 12 rotates the exhaust turbine 7, compressing the air in the intake passage 4 downstream of the compressor 5, and this compressed air is supplied to an intake manifold (not shown) of the engine body 1.

[0020] In the configuration shown in FIG. 1 , if a gasoline particulate filter (GPF) for removing particulate matter (PM) from the exhaust is provided, the GPF is placed in the downstream exhaust pipe 9 downstream of the exhaust turbine 7, and a bypass passage 14 provided with a wastegate valve 15 is placed in the downstream exhaust pipe 9 upstream of the GPF.

[0021] As described above, in the first embodiment, the catalytic converter 13 is arranged in the upstream exhaust pipe 8 connecting the cylinder 2 of the internal combustion engine and the exhaust turbine 7 of the exhaust turbocharger 3, that is, the catalytic converter 13 is arranged downstream of the cylinder 2, and the exhaust turbine 7 of the exhaust turbocharger 3 is arranged downstream of this catalytic converter 13. In this configuration, the downstream side of the catalytic converter 13 is connected to one end of the bypass passage 14, and this bypass passage 14 is connected to the downstream exhaust pipe 9, bypassing the exhaust turbine 7. Furthermore, a wastegate valve 15 is provided in the bypass passage 14, and the wastegate valve 15 and the bypass passage 14 are arranged so that condensed water that accumulates downstream in the catalytic converter 13 can be guided to the downstream exhaust pipe 9. This makes it less likely that corrosion of the catalytic converter 13 will be caused by condensed water, and furthermore, cracks in the material of the catalytic converter 13 that accompany this corrosion are less likely to occur, so that deterioration of the performance of the exhaust purification catalyst can be suppressed.

[0022] Furthermore, the wastegate valve 15 is provided separately from a housing (not shown) that houses the exhaust turbine 7 of the exhaust turbocharger 3. Generally, in a configuration in which an exhaust turbocharger is disposed downstream of a cylinder and an exhaust purification catalyst is further disposed downstream of this exhaust turbocharger, the wastegate valve is provided integrally with the housing that houses the exhaust turbine of the exhaust turbocharger and is constantly repeatedly opened and closed to control the boost pressure. However, it is possible to control the boost pressure even if the wastegate valve is provided separately from the housing and its installation position is changed. Therefore, in this embodiment, a separate wastegate valve 15 is provided in the bypass passage 14, thereby improving the degree of freedom in design.

[0023] Furthermore, in this embodiment, the control device controls the separate wastegate valve 15 to open when the vehicle is stopped. When the vehicle is stopped, the inflow of high-temperature exhaust gas into the catalytic converter 13 also stops, causing the temperature of the catalytic converter 13 to drop. This promotes condensation of moisture in the exhaust gas remaining in the catalytic converter 13, making it easier for condensed water to be generated. Therefore, by opening the wastegate valve 15 when the vehicle is stopped under conditions that make it easier for condensed water to be generated, the condensed water can be actively discharged, and deterioration of the catalytic converter 13's performance can be efficiently suppressed.

[0024] FIG. 2 is an explanatory diagram showing the internal configuration of a catalytic converter 13 according to a second embodiment. The catalytic converter 13 includes a first three-way catalyst (TWC1) 16 and a second three-way catalyst (TWC2) 17 arranged horizontally (left-right in FIG. 2 ), and a catalyst housing 18 that houses the first three-way catalyst 16 and the second three-way catalyst 17. The first three-way catalyst 16 side of the catalyst housing 18 is connected to a first section 12a of the pipe 12 through which exhaust gas from the exhaust port 10 flows, the first section 12a being upstream of the catalytic converter 13. Furthermore, an upper section 18a of the catalyst housing 18 in the vertical direction (up-down direction in FIG. 2 ) is connected to a second section 12b of the pipe 12 being downstream of the catalytic converter 13, and the exhaust turbine 7 is provided downstream of the second section 12b and vertically above the catalyst housing 18. Furthermore, when moisture in the exhaust gas flows into the catalyst housing 18 and condenses water, the condensed water flows down the inner wall of the catalyst housing 18 due to its own weight and accumulates downstream inside the catalytic converter 13 at the lower part 18b of the catalyst housing 18. A wastegate valve (W / G valve) 15 is provided at this location, and the condensed water is discharged to the downstream exhaust pipe 9 via this wastegate valve 15 and a bypass passage 14 that communicates with the wastegate valve 15.

