JP2006002728A - Control device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To start process at an early stage in response to process request of NO<SB>X</SB>regeneration or S poisoning recovery of a catalyst device or a particulate filter by combustion at theoretical air fuel ratio or rich air fuel ratio and to start acceleration at an early stage in response to acceleration request during treatment of NO<SB>X</SB>regeneration or S poisoning recovery or right after that in a control device for a diesel engine capable of performing combustion at theoretical air fuel ratio or rich air fuel ratio with a large quantity of exhaust gas recirculation. <P>SOLUTION: At a time of process of NO<SB>x</SB>regeneration and S poisoning recovery of the catalyst device or the particulate filter 12a arranged in an engine exhaust system and carrying NO<SB>x</SB>occlusion agent, combustion at theoretical air fuel ratio or rich air fuel ratio is performed in part of cylinders 1a, and an intake valve and an exhaust valve are kept closed to suspend combustion in remaining cylinders 1b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for a diesel engine.

The exhaust gas from diesel engines contains harmful NO _X, proposed to purify the NO _X, be placed _the NO _X storage reduction catalyst device carrying the _the NO _X storage agent in the engine exhaust system Has been. Also, by supporting the _the NO _X storage agent into the particulate filter, it has been proposed to collecting particulates with purification of NO _X. The NO _X storage agent stores NO _X in the form of nitrate when the oxygen concentration in the vicinity atmosphere is high, and releases the stored NO _X when the oxygen concentration in the vicinity atmosphere decreases.

Thereby, the NO _X storage agent stores NO _X well from the exhaust gas of a diesel engine that is combusted under excess air. However, since the NO _x storable amount stored in the form of nitrate in the NO _x occluding and reducing catalyst device is finite, before the NO _x storable amount is reached, the nearby air fuel ratio is set to the stoichiometric or rich air fuel ratio. In addition, it is necessary to perform NO _X regeneration treatment for releasing NO _X from the NO _X storage reduction catalyst device and reducing and purifying NO _X released by the reducing components in the atmosphere.

Further, sulfur S in the fuel is contained in the exhaust gas as SO _{X and} is stored in the NO _X storage reduction catalyst device in the form of sulfate to reduce the NO _X storage capacity. As a result, it is necessary to perform an S poison recovery process for reducing and purifying SO _X by releasing SO _X from the NO _X storage reduction catalyst device. Since sulfate is a more stable substance than nitrate, the sulfur poisoning recovery process brings the surrounding atmosphere to the stoichiometric or rich air-fuel ratio after raising the temperature of the NO _x storage reduction catalyst device.

By the way, when a large amount of exhaust gas is recirculated into a cylinder in a diesel engine, combustion at a stoichiometric air-fuel ratio or a rich air-fuel ratio becomes possible. Therefore, an exhaust gas recirculation passage is connected to a turbocharger compressor in an engine intake system. It has been proposed that a large amount of exhaust gas can be recirculated by connecting to the upstream side (see, for example, Patent Document 1). Thus, the combustion at the stoichiometric air-fuel ratio or rich air-fuel ratio is performed during the NO _X regeneration process or the S poison recovery process of the NO _X storage reduction catalyst device.

JP 2000-008835 A JP 08-061052 JP 09-112254 A JP 09-112257 A

However, the combustion at the stoichiometric air-fuel ratio or rich air-fuel ratio described above requires a large amount of exhaust gas to be recirculated and cannot be realized immediately due to a response delay in exhaust gas recirculation. The NO _X regeneration process and the S poison recovery process of the _X storage reduction catalyst device cannot be started immediately.

Further, during and immediately after the processing of NO _x regeneration and S poison recovery, even if there is an acceleration request, a large amount of exhaust gas is recirculated in combustion at the stoichiometric or rich air-fuel ratio. There is a large amount of exhaust gas in the relatively long part downstream of the turbocharger / compressor in the engine intake system. If this exhaust gas is not supplied into the cylinder, the amount of fresh air in the cylinder is reduced. It cannot be increased sufficiently. Thus, if the fresh air amount does not increase, the injected fuel cannot be increased, and the engine output cannot be increased immediately when acceleration is requested, and acceleration cannot be started.

