JP5733013B2 - Internal combustion engine control device - Google Patents

Description

  The present invention relates to an internal combustion engine control device, and more particularly, during execution of a fuel cut during deceleration, introduces fresh air in the vicinity of a sensor provided in an exhaust passage to perform scavenging in the vicinity of the sensor, and in the vicinity of the sensor. The present invention relates to an internal combustion engine controller that determines whether or not scavenging has been completed.

  In an internal combustion engine, the air-fuel ratio (actual air-fuel ratio) of exhaust gas is grasped based on a signal output from an air-fuel ratio sensor provided in the exhaust passage, and the fuel injection amount is determined so that the actual air-fuel ratio becomes a target air-fuel ratio. Performs fuel ratio feedback control. Here, the air-fuel ratio sensor outputs a signal (voltage) corresponding to the air-fuel ratio of the exhaust gas. Specifically, the air-fuel ratio sensor outputs a larger signal (voltage) as the exhaust air-fuel ratio becomes leaner, that is, increases. (For example, refer to FIG. 5 of Patent Document 1).

By the way, in such an internal combustion engine, an abnormality may occur in which a normal signal is not output from the air-fuel ratio sensor due to any cause.
Therefore, conventionally, abnormality diagnosis of the air-fuel ratio sensor is performed as follows. That is, first, while the fuel cut at the time of deceleration is being executed, that is, when the fuel injection is stopped, scavenging in the vicinity of the air-fuel ratio sensor is performed by fresh air introduced into the exhaust passage. When the amount of fresh air introduced becomes equal to or greater than a predetermined determination value, a signal output from the air-fuel ratio sensor is monitored assuming that scavenging near the air-fuel ratio sensor is complete.

  Here, when the signal output from the air-fuel ratio sensor (actual air-fuel ratio) is larger than the predetermined lean abnormality determination value AL for a predetermined period, the signal output from the air-fuel ratio sensor is abnormally large. It is determined that a lean abnormality has occurred.

  In addition, when the state where the actual air-fuel ratio is smaller than the predetermined rich abnormality determination value AR (<AL) continues for a predetermined period, the rich abnormality has occurred because the signal output from the air-fuel ratio sensor is abnormally small. Judgment is made.

JP 2009-197678 A

  By the way, in such an internal combustion engine control device, the following problems may occur. That is, scavenging in the vicinity of the air-fuel ratio sensor may not yet be completed even if the amount of fresh air introduced after the fuel cut at the time of deceleration exceeds a predetermined determination value. In this case, if the air-fuel ratio sensor abnormality diagnosis is performed assuming that scavenging in the vicinity of the air-fuel ratio sensor is completed, a false diagnosis is made that a lean abnormality or a rich abnormality has occurred even though the air-fuel ratio sensor is normal. .

  Such a problem is not limited to the abnormality diagnosis of the air-fuel ratio sensor, and can also occur in common in the abnormality diagnosis of other sensors. In addition, these problems are not limited to those for diagnosing abnormalities in sensors. After fuel injection is stopped, fresh air is introduced in the vicinity of the sensor provided in the exhaust passage to perform scavenging in the vicinity of the sensor. In the control device that determines whether or not scavenging has been completed in the vicinity of the sensor, it can occur generally in common.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine control device that can accurately determine whether scavenging is completed in the vicinity of a sensor provided in an exhaust passage. There is.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
In the first aspect of the present invention, after the fuel injection is stopped, fresh air is introduced into the vicinity of the sensor provided in the exhaust passage to perform scavenging in the vicinity of the sensor, and whether scavenging has been completed in the vicinity of the sensor. The gist of the present invention is to determine whether or not scavenging is completed according to the scavenging environment in the exhaust passage.

