JP2006336537A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable quick warming up of a catalyst in an internal combustion engine provided with an exhaust system on each bank. <P>SOLUTION: A control device for an internal combustion engine is provided with a first and a second exhaust passages to a first and a second cylinder groups. The first and the second exhaust passages are provided with a first and a second catalysts. A first and a second reduction agent addition valves are provided in upstream of the first and the second catalysts. A bypass passage is connected to the first and the second exhaust passages. Discharged exhaust gas can be made flow to the first and the second exhaust passages and also to the bypass passage. An exhaust passage control part controls flow passages to supply exhaust gas from the second cylinder group to only the first catalyst through the bypass passage at a time of catalyst warming up, and all exhaust gas is concentrated and supplied to the first catalyst to quickly warm up the first catalyst. Since the second catalyst is not used at a time of catalyst warming up, injection for preventing clogging of the reduction agent addition valve corresponding to the second catalyst can be stopped and reduction agent can be saved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device that performs catalyst warm-up control of an internal combustion engine.

  Usually, immediately after the engine is started, the temperature of the catalyst is low, and the purification action of the catalyst cannot be exhibited sufficiently. Also, during normal driving other than immediately after starting the engine, if the vehicle continues to travel in the city for a long time, and the low-load driving state continues, the exhaust temperature from the engine will always remain low. The catalyst does not work sufficiently.

  Further, in a vehicle equipped with an engine with a turbocharger, the turbocharger absorbs the exhaust temperature because the heat capacity of the turbocharger is large, and it is difficult to warm the catalyst early by the exhaust. From this point of view, in a supercharged engine, a method has been proposed in which the turbocharger is bypassed and exhaust is led to the catalyst when the catalyst is warmed up, such as immediately after the engine is started, so that the catalyst is warmed up early. For example, see Patent Documents 1 and 2.)

  On the other hand, an internal combustion engine having a configuration in which a plurality of cylinder groups (banks) are connected to different exhaust passages, such as a so-called V-type engine, is known. As an example of this type of internal combustion engine, in Patent Document 3, each of the first and second banks is provided with a catalyst, and when the catalyst is warmed up, the exhaust gas from the second bank is bypassed and the second catalyst is bypassed. Thus, a technique for quickly warming up the first catalyst by flowing it through the first catalyst is disclosed.

JP 2001-50038 A Japanese Patent Laid-Open No. 5-44448 JP 2003-343244 A

  As described above, in the case of an engine in which the exhaust system is divided into two, since the element parts, piping, etc. of each exhaust system are in two sets, the surface area becomes large. For this reason, the heat release amount of the exhaust gas increases, and the exhaust gas temperature tends to decrease. Also, if the fuel injection amount is increased, the exhaust temperature can be raised, but the fuel injection amount into the fuel chamber is determined by the sum of the resistance of the engine itself and the driver's required output. The amount of fuel injection cannot be increased unnecessarily for the purpose of promoting catalyst warm-up.

  In the configuration of the above-mentioned Patent Document 3, the combined exhaust gas from the first and second banks passes through the first catalyst, and is further supplied to the second catalyst. Therefore, when a reducing agent addition valve is provided upstream of each catalyst, it is necessary to periodically inject a small amount of reducing agent to prevent the addition valve from clogging.

  The present invention has been made in order to solve such problems, and an object of the present invention is an internal combustion engine that enables early warm-up of a catalyst in an internal combustion engine provided with an exhaust system for each bank. It is to provide a control device.

  In one aspect of the present invention, a control device for an internal combustion engine having first and second cylinder groups includes a first exhaust passage corresponding to the first cylinder group and a second cylinder group corresponding to the second cylinder group. Two exhaust passages, a first catalyst provided in the first exhaust passage, a second catalyst provided in the second exhaust passage, and a first catalyst provided upstream of the first catalyst. A reducing agent addition valve, a second reducing agent addition valve provided upstream of the second catalyst, a bypass passage connected to the first exhaust passage and the second exhaust passage, and catalyst warm-up And an exhaust flow path control unit that supplies exhaust gas from the second cylinder group only to the first catalyst using the bypass passage.

