JP2016098733A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can suppress the generation of continuous misfires when applying control for adjusting a fuel injection amount to lean burn operation so that a crank angle period from ignition timing up to a crank angle when reaching a prescribed combustion mass ratio approximates its target value.SOLUTION: A fuel injection amount is calculated by correcting a basic injection amount corresponding to an operation state during a lean burn operation by a correction amount. Usually, the correction amount is set so that a calculation value of a crank angle period from ignition timing up to CA10 approximates a target value during the lean burn operation. However, this setting may be stopped in some cases. At that time, when the succeeding correction amount shows an increase, the fuel injection amount is calculated by using the increase value, and when the succeeding correction amount shows a decrease, the fuel injection amount is calculated with the correction amount as zero.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, for example, Patent Document 1 discloses a combustion control device for an internal combustion engine. In this combustion control device, the amount of heat generated in the cylinder is calculated based on the in-cylinder pressure and the crank angle detected using the in-cylinder pressure sensor and the crank angle sensor. Then, after the actual combustion start point and the combustion gravity center position are calculated based on the heat generation amount, the combustion deteriorates when the crank angle of the combustion gravity center position relative to the actual combustion start point exceeds the upper limit value. It is judged that If it is determined that the combustion has deteriorated, measures such as increasing the fuel injection amount are taken to improve the combustion.

  The applicant has recognized the following documents including the above-mentioned documents as related to the present invention.

JP 2008-069713 A JP 2010-127103 A

  The fuel injection amount is calculated by correcting the basic injection amount according to the operating state with the correction amount. Regarding the correction amount, during lean burn operation, it is conceivable to set the correction amount so that the crank angle period from the ignition timing to the crank angle at which the combustion mass ratio becomes a predetermined value approaches the target value. However, during lean burn operation in which combustion is likely to be unstable as compared with stoichiometric air-fuel ratio combustion operation, the control may not always work properly, and the control may be stopped. In the above-mentioned patent document, it is not sufficiently studied how to set the correction amount when the control is stopped. It is desirable that sufficient measures have been taken to suppress the occurrence of continuous misfire when the control is stopped during lean burn operation.

  The present invention has been made to solve the above-described problems. The fuel injection amount is set so that the crank angle period from the ignition timing to the crank angle when the predetermined combustion mass ratio is reached approaches the target value. An object of the present invention is to provide a control device for an internal combustion engine that can suppress the occurrence of continuous misfire when the control to be adjusted is applied to lean burn operation.

  The control apparatus for an internal combustion engine according to the present invention includes crank angle detection means, combustion mass ratio calculation means, first crank angle acquisition means, fuel injection amount calculation means, and correction amount setting means. The crank angle detection means detects the crank angle. The combustion mass ratio calculation means calculates the combustion mass ratio. The first crank angle acquisition means acquires the first crank angle when the combustion mass ratio becomes a predetermined combustion mass ratio. The fuel injection amount calculation means calculates the fuel injection amount by correcting the basic injection amount according to the operation state with the correction amount during the lean burn operation. The correction amount setting means sets the correction amount so that the calculated value of the crank angle period from the ignition timing to the first crank angle approaches the target value of the crank angle period during the lean burn operation. In addition, when the correction amount setting by the correction amount setting unit is stopped and the previous correction amount indicates an increase, the fuel injection amount calculation unit calculates the basic injection amount in the next cycle. The fuel injection amount is calculated by correcting with the correction amount, and when the previous correction amount indicates a decrease, the basic injection amount is calculated as the fuel injection amount in the next cycle.

  According to the present invention, when setting of the correction amount by the correction amount setting means is stopped during lean burn operation, when the previous correction amount indicates an increase, the fuel injection amount is used using the previous correction amount. If the previous correction amount indicates a decrease, the correction amount is set to zero and the fuel injection amount is calculated. Therefore, according to the present invention, when the correction amount setting unit stops the correction amount setting during the lean burn operation, the fuel injection amount can be suppressed from being corrected to the decrease side, and the occurrence of continuous misfire can be suppressed. it can.