According to this configuration, the determination condition for determining whether or not scavenging is completed in the vicinity of the sensor in the exhaust passage is set according to the scavenging environment in the exhaust passage, in other words, the scavenging difficulty level. Specifically, in an environment where scavenging is difficult, the determination conditions are set more severely than in an environment where scavenging is easy. Therefore, it is possible to accurately determine whether scavenging is completed in the vicinity of the sensor provided in the exhaust passage.
According to the first aspect of the present invention, the internal combustion engine is for driving a vehicle, and it is determined whether or not scavenging is completed in the vicinity of the sensor during execution of fuel cut during deceleration of the internal combustion engine. It can be embodied with an embodiment. In this case, since the engine output shaft rotates in conjunction with the rotation of the wheels, fresh air is sucked through the intake passage, and scavenging is performed by introducing such fresh air into the vicinity of the sensor in the exhaust passage. Therefore, a special configuration for introducing fresh air in the vicinity of the sensor becomes unnecessary.
Further, if the scavenging completion determination condition is set so that scavenging is completed in the vicinity of the sensor when the integrated value of the intake air amount after the fuel injection is stopped is equal to or greater than the determination value, the exhaust passage Whether or not scavenging is completed can be determined according to the scavenging environment.
Further, in the first aspect of the present invention, the determination value includes the fuel injection amount immediately before the fuel injection is stopped, the additive supply amount immediately before the fuel injection is stopped, and the addition adhering to the exhaust manifold. The gist is to set according to the scavenging environment in the exhaust passage which varies depending on the evaporation amount of the agent.

The scavenging environment changes due to the engine operating condition when fuel injection is being performed . By appropriately setting the determination condition based on the engine operating state in the fuel injection stop just before, it is possible to determine accurately whether the scavenging is completed based on such determination condition. Incidentally, the engine operating state includes the fuel injection amount, the evaporation amount of the fuel adhering to the exhaust manifold, the EGR amount, and the like. Further, in a diesel engine equipped with a catalyst device for collecting particulate matter in the exhaust passage, the catalyst temperature, the amount of particulate matter deposited, and the amount of additive added to the catalyst device from the addition valve are limited. is there.
According to the above configuration, based on the fuel injection amount immediately before the fuel injection is stopped, the additive supply amount immediately before the fuel injection is stopped, and the evaporation amount of the additive adhering to the exhaust manifold. The judgment value can be set appropriately.
According to the invention of claim 2, in the internal combustion engine control apparatus of claim 1, the fuel injection amount immediately before the fuel injection is stopped, the additive supply amount immediately before the fuel injection is stopped, If the scavenging difficulty is calculated as a value obtained by adding the respective values calculated based on the evaporation amount of the additive adhering to the exhaust manifold and the scavenging difficulty calculated as a value indicating the scavenging environment in the exhaust passage. The determination value can be set.

  According to a third aspect of the present invention, in the internal combustion engine control device according to the first or second aspect, the internal combustion engine includes a plurality of cylinder rows and an exhaust passage is provided for each of the cylinder rows. The gist is to separately determine whether scavenging is completed in the vicinity of the sensor provided in the exhaust passage.

  In an internal combustion engine having a plurality of cylinder rows and having an exhaust passage for each cylinder row, the scavenging environment may be different for each exhaust passage. According to the above configuration, whether or not scavenging has been completed in the vicinity of the sensor provided in each exhaust passage is determined separately. Then, the determination condition is set according to the scavenging environment in each exhaust passage. Therefore, in the case where a plurality of cylinder rows are provided and an exhaust passage is provided for each cylinder row, it is possible to accurately determine whether or not scavenging is completed in the vicinity of the sensor provided in each exhaust passage. .

The gist of the invention described in claim 4 is that, in the internal combustion engine controller according to claim 3, the determination condition is set based on the layout of the exhaust passage.
In an internal combustion engine that includes a plurality of cylinder rows and in which an exhaust passage is provided for each cylinder row, the layout of the exhaust passage may differ for each cylinder row. In this case, the scavenging environment is different due to the layout of the exhaust passage. According to the above configuration, even when the scavenging environment in the exhaust passage is different due to the layout of the exhaust passage, the determination condition can be appropriately set according to the layout of each exhaust passage. Thus, it is possible to accurately determine whether scavenging is completed.

  Incidentally, it is desirable to consider the distance from the combustion chamber to the sensor as the layout of the exhaust passage. In particular, in a diesel engine having an addition valve in the exhaust passage, it is desirable to consider the distance from the addition valve to the sensor.

According to a fifth aspect of the present invention, in the internal combustion engine control apparatus according to any one of the first to fourth aspects, the sensor outputs a signal corresponding to the oxygen concentration around the sensor. The gist of the invention is to perform abnormality diagnosis of the sensor based on a signal output from the sensor after it is determined that scavenging has been completed in the vicinity of the sensor.