  The control device for an internal combustion engine described above is applied to an internal combustion engine including two cylinder groups (banks) such as a V-type engine. A first exhaust passage is provided corresponding to the first cylinder group, and a first catalyst is provided in the first exhaust passage. Similarly, a second exhaust passage is provided corresponding to the second cylinder group, and a second catalyst is provided in the second exhaust passage. For example, a NOx catalyst is used as the first and second catalysts. In addition, a first reducing agent addition valve is provided upstream of the first catalyst, and a second reducing agent addition valve is provided upstream of the second catalyst. When the NOx storage reduction catalyst is used as the first and second catalysts, the first and second reducing agent addition valves can be fuel addition valves that inject fuel as a reducing agent. On the other hand, when a selective reduction type NOx catalyst is used as the first and second catalysts, the first and second reducing agent addition valves inject urea, ammonia or the like as the reducing agent.

  Further, a bypass passage is connected to the first exhaust passage and the second exhaust passage, and exhaust gas discharged from the internal combustion engine flows to the bypass passage in addition to flowing to the first and second exhaust passages. Also configured to be able to. The exhaust flow path control unit can control the flow path of the exhaust gas discharged from the internal combustion engine. When the catalyst is warmed up, the exhaust gas from the second cylinder group is passed through the bypass passage only to the first catalyst. To control the flow path.

  At the time of warming up the catalyst, it is necessary to supply exhaust gas discharged from the internal combustion engine to the catalyst and warm the catalyst with the heat of the exhaust gas. Therefore, when the catalyst is warmed up, exhaust gas from the second cylinder group is supplied only to the first catalyst through the bypass passage, so that all exhaust gas is concentrated and supplied to the first catalyst. The first catalyst can be warmed up early. Since the exhaust gas does not flow to the second catalyst side when the catalyst is warmed up, the injection for preventing clogging of the reducing agent addition valve corresponding to the second catalyst can be stopped, and the reducing agent can be saved. It becomes possible.

  In one aspect of the control apparatus for an internal combustion engine, a cross-sectional area of the bypass passage is made smaller than a cross-sectional area of the first and second exhaust passages. By reducing the cross-sectional area of the bypass passage through which all exhaust gas passes when the catalyst warms up, the exhaust pressure of the exhaust manifold increases and the load on the internal combustion engine increases. Thereby, since the temperature of exhaust gas rises, the early warm-up of a catalyst can be promoted more.

  In another aspect of the control apparatus for an internal combustion engine, the amount of the noble metal supported by the first catalyst is made larger than the amount of the noble metal supported by the second catalyst. As a result, the amount of the noble metal supported on the second catalyst that is not used when the catalyst is warmed up can be reduced, and the cost of the catalyst can be reduced without reducing the exhaust purification capability.

  In another aspect of the control apparatus for an internal combustion engine, the first catalyst has a purification performance at a low temperature equal to or lower than a predetermined temperature higher than a purification performance at a high temperature equal to or higher than a predetermined temperature, and the second catalyst is The purification performance at a high temperature above the predetermined temperature is higher than the purification performance at a low temperature below the predetermined temperature. Since only the first catalyst is used at a low catalyst temperature such as when the catalyst is warmed up, it is preferable that the first catalyst has a high purification performance at a low temperature. On the other hand, since the second catalyst is not used at a low temperature of the catalyst, the second catalyst is not required to have a high purification performance at a low temperature. Therefore, the purification performance over a wide temperature range can be improved as a whole purification system by making the second catalyst have high purification performance at high temperatures.

  In another aspect of the control device for an internal combustion engine, the first reducing agent addition valve is provided on the bypass passage. When the catalyst is warmed up, since the flow rate and flow rate of the exhaust gas in the bypass passage are large, mixing of the reducing agent can be promoted by providing the first reducing agent addition valve on the bypass passage. Moreover, since the distance until the reducing agent injected from the first reducing agent addition valve reaches the first catalyst can be increased by providing it on the bypass passage, this also reduces the mixing of the reducing agent. The effect to promote is acquired.

  Another aspect of the control apparatus for an internal combustion engine includes a first supercharger provided on the first exhaust passage and upstream of the first catalyst, and the bypass passage includes It is connected to the first exhaust passage so as to bypass the first supercharger. Since turbochargers and other turbochargers generally have a large heat capacity, if exhaust gas is supplied to the catalyst through the turbocharger when the catalyst is warmed up, heat absorption by the turbocharger is large and the catalyst may be warmed up early. difficult. Therefore, by providing a bypass passage through which the exhaust gas passes when the catalyst warms up so as to bypass the supercharger, the heat of the exhaust gas is prevented from being taken away by the supercharger, and the catalyst is effectively warmed up. It becomes possible to do.

