JP2008267293A - Control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of restraining sticking of a deposit to a component in a combustion chamber, while avoiding influence on operation performance of an internal combustion engine. <P>SOLUTION: This invention relates to a control system of the internal combustion engine capable of advancing the ignition timing forward more than MBT being the ignition timing becoming substantially maximum in torque in the internal combustion engine. The fact of sticking the deposit to a spark plug is detected by satisfying a condition that starting-stopping in cold time is continuously performed by N1 times or more (S101) and the cooling water temperature is the predetermined temperature T1 or below (S102). When detecting the sticking of the deposit to the spark plug, a peak value of the temperature in the combustion chamber is raised by excessively advancing the ignition timing forward more than the MBT, and the deposit is oxidized and removed (S103). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a system for controlling a spark ignition type internal combustion engine, and more particularly to a system for removing deposits adhering to a combustion chamber of an internal combustion engine.

  As the internal combustion engine is used, deposits (deposits) that are considered to be incompletely combusted fuel and lubricating oil are known to adhere to and deposit on the combustion chamber wall surface and on the members arranged facing the combustion chamber. ing. This deposit is known to cause a decrease in the operating performance of the internal combustion engine and a deterioration in emissions. For this reason, various techniques for removing deposits accumulated in the combustion chamber have been disclosed.

  For example, in an internal combustion engine having a plurality of cylinders, when deposit adhesion is detected in at least one cylinder based on vibration from a knock sensor, a part of the plurality of cylinders is selected as a target for forced knocking. Technology has been proposed. In this technique, the ignition timing is advanced to forcibly generate knocking to remove deposits (see, for example, Patent Document 1).

  However, in the above technique, the occurrence of knocking is unavoidable in order to remove deposits (deposits), which may adversely affect the drivability of the vehicle.

On the other hand, in a spark ignition type internal combustion engine, the ignition timing is advanced ahead of MBT (Minimum spark advance for Best Torque), thereby promoting an increase in the temperature of the cooling water, thereby increasing the warm-up performance of the internal combustion engine. Techniques for improving are known (see, for example, Patent Document 2). The above-described conventional technology considers the warm-up property of the internal combustion engine, but does not consider the deposit in the combustion chamber.
JP 2006-118483 A JP 2000-240547 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique capable of suppressing the adhesion of deposits to the components in the combustion chamber while avoiding the influence on the operation performance of the internal combustion engine. It is.

  In order to solve the above-described problems, the present invention provides a control system for an internal combustion engine that can advance the ignition timing before MBT, which is the ignition timing at which the torque in the internal combustion engine becomes substantially maximum. The greatest feature is that the peak value of the temperature in the combustion chamber is increased by advancing the ignition timing before MBT when it is detected or estimated that deposits are attached to the components in the chamber. .

More specifically, an over-advance means for advancing the ignition timing of the spark ignition type internal combustion engine before MBT,
Deposit detection means for detecting or estimating the adhesion of deposits to components in the combustion chamber of the internal combustion engine;
Deposit removal means for causing the over-advance angle means to advance the ignition timing ahead of MBT when the deposit detection means detects or estimates deposit adhesion to the components in the combustion chamber;
It is characterized by providing.

  In other words, deposits may adhere to the components in the combustion chamber as the internal combustion engine is used. However, this deposit substantially changes the volume and shape of the combustion chamber itself, resulting in a decrease in operating performance. Or increased noise and worsened emissions. Moreover, it may become an obstacle to the normal operation of the functional parts arranged facing the combustion chamber.

  In contrast, in a spark ignition type internal combustion engine, it is found that the peak value of the in-cylinder temperature can be increased when the ignition timing is advanced to the front of the MBT (hereinafter also referred to as “over-advance angle”). It was done. This is because when the ignition timing is over-advanced, the amount of the air-fuel mixture that burns before the compression top dead center increases. This is thought to be due to a synergistic effect with the temperature effect.