  According to this configuration, it is possible to suppress the abnormality diagnosis of the sensor before scavenging in the vicinity of the sensor is completed. Therefore, the abnormality diagnosis of the sensor can be performed with high accuracy.

1 is a schematic configuration diagram showing a schematic configuration of an internal combustion engine according to an embodiment of an internal combustion engine control apparatus according to the present invention. The flowchart which shows the procedure of the abnormality diagnosis process of the air fuel ratio sensor in the embodiment. The flowchart which shows the procedure of the scavenging completion determination process in the embodiment. The graph which shows the relationship between scavenging difficulty and scavenging completion judgment value. The graph which shows the relationship between the fuel injection quantity just before a fuel cut, and a scavenging difficulty factor. The graph which shows the relationship between the integrated value of the additive supply amount and intake air amount just before a fuel cut, and a scavenging difficulty factor. The graph which shows the relationship between the amount of evaporation per unit time of the fuel adhering to an exhaust manifold, and a scavenging difficulty factor.

  1 to 7, an internal combustion engine control apparatus according to the present invention is applied to an internal combustion engine for driving a vehicle, more specifically, a V-type 8-cylinder diesel engine (hereinafter referred to as an internal combustion engine 10). An embodiment embodied as a control device will be described in detail.

As shown in FIG. 1, the internal combustion engine 10 includes two cylinder rows, and four cylinders (# 1 to # 4, # 5 to # 8) are provided in each of these cylinder rows.
An intake passage 11 and exhaust passages 21a and 21b are connected to each cylinder (# 1 to # 4, # 5 to # 8).

  An intake pipe 13 constituting the intake passage 11 is provided with a throttle valve 12 for adjusting the flow rate of intake air. In the intake pipe 13, two intake manifolds 14 a and 14 b corresponding to each cylinder row are connected to the downstream side of the throttle valve 12. Surge tanks 15a and 15b are formed in the intake manifolds 14a and 14b, and are connected to the intake ports of the cylinders (# 1 to # 4, # 5 to # 8) on the downstream side of the surge tanks 15a and 15b. Branch pipes 16a and 16b are provided.

  Branch pipes 23a, 23b of exhaust manifolds 22a, 22b are connected to the exhaust ports of the cylinders (# 1- # 4, # 5- # 8). Further, exhaust pipes 24a and 24b are connected to the downstream side of the exhaust manifolds 22a and 22b. The exhaust manifolds 22a and 22b and the exhaust pipes 24a and 24b constitute exhaust passages 21a and 21b.

  Between the exhaust manifolds 22a and 22b and the exhaust pipe 24a, turbines 31a and 31b constituting an exhaust drive type turbocharger are provided. Further, on the downstream side of the turbines 31a and 31b, oxidation catalysts 32a and 32b and DPFs 33a and 33b that function as filters for collecting particulate matter (hereinafter referred to as PM) contained in the exhaust are provided. . The oxidation catalysts 32a and 32b and the DPFs 33a and 33b correspond to the catalyst device according to the present invention.

The exhaust manifolds 22a and 22b are provided with addition valves 30a and 30b for adding fuel as an additive to the exhaust.
Further, the internal combustion engine 10 is provided with an EGR device 25 for returning a part of the exhaust gas to the intake passage 11. Specifically, EGR upstream passages 26a and 26b are connected to the exhaust manifolds 22a and 22b, and a common EGR collecting passage 28 is connected to the downstream side of these EGR upstream passages 26a and 26b. The EGR collecting passage 28 is connected to the downstream side of the throttle valve 12 in the intake pipe 13. EGR valves 27a and 27b are provided in the middle of the EGR upstream passages 26a and 26b.

  Various controls of the internal combustion engine 10 are performed by the electronic control unit 50. The electronic control unit 50 is connected to various sensors for grasping the vehicle running state, the engine operating state, and the like. As various sensors, for example, an engine rotation speed sensor that detects the engine rotation speed, a water temperature sensor that detects the temperature of the cooling water of the internal combustion engine, an accelerator sensor that detects the accelerator operation amount, a brake sensor that detects the depression state of the brake pedal, There is a vehicle speed sensor that detects the vehicle speed. Also, the air flow meter 51 that detects the intake air amount GA and the intake air temperature, the first exhaust temperature sensors 52a and 52b that detect the temperature of the exhaust gas flowing into the oxidation catalysts 32a and 32b, and the oxidation catalysts 32a and 32b flow out. There are second exhaust temperature sensors 53a and 53b that detect the temperature of the exhaust gas flowing into the DPFs 33a and 33b. Also, third exhaust temperature sensors 54a and 54b that detect the temperature of the exhaust gas flowing out from the DPFs 33a and 33b, differential pressure sensors 55a and 55b that detect the differential pressure between the upstream side and the downstream side of the DPFs 33a and 33b, and DPFs 33a and 33b. There are air-fuel ratio sensors 56a and 56b for detecting the air-fuel ratio of the exhaust gas flowing out.