  In another aspect of the control device for an internal combustion engine, the exhaust flow path control unit may control the exhaust gas when the temperature of the exhaust gas from the first and second cylinder groups is equal to or higher than a predetermined temperature. A portion is allowed to flow through the bypass passage. When the internal combustion engine is at a high load such as a full load, the temperature of the exhaust gas is high and the catalyst is likely to be thermally deteriorated. Therefore, when the exhaust gas reaches a high temperature, part of the exhaust gas is released to the bypass passage and radiated by the bypass passage. That is, the exhaust heat supplied to the catalyst is lowered using not only the normal exhaust passage but also the heat radiation by the bypass passage. Thereby, thermal deterioration of the catalyst can be prevented.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Configuration of control device for internal combustion engine]
FIG. 1 shows a configuration of a control device for an internal combustion engine according to an embodiment of the present invention. In FIG. 1, arrows indicated by solid lines indicate the flow of intake and exhaust, and arrows indicated by broken lines indicate signal input / output.

  In this embodiment, the internal combustion engine 1 is configured as a V-type 8-cylinder diesel engine in which four cylinders (cylinders) 3 are provided in each of the left and right banks (cylinder groups) 2L and 2R. The four cylinders 3 in the right bank 2R constitute a first cylinder group, and the four cylinders 3 in the left bank 2L constitute a second cylinder group.

  An intake passage 4 for guiding intake air to each cylinder 3 is divided into branch paths 4L and 4R for each bank downstream of the air cleaner 5, and turbochargers (superchargers) 6L and 6R are connected to the branch paths 4L and 4R. Compressors 6La and 6Ra are arranged. On the downstream side of the compressors 6La and 6Ra, the branch passages 4L and 4R pass through the intercooler 7 and are connected to a common intake manifold 8 constituting a part of the intake passage 4. An air flow meter 9 for detecting the amount of intake air is provided upstream of the branch paths 4L and 4R of the intake passage 4.

  On the other hand, the exhaust gas from the cylinders 3 of each bank is led from the exhaust manifolds 11L, 11R of the exhaust passages 10L, 10R provided to the banks to the turbines 6Lb, 6Rb of the turbochargers 6L, 6R, and further from the turbines 6Lb, 6Rb. Guided downstream. Catalysts 19L and 19R are provided on the exhaust passages 10L and 10R, respectively, downstream of the turbines 6La and 6Lb.

  Three-way valves 18L and 18R are provided between the exhaust manifolds 11L and 11R and the turbines 6La and 6Ra, respectively. The three-way valves 18L and 18R are provided with a bypass passage 17 that joins exhaust gases output from the three-way valves 18L and 18R and supplies them to the exhaust passage 10R. The bypass passage 17 joins the exhaust passage 10R at a position upstream from the catalyst 19R. That is, the bypass passage 17 has a function of joining exhaust gases discharged from the left and right banks 2L and 2R and flowing only to the catalyst 19R when the catalyst is warmed up, which will be described later.

  The opening and closing and the opening degree of the three-way valves 18L and 18R are controlled by an ECU (Engine Control Unit) 12. The ECU 12 functions as an exhaust flow path control unit that controls the three-way valves 18L and 18R and controls the flow path of exhaust gas from the exhaust manifolds 11L and 11R. The ECU 12 is a well-known computer that controls the operation state of the internal combustion engine 1 by adjusting the fuel injection amount from the fuel injection valve 20 provided in each cylinder 3.

  Each exhaust manifold 11L, 11R is connected to the intake manifold 8 via EGR passages 13L, 13R for each bank. The EGR passages 13L and 13R are provided with EGR coolers 14L and 14R for cooling the EGR gas, and EGR valves 15L and 15R for adjusting the EGR flow rate. The opening degree of the EGR valves 15L, 15R is controlled by the ECU 12 so that an appropriate amount of EGR gas corresponding to the operating state of the internal combustion engine 1 is supplied to the intake manifold 8. The EGR passage 13 has a bypass passage (not shown) for allowing the exhaust gas to flow around the EGR coolers 14L and 14R, and a flow for selectively guiding the exhaust gas to the bypass passage or the EGR coolers 14L and 14R. A path switching valve (not shown) is further provided.

