JP2019085879A - Fuel injection control device - Google Patents

Abstract

To prevent the inactivation of an oxidation catalyst.SOLUTION: A fuel injection control device 200 includes an information input part 201 for inputting upstream side temperature information, and an injection control part 202 for executing main injection to inject fuel to cylinders 2b, 2c corresponding to exhaust ports 3b, 3c where a DOC 4 is not arranged, and in addition sub injection to inject fuel to cylinders 2a, 2d corresponding to exhaust ports 3a, 3d where the DOC 4 is arranged. The injection control part 202 controls a main injection amount and a sub injection amount so as to avoid an upstream side temperature from being lower than a first set temperature.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a fuel injection control device.

  A vehicle is equipped with an aftertreatment device that purifies exhaust gas discharged from an internal combustion engine.

  For example, in Patent Document 1, in an exhaust pipe connected to an exhaust manifold, an oxidation catalyst (for example, Diesel Oxidation Catalyst: hereinafter referred to as DOC) is disposed on the upstream side, and a diesel particulate collection filter (for example, Diesel) is provided on the downstream side. A post-processing apparatus is disclosed in which Particulate Filter (hereinafter referred to as DPF) is disposed.

  In such an aftertreatment device, when PM (particulate matter) in the exhaust gas collected by the DPF reaches a predetermined amount, unburned fuel supplied by fuel injection (for example, post injection or exhaust pipe injection) It is known to perform DPF regeneration, which removes PM using the heat that the fuel burns in DOC.

JP, 2013-189900, A

  However, in the post-processing apparatus described above, inactivation of DOC may be a problem. The inactivation of DOC means that when the exhaust gas is in a low temperature and / or under a low oxygen atmosphere, the surface of DOC is covered with high molecular weight HC which is not easily decomposed, so that the temperature of DOC is lowered and monooxidation occurs in DOC. It is a phenomenon in which the combustion reaction of carbon (CO) and hydrocarbons (HCs) is inhibited. If the inactivation of DOC proceeds, the combustion reaction in DOC will be completely stopped.

  An object of the present disclosure is to provide a fuel injection control device capable of preventing the deactivation of an oxidation catalyst.

  A fuel injection control device according to an aspect of the present disclosure is a fuel injection control device that controls the injection of fuel to a plurality of cylinders of an internal combustion engine of a vehicle, and a part of a plurality of exhaust ports corresponding to each of the cylinders. The first oxidation catalyst is disposed at the exhaust port of the second exhaust gas flow path, and the second oxidation catalyst is disposed at the upstream side of the exhaust pipe connected to the downstream side of the plurality of exhaust ports. A collection filter is disposed, and an information input unit for inputting information on the upstream temperature detected downstream of the plurality of exhaust ports and upstream of the second oxidation catalyst, and the first oxidation catalyst are disposed In addition to the main injection for injecting fuel to the cylinder corresponding to the exhaust port not being used, a sub injection for injecting fuel to the cylinder corresponding to the exhaust port where the first oxidation catalyst is disposed Run And the upstream side temperature is lower than a first set temperature defined as a temperature at which it is assumed that inactivation of the second oxidation catalyst does not occur. The main injection amount, which is the amount of fuel injected in the main injection, and the sub injection amount, which is the amount of fuel injected in the sub injection, are controlled so as not to occur.

  According to the present disclosure, inactivation of the oxidation catalyst can be prevented.

A schematic view showing an example of the configuration of a post-processing apparatus according to an embodiment of the present invention Block diagram showing an example of the configuration of a fuel injection control device according to an embodiment of the present invention A flowchart showing an example of the operation of the fuel injection control device according to the embodiment of the present invention The schematic diagram which shows an example of a structure of the post-processing apparatus which concerns on the modification of this invention Block diagram showing an example of the configuration of a fuel injection control device according to a modification of the present invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, the post-processing apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic view showing an example of the configuration of the post-processing apparatus 100. As shown in FIG. In FIG. 1, dashed arrows indicate the flow of electrical signals.

  The post-processing device 100 shown in FIG. 1 is a device that is mounted on a vehicle and purifies harmful components contained in the exhaust gas of the diesel engine 1 (an example of an internal combustion engine). The harmful components are, for example, carbon monoxide (CO), hydrocarbons (HCs), soot and the like.