  Here, the air-fuel ratio sensors 56a and 56b output a signal (voltage) corresponding to the air-fuel ratio of the exhaust. Specifically, a larger signal (voltage) is output as the air-fuel ratio of the exhaust gas becomes leaner, that is, as it becomes larger.

  The electronic control unit 50 performs various controls such as opening control (throttle control) of the throttle valve 12, fuel injection control, and opening control (EGR control) of the EGR valves 27a and 27b. Further, PM regeneration control for burning and removing PM accumulated in the DPF 33a, 33b by adding fuel from the addition valves 30a, 30b, and sulfur component accumulated in the DPF 33a, 33b by adding fuel from the addition valves 30a, 30b. The S regeneration control for removing the combustion is executed. Further, deceleration fuel cut control is performed to stop fuel injection when a predetermined condition is satisfied while the vehicle is running. Specifically, for example, the fuel cut control during deceleration is performed on the condition that the accelerator operation amount is set to “0” when the vehicle speed is equal to or higher than a predetermined speed and the engine speed is equal to or higher than the predetermined speed. If the accelerator operation amount increases during execution of the fuel cut control during deceleration, the fuel cut control during deceleration is stopped and fuel injection is restarted.

  By the way, in such an internal combustion engine, an abnormality may occur in which a normal signal (actual air-fuel ratio AF) is not output from the air-fuel ratio sensors 56a and 56b due to any cause. That is, if the actual air-fuel ratio AF within a predetermined range is detected if it is normal, there may be a lean abnormality in which an actual air-fuel ratio AF that is larger than the upper limit value in the same range is output. Further, a rich abnormality in which an actual air-fuel ratio AF smaller than the lower limit value in the same range is output may occur.

Therefore, in the present embodiment, abnormality diagnosis of the air-fuel ratio sensors 56a and 56b is performed as follows.
FIG. 2 shows a procedure for abnormality diagnosis processing of the air-fuel ratio sensors 56a and 56b. This abnormality diagnosis process is executed when all of the following execution conditions (a) to (c) are satisfied when the fuel cut control during deceleration of the internal combustion engine 10 is executed.

(A) The air-fuel ratio sensors 56a and 56b are in the active state (not immediately after the cold start).
(B) The voltage of the battery that supplies power to the air-fuel ratio sensors 56a and 56b is equal to or higher than a predetermined voltage.
(C) No other abnormality such as disconnection occurs in the air-fuel ratio sensors 56a and 56b.

As shown in FIG. 2, in this series of processing, first, scavenging completion determination processing is performed in step S1.
Here, with reference to FIG. 3, the procedure of the scavenging completion determination process in the present embodiment will be described. This scavenging completion determination process is executed every time the process proceeds to step S1 in the process of the flowchart of FIG.

  As shown in FIG. 3, in this series of processing, first, in step S11, the scavenging difficulty D in the exhaust passages 21a and 21b where the air-fuel ratio sensors 56a and 56b are arranged is derived separately. Then, referring to the graph shown in FIG. 4, a scavenging completion determination value ΣGAt is set for each exhaust passage 21a, 21b based on the scavenging difficulty D. Specifically, the scavenging completion determination value ΣGAt is calculated as a larger value as the scavenging difficulty level D is larger, that is, as the exhaust passages 21a and 21b are more difficult to scavenge. The scavenging difficulty level D is a numerical value of the level of the scavenging environment according to the present invention.

Here, in this embodiment, the scavenging difficulty level D is calculated by adding a plurality of scavenging difficulty factors dn (n = 1, 2, 3).
Hereinafter, with reference to FIG. 5 to FIG. 7, how to derive each scavenging difficulty factor dn will be described.