  The control system for an internal combustion engine according to the present invention uses the effect of this over-advanced angle to promote and remove the oxidation of deposits as incompletely combusted substances adhering to the combustion chamber. That is, when deposit adhesion is detected or estimated by the deposit detection means to the components in the combustion chamber, the ignition timing in the internal combustion engine is advanced to a point before MBT to increase the peak value of the in-cylinder temperature, Oxidize the deposit.

  According to this, it is possible to remove deposits adhering to the components in the combustion chamber while suppressing adverse effects on the drivability of the internal combustion engine due to the occurrence of knocking or the like.

  In the present invention, when the ignition timing is over-advanced, the over-advance means means that the ignition timing of the internal combustion engine is earlier than MBT, and the pressure in the cylinder of the internal combustion engine is highest near TDC. You may make it advance to the ignition timing which becomes.

  Here, it is understood that the peak value of the in-cylinder temperature can be substantially maximized when the ignition timing of the internal combustion engine is before MBT and the pressure in the cylinder of the internal combustion engine is maximum near TDC. ing. Therefore, when the ignition timing is over-advanced in the present invention, the ignition timing of the internal combustion engine is advanced before the MBT, and is advanced to an ignition timing at which the pressure in the cylinder of the internal combustion engine becomes maximum near TDC. Therefore, it is possible to more efficiently remove deposits attached to the components in the combustion chamber.

  In the present invention, the component in the combustion chamber may be a spark plug of the internal combustion engine.

  When deposits adhere to the spark plug of an internal combustion engine, the insulation resistance of the spark plug is lowered, and so-called spark plug smoldering may occur. That is, since spark ignition in the spark plug is not performed normally, misfire or instability of ignition timing may occur. In the present invention, when such plug smoldering or plug smoldering may occur, the deposit is removed from the spark plug by over-advancing the ignition timing. As a result, plug smoldering can be avoided or eliminated.

  In the present invention, the component in the combustion chamber may be a direct injection type fuel injection valve that directly injects fuel into the combustion chamber of the internal combustion engine.

When deposits adhere to the direct injection type fuel injection valve of the internal combustion engine, the fuel injection amount and the fuel spray shape change, which may adversely affect the operation performance of the internal combustion engine more directly. Therefore, by removing the deposit of the direct injection type fuel injection valve according to the present invention, it is possible to more reliably suppress the deterioration of the operation performance of the internal combustion engine due to the adhesion of the deposit.

  In the present invention, the components in the combustion chamber include a part constituting the combustion chamber itself such as a cylinder inner wall and a piston top surface, and functional parts arranged facing the combustion chamber. The means for solving the problems in the present invention can be used in combination as much as possible.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesion of the deposit with respect to the component in a combustion chamber can be suppressed, avoiding the influence on the operation performance of an internal combustion engine.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine control system according to the present embodiment.

  An internal combustion engine 1 shown in FIG. 1 is a four-stroke cycle spark ignition type internal combustion engine (gasoline engine) having a plurality of cylinders 2. The cylinder 2 of the internal combustion engine 1 is connected to the intake passage 30 through the intake port 3 and is connected to the exhaust passage 40 through the exhaust port 4.

  The intake passage 30 is provided with a throttle valve 6 that controls the amount of air flowing through the intake passage 30. An intake pressure sensor 7 that measures the pressure (intake pressure) in the intake passage 30 is provided in the intake passage 30 downstream of the throttle valve 6. An air flow meter 8 that measures the amount of air flowing through the intake passage 30 is provided in the intake passage 30 upstream of the throttle valve 6.

  On the other hand, an exhaust purification device 9 is disposed in the exhaust passage 40. The exhaust purification device 9 includes a catalyst such as a three-way catalyst as an exhaust purification catalyst, and purifies exhaust when it is in a predetermined activation temperature range.

