JP2011241727A - Abnormality detection device for internal combustion engine and control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality detection device for an internal combustion engine which can capture a sign of abnormal combustion, and to provide a control device for the internal combustion engine which can prevent the occurrence of the abnormal combustion based on the captured sign of the abnormal combustion.SOLUTION: In the internal combustion engine with a cylinder pressure sensor, the probability distribution of combustion pressure (hereinafter, probability distribution of detected combustion pressure) is calculated based on the aggregation of the combustion pressure detected by the cylinder pressure sensor during a predetermined load operation. An abnormal combustion sign flag is turned on when the probability of the combustion pressure exceeding an upper-limit confidence value is higher than a threshold in the probability distribution of detected combustion pressure.

Description

  The present invention relates to an abnormality detection device for an internal combustion engine and a control device for the internal combustion engine.

  Conventionally, for example, as disclosed in Patent Document 1, an internal combustion engine including an ignition circuit including an ion current detection circuit is known. In addition, this publication discloses a method for determining whether or not abnormal combustion has occurred based on the ion current in the combustion chamber detected by the ion current detection circuit. In addition, this publication discloses that when abnormal combustion occurs, control for further suppressing abnormal combustion is performed.

JP 2009-30545 A

  However, the conventional internal combustion engine detects abnormal combustion afterwards, and cannot detect a sign of abnormal combustion. In order to prevent abnormal combustion in advance, it is desirable to grasp the signs of abnormal combustion.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an abnormality detection device for an internal combustion engine that can grasp a sign of abnormal combustion. Another object of the present invention is to provide a control device for an internal combustion engine that can suppress the occurrence of abnormal combustion based on the detected sign of abnormal combustion.

In order to achieve the above object, a first invention is an abnormality detection device for an internal combustion engine,
An in-cylinder pressure sensor for detecting the in-cylinder combustion pressure;
Upper limit reliability value storage means for storing an upper limit reliability value of the combustion pressure according to a predetermined load in a state where no oil is accumulated in the intake system;
Detected combustion pressure probability distribution calculating means for calculating a probability distribution of combustion pressure (hereinafter referred to as detected combustion pressure probability distribution) from a set of combustion pressures detected by the in-cylinder pressure sensor during operation at the load;
The detected combustion pressure probability distribution includes an abnormal combustion predictor flag setting unit that turns on an abnormal combustion predictor flag when the probability that the combustion pressure exceeds the upper limit reliability value is higher than a threshold value.

The second invention is the first invention, wherein
A reference combustion pressure probability distribution storage means for storing a probability distribution (hereinafter referred to as a reference combustion pressure probability distribution) based on a set of combustion pressures corresponding to the load in a state where no oil is accumulated in the intake system;
An intake system oil that calculates a difference in probability that the combustion pressure exceeds the upper limit reliability value in the detected combustion pressure probability distribution and the reference combustion pressure probability distribution, and calculates an amount of oil accumulated in the intake system based on the difference And a deposit amount calculating means.

The third invention is the first invention, wherein
A reference combustion pressure probability distribution storage means for storing a probability distribution (hereinafter referred to as a reference combustion pressure probability distribution) based on a set of combustion pressures corresponding to the load in a state where no oil is accumulated in the intake system;
Ignition timing advance means for advancing the ignition timing when the probability that the combustion pressure exceeds the upper limit reliability value is higher than the threshold in the detected combustion pressure probability distribution;
After the ignition timing is advanced by the ignition timing advance means, the probability distribution of the combustion pressure (hereinafter referred to as post-advance detection combustion pressure) from the set of combustion pressures detected by the in-cylinder pressure sensor during operation with the load. A post-advance detection combustion pressure probability distribution calculating means for calculating a probability distribution),
In the post-advance detection combustion pressure probability distribution and the reference combustion pressure probability distribution, a difference in probability that the combustion pressure exceeds the upper limit reliability value is calculated, and the amount of oil accumulated in the intake system is calculated based on the difference. Intake system oil accumulation amount calculating means;
The in-cylinder deposit that calculates the difference in the probability that the combustion pressure exceeds the upper limit reliability value in the post-advance detection combustion pressure probability distribution and the detected combustion pressure probability distribution, and calculates the in-cylinder deposit amount based on the difference And a quantity calculating means.

Moreover, 4th invention is set in 3rd invention,
An actual relationship storage means for storing an actual relationship between the execution interval of the ignition timing advance means and the in-cylinder deposit amount calculated by the in-cylinder deposit amount calculation means;
From the actual relationship, comprising an execution interval acquisition means for acquiring an execution interval corresponding to the in-cylinder deposit threshold,
The ignition timing advance means is after the execution interval acquired by the execution interval acquisition means has elapsed and the probability that the combustion pressure exceeds the upper limit reliability value in the detected combustion pressure probability distribution is higher than the threshold value Further, the ignition timing is advanced.

A fifth aspect of the invention is a control device for an internal combustion engine in order to achieve the above object,
An abnormality detection device for an internal combustion engine according to any one of claims 1 to 4,
In-cylinder oil calculating means for calculating the amount of oil flowing into the cylinder and its oil particle size,
From the relationship between the amount of oil flowing into the cylinder, the oil particle size, and the abnormal combustion occurrence probability, the abnormal combustion occurrence probability corresponding to the oil amount calculated by the in-cylinder oil calculating means and the oil particle size is calculated. An abnormal combustion probability calculating means;
Load reducing means for reducing the load when the abnormal combustion occurrence probability calculated by the abnormal combustion probability calculating means is higher than a predetermined value.

The sixth invention is the fifth invention, wherein
In the case where the load is reduced by the load reducing means, a flow velocity increasing means for increasing the flow velocity of the intake gas flowing through the intake system is provided.

  According to the first invention, when the probability that the combustion pressure exceeds the upper limit reliability value is higher than the threshold value in the detected combustion pressure probability distribution, the abnormal combustion predictor flag is turned ON. When the amount of oil accumulated in the intake system increases, the amount of oil and oil particle size flowing into the cylinder increases, so that the combustion pressure increases and the probability of exceeding the upper limit reliability value increases. For this reason, according to the present invention, a sign of abnormal combustion can be grasped.