FIG. 5 shows the relationship between the fuel injection amount ΣQ immediately before the fuel cut and the scavenging difficulty factor d1.
The more fuel is injected just before the fuel cut, the more exhaust is present in the exhaust passages 21a and 21b immediately after the fuel cut is performed, and the exhaust passages 21a and 21b are more difficult to scavenge. Become. Therefore, as shown in FIG. 5, the scavenging difficulty factor d1 is derived as a larger value as the fuel injection amount ΣQ immediately before the fuel cut is larger. Here, the fuel injection amount ΣQ immediately before the fuel cut is calculated by integrating the fuel injection amounts from the time point before the fuel cut start time to the time point when the fuel cut is started.

FIG. 6 shows the relationship between the additive supply amount ΣA immediately before the fuel cut and the integrated value ΣGAr of the intake air amount and the scavenging difficulty factor d2.
The more additive (fuel) is added immediately before the fuel cut, the more additive is present in the exhaust passages 21a and 21b immediately after the fuel cut is performed, and the exhaust passages 21a and 21b are more scavenged. It becomes an environment difficult to do. On the other hand, if the amount of additive present in the exhaust passages 21a and 21b is constant immediately after the fuel cut is performed, more intake air (fresh air) is introduced through the intake passage 11 after the fuel cut is performed. As a result, the exhaust passages 21a and 21b are more easily scavenged. Therefore, as shown in FIG. 6, the scavenging difficulty factor d2 is smaller as the additive supply amount ΣA immediately before the fuel cut is larger, and as the integrated value ΣGAr of the intake air amount after the fuel cut is performed is smaller. Derived as a value. Here, the additive supply amount ΣA immediately before the fuel cut is calculated by accumulating the additive supply amount from the time point a predetermined period before the fuel cut start point to the fuel cut start point. .

FIG. 7 shows the relationship between the evaporation amount per unit time of the additive (fuel) adhering to the exhaust manifolds 22a and 22b and the scavenging difficulty factor d3.
Part of the additive (fuel) supplied from the addition valves 30a and 30b adheres to the inner walls of the exhaust manifolds 22a and 22b. In addition, as the amount of fuel attached increases and the wall temperature of the exhaust manifolds 22a and 22b increases, more fuel evaporates from the inner walls of the exhaust manifolds 22a and 22b per unit time. 21b becomes an environment where scavenging is more difficult. Therefore, as shown in FIG. 7, the scavenging difficulty factor d3 is derived as a larger value as the evaporation amount per unit time of the fuel adhering to the exhaust manifolds 22a and 22b increases. Here, the fuel evaporation amount per unit time is calculated based on the wall temperature of the exhaust manifolds 22a and 22b and the additive supply amount ΣA immediately before the fuel cut. The wall temperatures of the exhaust manifolds 22a and 22b are estimated in a known manner based on the temperature of the cooling water of the internal combustion engine detected by the water temperature sensor and the exhaust temperature detected by the first exhaust temperature sensors 52a and 52b. .

  In the present embodiment, the layout of the exhaust passages 21a and 21b is different for each cylinder row. Specifically, distances and shapes from the addition valves 30a and 30b to the air-fuel ratio sensors 56a and 56b are different from each other due to restrictions on mounting on the vehicle. Therefore, the relationship between the various parameters described above and the scavenging difficulty factor dn is set for each exhaust passage 21a and 21b through experiments and simulations.

  When the EGR valves 27a and 27b are opened, the exhaust gas containing fuel added from the addition valves 30a and 30b is discharged into the exhaust manifolds 22a and 22b, the EGR upstream passages 26a and 26b, and the EGR collecting passage 28. Through the intake passage 11. Therefore, in this embodiment, the scavenging difficulty factor dn is set to a different value when the EGR valves 27a and 27b are opened and closed.

  Further, when the EGR valves 27a and 27b are opened, more exhaust tends to be returned to the exhaust passage 21a (21b) of one cylinder row due to the layout of the exhaust passages 21a and 21b. Therefore, in the present embodiment, the scavenging difficulty factor dn is set for each of the exhaust passages 21a and 21b in consideration of such a tendency.

  Now, as shown in FIG. 3, when each scavenging difficulty factor dn is derived and the scavenging completion determination value ΣGAt is set based on the scavenging difficulty D calculated from these scavenging difficulty factors dn (step S11), The process proceeds to step S12 to calculate the integrated value ΣGAr of the intake air amount after the fuel cut is started.