It is a figure for demonstrating the system configuration | structure of the internal combustion engine in Embodiment 1 of this invention. It is a figure for demonstrating the calculation procedure of a combustion mass ratio. It is a figure for demonstrating the definition of SA-CA10. It is a figure for demonstrating the feedback control of the fuel injection quantity based on SA-CA10. It is a figure for demonstrating the characteristic part of the control of Embodiment 1 of this invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a figure which shows the change of calculation SA-CA10 at the time of normal combustion and at the time of misfire. It is a figure for demonstrating the characteristic part of control of Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 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 diagram for explaining a system configuration of an internal combustion engine 10 according to Embodiment 1 of the present invention. The system shown in FIG. 1 includes a spark ignition type internal combustion engine 10. A piston 12 is provided in the cylinder of the internal combustion engine 10. A combustion chamber 14 is formed on the top side of the piston 12 in the cylinder. An intake passage 16 and an exhaust passage 18 communicate with the combustion chamber 14.

  An electronically controlled throttle valve 20 is provided in the intake passage 16. Each cylinder of the internal combustion engine 10 has a fuel injection valve 22 for directly injecting fuel into the combustion chamber 14 (inside the cylinder), and an ignition device 24 for igniting the air-fuel mixture (only the ignition plug is shown). , Each provided. Furthermore, an in-cylinder pressure sensor 26 for detecting the in-cylinder pressure is incorporated in each cylinder.

  Further, the system of the present embodiment includes an ECU (Electronic Control Unit) 30. In addition to the in-cylinder pressure sensor 26 described above, an input of the ECU 30 acquires engine operating conditions such as a crank angle sensor 32 for detecting a crank angle and an air flow meter 34 for measuring an intake air amount. The various sensors are connected. Further, various actuators for controlling the engine operation such as the throttle valve 20, the fuel injection valve 22, and the ignition device 24 are connected to the output portion of the ECU 30. The ECU 30 performs predetermined engine control such as fuel injection control and ignition control by driving the various actuators based on the sensor output and a predetermined program. Further, the ECU 30 has a function of acquiring the output signal of the in-cylinder pressure sensor 26 by performing AD conversion in synchronization with the crank angle. Thereby, the in-cylinder pressure at an arbitrary crank angle timing can be detected within a range allowed by the AD conversion resolution. Further, the ECU 30 has a function of calculating the value of the cylinder volume determined by the position of the crank angle according to the crank angle.

ただし、上記（１）式において、Ｐは筒内圧、Ｖは筒内容積、κは筒内ガスの比熱比である。また、上記（３）式において、θ_ｍｉｎは燃焼開始点（０％燃焼点ＣＡ０）であり、θ_ｍａｘは燃焼終了点（１００％燃焼点ＣＡ１００）である。 [Control of Embodiment 1]
(Calculation of combustion mass ratio)
FIG. 2 is a diagram for explaining the calculation procedure of the combustion mass ratio. According to the system of the present embodiment including the in-cylinder pressure sensor 26 and the crank angle sensor 32, in each cycle of the internal combustion engine 10, the in-cylinder pressure data (synchronized with the crank angle (CA) as shown in FIG. In-cylinder pressure waveform) can be acquired. Using the obtained in-cylinder pressure data and the first law of thermodynamics, the heat generation amount Q in the cylinder at an arbitrary crank angle θ can be calculated according to the following equations (1) and (2). FIG. 2B shows an example of heat generation amount Q data (heat generation amount waveform) calculated by such a method. The combustion mass ratio (hereinafter referred to as “MFB”) at an arbitrary crank angle θ can be calculated according to the following equation (3) using the calculated heat generation amount Q in the cylinder. . FIG. 2C shows an example of the MFB waveform calculated by such a method.

In the above equation (1), P is the in-cylinder pressure, V is the in-cylinder volume, and κ is the specific heat ratio of the in-cylinder gas. In the above equation (3), θ _min is the combustion start point (0% combustion point CA0), and θ _max is the combustion end point (100% combustion point CA100).

(Feedback control of fuel injection amount using SA-CA10)
According to the MFB waveform obtained by the above method, the crank angle (hereinafter referred to as “CAα”) when the MFB is a predetermined ratio α (%) can be acquired. In the control of the present embodiment, CA10 (corresponding to the “first crank angle” in the present invention) that is a 10% combustion point is used as follows.

  FIG. 3 is a diagram for explaining the definition of SA-CA10. In the present embodiment, the crank angle period from the ignition timing (SA) to CA10 is referred to as “SA-CA10”. More specifically, SA-CA10 calculated using the ignition timing and CA10 obtained from the analysis result of the in-cylinder pressure data shown in FIG. 2 is referred to as “calculated SA-CA10”.