[0025] In this way, also in the second embodiment, the wastegate valve 15 and the bypass passage 14 are arranged at a position where condensed water accumulates, which is a downstream portion within the catalyst housing 18 of the catalytic converter 13, and it is possible to guide the condensed water within the catalyst housing 18 to the downstream exhaust pipe 9. Therefore, the configuration of the second embodiment also makes it possible to suppress a decline in the function of the exhaust purification catalyst.

[0026] FIG. 3 is an explanatory diagram showing the internal configuration of a catalytic converter 13 of a third embodiment. This catalytic converter 13 is configured as the catalytic converter 13 of the second embodiment, with a gasoline particulate filter (hereinafter referred to as "GPF 19") located downstream of the second three-way catalyst 17. In this embodiment, the upper portion 18a of the catalyst housing 18 in the vertical direction (the up-down direction in FIG. 3 ) is connected to the second portion 12b of the piping 12 at a position facing the GPF 19. In this embodiment, a portion P1 of the lower portion 18b of the catalyst housing 18 facing the first three-way catalyst 16 and the second three-way catalyst 17 slopes downward toward the GPF 19, while a portion P2 of the lower portion 18b of the catalyst housing 18 facing the GPF 19 extends horizontally. Therefore, when moisture in the exhaust gas flows from the first portion 12a into the catalyst housing 18 and condenses, the condensed water flows along the inclined portion P1 of the lower portion 18b of the catalyst housing 18 and accumulates in a portion P2. A wastegate valve 15 is provided at this portion P2, and the condensed water is discharged to the downstream exhaust pipe 9 via this wastegate valve 15 and the bypass passage 14 that communicates with the wastegate valve 15.

[0027] In this way, also in the third embodiment, the wastegate valve 15 and the bypass passage 14 are arranged in the downstream portion P2 inside the catalyst housing 18 of the catalytic converter 13, where condensed water accumulates, and it is possible to guide the condensed water inside the catalyst housing 18 to the downstream exhaust pipe 9. Therefore, the configuration of the third embodiment also makes it possible to suppress deterioration in the function of the exhaust purification catalyst.

Claims

1. An internal combustion engine having an exhaust turbocharger, comprising: an exhaust purification catalyst that is arranged in an upstream exhaust pipe that connects a cylinder of the internal combustion engine to an exhaust turbine of the exhaust turbocharger and purifies exhaust gas; a bypass passage that bypasses the exhaust turbine and releases a portion of the exhaust gas that flows through the exhaust purification catalyst to a downstream exhaust pipe located downstream of the exhaust turbine; and a wastegate valve that adjusts the flow rate of the portion of the exhaust gas that flows through the bypass passage, wherein the wastegate valve and the bypass passage are arranged so that condensed water that accumulates downstream inside the exhaust purification catalyst can be guided to the downstream exhaust pipe.

2. The internal combustion engine according to claim 1, wherein the bypass passage has an inlet connected to a location downstream of the exhaust purification catalyst within a catalyst housing that houses the exhaust purification catalyst where condensed water accumulates due to its own weight, and an outlet connected to the downstream exhaust pipe.

3. The internal combustion engine according to claim 2, wherein the wastegate valve is disposed near the inlet of the bypass passage.

4. The internal combustion engine according to claim 2, wherein the exhaust turbine is disposed vertically above the catalyst housing.

5. The internal combustion engine according to claim 1, wherein the wastegate valve and the bypass passage are provided separately from a housing that accommodates the exhaust turbine.

6. An internal combustion engine as claimed in claim 1, further comprising a control device that controls the wastegate valve based on the operating state of the vehicle, the wastegate valve being provided separately from a housing that accommodates the exhaust turbine, and the control device controls the separate wastegate valve to open when the vehicle is stopped.

Images