  Then, the process proceeds to step S13, and it is determined whether or not the integrated value ΣGAr of the intake air amount is equal to or greater than the scavenging completion determination value ΣGAt. Here, if a negative determination is made, the determination processing of steps S11 to S13 is repeatedly executed until an affirmative determination is made.

On the other hand, if an affirmative determination is made in step S13, the process proceeds to step S14, where it is determined that scavenging has been completed, and this series of processes is temporarily terminated.
As shown in FIG. 2, when the scavenging completion determination process is performed in step S1, the process proceeds to step S2 to determine whether the scavenging completion determination is made. Here, if a negative determination is made, the processes of step S1 and step S2 are repeatedly executed until an affirmative determination is made.

  On the other hand, if an affirmative determination is made in step S2, it is determined that scavenging in the vicinity of the air-fuel ratio sensors 56a and 56b has been completed, and then the process proceeds to step S3 and the actual air-fuel ratio AF detected by the air-fuel ratio sensors 56a and 56b. To monitor.

  In step S3, it is determined whether or not the state in which the actual air-fuel ratio AF is greater than the lean abnormality determination value AL continues for a predetermined period. Here, if an affirmative determination is made, it is determined that the detected actual air-fuel ratio AF is abnormally large. Next, the routine proceeds to step S4, where it is determined that a lean abnormality has occurred in the air-fuel ratio sensor 56a (56b). To end this series of processing.

  On the other hand, if a negative determination is made in step S3, then the process proceeds to step S5 to determine whether or not the state where the actual air-fuel ratio AF is smaller than the rich abnormality determination value AR (<AL) continues for a predetermined period. to decide. Here, if an affirmative determination is made, it is determined that the detected actual air-fuel ratio AF is abnormally small, and then the routine proceeds to step S6, where it is determined that a rich abnormality has occurred in the air-fuel ratio sensor 56a (56b). To end this series of processing.

Further, if a negative determination is made in step S5, this series of processing is temporarily terminated, assuming that the detected actual air-fuel ratio AF is not abnormal.
According to the internal combustion engine control apparatus according to the present embodiment described above, the following effects can be obtained.

  (1) The electronic control unit 50 introduces fresh air in the vicinity of the air-fuel ratio sensors 56a, 56b provided in the exhaust passages 21a, 21b during execution of the fuel cut at the time of deceleration of the internal combustion engine 10, and the air-fuel ratio sensor. While scavenging in the vicinity of 56a, 56b is performed, it is determined separately whether scavenging is completed in the vicinity of the air-fuel ratio sensors 56a, 56b. More specifically, the vicinity of the air-fuel ratio sensors 56a and 56b when the integrated value ΣGAr of the intake air amount after the fuel cut at the time of deceleration, that is, the fuel injection is stopped, becomes equal to or greater than the scavenging completion determination value ΣGAt. It is determined that scavenging has been completed. The scavenging completion determination value ΣGAt is variably set according to the scavenging environment in the exhaust passages 21a and 21b.

  According to such a configuration, the scavenging completion determination value ΣGAt, which is a determination condition when determining whether or not scavenging is completed in the vicinity of the air-fuel ratio sensors 56a and 56b provided in the exhaust passages 21a and 21b, is set to each exhaust passage 21a. , 21b, in other words, according to the scavenging difficulty D. Specifically, in an environment in which scavenging is difficult, scavenging completion determination value ΣGAt is set to a larger value than in an environment in which scavenging is easy, and the determination conditions are set strictly. Accordingly, whether or not scavenging is completed in the vicinity of the air-fuel ratio sensors 56a and 56b provided in the exhaust passages 21a and 21b in the case where two cylinder rows are provided and the exhaust passages 21a and 21b are provided for the respective cylinder rows. Whether or not can be determined accurately.

  (2) The scavenging completion determination value ΣGAt is used as the engine operating state immediately before the stop of fuel injection (the fuel injection amount ΣQ immediately before the fuel cut, the supply amount of the additive immediately before the fuel cut, and the additive attached to the exhaust manifolds 22a and 22b. The amount of evaporation per unit time and the opening degree of the EGR valves 27a and 27b) are variably set. According to such a configuration, the scavenging completion determination value ΣGAt can be appropriately set based on the engine operating state immediately before the stop of fuel injection, and whether or not scavenging has been completed is accurately determined based on the scavenging completion determination value ΣGAt. Can be determined.