  In the present embodiment, as the catalysts 19L and 19R, NOx storage reduction catalysts that store and purify NOx are used. A fuel addition valve 21 </ b> R that injects a reducing agent into the bypass passage 17 is provided at the bent portion 17 x of the bypass passage 17. Further, a fuel addition valve 21L is provided in the exhaust passage 10L at a position upstream from the catalyst 19L. In the present embodiment, the fuel addition valves 21L and 21R inject fuel as a reducing agent. The fuel addition valves 21L and 21R are controlled by the ECU 12 in the amount of fuel added.

  The bypass passage 17 is preferably narrower than the exhaust passages 10L and 10R. That is, the cross-sectional area of the bypass passage 17 is smaller than the cross-sectional areas of the exhaust passages 10L and 10R. In general, it is known to provide an exhaust throttle valve in order to increase the exhaust pressure of the exhaust manifold to promote catalyst warm-up, but in this embodiment, exhaust from the left and right banks during catalyst warm-up. Since the gas merges and passes through the bypass passage 17, the exhaust manifold exhaust pressure can be increased by narrowing the bypass passage 17. Thereby, the load of the internal combustion engine 1 can be intentionally increased, the exhaust temperature can be raised, and the warm-up of the catalyst can be promoted.

  Next, the fuel addition valve in the present embodiment will be described in detail. As illustrated, the fuel addition valve 21L is provided at an upstream position of the catalyst 19L in the exhaust passage 10L. On the other hand, the fuel addition valve 21R is provided not on the exhaust passage 10R but on the bypass passage 17. As a result, when exhaust gas is allowed to flow only through the bypass passage 17 when the catalyst is warmed up, for example, only the fuel addition valve 21R may be used, and it is not necessary to use the fuel addition valve 21L on the exhaust passage 10L. Generally, a fuel addition valve needs to periodically inject a small amount of fuel to prevent clogging and to remove smoke in the nozzle. However, the fuel injected at that time is not used for the combustion of the internal combustion engine, and does not contribute to the generation of power. Therefore, when exhaust gas is allowed to flow only to the bypass passage 17 when the catalyst is warmed up, fuel injection for preventing clogging is not required for the fuel addition valve 21L on the exhaust passage 10L side where the exhaust gas does not flow, The fuel used to prevent clogging can be reduced. Thereby, fuel consumption is improved.

  Further, as shown in FIG. 1, the fuel addition valve 21R on the bypass passage 17 is attached to a curved portion 17x in front of the junction 17y with the exhaust passage 10R where it joins. In general, when a fuel addition valve is provided in the exhaust passage, the fuel is injected from the fuel addition valve into the exhaust passage having a small inner diameter, so that fuel injection and mixing with the exhaust become insufficient, Problems such as injection of fuel adhering to the wall surface of the exhaust passage are likely to occur. On the other hand, in the present embodiment, exhaust gas discharged from the two banks at the time of catalyst warm-up or the like passes through the bypass passage 17, so that the flow rate and flow rate of the exhaust gas become faster, and the fuel addition valve 21R. There is an advantage that mixing of the fuel injected from the fuel is promoted.

  Preferably, the bypass passage 17 has a tapered shape with a reduced cross-sectional area from the curved portion 17x toward the junction 17y with respect to the exhaust passage 10R. This further increases the flow rate of the exhaust gas downstream of the fuel addition valve 21R, further promoting fuel mixing.

  The direction of the injection nozzle of the fuel addition valve 21 </ b> R is preferably matched with the axial direction of the bypass passage 17. Further, the distance from the position of the fuel addition valve 21R to the merging portion 17y is set to a predetermined distance or more. Thereby, the distance until the injected fuel collides with the wall surface of the exhaust passage 10R can be increased, fuel mixing is promoted, and the fuel adhering to the wall surface of the exhaust passage 10R can be reduced.

  In the above-described embodiment, the storage reduction type catalysts 19L and 19R are used as the NOx catalyst, and the fuel is injected as the reducing agent from the fuel addition valves 21L and 21R. On the other hand, when a selective reduction type catalyst is used as the NOx catalyst as the catalysts 19L and 19R, a reducing agent addition valve for injecting a reducing agent such as urea or ammonia is provided instead of the fuel addition valves 21L and 21R. That's fine. In this case, it is possible to save reducing agents such as urea and ammonia by stopping the injection for preventing clogging.