  According to the second invention, in the detected combustion pressure probability distribution and the reference combustion pressure probability distribution, a difference in the probability that the combustion pressure exceeds the upper limit reliability value is calculated, and the amount of oil accumulated in the intake system is calculated based on the difference. Can be calculated. By grasping the amount of oil accumulated in the intake system, it is possible to grasp the likelihood of abnormal combustion.

According to the third invention, the in-cylinder deposit can be burned out by advancing the ignition timing. Further, in the post-advance detection combustion pressure probability distribution and the reference combustion pressure probability distribution, a difference in the probability that the combustion pressure exceeds the upper limit reliability value is calculated, and the amount of oil accumulated in the intake system is calculated based on the difference. Therefore, the amount of oil accumulated in the intake system can be calculated with high accuracy by eliminating the influence of in-cylinder deposits.
In addition, according to the third aspect of the present invention, the difference in the probability that the combustion pressure exceeds the upper limit reliability value is calculated in the post-advance detection combustion pressure probability distribution and the detected combustion pressure probability distribution, and the in-cylinder is calculated based on the difference. Calculate the deposit amount. Therefore, the in-cylinder deposit amount can be calculated with high accuracy.

  According to the fourth invention, from the actual relationship between the execution interval for advancing the ignition timing and the in-cylinder deposit amount, the execution interval corresponding to the in-cylinder deposit threshold is acquired, and the ignition timing is advanced after the execution interval elapses. To do. Therefore, according to the present invention, the advance timing of the ignition timing can be optimized, and deterioration of drivability and fuel consumption can be suppressed.

  According to the fifth aspect, the load is reduced when the abnormal combustion occurrence probability is higher than a predetermined value. For this reason, according to this invention, generation | occurrence | production of abnormal combustion can be suppressed based on the grasped sign of abnormal combustion.

  According to the sixth invention, when reducing the load, the flow velocity of the intake gas flowing through the intake system is increased. For this reason, according to the present invention, the oil accumulated in the intake system can be scavenged without causing abnormal combustion.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a relationship figure which shows the relationship between the ignition timing in Embodiment 1 of this invention, and a cylinder pressure. In Embodiment 1 of this invention, it is a related figure which shows the relationship between the oil quantity which accumulates in an intake system, and a knock generation rate. In Embodiment 1 of this invention, it is a related figure which shows the relationship between an oil particle size and abnormal combustion (a knocking is included) incidence rate. In Embodiment 1 of this invention, it is a figure showing the combustion pressure probability distribution in the predetermined load before and behind a time-dependent change. In Embodiment 1 of this invention, it is a flowchart of the abnormality detection routine which ECU50 performs. In Embodiment 2 of this invention, it is a figure for demonstrating the influence degree with respect to knocking of the oil quantity which flows in in a cylinder, and the amount of deposits in a cylinder. It is a figure for demonstrating the relationship between the ignition timing and cylinder temperature in Embodiment 2 of this invention. In Embodiment 2 of this invention, it is a flowchart of the abnormality detection routine which ECU50 performs. It is a relationship figure which shows the relationship between the implementation interval of the abnormality detection routine (FIG. 9) in Embodiment 2 of this invention, and the amount of deposits in a cylinder. In Embodiment 3 of this invention, it is a flowchart of the abnormality detection routine which ECU50 performs. In Embodiment 4 of this invention, it is a related figure which shows the relationship between the oil quantity which flows in in a cylinder, the oil particle size, atmospheric temperature, and the occurrence probability of abnormal combustion. In Embodiment 4 of this invention, it is a flowchart of the control routine which ECU50 performs. In Embodiment 4 of this invention, it is a relationship map which shows the relationship between the flow velocity and the particle size of oil, and the relationship between a load and the flow velocity in a surge tank. In Embodiment 5 of this invention, it is the relationship figure showing the relationship between the generation | occurrence | production area | region and operation line of abnormal combustion, preignition, insufficient flow velocity, and smoke (white smoke) in the state where oil accumulated in the intake system. In Embodiment 5 of this invention, it is a flowchart of the control routine which ECU50 performs. It is a figure for demonstrating positioning of each embodiment of this invention.

  First, the positioning of each embodiment of the present invention will be described with reference to FIG. FIG. 17 is a diagram for explaining the positioning of each embodiment of the present invention. Embodiments 1 to 3 of the present invention grasp a sign of abnormal combustion. Further, the fourth and fifth embodiments prevent abnormal combustion in advance based on the sign of abnormal combustion grasped by any one of the first to third embodiments. Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a schematic configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine (hereinafter simply referred to as an engine) 10. Although only one cylinder is illustrated in FIG. 1, in the present invention, the number of cylinders and the cylinder arrangement are not limited thereto.

  An ignition plug 12, an injector 14 that directly injects fuel into the cylinder, and an in-cylinder pressure sensor 16 for detecting in-cylinder pressure (combustion pressure) are attached to each cylinder of the engine 10. Further, a crank angle sensor 18 for detecting a rotation angle of the crankshaft (hereinafter referred to as a crank angle CA) is attached to the engine 10. The present invention is not limited to an in-cylinder injection engine, but can be applied to a port injection engine that injects fuel into an intake port, and an engine that uses both an in-cylinder injection type and a port injection type. .

  An intake passage 20 connected to each cylinder is provided in the intake system of the engine 10. An air cleaner 22 is provided at the inlet of the intake passage 20. An air flow meter 24 for detecting the flow rate of air taken into the intake passage 20 (hereinafter referred to as intake air amount Ga) is attached downstream of the air cleaner 22. An electronically controlled throttle valve 26 is provided downstream of the air flow meter 24. A surge tank 28 is provided downstream of the throttle valve 26. An intake pressure sensor 54 for detecting the intake pressure Pim is attached in the vicinity of the surge tank 28. Further, the engine 10 is provided with a blow-by gas reduction device (not shown) for introducing blow-by gas into the surge tank 28.

  An exhaust passage 32 connected to each cylinder is provided in the exhaust system of the engine 10. A catalyst 34 is provided in the exhaust passage 32. As the catalyst, for example, a three-way catalyst, a NOx catalyst, or the like is used. The exhaust passage 32 is provided with an EGR passage 36 connected to the intake passage 20. An EGR cooler 38 and an EGR valve 40 are provided in the EGR passage 36.