  Further, the internal combustion engine 1 is provided with an intake valve 10 that opens and closes an open end of the intake port 3 facing the cylinder 2 and an exhaust valve 11 that opens and closes an open end of the exhaust port 4 facing the cylinder 2. The intake valve 10 and the exhaust valve 11 are driven to open and close by an intake camshaft 12 and an exhaust camshaft 13, respectively.

  A spark plug 14 for igniting the air-fuel mixture in the cylinder 2 is disposed at the upper part of the cylinder 2. Further, a direct injection type fuel injection valve 5 that directly injects fuel into the cylinder 2 is disposed. Further, a piston 15 is slidably inserted into the cylinder 2. The piston 15 is connected to the crankshaft 17 via a connecting rod 16.

  A crank position sensor 18 that detects a rotation angle of the crankshaft 17 is disposed in the vicinity of the crankshaft 17. Furthermore, a water temperature sensor 19 for measuring the temperature of the cooling water circulating through the internal combustion engine 1 is attached to the internal combustion engine 1.

The internal combustion engine 1 configured as described above is provided with an ECU 20. The ECU 20
An electronic control unit including a CPU, ROM, RAM, and the like. The ECU 20 is electrically connected to various sensors such as the air flow meter 8, the intake pressure sensor 7, the crank position sensor 18, and the water temperature sensor 19 described above, and can input measurement values of the various sensors.

  The ECU 20 electrically controls the fuel injection valve 5, the throttle valve 6, the spark plug 14 and the like based on the measurement values of the various sensors described above.

  Here, deposits such as carbon may adhere to the cylinder 2 by the operation of the internal combustion engine 1. When this deposit adheres to the spark plug 14, the insulation resistance of the insulating portion of the spark plug is lowered, so that no spark is normally generated between the electrodes of the plug, and so-called plug smoldering may occur. In particular, when an operation such as stopping the internal combustion engine 1 in a state in which the fuel injection increase is performed after the internal combustion engine 1 is cold started and before it is completely warmed up, the plug smolder As a result, the ignition function of the spark plug 14 is lowered, and the operation performance and startability of the internal combustion engine 1 may be deteriorated.

  Therefore, in this embodiment, the adhesion of the deposit to the spark plug 14 is detected, and when it is detected that the deposit is adhered to the spark plug 14, the ignition timing of the spark plug 14 is advanced to before MBT. The peak value of the in-cylinder temperature in the cylinder 2 is increased, and the deposit is oxidized and removed.

  FIG. 2 is a graph showing how the relationship between various parameters in the cylinder 2 and the crank angle changes depending on the ignition timing in the cylinder 2. The horizontal axis represents the crank angle of the internal combustion engine 1, and the vertical axis represents each parameter in the cylinder 2. In FIG. 2, the graph when the ignition of the spark plug 14 is performed on the advance side (hereinafter referred to as “over-advance angle”) before the MBT is indicated by a solid line, and the graph when the ignition is performed by the MBT. Is indicated by a broken line, and a graph when ignition is performed at the compression top dead center (TDC) is indicated by a one-dot chain line.

  When the ignition timing is over-advanced, the air-fuel mixture burned before the compression top dead center is compared to when the ignition timing is set to MBT and when the ignition timing is set to compression top dead center (TDC). The amount of increases. For this reason, the peak of heat energy generated by the combustion of the air-fuel mixture (see the heat generation rate, generated heat amount, and combustion mass ratio in FIG. 2) shifts to before the compression top dead center.

  Therefore, in-cylinder pressure during the period from the compression stroke to the expansion stroke is obtained by a synergistic effect of the temperature increase / pressure increase effect due to the combustion of the air-fuel mixture and the compression effect due to the piston ascending operation (operation from bottom dead center to top dead center) In addition, the peak value of the in-cylinder temperature increases significantly. Note that, since the excessive advance angle of the ignition timing before the MBT is executed according to a command from the ECU 20, the excessive advance means includes the ECU 20 in this embodiment.