  In FIG. 1, the exhaust gas discharged from each of the cylinders 2 a to 2 d of the diesel engine 1 flows from the left side to the right side in the drawing.

  The fuel injection valves 10a to 10d are provided corresponding to the cylinders 2a to 2d, respectively, and inject fuel into the combustion chambers (not shown) of the cylinders 2a to 2d. In FIG. 1, illustration of a supply pump (high pressure pump) for supplying fuel to the fuel injection valves 10 a to 10 d, a common rail, and the like is omitted.

  The fuel injection valves 10 a to 10 d are controlled by a fuel injection control device 200. Details of this control will be described later.

  The exhaust manifold (Exhaust Manifold) 3 includes exhaust ports 3a to 3d connected to the cylinders 2a to 2d, respectively.

In each of the exhaust port 3a and the exhaust port 3d, a DOC (Diesel Oxidation Catalyst) 4 that oxidizes nitrogen monoxide (NO) in the exhaust gas to generate nitrogen dioxide (NO ₂ ) is disposed. On the other hand, the DOC 4 is not disposed in the exhaust port 3 b and the exhaust port 3 c. The DOC 4 corresponds to an example of the “first oxidation catalyst”.

  The DOC 4 is in contact with the exhaust gas as high as possible at the exhaust port 3a or the exhaust port 3d, and is disposed at a position where the time above the activation temperature of the DOC 4 is long. Therefore, DOC4 is in a high temperature environment while driving the diesel engine 1, and inactivation of DOC4 hardly occurs.

The DOC 4 includes, for example, a metal catalyst which is excellent in purification of carbon monoxide (CO), an oxide having an oxygen storage capacity (OSC: Oxygen Storage Capacity), and an oxide semiconductor. The oxide having the oxygen storage capacity may be, for example, an oxide containing Ce (cerium). In addition, a noble metal may be supported on an oxide having an oxygen storage capacity. The oxide semiconductor may be, for example, TiO ₂ (titanium dioxide), ZnO (zinc oxide), Y ₂ O ₃ (yttrium oxide), or the like.

  An exhaust pipe 5 is connected to the downstream side of the exhaust manifold 3.

  The exhaust pipe 5 is provided with an exhaust turbine 6 a of the turbocharger 6. The exhaust turbine 6 a is driven by the exhaust gas flowing through the exhaust pipe 5. The compressor 6b provided in the intake pipe (not shown) is coaxially driven by the drive of the exhaust turbine 6a to compress the intake air.

  In the exhaust pipe 5, a DOC (Diesel Oxidation Catalyst) 7 and a DPF (Diesel Particulate Filter) 8 are provided downstream of the exhaust turbine 6 a.

  DOC 7 oxidizes nitrogen monoxide (NO) and hydrocarbons (HCs) in the exhaust gas to produce nitrogen dioxide (NO 2) and water. The DOC 7 corresponds to an example of the “second oxidation catalyst”.

  The DPF 8 collects and removes PM (particulate matter) in the exhaust gas. The DPF 8 corresponds to an example of the “particulate collection filter”.

  The exhaust gas having passed through the DOC 7 and the DPF 8 is discharged to the outside of the vehicle from a discharge port (not shown).

  In the exhaust pipe 5, an upstream temperature detection unit 11 is provided on the upstream side of the DOC 7.

  The upstream temperature detection unit 11 appropriately detects the temperature of the exhaust gas downstream of the exhaust manifold 3 (exhaust ports 3a to 3d) and the upstream side of the DOC 7 (hereinafter referred to as the upstream temperature), and the detected upstream temperature Is output to the fuel injection control device 200 (hereinafter, referred to as upstream temperature information). The upstream temperature detection unit 11 is, for example, a thermistor, a sensor, or a thermocouple.

  The configuration of the post-processing apparatus 100 has been described above.

  Next, the configuration of the fuel injection control device 200 according to the present embodiment will be described using FIG. FIG. 2 is a block diagram showing an example of the configuration of the fuel injection control device 200. As shown in FIG.

  The fuel injection control device 200 shown in FIG. 2 is mounted on the same vehicle as the aftertreatment device 100. The fuel injection control device 200 includes, for example, a central processing unit (CPU), a storage medium such as a read only memory (ROM) storing a control program, a working memory such as a random access memory (RAM), and a communication circuit Not shown). The functions of the units shown in FIG. 2 are realized by the CPU executing a control program.