  An ECU (Electronic Control Unit) 50 is provided in the control system of the engine 10. Various sensors such as the in-cylinder pressure sensor 16, the crank angle sensor 18, the air flow meter 24, and the intake pressure sensor 54 are connected to the input unit of the ECU 50. Further, various actuators such as the ignition plug 12, the injector 14, the throttle valve 26, and the EGR valve 40 described above are connected to the output portion of the ECU 50. The ECU 50 controls the operating state of the engine 10 by executing predetermined programs based on input information from various sensors and operating various actuators.

[Characteristic Processing in Embodiment 1]
Incidentally, in the system configuration described above, a part of engine oil (hereinafter simply referred to as oil) is returned to the intake system together with blow-by gas. Therefore, oil accumulates in the intake system of the engine 10 due to changes over time. If the accumulated oil flows into the cylinder, the cylinder pressure rises due to combustion. If a large amount of oil is introduced, the in-cylinder pressure will increase greatly, and there is a concern that the operating condition will deteriorate due to abnormal combustion such as knocking. For this reason, it is desired to grasp a sign of abnormal combustion in order to perform control for suppressing deterioration of the operating state.

  An outline of control of this embodiment that solves such a problem will be described with reference to FIGS. FIG. 2 is a relationship diagram showing the relationship between the ignition timing and the in-cylinder pressure. A broken line 60a and a solid line 60b represent the ignition timing (MBT) at which the torque is maximum. A broken line 62a and a solid line 62b represent the knocking limit ignition timing (TK) that is the maximum advance angle at which knocking does not occur. In the system of the present embodiment, the operation is performed according to the ignition timing indicated by the solid line 60b and the solid line 62b.

  As described above, if oil accumulates in the intake system, the amount of oil flowing into the cylinder also increases. Therefore, the margin for knocking also decreases as shown by the broken line 62c in FIG. As a result, knocking is likely to occur in the operation in accordance with the ignition timing indicated by the solid line 60b and the solid line 62b described above.

  FIG. 3 is a relationship diagram showing the relationship between the amount of oil accumulated in the intake system and the knocking occurrence rate. As shown in FIG. 3, the knocking occurrence rate rapidly increases when the amount of oil accumulated in the intake system exceeds a certain amount. The reason for this will be described with reference to FIG. FIG. 4 is a relationship diagram showing the relationship between the oil particle size and the occurrence rate of abnormal combustion (including knocking). When oil accumulates in the intake system, the oil particle size increases as the amount of oil flowing into the cylinder increases. When the particle size of the oil becomes large to some extent, the incidence of abnormal combustion suddenly increases (FIG. 4). Therefore, as shown in FIG. 3, when the amount of oil accumulated in the intake system exceeds a certain amount, the occurrence rate of knocking increases rapidly.

  On the other hand, according to FIG. 3 and FIG. 4, while the amount of oil accumulated in the intake system is small and the oil particle size flowing into the cylinder is small, it gradually rises with a low knocking occurrence rate. Therefore, in the system of the present embodiment, while the amount of oil accumulated in the intake system is small and the oil particle size flowing into the cylinder is small, the change in the cylinder pressure (combustion pressure) is observed, and abnormal combustion is detected from the fluctuation. We decided to grasp the signs.

  A method for grasping a sign of abnormal combustion more specifically will be described with reference to FIG. FIG. 5 is a diagram showing a combustion pressure probability distribution at a predetermined load before and after a change with time. A broken line 64a represents a combustion pressure probability distribution before the change with time in which oil is not accumulated in the intake system. A solid line 64b represents the combustion pressure probability distribution after change with time in which oil has accumulated in the intake system. A solid line 64c represents a change in the combustion pressure probability distribution before and after the change with time. This change is considered to be mainly due to an increase in the amount of oil accumulated in the intake system. If the amount of oil accumulated in the intake system increases, the amount of oil flowing into the cylinder and the oil particle size increase, and the combustion pressure is biased toward the high pressure side. Even if the load is equal, the combustion pressure varies, but if the probability that the combustion pressure exceeds the upper limit reliability value α taking this variation into consideration is higher than a predetermined threshold, a sign of abnormal combustion ((future knocking) It is possible to determine that there is a sudden increase).

(Abnormality detection routine)
FIG. 6 is a flowchart of an abnormality detection routine executed by the ECU 50 in order to realize the above-described operation. In the routine shown in FIG. 6, first, in step 100, it is determined whether or not a predetermined time has elapsed. The predetermined time is, for example, 1 trip (time from starting the engine to stopping the engine after operation). If the predetermined time has not elapsed, the processing of this routine is terminated, and it is determined in the next routine whether or not the predetermined time has further elapsed.

  On the other hand, if the predetermined time has elapsed, it is determined in step 110 whether or not the vehicle is in steady running. For example, when it is a predetermined load and the engine rotational speed NE (the rotational speed per unit time), it is determined that the vehicle is in steady running. The load is calculated based on, for example, the intake air amount Ga, the intake pressure Pim, the in-cylinder volume V, and the like. The engine speed NE is calculated from the crank angle CA detected by the crank angle sensor 18. If it is not steady running, the routine is terminated.

  On the other hand, in the case of steady running, next, in a vehicle employing CVT or HV, the engine speed NE is fixed in order to secure N number (number of samples) for the processing of step 130 ( Step 120).

  Subsequently, a combustion pressure probability distribution at a predetermined load is calculated (step 130). Specifically, the ECU 50 determines a load (for example, a high load), and detects the combustion pressure at the load by the in-cylinder pressure sensor 16. Then, the ECU 50 calculates a combustion pressure probability distribution as shown by the solid line 64b in FIG. 5 from the set of combustion pressures detected by the cylinder pressure sensor 16 (hereinafter referred to as a detected combustion pressure probability distribution).

  Thereafter, in step 140, it is determined whether or not the combustion pressure average value of the detected combustion pressure probability distribution (correlated to the output average value in FIG. 5) is higher than the reference average value. The ECU 50 stores the average value of the combustion pressure corresponding to the load used in step 130 in a state where oil is not accumulated in the intake system (for example, when it is new) as the reference average value. When the combustion pressure average value of the detected combustion pressure probability distribution is less than or equal to the reference average value, it can be determined that the oil has not accumulated in the intake system so that the oil flows into the cylinder, so the processing of this routine ends. Is done.

