JP4782078B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to an apparatus that performs control according to an in-cylinder pressure detected by an in-cylinder pressure sensor.

  Conventionally, in diffusion combustion in a diesel engine, air taken into a combustion chamber is compressed, fuel is injected into the compressed air, and the fuel is burned by self-ignition. On the other hand, in recent years, premixed compression ignition combustion (hereinafter referred to as “PCCI combustion”) in which the fuel injection timing is advanced and the ignition delay period is combusted has been proposed. According to this PCCI combustion, the combustion temperature is low and NOx emissions can be reduced due to the combustion of a lean air-fuel mixture, and the generation of PM (Particulate Matter) such as soot is reduced because there are few overconcentrated portions of fuel. it can. However, in PCCI combustion, the range of control conditions for igniting at an appropriate time to establish combustion is limited.

  FIG. 5 is a diagram showing an example of the relationship between the crank angle and the in-cylinder pressure in the PCCI combustion, and is a diagram showing the influence of the control error of the exhaust gas recirculation rate (hereinafter referred to as “EGR rate”) on the PCCI combustion. A solid line A1 indicates a reference combustion state in which the EGR rate is 34.7%, and a broken line A2 and an alternate long and short dash line A3 indicate combustion states when a control error occurs in the EGR rate from the reference combustion state. As shown by the broken line A2, when an EGR rate control error of, for example, -2.2% occurs from the reference combustion state of the solid line A1, the ignition timing is advanced, the in-cylinder pressure is rapidly increased, and noise and vibration are generated. Further, as shown by the one-dot chain line A3, if an EGR rate control error of, for example, + 2.1% occurs from the reference combustion state of the solid line A1, the ignition timing may be delayed and misfire may occur.

  Therefore, Patent Document 1 discloses a control device that detects the actual ignition timing of the fuel from the in-cylinder pressure detected by the in-cylinder pressure sensor and corrects the fuel injection timing in accordance with the detected actual ignition timing.

FIG. 6 is a diagram showing an example of the relationship between the crank angle and the in-cylinder pressure in PCCI combustion, and is a diagram showing an example of control by the control device shown in Patent Document 1. Similarly to FIG. 5 described above, the solid line B1 indicates the reference combustion state, and the broken line B2 and the alternate long and short dash line B3 indicate the combustion state when a control error occurs in the EGR rate from the reference combustion state. According to the control device disclosed in Patent Document 1, when the actual ignition timing is F / B controlled to the target value in the reference combustion state, a control error occurs in the EGR rate as shown in FIG. However, it is possible to burn in a state close to the reference combustion state.
JP 2007-23881 A

By the way, in a running vehicle, a control error of ± 20% or more may occur in the EGR rate. 7 and 8, respectively, the ignition timing control target value (e.g., ADTC15.6 degrees) with F / B control, the time t = 0 by increasing the fresh air amount toward _{t 1} the EGR rate from 0 percent when changing to -30%, and the pressure change rate and Pmi in the cylinder in the case of decreasing the amount of fresh air from time t = 0 toward t ₂ by changing the EGR rate to 0% + 30% It is a figure which shows the relationship with a fluctuation rate. Here, the Pmi fluctuation rate is a fluctuation rate of the indicated mean effective pressure in the cylinder, and indicates instability of combustion.

  As shown in FIG. 7, when the EGR rate decreases, the ignition timing can be maintained at the control target value by retarding the fuel injection timing, but as the control error of the EGR rate increases, the pressure in the cylinder The rate of change exceeds the target upper limit value, and noise and vibration become intense. As shown in FIG. 8, when the EGR rate increases, the ignition timing can be maintained at the control target value by advancing the fuel injection timing, but as the control error of the EGR rate increases, the Pmi fluctuation The rate exceeds the target upper limit, combustion becomes unstable, and misfire occurs. As described above, by performing F / B control of the ignition timing to the control target value, the controllable operating range can be expanded to within the control error range of the EGR rate of about ± 30%, but the pressure change rate and Pmi fluctuation rate Will greatly increase.

  The present invention has been made in consideration of the above-described points, and is an internal combustion engine capable of appropriately controlling the ignition timing according to the control error of the exhaust gas recirculation rate, suppressing noise and vibration due to combustion, and preventing misfire. An object of the present invention is to provide an engine control device.