  (3) The scavenging completion determination value ΣGAt is set based on the layout of the exhaust passages 21a and 21b. The scavenging environment in the exhaust passages 21a and 21b differs depending on the layout of the exhaust passages 21a and 21b. According to such a configuration, the scavenging completion determination value ΣGAt is appropriately set according to the layout of the exhaust passages 21a and 21b. The scavenging completion determination value ΣGAt can be used to accurately determine whether or not scavenging has been completed.

  (4) After determining that scavenging has been completed in the vicinity of the air-fuel ratio sensor 56a, abnormality diagnosis of the air-fuel ratio sensors 56a, 56b is performed based on signals output from the air-fuel ratio sensors 56a, 56b. According to such a configuration, it is possible to suppress abnormality diagnosis of the air-fuel ratio sensors 56a and 56b before scavenging in the vicinity of the air-fuel ratio sensors 56a and 56b is completed. Therefore, the abnormality diagnosis of the air-fuel ratio sensors 56a and 56b can be performed with high accuracy.

The internal combustion engine control device according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and can be implemented as, for example, the following forms appropriately modified.
In the above embodiment, the scavenging completion determination value ΣGAt is variably set in consideration of the fact that the more the amount of fuel evaporated from the inner walls of the exhaust manifolds 22a, 22b, the more difficult the exhaust passages 21a, 21b are scavenged. did. However, when the amount of fuel that evaporates from the inner walls of the exhaust manifolds 22a and 22b is so large that the scavenging cannot be completed during the fuel cut during deceleration, the scavenging completion determination process and the air-fuel ratio sensor abnormality diagnosis process May be canceled. This makes it possible to perform other abnormality diagnosis processing and the like during execution of the fuel cut during deceleration.

  In the above embodiment, the fuel injection amount ΣQ immediately before the fuel cut is calculated by integrating the fuel injection amounts from the time point before the fuel cut start time to the time point when the fuel cut starts. Calculated. That is, the fuel injections within the predetermined period are integrated with the same weight. In practice, however, the fuel injected at an earlier time point has a smaller effect on scavenging during fuel cut. Therefore, the scavenging difficulty factor can be obtained with higher accuracy by calculating the fuel injection amount ΣQ immediately before the fuel cut by calculating the fuel injection amount ΣQ immediately before the fuel cut by integrating the fuel injected at the earlier time point. The same change is effective for the calculation mode of the additive supply amount ΣA immediately before the fuel cut.

  The scavenging environment in the exhaust passage varies depending on the supply timing of the additive by the addition valves 30a and 30b, specifically, the supply timing of the additive based on the time when the fuel cut is started. For this reason, the scavenging difficulty D may be calculated according to the supply timing of the additive.

  The scavenging environment in the vicinity of the air-fuel ratio sensors 56a and 56b varies depending on the amount of PM accumulated in the DPFs 33a and 33b. Therefore, the amount of PM accumulated in the DPFs 33a and 33b may be estimated, and the scavenging difficulty level D may be calculated based on the estimated PM accumulation amount. Further, the scavenging difficulty D may be calculated based on the temperatures of the oxidation catalysts 32a and 32b and the temperatures of the DPFs 33a and 33b.

  In the above embodiment, the scavenging difficulty level D is calculated from various parameters, and the scavenging completion determination value ΣGAt is calculated based on the scavenging difficulty level D. Instead of this, a map or an arithmetic expression for directly obtaining the scavenging completion determination value ΣGAt from various parameters may be employed.

  In the above embodiment, the scavenging completion determination is performed in the vicinity of the air-fuel ratio sensors 56a and 56b based on the comparison between the integrated value ΣGAr of the intake air amount and the scavenging completion determination value ΣGAt. However, the scavenging completion determination mode according to the present invention is not limited to this. For example, if the intake air amount GA per unit time can be assumed to be constant, the vicinity of the air-fuel ratio sensors 56a and 56b when the elapsed time from the start of the fuel cut at the time of deceleration exceeds a predetermined determination value It may be determined that scavenging has been completed.

  In the above embodiment, the scavenging completion determination in the vicinity of the air-fuel ratio sensors 56a and 56b is exemplified. However, the present invention is not limited to the one provided with the air-fuel ratio sensor, and the present invention may be applied to one that performs scavenging completion determination in the vicinity of another sensor.