  On the other hand, when the combustion pressure average value of the detected combustion pressure probability distribution is larger than the reference average value, the probability that the combustion pressure exceeds the upper limit reliability value α in the detected combustion pressure probability distribution is higher than the threshold value β. Is determined (step 150). The upper limit reliability value α is an upper limit value of the combustion pressure variation that can be determined to be normal combustion according to the load. The ECU 50 stores, for example, a value obtained by adding 3σ to the reference average value as the upper limit reliability value α. Further, the ECU 50 stores, as the threshold value β, for example, a probability (region 64d in FIG. 5) that the combustion pressure corresponding to the load is higher than the upper limit reliability value α in a state where oil is not accumulated in the intake system. . When the probability that the combustion pressure exceeds the upper limit reliability value α is equal to or less than the threshold value β, the processing of this routine is ended.

  On the other hand, when the probability that the combustion pressure exceeds the upper limit reliability value α is higher than the threshold value β, it can be determined that the rate at which the in-cylinder pressure becomes high and the occurrence probability of abnormal combustion has increased. The predictive flag abcom is turned ON.

  Further, in the detected combustion pressure probability distribution, the amount of oil accumulated in the intake system is calculated from the probability that the combustion pressure exceeds the upper limit reliability value α (step 170). Specifically, the ECU 50 stores a combustion pressure probability distribution (hereinafter referred to as a reference combustion pressure probability distribution) corresponding to the above-described load in a state where oil is not accumulated in the intake system. Then, the ECU 50 calculates the difference (region 64e in FIG. 5) between the probability that the combustion pressure exceeds the upper limit reliability value α in the detected combustion pressure probability distribution and the probability that the combustion pressure exceeds the upper limit reliability value α in the reference combustion pressure probability distribution. calculate. Further, the ECU 50 stores a map that defines the amount of oil accumulated in the intake system based on the difference. The ECU 50 calculates the oil accumulation amount corresponding to the difference and the increase amount based on the map.

  As described above, according to the routine shown in FIG. 6, the probability that the combustion pressure exceeds the upper limit reliability value α is higher than the threshold value β in the detected combustion pressure probability distribution after oil has accumulated in the intake system due to a change over time. In this case, the abnormal combustion sign flag abcom can be turned on. For this reason, in the system of the present embodiment, by observing the fluctuation of the combustion pressure probability distribution, it is possible to detect the sign before abnormal combustion rapidly increases. For this reason, it is possible to implement control for preventing future abnormal combustion in advance in another routine.

  Further, according to the routine shown in FIG. 6, the amount of oil accumulated in the intake system can be calculated. As described with reference to FIGS. 3 and 4, when the amount of oil accumulated in the intake system exceeds a certain amount, the particle size of the oil flowing into the cylinder increases and the knocking occurrence rate increases rapidly. Therefore, by grasping the oil accumulation amount, it is possible to grasp the likelihood of occurrence of abnormal combustion, and it is possible to carry out control for preventing abnormal combustion more appropriately.

  By the way, in the system of the first embodiment described above, when detecting an abnormal combustion sign, the abnormal combustion sign flag is turned on and the amount of oil accumulated in the intake system is calculated. It is good also as detecting the sign of abnormal combustion only with a flag.

  By the way, in the system of the first embodiment described above, the amount of oil accumulated in the intake system is calculated using the reference combustion pressure probability distribution and the detected combustion pressure probability distribution. It is not limited. For example, it may be calculated using the detected combustion pressure probability distribution and the threshold value β. Specifically, the difference (the region 64e in FIG. 5) between the probability that the combustion pressure exceeds the upper limit reliability value α and the threshold value β in the detected combustion pressure probability distribution is calculated, and the map described in step 170 based on the difference. Alternatively, the amount of oil accumulated in the intake system may be calculated. The threshold value β is set with a probability (region 64d in FIG. 5) that the combustion pressure corresponding to the load becomes higher than the upper limit reliability value α in a state where no oil is accumulated in the intake system. And

In the first embodiment described above, the in-cylinder pressure sensor 16 is the “in-cylinder pressure sensor” in the first invention, and the ECU 50 is the “upper limit reliability value storage means” and the second invention in the first invention. Corresponds to “reference combustion pressure probability distribution storage means” in FIG.
In addition, here, the ECU 50 executes the process of step 130, so that the “detected combustion pressure probability distribution calculating means” in the first aspect of the invention executes the processes of steps 150 to 160. The “abnormal combustion predictor flag setting means” in the present invention implements the “intake system oil accumulation amount calculating means” in the second invention by executing the processing of step 170 described above.
Further, in the first embodiment, the upper limit reliability value α used in step 150 is the “upper limit reliability value” in the first invention, and the threshold value β used in step 150 is the “threshold value in the first invention”. ”Respectively.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 9 described later in the configuration shown in FIG. In the system of the present embodiment, a knock sensor 52 for detecting the knock level is connected to the input unit of the ECU 50.

[Characteristic Processing in Embodiment 2]
In the first embodiment described above, the amount of oil accumulated in the intake system is determined based on the probability that the combustion pressure exceeds the upper limit reliability value α in the detected combustion pressure probability distribution and the combustion pressure exceeds the upper limit reliability value α in the reference combustion pressure probability distribution. It is calculated based on the difference from the probability (region 64e in FIG. 5).

  However, as an influence factor of knocking, in-cylinder deposits can be considered in addition to oil. FIG. 7 is a diagram for explaining the degree of influence of the amount of oil flowing into the cylinder and the amount of deposit in the cylinder on knocking. As shown in FIG. 7, the effect on knocking is initially greatly influenced by an increase in oil, but after the effect of oil has converged, the effect of in-cylinder deposits also increases. Therefore, in order to calculate the amount of oil accumulated in the intake system with high accuracy, it is desirable to remove the influence of this in-cylinder deposit.

  Next, a method for removing the influence of in-cylinder deposits will be described. FIG. 8 is a diagram for explaining the relationship between the ignition timing and the in-cylinder temperature. A broken line 66a indicates the maximum in-cylinder pressure Pmax before the ignition timing is advanced. A solid line 66b indicates the maximum in-cylinder pressure Pmax after the ignition timing is advanced. As shown in FIG. 8, the maximum in-cylinder pressure Pmax can be increased by advancing the ignition timing. By increasing the maximum in-cylinder pressure Pmax, the in-cylinder temperature can be increased. By raising the in-cylinder temperature, the in-cylinder deposit can be burned out.