  FIG. 3 shows a graph of the relationship between the ignition timing and torque in the cylinder 2 and the maximum in-cylinder temperature. The horizontal axis represents the ignition timing of the spark plug 14, and the vertical axis represents the torque and the maximum temperature in the cylinder. As can be seen from FIG. 3, when the ignition timing is advanced to the front of MBT, the torque decreases, while the in-cylinder maximum temperature increases and reaches the highest in ST1.

  In this way, by advancing the ignition timing to a point before MBT, the in-cylinder maximum temperature can be raised, and deposits adhering to the ignition plug 14 of the internal combustion engine 1 can be efficiently oxidized and removed.

In this embodiment, the target ignition timing when the ignition timing is over-advanced is particularly preferably an ignition timing at which the in-cylinder pressure becomes maximum at TDC shown in FIG. It is known that this ignition timing corresponds to ST1 that is the ignition timing at which the in-cylinder maximum temperature becomes the highest in FIG. 3, and by setting the ignition timing in this way, the ignition timing is most efficiently attached to the spark plug 14. The deposit can be removed by oxidation.

  However, as shown in the lower graph of FIG. 3, if the ignition timing is excessively advanced and exceeds the misfire limit ignition timing (ST2) determined by the operating state, the risk of misfire increases. Must not be advanced from the misfire limit ignition timing (ST2). Similarly, if the ignition timing is advanced from the knock limit ignition timing (ST3) determined by the operating state, the risk of knocking increases, so the ignition timing is advanced from the knock limit ignition timing. It is necessary not to become. Therefore, in this embodiment, ST1, ST2, and ST3 are derived, respectively, and the most retarded ignition timing among these three ignition timings is defined as STF, and the ignition timing of the spark plug 14 is advanced to this ignition timing STF. I decided to make it horn. FIG. 5 shows examples of graphs that serve as the basis of maps of the relationship between the operating state of the internal combustion engine 1 and ST1, ST2, and ST3, respectively.

  Next, FIG. 6 shows a flowchart of a spark plug deposit removal routine in the present embodiment. This routine is a program stored in the ROM of the ECU 20, and is executed by the ECU 20 every predetermined period while the internal combustion engine 1 is in operation.

  When this routine is executed, first, in S101, it is determined whether the start / stop of the internal combustion engine 1 is continuously executed N1 times or more. Here, when the internal combustion engine 1 is sufficiently warmed up and the spark plug 14 is exposed to a high temperature, the deposit attached to the spark plug 14 may be automatically oxidized and removed. On the other hand, when the internal combustion engine 1 is repeatedly started and stopped when it is cold, the fuel repeatedly adheres without the spark plug 14 being exposed to a sufficiently high temperature, so that the deposit adheres and accumulates. It becomes easy.

  Therefore, in this routine, the adhesion of deposit to the spark plug 14 is estimated and detected depending on whether or not the internal combustion engine 1 has been started and stopped when it is cold for a predetermined number of times N1 or more. Here, N1 is a threshold at which it is determined that the amount of deposit attached to the spark plug 14 increases and the risk of smoldering of the plug occurs when the internal combustion engine 1 is continuously started and stopped when it is cold. The number of start / stop times is obtained in advance through experiments or the like.

  In the process of S101, if it is determined that the start / stop of the internal combustion engine 1 during the cold state has been continuously executed for N1 or more, a large amount of deposit may adhere to the spark plug 14, and plug smoldering may occur. Therefore, the process proceeds to S102. On the other hand, when it is determined in S101 that the start / stop of the internal combustion engine 1 during the cold state is not continuously executed for N1 or more, the amount of deposit attached to the spark plug 14 does not lead to plug smoldering. Therefore, the process proceeds to S104.

  Next, in S102, it is determined whether the coolant temperature is equal to or lower than a predetermined temperature T1. Specifically, the output signal of the water temperature sensor 19 is read into the ECU 20, and this water temperature value is compared with the value of a predetermined temperature T1 stored in advance. Here, the predetermined temperature T1 is a threshold value for determining that the deposit attached to the spark plug 14 is removed by oxidation even when the ignition timing is normal when the cooling water temperature of the internal combustion engine 1 is higher than the predetermined temperature T1. The cooling water temperature is obtained in advance by experiments or the like.