  As shown in FIG. 2, the fuel injection control device 200 has an information input unit 201 and an injection control unit 202.

  The information input unit 201 appropriately receives upstream temperature information from the upstream temperature detection unit 11.

  The injection control unit 202 causes the fuel injection valves 10a to 10d to execute injection of fuel. The details will be described below. In the present embodiment, although the case where fuel injection is post injection will be described as an example, the present invention is not limited to this. In addition, the purpose of the fuel injection is not limited to the regeneration of the DPF 8.

  In the present embodiment, as an example, post injection (hereinafter referred to as main injection) for the cylinders 2b and 2c and post injection (hereinafter referred to as sub injection) for the cylinders 2a and 2d will be described separately.

  The present embodiment is characterized in that sub-injection is performed in addition to main injection conventionally generally performed. When sub injection is performed, a combustion reaction occurs in DOC 4 shown in FIG. Therefore, the upstream temperature can be raised compared to the case where only the main injection is performed.

  The target amount of post injection is predetermined according to, for example, the engine speed. This target amount is the total amount of the amount injected in the main injection (hereinafter referred to as the main injection amount) and the amount injected in the sub injection (hereinafter referred to as the sub injection amount).

  The injection control unit 202 controls the main injection amount and the sub injection amount so that the upstream temperature indicated by the upstream temperature information does not fall below a predetermined first set temperature (for example, 200 degrees).

  The first set temperature is a value obtained by an experiment, a simulation, or the like performed in advance, and is a value assumed that inactivation of the DOC 7 does not occur.

  Here, an example of calculation processing of the main injection amount and the sub injection amount will be described.

  For this processing, a map obtained as a result of an experiment or simulation performed in advance is used. This map is data in which the ratio between the main injection amount and the sub injection amount (hereinafter referred to as the injection amount ratio) is determined according to each temperature equal to or higher than the first set temperature. For example, the injection amount ratio is set such that the ratio of the sub injection amount increases as the temperature increases.

  If the sub injection amount is made larger than the main injection amount at the injection amount ratio, the heat loss from the exhaust manifold 3 to the DOC 7 increases, and the DPF 8 may be difficult to heat. Therefore, it is preferable that the injection amount ratio in the map is determined such that the main injection amount is larger than the sub injection amount.

  First, the injection control unit 202 specifies, from the map, an injection amount ratio associated with a predetermined temperature that is equal to or higher than the upstream temperature indicated by the upstream temperature information. Then, the injection control unit 202 calculates the main injection amount and the sub injection amount based on the above-described target amount and the specified injection amount ratio.

  In the above, an example of calculation processing of the main injection amount and the sub injection amount has been described.

  The injection control unit 202 controls the fuel injection valves 10a to 10d to execute the main injection and the sub injection based on the calculated main injection amount and the sub injection amount.

  Specifically, the injection control unit 202 controls the fuel injection valves 10b and 10c so that the fuel of the calculated main injection amount is injected from the fuel injection valves 10b and 10c. Further, the injection control unit 202 controls the fuel injection valves 10a and 10d so that the fuel of the calculated sub injection amount is injected from the fuel injection valves 10a and 10d.

  The main injection and the sub injection may be performed at the same timing or may be performed at different timings.

  The configuration of the fuel injection control device 200 has been described above.

  Next, the operation of the fuel injection control device 200 according to the present embodiment will be described using FIG. FIG. 3 is a flowchart showing an example of the operation of the fuel injection control device 200.

  First, the information input unit 201 receives upstream temperature information from the upstream temperature detection unit 11 (step S101).

  Next, the injection control unit 202 determines the injection amount ratio based on the upstream temperature information and the map (step S102).

  Next, the injection control unit 202 calculates the main injection amount and the sub injection amount based on the target amount and the injection amount ratio (step S103).

  Next, the injection control unit 202 causes the fuel injection valves 10a to 10d to execute the main injection and the sub injection based on the main injection amount and the sub injection amount (step S104).

  The operation of the fuel injection control device 200 has been described above.

