JP2006307734A - Exhaust device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently purify exhaust emission in an exhaust device of an internal combustion engine. <P>SOLUTION: This exhaust device of the internal combustion engine having an exhaust gas turbine-driven supercharger comprises: an exhaust flow passage; a catalyst purifying nitrogen oxides installed in the exhaust flow passage on the downstream side of the supercharger; and a reducer feed valve feeding a reducer into the exhaust flow passage. The reducer feed valve jets the reducer from a predetermined position between the supercharger and the catalyst in the exhaust flow passage toward the upstream side direction of the exhaust flow passage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to exhaust gas from an internal combustion engine, and more particularly to a technique for purifying exhaust gas from an internal combustion engine.

  As one measure for purifying the exhaust gas of the internal combustion engine, a catalyst is generally provided in the exhaust passage of the exhaust device. In a catalyst, in order to efficiently purify nitrogen oxides (NOx) and the like contained in exhaust gas, a technique for supplying fuel (for example, light oil) as a reducing agent into an exhaust passage upstream of the catalyst is known. (For example, Patent Document 1).

JP-A-8-200047 Japanese Patent Laid-Open No. 7-102949

  In the above prior art, the atomization of the fuel and the mixing with the exhaust gas from the time when the fuel as the reducing agent is supplied into the exhaust flow path to the catalyst becomes insufficient, and the purification of nitrogen oxides and the like in the catalyst is efficient. There was a case that could not be done well.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a technique capable of efficiently purifying exhaust gas in an exhaust device of an internal combustion engine.

In order to solve the above problems, an exhaust device for an internal combustion engine according to the present invention includes:
An exhaust system for an internal combustion engine having an exhaust turbine driven supercharger,
An exhaust passage;
A catalyst for purifying nitrogen oxides installed downstream of the supercharger in the exhaust passage;
A reducing agent supply valve for supplying a reducing agent into the exhaust passage,
The reducing agent supply valve injects the reducing agent from a predetermined position in the exhaust passage between the supercharger and the catalyst toward the upstream side of the exhaust passage. .

  In the exhaust device of the internal combustion engine, the reducing agent is injected from a predetermined position in the exhaust passage between the supercharger and the catalyst toward the upstream side of the exhaust passage. The turbulent flow generated in the exhaust flow path by the action of the supercharger promotes atomization and mixing with the exhaust. Therefore, the exhaust device of the internal combustion engine can efficiently purify the exhaust gas.

  In the exhaust system of the internal combustion engine, the reducing agent supply valve is configured such that an angle formed by a vector of an injection axis of the reducing agent supply valve and a vector in an exhaust flow direction in the exhaust passage is 90 degrees or more. It may be.

  According to this configuration, the reducing agent can be injected toward the upstream side of the exhaust passage by the reducing agent supply valve.

  Further, in the exhaust system of the internal combustion engine, the reducing agent supply valve is configured so that the reducing agent injected when there is no exhaust flow in the exhaust passage directly reaches the exhaust turbine of the supercharger. It may be configured to inject a reducing agent.

  According to this configuration, the reducing agent is injected into the exhaust flow path by the reducing agent supply valve because the swirling turbulence generated in the exhaust flow path by the action of the supercharger is injected into a relatively strong portion. The atomization of the reducing agent and the mixing with the exhaust are strongly promoted. Therefore, the exhaust gas can be purified efficiently.

  In the exhaust system for an internal combustion engine, a distance between the predetermined position in the exhaust passage and the exhaust turbine of the supercharger may be not more than five times an inner diameter of the exhaust passage. .

  According to this configuration, the reducing agent supply valve causes the reducing agent to be injected into the portion where the swirling turbulence generated in the exhaust passage due to the action of the supercharger remains, and the fuel is atomized and exhausted. Mixing with is promoted. Therefore, the exhaust gas can be purified efficiently.

Further, in the exhaust device for the internal combustion engine,
A mechanism having a movable part installed upstream of the exhaust turbine of the supercharger may be provided.