  Therefore, in the system of the present embodiment, the amount of oil accumulated in the intake system is calculated with high accuracy by comparing the combustion pressure probability distribution before and after the ignition timing is advanced.

(Abnormality detection routine)
FIG. 9 is a flowchart of an abnormality detection routine executed by the ECU 50 in order to realize the above-described function. In the routine shown in FIG. 9, first, in step 200, a probability distribution (hereinafter referred to as a reference combustion pressure probability distribution) based on a set of combustion pressures corresponding to a predetermined load in a state where no oil is accumulated in the intake system is acquired. Is done. The ECU 50 stores a reference combustion pressure probability distribution in advance. Note that the reference combustion pressure probability distribution may be calculated and stored in the ECU 50 during operation at a predetermined load.

  Next, in step 210, it is determined whether or not a predetermined time has elapsed. The ECU 50 stores, as a predetermined time, a time (a time indicated by time a in FIG. 7) in which a certain amount of deposit is accumulated in the cylinder due to aging. As an example, when the accumulated operation time in the deposit generation region has exceeded several tens of hours, it is determined that a predetermined time has elapsed. If the predetermined time has not elapsed, the processing of this routine is terminated, and it is determined in the next routine whether or not the predetermined time has elapsed.

  On the other hand, if the predetermined time has elapsed, then the combustion pressure probability distribution at a predetermined load is calculated (step 220). Specifically, the ECU 50 detects the combustion pressure at a predetermined load (equivalent to the load in the reference combustion pressure probability distribution) by the in-cylinder pressure sensor 16. Then, the ECU 50 calculates a combustion pressure probability distribution as shown by the solid line 64b in FIG. 5 from the detected N number of combustion pressures (hereinafter referred to as a detected combustion pressure probability distribution).

  Subsequently, in step 230, it is determined whether or not the determination conditions in steps 140 and 150 described above are satisfied. Since these determination conditions are as described in the first embodiment, the description thereof is omitted here. If at least one of the determination conditions of step 140 and step 150 described above is not satisfied, the process of this routine is terminated.

  On the other hand, when the determination condition of step 230 is satisfied, the ECU 50 turns on the abnormal combustion sign flag abcom (step 235). In step 240, the ignition timing is advanced. The ECU 50 stores an advance amount that causes a small knock as the advance amount.

  Thereafter, in step 250, it is determined whether or not the maximum in-cylinder pressure Pmax increased by the advance angle is lower than the design value. If the detected maximum in-cylinder pressure Pmax is greater than or equal to the design value, the ignition timing is retarded to prevent engine damage (step 255).

  On the other hand, if the detected maximum in-cylinder pressure is lower than the design value, it is subsequently determined whether the knock level is lower than the specified value (step 260). If the knock level detected by knock sensor 52 is equal to or higher than a predetermined value determined by experiments or the like, the ignition timing is retarded to prevent engine damage (step 255).

  On the other hand, if the knock level is lower than the specified value, it is subsequently determined whether or not a predetermined time has passed (step 265). As the predetermined time, the ECU 50 sets a time for detecting the N number of combustion pressures when the ignition timing is advanced. The ECU 50 detects N number of combustion pressures at a predetermined load (equivalent to the load in step 220) by the in-cylinder pressure sensor 16. If the predetermined time has not elapsed, the processes of steps 240 to 265 are repeated.

  On the other hand, if the predetermined time has elapsed, in step 270, the combustion pressure probability distribution is calculated from the N combustion pressures detected by advancing the ignition timing (hereinafter referred to as post-advance detection combustion pressure probability distribution). That said.)

  In step 275, the amount of oil accumulated in the intake system is calculated. Specifically, the ECU 50 calculates a difference γ of the probability that the combustion pressure exceeds the upper limit reliability value α in the post-advance detection combustion pressure probability distribution and the reference combustion pressure probability distribution. The ECU 50 stores a map that defines the amount of oil accumulated in the intake system based on the difference γ. Based on this map, the ECU 50 calculates an oil accumulation amount corresponding to the difference γ and an increase amount thereof.

  Further, in step 280, the in-cylinder deposit amount is calculated. Specifically, the ECU 50 calculates a difference δ of the probability that the combustion pressure exceeds the upper limit reliability value between the post-advance detection combustion pressure probability distribution and the detected combustion pressure probability distribution. The ECU 50 stores a map that determines the in-cylinder deposit amount based on the difference δ. Based on this map, the ECU 50 calculates the in-cylinder deposit amount and the increase amount corresponding to the difference δ.

  As described above, according to the routine shown in FIG. 9, even if oil accumulates in the intake system due to secular change and deposits accumulate in the cylinder, the ignition timing is advanced to advance the cylinder. Deposit can be burned out. By burning out the in-cylinder deposit, the influence of the in-cylinder deposit can be eliminated, and the amount of oil accumulated in the intake system can be calculated with high accuracy. In addition, the in-cylinder deposit amount can be calculated with high accuracy from the combustion pressure probability distribution before and after the advance angle. Thus, in the system of the present embodiment, the oil accumulation amount and the in-cylinder deposit amount can be grasped with high accuracy. For this reason, it is possible to implement control for preventing future abnormal combustion in advance in another routine.

  In the second embodiment described above, the ECU 50 corresponds to the “reference combustion pressure probability distribution storage means” in the third invention. Further, here, the ECU 50 executes the process of step 240, so that the “ignition timing advance means” in the third invention executes the process of step 270. When the post-advance detection combustion pressure probability distribution calculating means ”executes the process of step 275, the“ intake system oil accumulation amount calculating means ”according to the third aspect of the invention executes the process of step 280. The “in-cylinder deposit amount calculation means” in the third aspect of the invention is realized.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 11 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 3]
In the second embodiment described above, in the processes of steps 210 to 240 in FIG. 9, the ignition timing is advanced on the condition that a predetermined time has passed. However, if such control is frequently performed, there is a concern about deterioration of drivability and fuel consumption. Therefore, it is desirable to optimize the implementation time.

  Next, a control outline of the present embodiment for optimizing the execution time will be described with reference to FIG. FIG. 10 is a relational diagram showing the relationship between the execution interval of the abnormality detection routine (FIG. 9) in Embodiment 2 and the in-cylinder deposit amount. Each point shown in FIG. 10 is an actual calculated value of the in-cylinder deposit amount calculated in step 280 of FIG. 9 at a predetermined execution interval. If the abnormality detection routine (FIG. 9) in the second embodiment is performed at the time when the in-cylinder deposit amount is equal to or greater than the threshold value using the approximate line 68 of these actual calculation values, the implementation can be minimized. it can.