  Here, when it is determined that the cooling water temperature is higher than the predetermined temperature T1, the deposit attached to the spark plug 14 is oxidized and removed even if the start / stop in the cold state is repeated N1 times or more continuously. Since it can be determined that the process has been completed, the process proceeds to S104. On the other hand, when it is determined that the cooling water temperature is equal to or lower than the predetermined temperature T1, the process proceeds to S103.

  In S103, the ignition timing of the internal combustion engine 1 is over-advanced to STF before MBT. As a result, the peak value of the in-cylinder temperature in the cylinder 2 of the internal combustion engine 1 increases, and the deposit attached to the spark plug 14 is oxidized and removed. When the process of S103 is completed, this routine is temporarily ended.

  In S104, the ignition time of the internal combustion engine 1 is set to the normal ignition timing. Specifically, the ignition timing is set to be retarded from MBT or MBT. When the process of S104 is completed, this routine is temporarily ended.

  As described above, in this embodiment, in the present embodiment, when the internal combustion engine 1 is cold, whether the start / stop is continuously repeated N1 times or more, and the condition that the cooling water temperature at that time is equal to or lower than the predetermined temperature T1. By satisfying both of these, it was estimated (or detected) that deposits might adhere to the spark plug 14 and plug smoldering might occur.

  When it was estimated (or detected) that deposits were attached to the spark plug 14 and there was a possibility of plug smoldering, control was performed to over-advance the ignition timing to the STF before MBT. As a result, the peak value of the in-cylinder temperature of the cylinder 2 is increased, and the deposit of the spark plug 14 is removed by oxidation. Further, in this embodiment, the target ignition timing of the over-advanced angle is set to the most retarded side among ST1, which is the ignition timing at which the in-cylinder maximum temperature is highest, the misfire limit ignition timing ST2, and the knock limit ignition timing ST3. The ignition timing is STF. Therefore, according to the present embodiment, it is possible to more reliably remove deposits attached to the spark plug 14 while avoiding the occurrence of misfire or knocking.

  In this embodiment, the ECU 20 that executes the processes of S101 and S102 constitutes a deposit detection means. Moreover, ECU20 which performs the process of S103 comprises a deposit removal means.

  Next, a second embodiment of the present invention will be described. In this embodiment, an example will be described in which deposits are prevented from adhering to a direct injection fuel injection valve that directly injects fuel into a cylinder of an internal combustion engine. The schematic configuration of the internal combustion engine and its intake / exhaust system and control system in this embodiment is the same as that shown in FIG.

  Here, in the gasoline direct-injection internal combustion engine as shown in FIG. 1, the fuel in the temperature range where the temperature of the tip of the fuel injection valve 5 is about 150 ° C. (hereinafter referred to as “deposit adhesion temperature range”). It is known from experiments that deposits are likely to adhere to the injection valve 5 and that the deposit is oxidized and removed in a higher temperature range where the temperature at the tip of the fuel injection valve 5 is 200 ° C. or higher, for example.

  However, in an actual operation state, the frequency of operation in a high temperature range where the deposit adhering to the fuel injection valve 5 is oxidized and removed is low. There is. When deposits adhere to the fuel injection valve 5, there is a possibility that the operating performance of the internal combustion engine 1 may be adversely affected by changes in the fuel injection amount or changes in the fuel spray shape.

  Therefore, in this embodiment, when it is estimated or detected that deposits are attached to the fuel injection valve 5, the ignition timing is over-advanced to the STF before the MBT and attached to the fuel injection valve 5. The deposit was removed by oxidation.

  FIG. 7 is a flowchart of the fuel injection valve deposit removal routine in this embodiment. This routine is a program stored in the ROM of the ECU 20, and is executed by the ECU 20 every predetermined period while the internal combustion engine 1 is in operation.