Accordingly, an object of the present invention is a control apparatus for a diesel engine that enables combustion at a stoichiometric air-fuel ratio or a rich air-fuel ratio by a large amount of exhaust gas recirculation, and a catalyst by combustion at the stoichiometric air-fuel ratio or rich air-fuel ratio. the processing for the apparatus or processing requirements of the particulate filter of the NO _X regeneration or S-poisoning recovery while enabling early start for processing of the NO _X regeneration or S-poisoning recovery and the immediately following acceleration request It is possible to start acceleration early.

According to a first aspect of the present invention, there is provided a control device for a diesel engine, wherein a large amount of exhaust gas is recirculated into a cylinder to enable combustion at a stoichiometric air-fuel ratio or a rich air-fuel ratio. upon NO _X regeneration or S processing poisoning recovery of the catalytic converter or particulate filter to be disposed in an exhaust system carrying _the NO _X storage agent, carrying out the combustion at the stoichiometric air-fuel ratio or a rich air-fuel ratio in some cylinders In the remaining cylinders, combustion is stopped while the intake valve and the exhaust valve are closed.

According to a second aspect of the present invention, there is provided a diesel engine control apparatus according to the second aspect of the present invention, wherein a large amount of exhaust gas is recirculated into a cylinder to allow combustion at a stoichiometric air-fuel ratio or a rich air-fuel ratio. In the diesel engine, the engine exhaust system of one cylinder group and the engine exhaust system of the other cylinder group are independent from each other, and the catalyst device is disposed in the engine exhaust system of one cylinder group and carries the NO _x storage agent or upon the processing of the NO _X regeneration or S-poisoning recovery of the particulate filter, carried out the combustion at the stoichiometric air-fuel ratio or a rich air-fuel ratio in one cylinder group, that halting the combustion in the other cylinder group Features.

According to the control apparatus for a diesel engine according to the first aspect of the present invention, the remaining part other than some cylinders is subjected to the NO _x regeneration or the S poison recovery process of the catalyst device or particulate filter carrying the NO _x storage agent. Combustion is stopped in the cylinder. Accordingly, the fuel injection amount is inevitably increased in some cylinders in order to maintain the engine output. The amount of fresh air in some cylinders required to perform combustion at the desired stoichiometric or rich air-fuel ratio with respect to the fuel injection amount thus increased is the desired stoichiometric or rich air-fuel ratio for all cylinders. Therefore, the amount of recirculated exhaust gas to be increased from the time of combustion with a lean air-fuel ratio is not so large in some cylinders.

In this way, even with a response delay in exhaust gas recirculation, combustion at a desired theoretical air-fuel ratio or rich air-fuel ratio can be realized early in some cylinders, and NO _x regeneration or S of the catalyst device or particulate filter can be achieved. The poisoning recovery process can be started early. At this time, since the intake valve and the exhaust valve are closed in the remaining cylinders that are stopped, the exhaust gas of the remaining cylinders does not make the exhaust gas of the stoichiometric or rich air-fuel ratio of some cylinders lean. Absent.

Further, for the processing of the NO _X regeneration or S-poisoning recovery and the immediately following acceleration request can initiate accelerated early enhances the engine output by initiating combustion in the remaining cylinders. Further, during the processing of the NO _X regeneration or S-poisoning recovery, to the to some cylinders not very recirculating a large amount of exhaust gas, rather than the presence of a large amount of recirculated exhaust gas to the engine intake system When acceleration is requested, a sufficient amount of fresh air can be supplied to the remaining cylinders. As a result, in response to the acceleration request, the remaining cylinders operate the intake and exhaust valves and start fuel injection, and in some cylinders, the fuel injection amount is reduced, so that the fuel injection amounts of all the cylinders become substantially equal. Even if combustion at a lean air-fuel ratio is started in all cylinders, the engine output can be sufficiently increased and acceleration can be started early.

According to the control device for a diesel engine according to claim 2 of the present invention, the engine exhaust system of one cylinder group and the engine exhaust system of the other cylinder group are independent from each other. upon catalytic converter or NO _X regeneration or S processing poisoning recovery of the particulate filter is arranged in the engine exhaust system carrying _the NO _X storage agent, the combustion at the stoichiometric air-fuel ratio or a rich air-fuel ratio in one cylinder group The combustion is stopped in the other cylinder group. Thereby, similarly to the control device for the diesel engine according to claim 1, the NO _X regeneration or S poison recovery process can be started early, and the NO _X regeneration or S poison recovery process is in progress. And immediately after that, even if there is an acceleration request, the acceleration can be started at an early stage. Further, in the diesel engine, the engine exhaust system of one cylinder group and the engine exhaust system of the other cylinder group are independent from each other. Therefore, during the NO _x regeneration or the S poison recovery process, the other cylinder group Even when air and recirculated exhaust gas are exhausted as they are from the other cylinder group during cylinder deactivation at the same time, they are supplied to the catalyst device or particulate filter of one cylinder group, and the stoichiometric air-fuel ratio or rich gas from one cylinder group The air-fuel ratio exhaust gas is not diluted.