  As described above in detail, according to the fuel injection control device 200 of the present embodiment, the main injection for injecting the fuel to the cylinders 2b and 2c corresponding to the exhaust ports 3b and 3c in which the DOC 4 is not disposed In addition, sub injection for injecting fuel is executed to the cylinders 2a and 2d corresponding to the exhaust ports 3a and 3d in which the DOC 4 is disposed, and at that time, the upstream temperature is not less than the first set temperature. A main injection amount and a sub injection amount are controlled. Thereby, since the upstream temperature can be raised using the combustion reaction of DOC4, inactivation of DOC7 can be prevented. As a result, for example, the effect of DPF regeneration can be sufficiently obtained.

  The present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present invention. Each modification will be described below.

[Modification 1]
Notwithstanding the operation of the fuel injection control device 200 described in the embodiment, there is a possibility that inactivation of the DOC 7 may occur or inactivation may actually occur. An example of the configuration and operation for coping with such a case will be described below with reference to FIGS. 4 and 5. In FIGS. 4 and 5, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof is omitted here.

  As shown in FIG. 4, in the present modification, in the exhaust pipe 5, a downstream temperature detection unit 12 is provided downstream of the DOC 7 and upstream of the DPF 8.

  The downstream temperature detection unit 12 appropriately detects the temperature of the exhaust gas downstream of the DOC 7 and the upstream of the DPF 8 (hereinafter referred to as the downstream temperature), and a signal (downstream temperature information) indicating the detected downstream temperature. ) Is output to the fuel injection control device 200. The downstream temperature detection unit 12 is, for example, a thermistor, a sensor, or a thermocouple.

  As shown in FIG. 5, in the present modification, the fuel injection control device 200 includes a deactivation determination unit 203 in addition to the information input unit 201 and the injection control unit 202.

  The information input unit 201 receives downstream temperature information from the downstream temperature detection unit 12 in addition to the upstream temperature information described above.

  When the DOC 7 is in the active state, the downstream side temperature becomes higher than the upstream side temperature by the combustion reaction in the DOC 7. For example, when the upstream temperature is about 300 degrees, the downstream temperature is about 500 to 600 degrees. On the other hand, if the DOC 7 has a risk of inactivation or if the inactivation occurs, the downstream temperature hardly rises, so the difference between the downstream temperature and the upstream temperature is determined by the fact that the DOC 7 is in the active state. It becomes smaller than the difference when. In this modification, using this, the inactivation determination unit 203 determines whether or not the DOC 7 has a possibility of inactivation, and determines whether or not inactivation has occurred. Hereinafter, the determination process of the inactivation determination unit 203 will be specifically described.

  First, the inactivation determination unit 203 indicates the difference between the downstream temperature and the upstream temperature (hereinafter referred to as an assumed difference) predetermined according to the main injection amount and the sub injection amount, and the downstream temperature information. A difference between the downstream temperature and the upstream temperature indicated in the upstream temperature information (hereinafter referred to as a detection difference) is calculated.

  Next, the inactivation determination unit 203 determines whether the calculated difference is less than a predetermined first threshold.

  If the calculated difference is less than the first threshold, the inactivation determination unit 203 determines that the DOC 7 has no possibility of inactivation. In this case, the injection control unit 202 subsequently controls the main injection amount and the sub injection amount so that the upstream temperature does not become lower than the first set temperature.

  If the calculated difference is equal to or greater than the first threshold, the inactivation determination unit 203 determines whether the calculated difference is less than the second threshold (a value larger than the first threshold).

  If the calculated difference is less than the second threshold, the inactivation determination unit 203 determines that the DOC 7 is likely to be inactivated.

  In this case, the injection control unit 202 temporarily (during a preset period) changes it to a second set temperature (for example, 300 degrees) larger than the first set temperature, and is indicated by the upstream temperature information. The main injection amount and the sub injection amount are controlled so that the upstream temperature does not become lower than the second set temperature. The calculation process of the main injection amount and the sub injection amount at this time is the same as that of the above embodiment. Thus, the sub injection amount is controlled to be larger.

  Such control can prevent the occurrence of inactivation when there is a risk of inactivation in DOC7.

  On the other hand, when the calculated difference is equal to or greater than the second threshold, the inactivation determination unit 203 determines that inactivation of the DOC 7 is occurring.

  In this case, when performing the sub-injection, the injection control unit 202 performs a rich spike that reduces the amount of intake air to the combustion chamber of the cylinders 2a and 2b and temporarily reduces λ to 1 or less. Note that rich spikes are not performed when main injection is performed.