(Characteristics of catalyst)
Next, the characteristics of the catalysts 19L and 19R provided in the exhaust passages 10L and 10R will be described. Generally, it is known that warming up of a catalyst by exhaust gas is accelerated by increasing the amount of noble metal supported on the catalyst. For this reason, in order to accelerate the warm-up of the catalyst when the engine is cold, the amount of noble metal supported on the catalyst is increased.

  In this respect, in the present embodiment, when the catalyst is warmed up, the exhaust gas is supplied only to the catalyst 19R. Therefore, the catalyst 19L that is not used when the catalyst is warmed does not need to be warmed up earlier. Therefore, the amount of noble metal supported on the catalyst 19R side used when the catalyst is warmed up can be increased, and the amount of noble metal supported on the catalyst 19L not used when the catalyst is warmed up can be reduced. Thereby, the cost of a catalyst can be reduced without impairing exhaust gas purification performance.

  In general, it is difficult to produce a catalyst having high exhaust gas purification performance at both low and high temperatures, and the purification performance must be biased toward the low temperature side or the high temperature side. In the present embodiment, since only the catalyst 19R is used at a low temperature such as when the catalyst is warmed up, the catalyst 19R may be a specification having a high purification performance at a low temperature, and the catalyst 19L may be a specification having a high purification performance at a high temperature. preferable. That is, the catalyst 19R has a purifying performance on the low temperature side from the predetermined temperature, which is superior to the purifying performance on the high temperature side from the predetermined temperature. On the other hand, the catalyst 10L has higher purification performance on the higher temperature side than the predetermined temperature, superior to purification performance on the lower temperature side than the predetermined temperature. Thereby, as a whole exhaust gas purification system, it becomes possible to obtain an appropriate purification performance according to the temperature of the exhaust gas.

[Exhaust flow path control]
Next, exhaust flow path control performed using the bypass passage 17 will be described. As described above, the exhaust flow path control is performed by the ECU 12 controlling the three-way valves 18L and 18L.

(During steady driving)
During steady running of the vehicle, the ECU 12 controls the three-way valves 18L and 18R so that the output to the exhaust passages 10L and 10R is fully open and the output to the bypass passage 17 is fully closed, and the exhaust manifolds 11L and 11R The exhaust gas discharged is supplied to the exhaust passages 10L and 10R, respectively. Therefore, the bypass passage 17 is basically not used during steady running.

(Immediately after starting the internal combustion engine, during low load driving)
When the temperature of the catalysts 19L and 19R is low (when the catalyst is warmed up), such as immediately after starting the internal combustion engine or when low-load running has continued for a long time, it is necessary to warm the catalyst early to improve the exhaust purification performance There is. In this case, the ECU 12 controls the three-way valves 18L and 18R so that the output to the exhaust passages 10L and 10R is fully closed and the output to the bypass passage 17 is fully opened, and the exhaust gas discharged from the exhaust manifolds 11L and 11R. Are all supplied to the bypass passage 17. As a result, all exhaust gases discharged from the exhaust manifolds 11L and 11R are supplied only to the single catalyst 19R, so that the left and right catalysts 19L and 19R are independently warmed using the left and right exhaust passages 10L and 10R. The catalyst can be warmed up more quickly than in the case of using it. In other words, the exhaust gas is concentrated and supplied only to one catalyst 19R, so that the time required for warming up the catalyst can be shortened. When the catalyst is warmed up, the other catalyst 19L is not used for exhaust purification.

  Further, by passing the exhaust gas only through the bypass passage, the exhaust gas bypasses the turbochargers 6L and 6R and is supplied to the catalyst 19R. Therefore, it is avoided that the heat of the exhaust gas is taken away by the turbocharger having a large heat capacity, and the exhaust gas can be supplied to the catalyst while maintaining the exhaust temperature at a higher level. This also promotes warming up of the catalyst. .

(At high load)
As described above, the ECU 12 controls the exhaust gas to flow only in the exhaust passages 10L and 10R and not to the bypass passage 17 during steady running. However, when the internal combustion engine is running at a high load, the ECU 12 controls the three-way valve 18L. , 18R is controlled to supply a part of the exhaust gas to the bypass passage 17. Thereby, the bypass channel | path 17 can be used instead of a wastegate.