  FIG. 1 is a schematic diagram showing a diesel engine equipped with a control device according to the present invention. In the figure, reference numeral 1 denotes, for example, a V-type 8-cylinder diesel engine body, and four cylinders are arranged in each of the first bank 1a and the second bank 1b. An intake valve (not shown) and an exhaust valve (not shown) of each cylinder are opened and closed by, for example, an electromagnetic or hydraulic actuator, or opened and closed by an electric camshaft or the like, and the intake valve and the exhaust valve are closed. Cylinder deactivation is possible. 2 is an air cleaner common to both banks, and the downstream side of the air cleaner 2 is branched into a first intake passage 3a and a second intake passage 3b. The first intake passage 3a is a first compressor 4a of the first turbocharger, It is connected to the first bank 1a via the intercooler 5 common to both banks and the first intake manifold 6a, while the second intake passage 3b is connected to the second compressor 4b of the second turbocharger, It is connected to the second bank 1b via the cooler 5 and the second intake manifold 6b.

  In the first intake passage 3a, a first throttle valve 7a is disposed between the intercooler 5 and the first intake manifold 6a, while in the second intake passage 3b, between the intercooler 5 and the second intake manifold 6b. Is provided with a second throttle valve 7b. Since each cylinder is an intake two-valve type having a straight port and a helical port, the first intake manifold 6a and the second intake manifold 6b are bifurcated with respect to one cylinder, respectively. If a swirl control valve (not shown) is arranged so that the straight port side is closed, swirl can be generated in the cylinder by intake air supplied through the helical port.

A first exhaust passage 9a is connected to the first bank 1a via a first exhaust manifold 8a. The first exhaust passage 9a includes a first turbine 10a of a first turbocharger, a first particulate filter 11a, and leads to the atmosphere via the first _the NO _X storage reduction catalyst device 12a. A second exhaust passage 9b is connected to the second bank 1b via a second exhaust manifold 8b. The second exhaust passage 9b includes a second turbine 10b of a second turbocharger, a second particulate filter 11b, and leads to the atmosphere via the second _the NO _X storage reduction catalyst device 12b.

13a is a first exhaust gas recirculation passage, in communication with the downstream side of the first _the NO _X storage reduction catalyst device 12a of the first exhaust passage 9a, the upstream side of the first compressor 4a of the first intake passage 3a Yes. Moreover, 13b is a second exhaust gas recirculation passage, communicating with the downstream side of the second _the NO _X storage reduction catalyst device 12b of the second exhaust passage 9b, the upstream side of the second compressor 4b of the second intake passage 3b is doing. A first exhaust cooling device (EGR cooler) 14a is disposed on the first exhaust passage 9a side of the first exhaust gas recirculation passage 13a, and a first exhaust passage for controlling the amount of recirculated exhaust gas on the first intake passage 3a side. One control valve (EGR valve) 15a is arranged. A second exhaust cooling device (EGR cooler) 14b is disposed on the second exhaust passage 9b side of the second exhaust gas recirculation passage 13b, and the recirculation exhaust gas amount is controlled on the second intake passage 3b side. The second control valve (EGR valve) 15b is arranged.

Thus, the first exhaust gas recirculation passage 13a is the purified exhaust gas by the first particulate filter 11a and the first _the NO _X storage reduction catalyst device 12a, is recycled to the upstream side of the first compressor 4a, the second exhaust gas recirculation passage 13b is the purified exhaust gas through the second particulate filter 11b and the second _the NO _X storage reduction catalyst device 12b, are adapted to recirculate to the upstream side of the second compressor 4b, further Since the exhaust gas is cooled by the exhaust cooling devices 14a and 14b, a very large amount of exhaust gas can be recirculated. Thereby, the low temperature combustion disclosed in Japanese Patent No. 3116876 can be performed in the cylinders of the banks 1a and 1b. Of course, the first and second compressors 4a and 4b may be superchargers such as a supercharger.