  SA-CA10 is a parameter representing ignition delay, and there is a certain correlation between SA-CA10 and the air-fuel ratio. More specifically, as shown in FIG. 8 described later, in a lean air-fuel ratio region where the air-fuel ratio is larger than the stoichiometric air-fuel ratio, there is a relationship that SA-CA10 increases as the air-fuel ratio becomes leaner. Therefore, in the present embodiment, during lean burn operation at an air fuel ratio larger than the stoichiometric air fuel ratio, engine operation is performed so that the calculated SA-CA10 approaches the target SA-CA10 associated with the target air fuel ratio. The feedback control for calculating the fuel injection amount by correcting the basic injection amount according to the state (for example, engine speed, intake air amount) with the correction amount is executed.

  FIG. 4 is a diagram for explaining feedback control of the fuel injection amount based on SA-CA10. FIG. 4B shows the MFB waveform when the calculated SA-CA10 is controlled to the target SA-CA10 according to the operating conditions.

  FIG. 4A shows an MFB waveform in which a calculated SA-CA10 smaller than the target SA-CA10 shown in FIG. 4B is obtained. In the cylinder from which such an MFB waveform is obtained, a correction for reducing the fuel injection amount used in the next cycle is executed in order to make the air-fuel ratio lean and increase the actual SA-CA10. More specifically, a reduction correction amount for adding the calculated SA-CA10 to the target SA-CA10 is added to the fuel injection amount for the next cycle based on the basic injection amount corresponding to the intake air amount of each cylinder. . FIG. 4C shows an MFB waveform in which a calculated SA-CA10 larger than the target SA-CA10 shown in FIG. 4B is obtained, contrary to FIG. 4A. In the cylinder in which such an MFB waveform is obtained, correction for increasing the fuel injection amount used in the next cycle is executed in order to enrich the air-fuel ratio and reduce the actual SA-CA10.

  The fuel injection amount feedback control based on SA-CA10 is executed for each cylinder in the manner described above. The internal combustion engine 10 of the present embodiment includes the in-cylinder pressure sensor 26 in each cylinder. For example, if the internal combustion engine has a configuration in which only one representative cylinder includes the in-cylinder pressure sensor, a single cylinder You may correct | amend the fuel injection amount of all the cylinders so that calculation SA-CA10 based on the cylinder pressure obtained from a cylinder pressure sensor may approach target SA-CA10.

(Problem of feedback control of fuel injection amount based on SA-CA10)
By the way, there is a case where feedback control of the fuel injection amount based on SA-CA10 during lean burn operation is stopped.

  One case is a case where noise is added to the output signal of the crank angle sensor 32, the crank angle is shifted, and there is no certainty. In this case, since the association between the acquired in-cylinder pressure and the crank angle is not reliable, the calculated SA-CA10 is also not reliable. Therefore, the feedback control during the lean burn operation is stopped. The certainty of the crank angle can be determined by detecting the missing crank angle tooth or the like.

  The other case is a misfired case. Normally, when the combustion speed decreases, the calculated SA-CA10 becomes larger than the target SA-CA10. In this case, according to the feedback control, the fuel injection amount is corrected to increase. However, when a misfire occurs, the calculated SA-CA10 decreases. According to the feedback control, when the calculated SA-CA10 is smaller than the target SA-CA10, the fuel injection amount is corrected to decrease. That is, when misfire occurs during lean burn operation, the fuel injection amount is originally intended to be increased, but since the calculated SA-CA10 is small, the amount of fuel injection is corrected by the feedback control. If the feedback control is continued, the injected fuel is further reduced and the possibility of continuous misfire increases. Therefore, the feedback control during the lean burn operation is stopped. Note that the misfire occurrence can be determined, for example, when misfire has occurred when the calculated SA-CA10 is equal to or less than a predetermined value set in advance. The predetermined value is set to a value lower than the lower limit of combustion variation during lean burn operation and higher than SA-CA10 during misfire.