  According to this configuration, even when a mechanism having a movable part is installed upstream of the exhaust turbine of the turbocharger, fuel atomization and mixing with the exhaust are suppressed while suppressing the occurrence of the malfunction of the movable part. And the exhaust gas can be purified efficiently.

  Note that the present invention can be realized in various modes, such as an exhaust device and an exhaust method for an internal combustion engine, an exhaust purification device and an exhaust purification method for an internal combustion engine, an internal combustion engine, a vehicle including an internal combustion engine, and the like. It can be realized in a mode such as a moving body.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Example:
B. Variations:

A. Example:
FIG. 1 is an explanatory diagram schematically showing the configuration of an engine 10 as an embodiment of the present invention. The engine 10 is an automobile diesel engine having an exhaust turbine-driven supercharger (turbocharger) 200. The engine 10 includes a cylinder block 110 having a hollow cylindrical cylinder 112 therein, a cylinder head 120 provided at an upper portion of the cylinder block 110, and a piston 114 that slides up and down in the cylinder 112. The combustion chamber 130 is formed by these elements.

  The cylinder head 120 has an intake valve 140 that opens and closes an opening of an intake port 122 into which intake air flows, an exhaust valve 150 that opens and closes an opening of an exhaust port 124 through which exhaust gas flows out, and fuel spray in the combustion chamber. And a fuel injection valve 160 that injects fuel. The intake valve 140 and the exhaust valve 150 are driven by electric actuators 142 and 152, respectively.

  An exhaust flow path 180 through which exhaust gas passes is connected to the exhaust port 124. The exhaust passage 180 is provided with a supercharger 200 and a catalyst 182 for purifying air pollutants contained in the exhaust disposed on the downstream side of the supercharger 200. In this embodiment, a three-way catalyst is used as the catalyst 182. A fuel injection valve 184 is provided between the supercharger 200 and the catalyst 182 in the exhaust passage 180. The fuel injection valve 184 is connected to a fuel tank (not shown) and supplies fuel (light oil) into the exhaust passage 180. Details of the supercharger 200 and the fuel injection valve 184 will be described later.

  An intake flow path 170 that guides intake air is connected to the intake port 122. The intake passage 170 is provided with an air cleaner 172, the above-described supercharger 200, and an intercooler 174 for cooling intake air disposed on the downstream side of the supercharger 200. The intake flow path 170 is also provided with a surge tank 178 and a throttle valve 176. The surge tank 178 has a function of relaxing pressure waves generated when the combustion chamber 130 sucks air. The throttle valve 176 is set to an appropriate opening by the electric actuator 177 and has a function of adjusting the intake air amount.

  The piston 114 is connected to the crankshaft 118 via the connecting rod 116. A crank angle sensor 192 that detects a crank angle is attached to the crankshaft 118.

  The operation of the engine 10 is controlled by an engine control unit (hereinafter referred to as “ECU”) 190. The ECU 190 detects the engine speed Ne and the accelerator opening θac, and controls the opening of the throttle valve 176, the fuel injection control of the fuel injection valves 160 and 184, and the drive of the intake valve 140 and the exhaust valve 150 based on these. Execute control etc. The engine speed Ne is detected by a crank angle sensor 192, and the accelerator opening θac is detected by an accelerator opening sensor 194 built in the accelerator pedal.

  FIG. 2 is an explanatory diagram showing a detailed structure around the supercharger 200 of the engine 10 of this embodiment. Moreover, FIG. 3 is explanatory drawing which shows the 3-3 cross section of FIG. As shown in FIG. 2, the supercharger 200 includes a turbine 220 and a compressor 230 inside a housing 210. The turbine 220 and the compressor 230 are connected by a shaft 240.