  Reference numeral 16a denotes a first pressure accumulation chamber that supplies pressurized fuel to a fuel injection valve (not shown) disposed in each cylinder of the first bank 1a. Reference numeral 16b denotes a second pressure accumulation chamber that supplies pressurized fuel to a fuel injection valve (not shown) disposed in each cylinder of the second bank 1b. The first pressure accumulation chamber 16a and the second pressure accumulation chamber 16b may be communicated with each other so that fuel of equal pressure is accumulated in each.

  When the ratio of the recirculated exhaust gas amount to the EGR rate, that is, the in-cylinder gas amount (fresh air amount + recirculated exhaust gas amount) is increased, the amount of smoke generated increases and reaches a peak. Next, when the EGR rate is further increased, the amount of smoke generated decreases, and finally no soot is generated. Thus, low temperature combustion is a combustion method in which a larger amount of exhaust gas is recirculated than the amount of recirculated exhaust gas that maximizes the generation of soot so as to hardly generate soot. The higher the fuel injection amount and the higher the load, the greater the amount of recirculated exhaust gas required to realize low temperature combustion, whereby the first and second exhaust gas recirculation passages 13a and 13b described above are used in the cylinders of each bank. If a very large amount of exhaust gas recirculation is possible, low temperature combustion can be carried out until the engine load is relatively high.

Becomes less NO _X generation amount at the time of low temperature combustion, can not be carried out low-temperature combustion at all engine operating conditions, it is still recirculated exhaust gas recirculation amount from less exhaust gas to maximize the generation of soot general Normal combustion (diffusion combustion) at a lean combustion air-fuel ratio is also performed, and at this time, a relatively large amount of NO _x is generated. Thereby, NO _x purification is required.

The first and second _the NO _X storage reduction catalyst device 12a in the first and second exhaust gas passage 9a, 9b, 12b occludes the air-fuel ratio is the NO _X when the lean atmosphere, the air-fuel ratio is stoichiometric or rich When will the _the NO _X storage agent releases the occluded NO _X supported, in regardless of the low-temperature combustion and ordinary combustion (diffusion combustion), to better absorb NO _X from the exhaust gas of a lean air-fuel ratio.

Meanwhile, there is a limit to _the NO _X storage ability of the NO _X absorbent, _the NO _X storage ability of the NO _X occluding agent is necessary to release the NO _X from _the NO _X storage agent prior to saturation. That is, the first and second _the NO _X storage reduction catalyst device 12a, before the amount of NO _X occluded in the 12b reaches the NO _X storable amount, it is necessary for reproduction to be reduced and purified to release the NO _X, therefore Therefore, it is necessary to estimate this amount of NO _x . For example, the NO _x storage amount per unit time when low-temperature combustion and normal combustion (diffusion combustion) are performed is previously mapped as a function of the required load and the engine speed, and the NO per unit time for each combustion. By accumulating the _X storage amount, the NO _X amount stored in each of the first and second NO _X storage reduction catalyst devices 12a and 12b can be estimated.

In the present embodiment, the first and second NO _X storage reduction catalyst devices 12a and 12b are regenerated when the NO _X storage amount exceeds a predetermined allowable value. Since the low-temperature combustion described above can be performed at a stoichiometric air-fuel ratio or a rich air-fuel ratio, this NO _x regeneration process includes low-temperature combustion in which the air-fuel ratio of the exhaust gas is set to a desired stoichiometric air-fuel ratio or rich air-fuel ratio. Is implemented.

  However, if low temperature combustion at a desired stoichiometric or rich air / fuel ratio is performed in all cylinders, the fuel injection amount of each cylinder can be increased only slightly in order to suppress an increase in engine output. Since the amount of recirculated exhaust gas has to be considerably increased as compared with conventional lean air-fuel ratio combustion, low temperature combustion cannot be started immediately due to a response delay in exhaust gas recirculation.

  In contrast, in the present embodiment, low-temperature combustion at a desired stoichiometric or rich air-fuel ratio is performed in the cylinder of one bank 1a or 1b, and an intake valve and a cylinder in the other bank 1a or 1b are performed. The fuel injection is stopped with the exhaust valve closed to stop the combustion.