  The other case is a case where the combustion itself is in a special state (a special state does not always occur). Specifically, such a state occurs when a low-speed pre-ignition occurs, when the ignition is retarded, and when the amount of fuel is increased. When low-speed pre-ignition occurs, CA10 is on the advance side, and the calculated SA-CA10 is very small. Therefore, the amount of correction is corrected by the feedback control. Therefore, the feedback control during the lean burn operation is stopped. Note that it is possible to determine that the low speed pre-ignition has occurred, for example, when the calculated SA-CA 10 is equal to or less than a predetermined value set in advance. Further, the feedback control is stopped when the ignition is retarded to reduce the torque, or when the injection is increased in response to an instantaneous torque request, a catalyst request, a component cooling request, or the like.

  In this way, when the combustion during lean burn operation is different from the normal time due to misfire, occurrence of low speed pre-ignition, ignition retardation, injection increase, etc., the calculated SA-CA10 is different from the normal time. It is not preferable to execute the feedback control using the above. Although it may be possible to set the correction amount to 0 once, the lean misfire limit is near during lean burn operation, so if the correction amount becomes 0 when the increase amount is corrected by the above feedback control, the amount is reduced from the appropriate state. There is a problem that misfire occurs.

  FIG. 5 is a diagram for explaining the characteristic part of the control according to the first embodiment of the present invention. In the present embodiment, the ECU 30 calculates the fuel injection amount by correcting the basic injection amount according to the operating state with the correction amount during the lean burn operation. This correction amount is set so that the calculated SA-CA10 approaches the target SA-CA10 during lean burn operation, and is used for feedback control of the fuel injection amount. In the present embodiment, when the feedback control is stopped during the lean burn operation (time t0 in FIG. 5), when the previous correction amount indicates an increase as shown in FIG. The fuel injection amount is calculated by correcting the basic injection amount with the previous correction amount in the cycle. Also, as shown in FIG. 5B, when the previous correction amount indicates a decrease, the correction amount is set to zero in the next cycle, and the basic injection amount is calculated as the fuel injection amount.

  FIG. 6 is a flowchart showing a control routine executed by the ECU 30 in order to realize the control of the first embodiment of the present invention. This routine is repeatedly executed for each cycle at a predetermined timing after the end of combustion in each cylinder.

  In the routine shown in FIG. 6, the ECU 30 first determines in step S100 whether or not a lean burn operation is being performed. In the internal combustion engine 10, a lean burn operation is performed at an air-fuel ratio larger than the stoichiometric air-fuel ratio in a predetermined operation region. Here, it is determined whether or not the current operation region corresponds to an operation region in which such lean burn operation is performed. As a result, when it is determined that the lean burn operation is not being performed, the ECU 30 ends the processing of this routine.

  On the other hand, when it is determined in step S100 that the lean burn operation is being performed, the ECU 30 executes the process of step S110. In step S110, the ECU 30 determines whether or not feedback control of the fuel injection amount based on SA-CA10 is feasible. The case of stopping the feedback control during the lean burn operation is as described above, and the description thereof is omitted.

  When it is determined in step S110 that the feedback control of the fuel injection amount based on SA-CA10 can be executed, the ECU 30 executes the process of step S120. In step S120, the ECU 30 calculates a target SA-CA10. The target SA-CA10 is determined according to the operating conditions, and the intake air amount, the engine speed, and the like correspond to the operating conditions here.

  Next, in step S130, the ECU 30 calculates the calculated SA-CA10. In step S130, the calculated SA-CA10 is calculated according to the method already described with reference to FIGS. As the ignition timing used to calculate the calculated SA-CA10, for example, the current target ignition timing can be used.

  Next, in step S140, the ECU 30 calculates a fuel injection amount correction amount for bringing the calculated SA-CA10 closer to the target SA-CA10. When the calculated SA-CA10 is smaller than the target SA-CA10, a correction amount for reducing the fuel injection amount used in the next cycle is set in order to make the air-fuel ratio lean and increase the actual SA-CA10. On the other hand, when the calculated SA-CA10 is larger than the target SA-CA10, a correction amount for increasing the fuel injection amount used in the next cycle is set in order to reduce the actual SA-CA10 by enriching the air-fuel ratio. .

  Next, in step S150, the ECU 30 determines the fuel injection amount by correcting the basic injection amount according to the operating state with the correction amount.