  Exhaust gas discharged from the exhaust port 124 (FIG. 1) passes through the supercharger 200 and the catalyst 182 (FIG. 1) in the exhaust flow path 180 and is then released to the atmosphere. At this time, the turbine 220 inside the supercharger 200 is rotated by the exhaust flow, and the compressor 230 connected to the turbine 220 is also rotated. Air sucked from the air cleaner 172 (FIG. 1) is pressurized by the rotating action of the compressor 230 inside the supercharger 200, cooled by the intercooler 174 (FIG. 1), and then pumped to the intake port 122. . In FIG. 2, the flow of exhaust and intake air is shown using broken-line arrows.

  A variable nozzle mechanism 250 is also provided inside the supercharger 200. The variable nozzle mechanism 250 includes a blade portion 252, a shaft portion 254, and a drive portion 256. The blade part 252 is driven by the drive part 256 and rotates around the shaft part 254. As the blade portion 252 rotates, the exhaust passage area on the upstream side of the turbine 220 changes as shown in FIG. FIG. 3A shows a state when the channel area is increased, and FIG. 3B shows a state when the channel area is decreased. In this way, the variable nozzle mechanism 250 can change the capacity of the turbine 220 by changing the flow path area of the exhaust gas upstream of the turbine 220.

  Here, in the engine 10 of the present embodiment, as shown in FIG. 2, a fuel injection valve 184 is provided in the exhaust passage 180. The fuel injection valve 184 supplies fuel into the exhaust passage 180 as a reducing agent for purifying nitrogen oxides in the catalyst 182 (FIG. 1).

  The fuel injection by the fuel injection valve 184 is performed toward the upstream side of the exhaust passage 180. That is, the injection is performed so that the angle formed by the vector of the injection axis of the fuel injection valve 184 and the vector of the exhaust flow direction in the exhaust flow path 180 is 90 degrees or more. FIG. 2 shows a state in which the fuel injection valve 184 is injecting fuel. The injected fuel changes its direction in the downstream direction by the exhaust flow and is supplied to the catalyst 182 (FIG. 1) as indicated by the solid arrow in FIG.

  In addition, the fuel injection valve 184 in the engine 10 of the present embodiment is positioned so that the fuel injected from the fuel injection valve 184 directly reaches the turbine 220 when there is no exhaust flow in the exhaust flow path 180. An injection angle, an injection pressure, etc. are set.

  In the engine 10 of this embodiment, as described above, fuel is injected from the fuel injection valve 184 toward the upstream side of the exhaust passage 180. Therefore, the injected fuel is promoted to be atomized and mixed with the exhaust gas by the swirling turbulent flow generated in the exhaust flow path 180 by the rotation of the turbine 220. In particular, in the engine 10 of this embodiment, as described above, the fuel injection valve so that the fuel injected from the fuel injection valve 184 directly reaches the turbine 220 when there is no exhaust flow in the exhaust flow path 180. Since 184 is configured, fuel is injected into a portion where the swirling turbulence generated by the rotation of the turbine 220 is relatively strong. Therefore, the atomization of the fuel injected into the exhaust passage 180 and the mixing with the exhaust are strongly promoted. Therefore, in the engine 10 of the present embodiment, atomization of fuel as a reducing agent supplied into the exhaust passage 180 and mixing with exhaust can be promoted, and exhaust purification can be performed efficiently.

  In order to promote fuel atomization and mixing with exhaust, fuel is injected at a position upstream of the supercharger 200 in the exhaust path (for example, the position of the exhaust port 124 (FIG. 1)). Is also considered effective. However, the supercharger 200 in the engine 10 of the present embodiment is provided with a variable nozzle mechanism 250 having a movable portion immediately upstream of the turbine 220, and fuel is supplied at a position upstream of the supercharger 200. If injected, the movable part of the variable nozzle mechanism 250 may be fixed by the injected fuel, which may cause a problem. In the engine 10 according to the present embodiment, even when a mechanism having a movable part is provided in the exhaust path upstream of the turbine 220 of the supercharger 200 as described above, the occurrence of the malfunction of the movable part is suppressed. Further, fuel atomization and mixing with exhaust gas can be promoted, and exhaust gas purification can be performed efficiently.

B. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

B1. Modification 1:
In the above-described embodiment, the fuel injection valve 184 is necessarily set so that the fuel injected from the fuel injection valve 184 reaches the turbine 220 directly when there is no exhaust flow in the exhaust flow path 180. There is no. Instead, in the above embodiment, in the fuel injection valve 184, the distance between the position of the injection hole of the fuel injection valve 184 and the turbine 220 of the supercharger 200 is not more than 5 times the inner diameter of the exhaust passage 180. As such, it may be installed. With such a configuration, the fuel is injected into the portion where the swirling turbulence generated by the rotation of the turbine 220 remains, and the atomization of the fuel and the mixing with the exhaust are promoted.

B2. Modification 2:
In the said Example, the structure of the engine 10 is an example to the last, and it is also possible to make the structure of the engine 10 into another structure. For example, the engine 10 does not necessarily need to include the variable nozzle mechanism 250. Further, the engine 10 does not have to be a diesel engine, and may be another combustion type engine such as a gasoline engine. Further, the engine 10 can be used for a moving body other than an automobile, or can be a stationary engine.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed schematically the structure of the engine as an Example of this invention. Explanatory drawing which shows the detailed structure of the supercharger periphery of the engine of a present Example. It is explanatory drawing which shows the 3-3 cross section of FIG.

Explanation of symbols

10 ... Engine 110 ... Cylinder block 112 ... Cylinder 114 ... Piston 116 ... Connecting rod 118 ... Crankshaft 120 ... Cylinder head 122 ... Intake port 124 ... Exhaust Port 130 ... Combustion chamber 140 ... Intake valve 142 ... Electric actuator 150 ... Exhaust valve 152 ... Electric actuator 160 ... Fuel injection valve 170 ... Intake flow path 172 ... Air cleaner 174 ... Intercooler 176 ... Throttle valve 177 ... Electric actuator 178 ... Surge tank 180 ... Exhaust flow path 182 ... Catalyst 184 ... Fuel injection valve 190 ... ECU
192 ... Crank angle sensor 194 ... Accelerator opening sensor 200 ... Supercharger 210 ... Housing 220 ... Turbine 230 ... Compressor 240 ... Shaft 250 ... Variable nozzle mechanism 252 ... blade part 254 ... shaft part 256 ... drive part

Claims (6)

An exhaust system for an internal combustion engine having an exhaust turbine driven supercharger,
An exhaust passage;
A catalyst for purifying nitrogen oxides installed downstream of the supercharger in the exhaust passage;
A reducing agent supply valve for supplying a reducing agent into the exhaust passage,
The reducing agent supply valve injects a reducing agent from a predetermined position in the exhaust passage between the supercharger and the catalyst toward the upstream side of the exhaust passage. An exhaust system for an internal combustion engine. An exhaust system for an internal combustion engine according to claim 1,
The reducing agent supply valve is configured so that an angle formed by a vector of an injection axis of the reducing agent supply valve and a vector of an exhaust flow direction in the exhaust flow path is 90 degrees or more. apparatus. An exhaust system for an internal combustion engine according to claim 1 or 2,
The reducing agent supply valve is configured to inject the reducing agent so that the reducing agent injected when there is no exhaust flow in the exhaust passage directly reaches the exhaust turbine of the supercharger. An exhaust device for an internal combustion engine. An exhaust system for an internal combustion engine according to claim 1 or 2,
An exhaust system for an internal combustion engine, wherein a distance between the predetermined position in the exhaust passage and the exhaust turbine of the supercharger is not more than 5 times an inner diameter of the exhaust passage. An exhaust device for an internal combustion engine according to any one of claims 1 to 4, further comprising:
An exhaust system for an internal combustion engine, comprising a mechanism having a movable part installed upstream of an exhaust turbine of the supercharger.   An internal combustion engine comprising the exhaust device for an internal combustion engine according to any one of claims 1 to 5.

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