  When this routine is executed, first, in S201, it is determined whether or not the integrated value of the operation time in the deposit adhesion temperature region is equal to or longer than the predetermined time t1. Here, when it is determined that the integrated value of the operation time in the deposit adhesion temperature region is equal to or longer than the predetermined time t1, the process proceeds to S205. On the other hand, when it is determined that the integrated value of the operation time in the deposit adhesion temperature range is shorter than the predetermined time t1, the process proceeds to S202.

  In S202, it is determined whether or not the stability of the rotational speed in idling has deteriorated. Specifically, the output signal from the crank position sensor 18 may be read into the ECU 20 in the idle state, and the determination may be made based on whether or not the fluctuation range of the rotational speed obtained from the output is larger than a predetermined threshold value. Here, if it is determined that the rotational speed stability in the idle operation is deteriorated, the process proceeds to S205. If it is determined that the rotational speed stability in the idle operation has not deteriorated, the process proceeds to S203.

  In S203, it is determined whether or not the variation in the generated torque in each cylinder 2 has increased. Specifically, an output signal from the crank position sensor 18 may be read into the ECU 20 in a steady operation state, and the rotation speed at a timing corresponding to the combustion stroke of each cylinder 2 may be acquired from the output. Then, the determination may be made based on whether or not the variation in the rotational speed in the combustion stroke of each cylinder 2 is larger than a predetermined second threshold value. Here, if it is determined that the variation in the generated torque in each cylinder 2 is increasing, the process proceeds to S205. On the other hand, if it is determined that the variation in the generated torque in each cylinder 2 has not increased, the process proceeds to S204.

  In S204, the ignition timing of the spark plug 14 is set to a normal ignition timing. Specifically, it is set on the retard side from MBT or MBT. In S205, the ignition timing of the spark plug 14 is over-advanced to STF before MBT. This STF has the same ignition timing as the STF described in the first embodiment. Thereby, the deposit adhering to the fuel injection valve 5 is oxidized and removed. When the process of S204 or S205 is finished, this routine is once finished.

  As described above, in the present embodiment, it is determined in order by the processing from S201 to S203 whether or not three conditions for depositing to the fuel injection valve 5 are satisfied, and any one of them is applicable. In this case, it is determined that there is a high possibility that deposits are attached to the fuel injection valve 5, and in S205, the ignition timing is advanced excessively. On the other hand, if it is determined that all of the above three conditions are not satisfied, it is determined that no deposit is adhered to the fuel injection valve 5, and ignition is performed at the normal ignition timing in S204.

  Thereby, when it is estimated or detected that the deposit adheres to the fuel injector valve 5, it is possible to more reliably oxidize and remove the deposit and to suppress the operating performance of the internal combustion engine 1 from being deteriorated by the deposit. In this embodiment, the ECU 20 that executes the processing from S201 to S203 constitutes a deposit detection means. Moreover, ECU20 which performs the process of S205 comprises a deposit removal means.

Next, the fuel injection valve in the internal combustion engine 1 is a twin-injector internal combustion engine having a direct injection type first fuel injection valve 5a and a port injection type second fuel injection valve 5b as shown in FIG. Think about a case. In this case, when it is determined that deposits are attached to the first fuel injection valve 5a, the ignition timing is over-advanced to the STF before MBT, and the second fuel injection valve 5b is The injection ratio of the single fuel injection valve 5a may be reduced.

  By doing so, the amount of heat taken away by the fuel injection in the first fuel injection valve 5a is reduced, so that the temperature of the first fuel injection valve 5a can be raised to a higher temperature. Thereby, the deposit adhering to the 1st fuel injection valve 5a can be oxidized and removed more reliably.

  In the above embodiment, the case where deposits are attached to the spark plug 14 and the fuel injection valve 5 which are functional parts arranged facing the combustion chamber of the internal combustion engine 1 has been described. However, actually, in addition to the above, deposits such as carbon may adhere to the wall surface in the cylinder 2 or the top surface of the piston 15 by the operation of the internal combustion engine 1.