  When it is determined in step S110 described above that the fuel injection amount feedback control based on SA-CA10 cannot be executed, the ECU 30 stops the feedback control and executes the process of step S160. In step S160, the ECU 30 acquires a correction amount in the feedback control of the fuel injection amount based on the previous calculation SA-CA10.

  Next, in step S170, the ECU 30 determines whether or not the previous correction amount is greater than zero. When it is determined that the correction amount calculated in the feedback control based on the previous calculation SA-CA10 is greater than 0, the ECU 30 executes the process of step S180. In step S180, the ECU 30 sets the previous correction amount as the correction amount in the next cycle. Thereafter, in step S150, the ECU 30 determines the fuel injection amount by correcting the basic injection amount according to the operating state with a correction amount (indicating an increase correction). That is, an injection amount larger than the basic injection amount is determined as the final fuel injection amount.

  On the other hand, when it is determined in step S170 that the previous correction amount is 0 or less, the ECU 30 executes the process of step S190. In step S190, the ECU 30 clears the correction amount in the next cycle to zero. Thereafter, in step S150, the ECU 30 determines the fuel injection amount by correcting the basic injection amount corresponding to the operating state with the correction amount (the correction amount is 0). That is, the basic injection amount is determined as the final fuel injection amount.

  As described above, according to the routine shown in FIG. 6, when the feedback control based on the correction amount that brings the calculated SA-CA10 closer to the target SA-CA10 is stopped during the lean burn operation, the previous correction amount is increased. If the previous correction amount indicates a decrease, the correction amount is cleared to zero and the fuel injection amount is calculated. According to such control, when the feedback control is stopped during the lean burn operation, it is possible to prevent the fuel injection amount from being corrected to the decrease side. Therefore, the air-fuel ratio is prevented from further leaning in the next cycle, and the occurrence of continuous misfire can be suppressed.

  By the way, in Embodiment 1 mentioned above, CA10 which is a 10% combustion point is used as the “first crank angle” that defines the crank angle period with respect to the ignition timing. However, the combustion point that is the target of the first crank angle in the present invention is not limited to CA10, and may be CAα that is a crank angle when an arbitrary combustion mass ratio (α%) is obtained. In addition, it can be said that the use of CA10 is preferable to the use of other combustion points for the following reasons. That is, when the combustion point in the main combustion period (CA10-CA90) after CA10 is used, the obtained crank angle period is a parameter (EGR rate, intake air temperature and intake temperature) that affects combustion when the flame spreads. Greatly affected by the tumble ratio). That is, the crank angle period obtained in this case is not purely focused on the air-fuel ratio, and is weak against disturbance. In order to eliminate the influence of such disturbance, the configuration in which the crank angle period is corrected in accordance with the above parameters increases the number of man-hours for adaptation. On the other hand, when the combustion point in the initial combustion period (CA0-CA10) is used, the obtained crank angle period is not easily influenced by the above parameters, and the influence of the factors affecting the ignition appears well. It becomes. As a result, controllability is improved. On the other hand, the combustion start point (CA0) and the combustion end point (CA100) are likely to have errors due to the influence of noise superimposed on the output signal from the in-cylinder pressure sensor 26 acquired by the ECU 30. The influence of this noise decreases as the distance from the combustion start point (CA0) or combustion end point (CA100) increases. Therefore, in consideration of noise resistance and reduction in the number of man-hours, it can be said that CA10 is the most excellent as the first crank angle as used in the present embodiment. The same applies to the following embodiments.

  In the first embodiment described above, the analysis result of the in-cylinder pressure data acquired using the in-cylinder pressure sensor 26 and the crank angle sensor 32 is used to calculate the combustion mass ratio (MFB). However, the calculation of the combustion mass ratio in the present invention is not necessarily limited to that performed using the in-cylinder pressure data. That is, the combustion mass ratio may be calculated, for example, by detecting an ion current generated by combustion with an ion sensor and using the detected ion current, or measuring an in-cylinder temperature. If possible, it may be calculated using a history of in-cylinder temperature. The same applies to the following embodiments.

Embodiment 2. FIG.
[System Configuration of Embodiment 2]
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 30 to execute a routine of FIG. 9 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 2]
In the above-described first embodiment, when the feedback control of the fuel injection amount based on SA-CA10 is stopped during the lean burn operation, if the previous correction amount indicates an increase, the fuel using the previous correction amount is used. When the injection amount is calculated and the previous correction amount indicates a decrease, the correction amount is cleared to 0 and the fuel injection amount is calculated. However, when the feedback control is stopped due to the occurrence of misfire, even if the fuel injection amount is calculated using the previous correction amount (indicating an increase), misfire may occur again in the subsequent cycle.