  The execution timing of scavenging and scavenging completion determination according to the present invention is not limited to execution of the fuel cut at deceleration, but may be other determination of scavenging completion after the engine is stopped, for example. In this case, for example, the engine output shaft can be forcibly rotated by a starter motor to introduce scavenging air in the vicinity of a sensor provided in the exhaust passage. Even in such a case, if the present invention is applied, it is possible to accurately determine whether or not scavenging is completed in the vicinity of the sensor provided in the exhaust passage.

  In the above-described embodiment, the scavenging completion determination condition is variably set based on the engine operating state immediately before stopping fuel injection. However, the present invention is not limited to this, and the determination condition may be set based only on the difference in the layout of the plurality of exhaust passages.

  In the above embodiment, the present invention is applied to a V-type 8-cylinder diesel engine. However, the present invention is applied to, for example, a V-type engine other than an 8-cylinder type or a horizontally opposed engine. You can also. The present invention can also be applied to a gasoline engine.

  In the above-described embodiment and its modification, the present invention is applied to an engine having a plurality of cylinder rows, but in addition to this, for example, an in-line type consisting of a single cylinder row The present invention can also be applied to an engine.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Throttle valve, 13 ... Intake pipe, 14a, 14b ... Intake manifold, 15a, 15b ... Surge tank, 16a, 16b ... Branch pipe, 21a, 21b ... Exhaust passage, 22a, 22b ... exhaust manifold, 23a, 23b ... branch pipe, 24a, 24b ... exhaust pipe, 25 ... EGR device, 26a, 26b ... EGR upstream passage, 27a, 27b ... EGR valve, 28 ... EGR collecting passage, 30a, 30b ... Addition valve, 31a, 31b ... turbocharger, 32a, 32b ... oxidation catalyst, 33a, 33b ... DPF, 50 ... electronic control device, 51 ... air flow meter, 52a, 52b ... first exhaust temperature sensor, 53a, 53b ... second Exhaust temperature sensor, 54a, 54b ... third exhaust temperature sensor, 55a, 55b ... differential pressure sensor, 56a, 56b ... air-fuel ratio sensor .

Claims (5)

Applied to internal combustion engines for driving vehicles,
After the fuel cut at the time of deceleration of the internal combustion engine is executed and the fuel injection is stopped, fresh air is introduced near the sensor provided in the exhaust passage to scavenge the vicinity of the sensor, and the fuel cut at the time of deceleration of the internal combustion engine An internal combustion engine control device that determines whether scavenging is completed in the vicinity of the sensor during the execution of
The scavenging completion judgment condition is set according to the scavenging environment in the exhaust passage , and scavenging is completed in the vicinity of the sensor when the integrated value of the intake air amount after the fuel injection is stopped exceeds the judgment value. Determined that
The determination value varies depending on the fuel injection amount immediately before the fuel injection is stopped, the additive supply amount immediately before the fuel injection is stopped, and the evaporation amount of the additive adhering to the exhaust manifold. An internal combustion engine control device characterized by being set according to a scavenging environment in an exhaust passage . The internal combustion engine control apparatus according to claim 1,
The determination value is set based on the scavenging difficulty calculated as a value indicating the scavenging environment in the exhaust passage,
The scavenging difficulty is calculated based on the fuel injection amount immediately before the fuel injection is stopped, the additive supply amount immediately before the fuel injection is stopped, and the evaporation amount of the additive adhering to the exhaust manifold. An internal combustion engine control device characterized by being a value obtained by adding the respective values . The internal combustion engine control device according to claim 1 or 2,
The internal combustion engine includes a plurality of cylinder rows and an exhaust passage is provided for each cylinder row.
An internal combustion engine control apparatus, comprising: separately determining whether scavenging has been completed in the vicinity of a sensor provided in each exhaust passage. The internal combustion engine control apparatus according to claim 3,
The internal combustion engine control device, wherein the determination condition is set based on a layout of the exhaust passage. The internal combustion engine control apparatus according to any one of claims 1 to 4 ,
The sensor outputs a signal corresponding to the oxygen concentration around the sensor,
An internal combustion engine control device, wherein after determining that scavenging has been completed in the vicinity of the sensor, an abnormality diagnosis of the sensor is performed based on a signal output from the sensor.

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