When rich spike is performed, reactions (steam reforming reaction and water gas shift reaction) of generating carbon monoxide (CO) and hydrogen (H ₂ ) occur while consuming oxygen by combustion reaction in DOC 4. Since carbon monoxide (CO) and hydrogen (H ₂ ) are gases having high reactivity with oxygen (O ₂ ), they react with oxygen (O ₂ ) contained in the exhaust gas from exhaust ports 2 b and 2 c in DOC 7 Burn immediately. By this reaction, the inactivation of DOC 7 can be eliminated in a short time.

  In this modification, as shown in FIG. 4, the downstream temperature detection unit 12 is provided downstream of the DOC 7 and upstream of the DPF 8 by way of example. However, the downstream temperature detection unit 12 It may be provided on the downstream side of the DPF 8. However, the position shown in FIG. 4 is preferable because the response is excellent.

[Modification 2]
In the embodiment, the case where the DOC 4 is disposed at the exhaust port 3a and the exhaust port 3d has been described as an example, but the present invention is not limited to this. For example, DOC 4 may be disposed at exhaust port 3a and exhaust port 3b, may be disposed at exhaust port 3a and exhaust port 3c, or may be disposed at exhaust port 3b and exhaust port 3c. It may be disposed in the exhaust port 3b and the exhaust port 3d.

[Modification 3]
Although the embodiment has been described by taking the case where two exhaust ports are provided in which DOC 4 is disposed, the present invention is not limited to this. For example, the DOC 4 may be disposed only in the exhaust port 3a, or the DOC 4 may be disposed in each of the exhaust ports 3a to 3c. That is, the DOC 4 may not be disposed in at least one of the exhaust ports 3a to 3d. In other words, when the exhaust manifold includes N (N is an integer of 2 or more) exhaust ports, the number of exhaust ports in which the DOC 4 is disposed may be (N-1) or less.

[Modification 4]
In the embodiment, although the case where the diesel engine 1 has four cylinders and the exhaust manifold 3 has the exhaust ports 3a to 3d corresponding to the cylinders 2a to 2d has been described as an example, the invention is not limited thereto. For example, when the diesel engine 1 has six cylinders and the exhaust manifold 3 has six exhaust ports corresponding to six cylinders, DOC 4 is arranged at some of the six exhaust ports. May be In other words, the DOC 4 may not be disposed in at least one of the six exhaust ports. In this case, the maximum number of DOCs 4 is five.

  Moreover, although the case where an internal combustion engine is a diesel engine was mentioned as the example and demonstrated in this Embodiment, it is not limited to this, For example, a gasoline engine may be sufficient.

  In the second to fourth modifications, as in the embodiment, the main injection is performed on the cylinder corresponding to the exhaust port where the DOC 4 is not disposed, and the sub injection is the exhaust port where the DOC 4 is disposed. Is performed for the cylinder corresponding to.

<Summary of this disclosure>
The fuel injection control apparatus according to the present invention is a fuel injection control apparatus that controls the injection of fuel to a plurality of cylinders of an internal combustion engine of a vehicle, and a part of exhaust ports among a plurality of exhaust ports corresponding to each of the cylinders. The first oxidation catalyst is disposed in the exhaust pipe connected to the downstream side of the plurality of exhaust ports, the second oxidation catalyst is disposed on the upstream side, and the particulate collection filter is disposed on the downstream side. Information input unit for inputting information on the upstream temperature detected downstream of the plurality of exhaust ports and upstream of the second oxidation catalyst, and corresponding to the exhaust port where the first oxidation catalyst is not disposed And an injection control unit for executing a sub-injection for injecting fuel to the cylinder corresponding to the exhaust port where the first oxidation catalyst is disposed, in addition to the main injection for injecting the fuel to the cylinder, The injection control unit is upstream The main injection amount, which is the amount of fuel injected by the main injection, so that the degree does not fall below a first set temperature set as a temperature at which it is assumed that deactivation of the second oxidation catalyst does not occur. And sub injection amount which is the amount of fuel injected by sub injection is controlled.