  The turbocharger has a problem in that the amount of exhaust gas increases during high-speed, high-load driving, and the turbo rotation increases too much. For this reason, conventionally, a method has been adopted in which a wastegate is provided in the turbine housing, and a part of the exhaust gas escapes without passing through the turbine. On the other hand, in this embodiment, the function of the wastegate is realized by the bypass passage 17. That is, when the amount of exhaust gas increases and the exhaust pressure becomes greater than a predetermined pressure, a part of the exhaust gas flows into the bypass passage 17 to lower the exhaust pressure. Actually, since the relationship between the supercharging pressure and the exhaust pressure is known, the ECU 12 monitors the supercharging pressure, and controls the three-way valves 18L and 18R when the supercharging pressure exceeds a predetermined pressure. A part of the exhaust gas may be supplied to the bypass passage 17.

  As described above, by realizing the function of the wastegate using the bypass passage when the internal combustion engine is traveling at a high load, it is not necessary to provide the wastegate separately from the bypass passage 17. Therefore, it is not necessary to provide a wastegate and its actuator in each turbocharger 6L, 6R, and the cost of the turbocharger can be reduced. In addition, since a wastegate is not required in the turbine housing, the degree of freedom in designing the turbine housing is increased, and the efficiency of the turbo can be improved.

  In addition, by flowing a part of the exhaust gas through the bypass passage 17 during traveling at a high load in this way, an effect of suppressing deterioration of the catalyst can be obtained. In general, the exhaust gas temperature becomes high during high-load traveling, so that there is a problem that the catalyst becomes high temperature and deteriorates. In this regard, as described above, when a part of the exhaust gas is supplied to the bypass passage 17 at the time of traveling at a high load, the heat of the exhaust gas can be radiated also by the bypass passage 17. At the same time, since the flow rate of the exhaust gas flowing into the exhaust passages 10L and 10R is reduced, the temperature of the exhaust gas supplied to the catalysts 19L and 19R can be reduced. Thereby, the thermal deterioration of a catalyst can be suppressed. In particular, in the present embodiment, since the catalyst 19R on the exhaust passage 10R side to which the bypass passage 17 is connected as described above is a specification having a high purification performance at a low temperature, the catalyst 19R is more easily affected by the high temperature. . Therefore, by using the bypass passage 17 to dissipate a part of the heat of the exhaust gas, it is possible to effectively suppress the thermal deterioration of the catalyst.

1 is a block diagram showing a schematic configuration of a control device for an internal combustion engine according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2L, 2R Bank 3 Cylinder 4 Intake passage 6 Variable nozzle type turbocharger 10L, 10R Exhaust passage 12 ECU
13L, 13R EGR passage 18L, 18R Three-way valve 17 Bypass passage 19L, 19R Catalyst

Claims (7)

A control device for an internal combustion engine having first and second cylinder groups,
A first exhaust passage corresponding to the first cylinder group and a second exhaust passage corresponding to the second cylinder group;
A first catalyst provided in the first exhaust passage and a second catalyst provided in the second exhaust passage;
A first reducing agent addition valve provided upstream of the first catalyst and a second reducing agent addition valve provided upstream of the second catalyst;
A bypass passage connected to the first exhaust passage and the second exhaust passage;
An exhaust passage control unit that supplies exhaust gas from the second cylinder group only to the first catalyst using the bypass passage when the catalyst is warmed up. Control device.   2. The control device for an internal combustion engine according to claim 1, wherein a cross-sectional area of the bypass passage is smaller than a cross-sectional area of the first and second exhaust passages.   3. The control device for an internal combustion engine according to claim 1, wherein the amount of the noble metal supported by the first catalyst is larger than the amount of the noble metal supported by the second catalyst. The first catalyst has a higher purification performance at a low temperature of a predetermined temperature or lower than that at a high temperature of the predetermined temperature or higher,
3. The control device for an internal combustion engine according to claim 1, wherein the second catalyst has a purification performance at a high temperature equal to or higher than a predetermined temperature higher than a purification performance at a low temperature equal to or lower than the predetermined temperature.   The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the first reducing agent addition valve is provided on the bypass passage. A first supercharger provided on the first exhaust passage and upstream of the first catalyst;
The control of the internal combustion engine according to any one of claims 1 to 5, wherein the bypass passage is connected to the first exhaust passage so as to bypass the first supercharger. apparatus.   The exhaust flow path control unit causes a part of the exhaust gas to flow through the bypass passage when the temperature of the exhaust gas from the first and second cylinder groups is equal to or higher than a predetermined temperature. Item 7. The control device for an internal combustion engine according to any one of Items 1 to 6.

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