In the time chart of FIG. 2, in order to initiate the NO _X regeneration process at time T1, both the throttle valves 7a, 7b both of the control valve 15a while decreasing the opening degree, 15b to increase the opening degree. As a result, the intake air amount decreases and the recirculated exhaust gas amount (EGR amount) increases. When performing low temperature combustion at a desired theoretical air-fuel ratio or rich air-fuel ratio in all cylinders, as shown by the dotted lines for realizing the desired air-fuel ratio for the slightly increased amount of injected fuel, It is necessary to considerably reduce the intake air amount and increase the EGR amount considerably, and low-temperature combustion at a desired theoretical air-fuel ratio or rich air-fuel ratio is started only at time T3.

On the other hand, in the present embodiment, the cylinders in the other bank are deactivated, and in order to maintain the engine output, the cylinders in one bank require a considerable increase in injected fuel. As a result, in order to achieve this desired air-fuel ratio, the intake air amount is decreased by a small amount and the EGR amount is increased by a small amount, as indicated by the solid line, in order to achieve this desired air-fuel ratio in the cylinder fuel of one bank. You can do it. Thereby, desired low-temperature combustion can be started at time T2 before time T3. In this way, the NO _x regeneration process can be started at an early stage.

When performing low temperature combustion at a desired theoretical air-fuel ratio or rich air-fuel ratio in all cylinders, the compressors 4a, 3a, 3b in the first and second intake passages 3a, 3b during and immediately after the NO _x generation process. A large amount of recirculated exhaust gas exists in a relatively long portion downstream of 4b. As a result, even if there is an acceleration request during and immediately after the NO _x regeneration process, the amount of fresh air in each cylinder can be increased sufficiently unless this large amount of exhaust gas is supplied into the cylinder. In this way, it is not possible to increase the engine output by increasing the amount of injected fuel directly from the acceleration request.

In contrast, in the present embodiment, in order to implement a low-temperature combustion at the desired stoichiometric or rich air-fuel ratio only in the cylinders of one bank in NO _X regeneration process and immediately after that, there is an acceleration request If combustion is started in the cylinder of the other bank, the engine output can be increased and acceleration can be started immediately. Further, during and immediately after NO _X regeneration process, the first and second intake passages 3a, each compressor 4a of 3b, the relatively long portions of 4b downstream of, if there is much quantity of recirculated exhaust gas However, a relatively large amount of fresh air is supplied to one of the cylinders, and a relatively large amount of fresh air is supplied to the other cylinder if the intake valve is opened. As a result, when acceleration is requested, fuel injection is started in the other cylinder and the injected fuel is reduced in one cylinder, and the engine output is directly increased even if each cylinder is operated at the same lean air-fuel ratio. You can start accelerating.

By the way, sulfur S is contained in the fuel, and this sulfur S reacts with oxygen in the cylinder chamber and becomes SO _x . Therefore, the exhaust gas also contains SO _X not only NO _X, the first and second _the NO _X storage reduction catalyst device 12a by the SO _X also NO _X similar mechanisms, and are inserted into 12b. NO _X is stored as nitrate, whereas SO _X is stored as sulfate, which is more stable than nitrate, so the air-fuel ratio of the exhaust gas can be released simply as the stoichiometric or rich air-fuel ratio. However, the amount of occlusion increases gradually.

Thereby, for example, the SO _X storage amounts of the first and second NO _X storage reduction catalyst devices 12a and 12b are estimated based on the integrated fuel injection amounts, and when this estimated amount reaches the set amount, second _the NO _X storage reduction catalyst device 12a, 12b causes the heated to a predetermined temperature, performing the S-poisoning recovery process to be subsequently releasing SO _X fuel ratio of the exhaust gas as the stoichiometric air-fuel ratio or a rich air-fuel ratio. In this S poisoning recovery process, carried out low temperature combustion of only the stoichiometric air-fuel ratio or a rich air-fuel ratio in the cylinders of the foregoing of the NO _X regeneration process as well as one bank, to pause the combustion in the cylinders of the other bank.