  Note that, in the fuel injection control device, the injection control unit determines a predetermined temperature that is equal to or higher than the upstream temperature from data in which the ratio of the main injection amount and the sub injection amount is determined according to the temperature equal to or higher than the first set temperature. May be specified, and the main injection amount and the sub injection amount may be calculated based on the total amount of the main injection amount and the sub injection amount determined in advance and the specified ratio. .

  Further, in the fuel injection control device, whether or not there is a risk of inactivation of the second oxidation catalyst based on the difference between the downstream temperature detected on the downstream side of the second oxidation catalyst and the upstream temperature. And the injection control unit temporarily determines that the upstream temperature is higher than the first set temperature, when it is determined that the second oxidation catalyst is likely to be inactivated. The main injection amount and the sub injection amount may be controlled so that the temperature does not fall below the large second set temperature.

  Further, in the fuel injection control device, the inactivation determination unit further determines whether or not inactivation of the second oxidation catalyst is occurring, based on the difference between the downstream temperature and the upstream temperature. When it is determined that the second oxidation catalyst is inactivated, the injection control unit may perform rich spike when executing the sub injection.

  Further, in the fuel injection control device, when it is determined that the injection control unit does not have a risk of inactivation of the second oxidation catalyst, the main injection amount and the sub injection are continuously controlled so as not to fall below the first set temperature. The amount may be controlled.

  The present invention is applicable to the technology of controlling the injection of fuel in an internal combustion engine.

1 diesel engine 2a to 2d cylinder 3 exhaust manifold 3a to 3d exhaust port 4, 7 DOC
5 exhaust pipe 6 turbocharger 6a exhaust turbine 6b compressor 8 DPF
10a to 10d Fuel injection valve 11 upstream temperature detection unit 12 downstream temperature detection unit 100 post-processing device 200 fuel injection control device 201 information input unit 202 injection control unit 203 deactivation determination unit

Claims (5)

A fuel injection control device for controlling the injection of fuel to a plurality of cylinders of an internal combustion engine of a vehicle, comprising:
Among the plurality of exhaust ports corresponding to each of the cylinders, a first oxidation catalyst is disposed at a part of the exhaust ports,
In the exhaust pipe connected to the downstream side of the plurality of exhaust ports, the second oxidation catalyst is disposed on the upstream side, and the particulate collection filter is disposed on the downstream side,
An information input unit that inputs information on the upstream temperature detected on the downstream side of the plurality of exhaust ports and on the upstream side of the second oxidation catalyst;
In addition to main injection for injecting fuel to the cylinder corresponding to the exhaust port where the first oxidation catalyst is not disposed, the cylinder corresponding to the exhaust port where the first oxidation catalyst is disposed And an injection control unit for executing a sub-injection for injecting fuel.
The injection control unit
The amount of fuel injected in the main injection is set so that the upstream temperature does not fall below a first set temperature defined as a temperature where it is assumed that inactivation of the second oxidation catalyst does not occur. Controlling a main injection amount and a sub injection amount which is an amount of fuel injected by the sub injection;
Fuel injection control device. The injection control unit
From the data in which the ratio of the main injection amount and the sub injection amount is determined according to each temperature equal to or higher than the first set temperature, the ratio associated with the predetermined temperature equal to or higher than the upstream temperature Identify
The main injection amount and the sub injection amount are calculated based on the total amount of the main injection amount and the sub injection amount determined in advance and the specified ratio.
The fuel injection control device according to claim 1. Inactivation to determine whether or not there is a risk of inactivation of the second oxidation catalyst based on the difference between the downstream temperature detected downstream of the second oxidation catalyst and the upstream temperature It further has a judgment unit,
The injection control unit
When it is determined that there is a possibility of inactivation of the second oxidation catalyst, the main injection temporarily prevents the upstream temperature from becoming lower than a second set temperature that is higher than the first set temperature. Control the amount and the sub injection amount,
The fuel injection control device according to claim 1. The inactivation determination unit
Further, based on the difference between the downstream temperature and the upstream temperature, it is determined whether or not inactivation of the second oxidation catalyst has occurred.
The injection control unit
If it is determined that inactivation of the second oxidation catalyst is occurring, a rich spike is performed when executing the sub injection.
The fuel injection control device according to claim 3. The injection control unit
If it is determined that there is no possibility of inactivation of the second oxidation catalyst, the main injection amount and the sub injection amount are controlled so as not to fall below the first set temperature.
The fuel injection control device according to claim 3 or 4.

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