(Abnormality detection routine)
FIG. 11 is a flowchart of an abnormality detection routine executed by the ECU 50 in order to realize the above-described function. This routine is executed after the abnormality detection routine (FIG. 9) of the second embodiment is executed. In the routine shown in FIG. 11, first, in step 300, it is determined whether or not the abnormality detection routine (FIG. 9) of the second embodiment is being performed. If the determination condition is not satisfied, the process of this routine is terminated.

  On the other hand, when the abnormality detection routine of the second embodiment (FIG. 9) is being executed, the execution interval of the abnormality detection routine is calculated (step 310). Subsequently, the in-cylinder deposit amount is acquired (step 320). This in-cylinder deposit amount is a value calculated by the processing of step 280 in FIG.

  Next, the ECU 50 plots the relationship between the execution interval calculated in step 310 and the in-cylinder deposit amount calculated in step 320 on the relationship map shown in FIG. 10 (step 330). The ECU 50 stores a relationship map shown in FIG.

  It is determined whether or not the number of plots is greater than a predetermined value (step 340). The predetermined number is a value that correlates with the accuracy of the approximate line 68 shown in FIG. If the number of plots is still below the predetermined value, the relationship between the execution interval and the in-cylinder deposit amount is plotted in the relationship map shown in FIG.

  On the other hand, when the number of plots is greater than the predetermined value, the execution interval at which the in-cylinder deposit amount is equal to or greater than the threshold ε is calculated from the approximate line 68 in FIG. 10 (step 350). The ECU 50 stores, as the threshold value ε, a value at which the influence of in-cylinder deposits determined in advance through experiments or the like becomes significant.

  Then, the predetermined time of step 210 in FIG. 9 is set according to the execution interval calculated in step 350 (step 360). Based on the newly set predetermined time, the processing after step 220 in FIG. 9 is executed.

  As described above, according to the routine shown in FIG. 11, it is possible to set the execution timing of the abnormality detection routine (FIG. 9) of the second embodiment in which the in-cylinder deposit amount is equal to or greater than the threshold value ε. Therefore, it is possible to minimize the execution time of the abnormality detection routine of the second embodiment. For this reason, in the system of this embodiment, optimization of an implementation time can be achieved and deterioration of drivability and fuel consumption can be suppressed.

  In the third embodiment described above, the ECU 50 corresponds to the “actual relationship storage means” in the fourth aspect of the invention. In addition, here, the ECU 50 executes the process of step 350 above, so that the “implementation interval acquisition means” in the fourth invention executes the process of step 360 above, thereby performing the “ignition” in the fourth invention. Each “time advance means” is realized. Further, in the third embodiment, the threshold value ε in step 350 corresponds to the “in-cylinder deposit threshold value” in the fourth invention.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute the routine of FIG. 13 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 4]
In the first and second embodiments described above, a sign of abnormal combustion can be grasped based on a change in the combustion pressure probability distribution. It is desirable to implement control to prevent future abnormal combustion in advance based on the known signs of abnormal combustion

  Next, an outline of control for preventing abnormal combustion will be described with reference to FIG. First, the phenomenon in which abnormal combustion occurs when oil ignites is determined by the heat source (oil energy), the ambient temperature, and the time. Here, the heat source correlates with the amount of oil flowing into the cylinder and the oil particle size. The ambient temperature is the in-cylinder temperature and correlates with the in-cylinder air amount and the internal EGR. This internal EGR correlates with the valve timing of the intake and exhaust valves. The time correlates with the engine speed NE.

  FIG. 12 is a relationship diagram showing the relationship between the amount of oil flowing into the cylinder, the oil particle size, the ambient temperature, and the occurrence probability of abnormal combustion. As shown in FIG. 12, the probability of occurrence of abnormal combustion is determined based on the in-cylinder oil amount and the oil particle size at a certain in-cylinder temperature. Therefore, in the system of the present embodiment, the occurrence probability of abnormal combustion is controlled to a predetermined value or less using the relationship shown in FIG.

(Control routine)
FIG. 13 is a flowchart of a control routine executed by the ECU 50 in order to realize the above function. This routine is executed after the abnormality detection routine of FIG. 6 or FIG. 9 is performed. In the routine shown in FIG. 13, first, in step 400, it is determined whether or not the abnormal combustion sign flag abcom is ON. When the abnormal combustion predictor flag abcom is OFF, the process of this routine is ended.

  On the other hand, if the abnormal combustion sign flag abcom is ON, it is next determined whether or not the current engine speed NE is equal to or lower than a predetermined engine speed (step 410). The ECU 50 calculates the engine speed NE from the signal CA of the crank angle sensor 18. Moreover, ECU50 has memorize | stored the rotation speed which shows a low rotation area | region as predetermined rotation speed. If the current engine speed NE is higher than the predetermined engine speed, the routine is terminated.

  On the other hand, when the current engine speed NE is equal to or lower than the predetermined engine speed, the load is subsequently read (step 420). The load is calculated based on, for example, the intake air amount Ga, the intake pressure Pim, the in-cylinder volume V, and the like.

  The in-cylinder temperature from the load read in step 420 to the compression end is estimated (step 430). The in-cylinder temperature up to the compression end is calculated by using a well-known adiabatic compression formula using in-cylinder pressure, intake air temperature, in-cylinder volume V, and the like as parameters.

  Next, the flow velocity in the surge tank 28 is acquired from the load read in step 420 (step 440). FIG. 14B is a relationship map showing the relationship between the load and the flow velocity in the surge tank. As the intake air amount Ga increases, the load increases and the flow velocity also increases. The ECU 50 stores the relationship map shown in FIG. 14B, and acquires the flow velocity corresponding to the load from this relationship map.

  Further, the oil particle size of the oil flowing into the cylinder is acquired from the flow velocity acquired in step 440 (step 450). FIG. 14A stores a relationship map showing the relationship between the flow velocity and the oil particle size. As described above, the flow rate increases with load. If the flow velocity increases, the amount of oil accumulated in the intake system is increased in the cylinder, and the oil particle size also increases. The ECU 50 stores a relationship map shown in FIG. 14A, and acquires the oil particle size corresponding to the flow velocity from the relationship map.