Thus, if NO _X regeneration process or the S-poisoning recovery process of the NO _X occluding and reducing catalyst device 12a or 12b corresponding to one bank 1a also 1b is completed, then the desired stoichiometric air in the other bank 1a or 1b ratio or with out the low-temperature combustion of a rich air-fuel ratio, suspended combustion in one bank, NO _X regeneration process or S to be in _the NO _X storage reduction catalyst device 12a or 12b corresponding to the other bank 1a or 1b Carry out poison recovery treatment. Thus, it may be continuously NO _X regeneration process or the S-poisoning recovery process in the first and second _the NO _X storage reduction catalyst device implemented. For example, in one of the NO _X occluding and reducing catalyst device, one times is performed NO _X regeneration processing and the S-poisoning recovery process before the timing NO _X regeneration timing and S-poisoning recovery, the first and second _the NO _X storage reduction catalyst device 12a, 12b at the same time NO _X regeneration If the timing and the S poison recovery time are not reached, then the NO _X storage reduction catalyst device 12a or 12b that has reached the NO _X regeneration timing and S poison recovery time is desired only in the corresponding bank. You may make it implement low temperature combustion by a theoretical air fuel ratio or a rich air fuel ratio.

In the present embodiment, the intake valve and the exhaust valve are kept closed in the cylinder of the bank that stops combustion, and the recirculated exhaust gas and the air having a relatively high oxygen concentration are supplied to the corresponding NO _x storage reduction catalyst device 12a or 12b. The mixed gas with the fuel ratio is prevented from flowing in. This is to suppress sintering of an oxidation catalyst such as platinum supported on the NO _x storage reduction catalyst. However, when the exhaust systems of the banks are independent from each other as in this embodiment, if there is no problem of sintering, the intake valve and the exhaust valve may be opened and closed in the cylinder of the bank to be deactivated. .

If the engine exhaust system is single in a V-type engine or an in-line engine, etc., the desired theory is obtained for some cylinders in the NO _X regeneration process or S poison recovery process of the NO _X storage reduction catalyst device. It is only necessary to perform combustion at an air-fuel ratio or a rich air-fuel ratio and deactivate the remaining cylinders. In this case, unless the intake valve and the exhaust valve are kept closed in the deactivated cylinder, the recirculated exhaust gas and air sucked from the deactivated cylinder are discharged as they are to the NO _X storage reduction catalyst device. Therefore, the inside of the NO _x storage reduction catalyst device cannot be set to a desired theoretical air-fuel ratio or rich air-fuel ratio. Accordingly, in this case, the intake valve and the exhaust valve must be kept closed in the idle cylinder.

In case of carrying _the NO _X storage agent to the second particulate filter 11b of the first particulate filter 11a and the second exhaust passage 9b of the first exhaust passage 9a, a first particulate filter 11a and a second particulate filter In 11b, the same NO _x regeneration process and S poison recovery process are required. Shinashi while, when supporting the _the NO _X storage agent into the particulate filter, it is possible to automatically oxidized and removed trapped particulates by active oxygen released from _the NO _X storage agent.

It is the schematic of the diesel engine provided with the control apparatus by this invention. It is a time chart of intake air amount, injection amount, EGR amount, and A / F.

Explanation of symbols

1 diesel engine body 2 an air cleaner 3a first intake passage 3b second intake passage 4a first compressor 4b first exhaust passage 9b second compressor 9a second exhaust passage 12a first _the NO _X storage reduction catalyst device 12b Second _the NO _X storage reduction Catalyst device 13a First exhaust gas recirculation passage 13b Second exhaust gas recirculation passage

Claims (2)

In a control device for a diesel engine that enables combustion at a stoichiometric air-fuel ratio or a rich air-fuel ratio by recirculating a large amount of exhaust gas into a cylinder, a catalyst device that is disposed in the engine exhaust system and carries a NO _x storage agent or upon processing of the NO _X regeneration or S-poisoning recovery of the particulate filter, in the partial-cylinder carried the combustion at the stoichiometric air-fuel ratio or a rich air-fuel ratio, to close the intake and exhaust valves in the remaining cylinders A control device for a diesel engine, characterized in that the combustion is stopped while standing. In a control apparatus for a diesel engine that enables combustion at a stoichiometric air-fuel ratio or a rich air-fuel ratio by recirculating a large amount of exhaust gas into the cylinder, the diesel engine includes an engine exhaust system of one cylinder group and the other cylinder are independent and the group of engine exhaust system with each other, upon the processing of the NO _X regeneration or S-poisoning recovery of the catalytic converter or particulate filter to be arranged in the exhaust system of one cylinder group carrying _the NO _X storage agent The diesel engine control apparatus, wherein the combustion is performed at a stoichiometric air-fuel ratio or a rich air-fuel ratio in one cylinder group, and the combustion is stopped in the other cylinder group.

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