  When deposits adhere to the wall surface in the cylinder 2 or the top surface of the piston 15, the volume and shape of the combustion chamber itself change, so that the air-fuel ratio and compression ratio of the air-fuel mixture change from the target values. The driving performance may be degraded. It is also conceivable that the fuel introduced into the cylinder 2 is temporarily absorbed by the deposit and discharged from the exhaust passage after a while, thereby deteriorating the emission. Further, it is conceivable that the deposits collide with each other due to the reciprocating motion of the piston 15 to increase the noise.

  In the present invention, in such a case, the deposit adhesion to the wall surface in the cylinder 2 or the top surface of the piston 15 is estimated or detected from the deterioration of the driving performance, the emission, or the noise, and the deposits of these deposits are detected. When the adhesion is estimated or detected, the deposit may be removed by over-advancing the ignition timing to an STF before MBT. According to this, it is possible to suppress deterioration of driving performance, emission, and noise due to deposits adhering to the wall surface in the cylinder 2 or the top surface of the piston 15.

It is a figure which shows schematic structure of the internal combustion engine, the intake / exhaust system, and the control system in the Example of this invention. It is a graph which shows the relationship between the ignition timing in the cylinder which concerns on the Example of this invention, and the state in a cylinder. It is a graph which shows the relationship between the ignition timing in the cylinder which concerns on the Example of this invention, the torque of an internal combustion engine, and the highest in-cylinder temperature. It is a graph for demonstrating the difference by the ignition timing of the relationship between the crank angle and cylinder pressure in the cylinder which concerns on the Example of this invention. FIG. 5 is a graph serving as a reference of a map showing the relationship between the operating state of the internal combustion engine according to the embodiment of the present invention and the ignition timing at which the in-cylinder pressure becomes maximum at TDC, the ignition timing at the misfire limit, and the ignition timing at the knock limit. It is an example. It is a flowchart which shows the spark plug deposit removal routine which concerns on Example 1 of this invention. It is a flowchart which shows the fuel injection valve deposit removal routine in Example 2 of this invention. It is a figure which shows the other example of schematic structure of the internal combustion engine in the Example of this invention, an intake / exhaust system, and a control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Intake port 4 ... Exhaust port 5 ... Fuel injection valve 5a ... First fuel injection valve 5b ... Second fuel injection valve 6 ... Throttle valve 7 ... Intake pressure sensor 8 ... Air flow meter 9 ... Exhaust gas purification device 10 ... Intake air Valve 11 ... Exhaust valve 12 ... Intake side camshaft 13 ... Exhaust side camshaft 14 ... Ignition plug 15 ... Piston 16 ... Connecting rod 17 ...・ Crankshaft 18 ・ ・ ・ ・ Crank position sensor 19 ・ ・ ・ ・ Water temperature sensor 20 ・ ・ ・ ・ ECU
30 ... Intake passage 40 ... Exhaust passage

Claims (4)

Over-advance means for advancing the ignition timing of the spark ignition type internal combustion engine before MBT;
Deposit detection means for detecting or estimating the adhesion of deposits to components in the combustion chamber of the internal combustion engine;
Deposit removal means for causing the over-advance angle means to advance the ignition timing ahead of MBT when the deposit detection means detects or estimates deposit adhesion to the components in the combustion chamber;
An internal combustion engine control system comprising:   2. The over-advance means advances the ignition timing of the internal combustion engine to an ignition timing before MBT and at which the pressure in the cylinder of the internal combustion engine becomes maximum near TDC. A control system for an internal combustion engine according to claim 1.   The internal combustion engine control system according to claim 1 or 2, wherein the component in the combustion chamber is a spark plug of the internal combustion engine.   The internal combustion engine control system according to claim 1 or 2, wherein the component in the combustion chamber is a direct injection type fuel injection valve that directly injects fuel into the combustion chamber of the internal combustion engine.

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