  Next, the amount of oil flowing into the cylinder is calculated (step 460). Specifically, the ECU 50 acquires the amount of oil accumulated in the intake system calculated in the abnormality detection routine shown in FIG. Further, the ECU 50 stores a map in which the amount of oil accumulated in the intake system, the amount of in-cylinder oil corresponding to the flow velocity / load is determined. From this map, the in-cylinder oil amount corresponding to the amount of oil accumulated in the intake system and the flow velocity / load is calculated.

  Subsequently, it is determined whether or not the occurrence probability of abnormal combustion is higher than a predetermined value (step 470). Specifically, the ECU 50 stores the relationship map shown in FIG. 12 described above for each in-cylinder temperature. From this relationship map, the ECU 50 acquires the probability of occurrence of abnormal combustion in accordance with the in-cylinder temperature calculated in step 430, the oil particle size acquired in step 450, and the oil amount acquired in step 460. Thereafter, it is determined whether or not the acquired probability of occurrence of abnormal combustion is higher than a predetermined value. If the occurrence probability of abnormal combustion is equal to or less than a predetermined value, the routine is terminated.

  On the other hand, when the occurrence probability of abnormal combustion is higher than a predetermined value, the opening degree of throttle valve 26 is subsequently changed so that the occurrence probability becomes equal to or less than the predetermined value (step 480). As described above, as the load increases, the amount of oil flowing into the cylinder and the oil particle size increase, so the throttle opening is limited to reduce the load. Further, the engine speed is changed so that the output is constant (step 490). The ECU 50 stores an operation map in which output characteristics are determined according to the load (correlated to the throttle opening) and the rotational speed. Based on this operation map, the load that satisfies the required output and the engine speed are calculated.

  As described above, according to the routine shown in FIG. 13, it is possible to control the occurrence probability of abnormal combustion below a predetermined value by changing the load and the engine speed. In particular, abnormal combustion due to inflow of oil into the cylinder is likely to occur at a low rotation and high load, so that the use at a low rotation and high load can be limited by this routine. For this reason, in the system according to the present embodiment, it is possible to prevent unburned abnormal combustion and to prevent engine damage.

  By the way, in the system of the fourth embodiment described above, the control routine of FIG. 13 is executed after the abnormality detection routine of FIG. 6, FIG. 9 or FIG. It may be executed alone without assuming a routine. This point is the same in the following embodiments.

  In the above-described fourth embodiment, the ECU 50 executes the processing of steps 450 to 460, whereby the “cylinder oil calculation means” in the fifth aspect of the invention executes the processing of step 470. Thus, the “abnormal combustion probability calculating means” in the fifth invention realizes the “load reducing means” in the fifth invention by executing the processing of step 480.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 16 described later in the configuration shown in FIG. Note that the system of the present embodiment is provided with a variable valve mechanism 56 for adjusting the opening and closing timing of the intake valve and the exhaust valve. The variable valve mechanism 56 is connected to the output unit of the ECU 50.

[Characteristic Control in Embodiment 5]
In the above-described third embodiment, it is possible to limit the use of the oil accumulated in the intake system at a low rotation and high load where abnormal combustion due to oil inflow into the cylinder easily occurs. However, as a result of this limitation, it is also conceivable that areas where smoke (white smoke) is generated are used. In addition, since oil remains accumulated in the intake system, the use load is limited unless it is removed. Therefore, in the system of the present embodiment, control is performed to reduce oil accumulated in the intake system while suppressing abnormal combustion.

  Next, a control outline of the present embodiment for reducing oil accumulated in the intake system while suppressing abnormal combustion will be described with reference to FIG. FIG. 15 is a relationship diagram showing the relationship between the abnormal combustion, pre-ignition, insufficient flow velocity, smoke (white smoke) generation region and operation line in a state where oil is accumulated in the intake system. A broken line represents an iso-output line. As shown in FIG. 15, abnormal combustion and pre-ignition occur on the operation line 70. Therefore, in this embodiment, the operation by the operation line 72 is performed in order to avoid abnormal combustion, pre-ignition, and smoke. By the way, in the operation | movement by the operation line 72, a light load will be used and a flow velocity will fall. Therefore, in this embodiment, control for increasing the flow rate is further added to reduce oil accumulated in the intake system by scavenging.

(Control routine)
FIG. 16 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described function. In the routine shown in FIG. 16, first, in step 500, it is determined whether or not the control routine of the fourth embodiment (FIG. 13) has been executed. If the determination condition is not satisfied, the process of this routine is terminated.

  On the other hand, when the determination condition is satisfied, the load is reduced by the control routine of FIG. Subsequently, it is determined whether or not the operation region is a smoke generation region (step 510). The ECU 50 stores a relationship map shown in FIG. 15, and in this relationship map, occurrence regions for abnormal combustion, pre-ignition, smoke, and the like corresponding to the engine speed NE and the load are defined. The ECU 50 determines whether or not the operation region is a smoke generation region from the current engine speed NE and load using this relationship map. When the operation area is not the smoke generation area, the routine is terminated.

  On the other hand, when the operation region is a smoke generation region, the ECU 50 controls the operation according to the operation line 72 by reducing the engine speed NE on the iso-output line shown in FIG. 15 (step 520).

  Next, it is determined whether or not the ambient temperature (in-cylinder temperature) exceeds a predetermined temperature (step 530). The ambient temperature is calculated using the same process as in step 430 in FIG. 13 described above. The ECU 50 stores the in-cylinder temperature at which abnormal combustion is a concern as the predetermined temperature. When the atmospheric temperature is lower than the predetermined temperature, the routine is terminated.

  As described above, in the operation line 72, the flow velocity becomes insufficient at a light load, so that the valve overlap between the intake valve and the exhaust valve in the intake stroke is subsequently reduced (step 540). The ECU 50 controls the opening / closing timing of the intake valve and the exhaust valve by the variable valve mechanism 56 to reduce the valve overlap. At this time, the closing timing on the exhaust valve side is preferentially controlled. The flow velocity can be increased by reducing the valve overlap.

  Thereafter, it is determined whether or not the flow rate has reached the target flow rate (step 550). The flow velocity can be calculated from the intake air amount Ga, the intake pressure Pim, and the like. If the target flow velocity has been reached, the process returns to step 510 and subsequent steps. If the determination condition in step 510 or step 530 is not satisfied, the process of this routine is terminated.