  FIG. 7 is a diagram showing a change in the calculated SA-CA10 during normal combustion and misfire. Due to variations in the combustion of the gasoline engine itself, even if the operation amount of each actuator is the same, the combustion differs from cycle to cycle. In a lean burn engine, combustion becomes more unstable in a region closer to the lean misfire limit, and the combustion variation is large. Therefore, in the lean burn operation in such a region, misfire may occur again even if the previous correction amount (indicating an increase) is used. Note that the reason why misfire occurs is that there is an overshoot of the feedback correction amount (including a reaction in which the fuel injection amount is reduced by feedback control when the calculated SA-CA10 becomes smaller due to variations in combustion).

  FIG. 8 is a diagram for explaining the characteristic part of the control according to the second embodiment of the present invention. As shown in FIG. 8B, in the lean burn operation close to the lean misfire limit, misfire may occur again even if the previous correction amount (indicating an increase) is used. Therefore, in the present embodiment, as shown in FIG. 8A, when the feedback control is stopped due to the occurrence of misfire, the previous correction amount (indicating the increase) is not held, but the increase correction is further performed. It was decided.

  FIG. 9 is a flowchart of a routine executed in the second embodiment of the present invention. This routine is repeatedly executed for each cycle at a predetermined timing after the end of combustion in each cylinder. This routine is the same as the routine shown in FIG. 6 except that steps S200 and S210 are added. In FIG. 9, the same steps as those shown in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 9, when it is determined in step S110 that the fuel injection amount feedback control based on SA-CA10 cannot be executed, the ECU 30 executes the process of step S200. In step S200, the ECU 30 determines whether the feedback control is stopped due to misfire. As a method of determining misfire, it is determined whether or not the calculated SA-CA10 is equal to or less than a predetermined value due to the occurrence of misfire, and when it is equal to or less than a predetermined value, feedback control is stopped due to misfire. And As this predetermined value, a value lower than the lower limit of the variation in combustion shown in FIG. 7 and higher than SA-CA10 at the time of misfire is set.

  If it is determined in step S200 that the feedback control is stopped due to misfire, then in step S210, the ECU 30 calculates a correction amount for increasing the fuel injection amount. If the previous correction amount indicates an increase, the correction amount is further increased. When the previous correction amount indicates a decrease, the correction amount indicates at least an increase.

  If it is determined in step S200 that the feedback control is not stopped due to misfire, the processes after step S160 in FIG. 6 are executed.

  As described above, according to the routine shown in FIG. 9, when the feedback control is stopped due to misfire, the previous correction amount (indicating an increase) is not used, but further increase correction is performed, and the subsequent cycle is performed. It is possible to suppress the occurrence of continuous misfire in Further, after the feedback control is resumed, it is possible to return more quickly to a state where no misfire occurs.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Piston 14 Combustion chamber 16 Intake passage 18 Exhaust passage 20 Throttle valve 22 Fuel injection valve 24 Ignition device 26 In-cylinder pressure sensor 30 ECU (Electronic Control Unit)
32 Crank angle sensor 34 Air flow meter

Claims (1)

Crank angle detecting means for detecting the crank angle;
A combustion mass ratio calculating means for calculating a combustion mass ratio;
First crank angle acquisition means for acquiring a first crank angle when the combustion mass ratio becomes a predetermined combustion mass ratio;
A fuel injection amount calculating means for calculating a fuel injection amount by correcting a basic injection amount according to an operation state with a correction amount during lean burn operation;
Correction amount setting means for setting the correction amount so that the calculated value of the crank angle period from the ignition timing to the first crank angle approaches the target value of the crank angle period during the lean burn operation,
When the correction amount setting by the correction amount setting means is stopped and the previous correction amount indicates an increase, the fuel injection amount calculating means sets the basic injection amount at the previous correction amount in the next cycle. Correcting and calculating the fuel injection amount, and when the previous correction amount indicates a decrease, calculating the basic injection amount as the fuel injection amount in the next cycle;
A control device for an internal combustion engine.

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