  On the other hand, if it is determined in step 550 that the flow velocity has not reached the target flow velocity, then the ECU 50 controls the EGR valve 40 to increase the EGR valve opening (step 560). By increasing the EGR valve opening, the flow velocity can be further increased.

  Subsequently, it is determined whether or not the output fluctuation amount is within the allowable value TF (step 570). The output fluctuation amount is calculated based on, for example, the load and the rotation speed. The ECU 50 stores, for example, a design value determined in consideration of drivability and fuel consumption deterioration as the allowable value TF. If the output fluctuation amount is within the permissible value TF, the process returns to step 510 and subsequent steps. If the determination condition in step 510 or step 530 is not satisfied, the process of this routine is terminated.

  On the other hand, when the output fluctuation amount exceeds the allowable value TF, the EGR valve opening is reduced (step 580). Thereafter, the processing returns to step 510 and subsequent steps, and if the determination condition of step 510 or step 530 is not satisfied, the processing of this routine is terminated.

As described above, according to the routine shown in FIG. 16, abnormal combustion, preignition, and smoke can be avoided by operating on the operation line 72 in a state where oil is accumulated in the intake system. In addition, by reducing the valve overlap, the internal EGR can be reduced and the flow rate can be increased. By increasing the flow velocity, the oil accumulated in the intake system can be scavenged. In addition, according to the routine shown in FIG. 16, the flow rate can be further increased by increasing the EGR valve opening.
For this reason, in the system of the present embodiment, it is possible to reduce oil accumulated in the intake system even at a light load while suppressing the occurrence of abnormal combustion, smoke, and the like. In addition, a reduction in fuel consumption can be suppressed.

  In the fifth embodiment described above, the “flow velocity increasing means” in the sixth aspect of the present invention is realized by the ECU 50 executing at least one of the steps 540 and 560.

10 Engine 16 In-cylinder pressure sensor 18 Crank angle sensor 24 Air flow meter 26 Throttle valve 28 Surge tank 40 EGR valve 50 ECU
52 Knock sensor 54 Intake pressure sensor 56 Variable valve mechanism 68 Approximate line 70, 72 Operation line abcom Abnormal combustion predictor flag

Claims (6)

An in-cylinder pressure sensor for detecting the in-cylinder combustion pressure;
Upper limit reliability value storage means for storing an upper limit reliability value of the combustion pressure according to a predetermined load in a state where no oil is accumulated in the intake system;
Detected combustion pressure probability distribution calculating means for calculating a probability distribution of combustion pressure (hereinafter referred to as detected combustion pressure probability distribution) from a set of combustion pressures detected by the in-cylinder pressure sensor during operation at the load;
In the detected combustion pressure probability distribution, when the probability that the combustion pressure exceeds the upper limit reliability value is higher than a threshold value, an abnormal combustion predictor flag setting unit that turns on an abnormal combustion predictor flag;
An abnormality detection device for an internal combustion engine, comprising: A reference combustion pressure probability distribution storage means for storing a probability distribution (hereinafter referred to as a reference combustion pressure probability distribution) based on a set of combustion pressures corresponding to the load in a state where no oil is accumulated in the intake system;
An intake system oil that calculates a difference in probability that the combustion pressure exceeds the upper limit reliability value in the detected combustion pressure probability distribution and the reference combustion pressure probability distribution, and calculates an amount of oil accumulated in the intake system based on the difference A deposit amount calculating means;
The abnormality detection device for an internal combustion engine according to claim 1, further comprising: A reference combustion pressure probability distribution storage means for storing a probability distribution (hereinafter referred to as a reference combustion pressure probability distribution) based on a set of combustion pressures corresponding to the load in a state where no oil is accumulated in the intake system;
Ignition timing advance means for advancing the ignition timing when the probability that the combustion pressure exceeds the upper limit reliability value is higher than the threshold in the detected combustion pressure probability distribution;
After the ignition timing is advanced by the ignition timing advance means, the probability distribution of the combustion pressure (hereinafter referred to as post-advance detection combustion pressure) from the set of combustion pressures detected by the in-cylinder pressure sensor during operation with the load. A post-advance detection combustion pressure probability distribution calculating means for calculating a probability distribution),
In the post-advance detection combustion pressure probability distribution and the reference combustion pressure probability distribution, a difference in probability that the combustion pressure exceeds the upper limit reliability value is calculated, and the amount of oil accumulated in the intake system is calculated based on the difference. Intake system oil accumulation amount calculating means;
In-cylinder deposit for calculating the difference in the probability that the combustion pressure exceeds the upper limit reliability value in the post-advance detection combustion pressure probability distribution and the detected combustion pressure probability distribution, and calculating the in-cylinder deposit amount based on the difference A quantity calculating means;
The abnormality detection device for an internal combustion engine according to claim 1, further comprising: An actual relationship storage means for storing an actual relationship between the execution interval of the ignition timing advance means and the in-cylinder deposit amount calculated by the in-cylinder deposit amount calculation means;
From the actual relationship, comprising an execution interval acquisition means for acquiring an execution interval corresponding to the in-cylinder deposit threshold,
The ignition timing advance means is after the execution interval acquired by the execution interval acquisition means has elapsed and the probability that the combustion pressure exceeds the upper limit reliability value in the detected combustion pressure probability distribution is higher than the threshold value To advance the ignition timing,
The abnormality detection device for an internal combustion engine according to claim 3. An abnormality detection device for an internal combustion engine according to any one of claims 1 to 4,
In-cylinder oil calculating means for calculating the amount of oil flowing into the cylinder and its oil particle size,
From the relationship between the amount of oil flowing into the cylinder, the oil particle size, and the abnormal combustion occurrence probability, the abnormal combustion occurrence probability corresponding to the oil amount calculated by the in-cylinder oil calculating means and the oil particle size is calculated. An abnormal combustion probability calculating means;
A load reducing means for reducing a load when the abnormal combustion occurrence probability calculated by the abnormal combustion probability calculating means is higher than a predetermined value;
A control device for an internal combustion engine, comprising:   6. The control apparatus for an internal combustion engine according to claim 5, further comprising a flow speed increasing means for increasing a flow speed of the intake gas flowing through the intake system when the load is reduced by the load reducing means.

Images