In order to achieve the above object, an invention according to claim 1 is provided in a combustion chamber of an internal combustion engine (1), fuel injection means (6) for injecting fuel into the combustion chamber, and intake air from the internal combustion engine. In a control device for an internal combustion engine comprising an exhaust gas recirculation mechanism (9, 20) that recirculates to the system, fuel injection timing (CAIMM) by the fuel injection means set according to the operating state (NE, TRQ) of the internal combustion engine The fuel injection timing storage means for storing the engine, the operating state detection means (3, 21) for detecting the operating state of the internal combustion engine, and the engine operating state for detecting the fuel injection timing stored in the fuel injection timing storage means The fuel injection timing is determined by searching according to the fuel injection control means for executing the fuel injection by the fuel injection means, and the fuel injected into the combustion chamber is set according to the operating state of the internal combustion engine An ignition timing storage means for storing a target ignition timing (CAFMM), an ignition timing detection means for detecting an actual ignition timing (CAFM) of the fuel injected into the combustion chamber, and an operating state of the internal combustion engine are set. An exhaust gas recirculation rate control value storage means for storing an exhaust gas recirculation rate control value (GEGRM) by the exhaust gas recirculation mechanism; an exhaust gas recirculation rate calculation means for calculating an actual exhaust gas recirculation rate (GEGR) by the exhaust gas recirculation mechanism; A deviation (ΔGEGRM) is calculated by subtracting the control value of the exhaust gas recirculation rate from the actual exhaust gas recirculation rate. If the calculated deviation is positive, the target ignition timing is corrected to the advance side, In this case, the target ignition timing correcting means for correcting the target ignition timing to the retard side, and the deviation between the target ignition timing (CAFMCC) corrected by the target ignition timing correcting means and the actual ignition timing ( Fuel injection timing correction amount calculating means for calculating a fuel injection timing correction amount (CAD) so as to decrease ΔCAM), and the fuel injection control means corrects the fuel injection timing by the fuel injection timing correction amount. The fuel injection is executed in accordance with the corrected fuel injection timing.

  According to the first aspect of the invention, the fuel injection timing is calculated by searching the fuel injection timing storage means in which the fuel injection timing set according to the operating state of the internal combustion engine is stored, and the internal combustion engine The target ignition timing is calculated by searching the ignition timing storage means in which the target ignition timing set according to the engine operating state is stored. Also, the target ignition timing is corrected according to the deviation between the control value of the exhaust gas recirculation rate and the actual exhaust gas recirculation rate, and the fuel injection timing correction amount so that the deviation between the corrected target ignition timing and the actual ignition timing is reduced. Is calculated. Further, the fuel injection timing is corrected by the fuel injection timing correction amount, and fuel injection is executed in accordance with the corrected fuel injection timing. By appropriately correcting the target ignition timing according to the deviation between the control value of the exhaust gas recirculation rate set in advance according to the operating state of the engine and the actual exhaust gas recirculation rate, the pressure change rate in the cylinder increases. It is possible to prevent a large noise or vibration from occurring or a misfire due to deterioration of the Pmi fluctuation rate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are diagrams showing the configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. The following description will be given with reference to both figures. An internal combustion engine (hereinafter simply referred to as “engine”) 1 having four cylinders is a diesel engine that directly injects fuel into a combustion chamber, and a fuel injection valve 6 is provided in the combustion chamber of each cylinder. The fuel injection valve 6 is electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 4, and the valve opening time and valve opening timing of the fuel injection valve 6, that is, the fuel injection time and fuel injection timing are determined by the ECU 4. Controlled by

  The engine 1 includes an intake pipe 7 and an exhaust pipe 8. An exhaust gas recirculation passage 9 is provided between the exhaust pipe 8 and the intake pipe 7 to recirculate part of the exhaust gas to the intake pipe 7. The exhaust gas recirculation passage 9 is provided with an exhaust gas recirculation control valve (hereinafter referred to as “EGR valve”) 20 for controlling the exhaust gas recirculation amount. The EGR valve 20 is an electromagnetic valve having a solenoid, and the valve opening degree is controlled by the ECU 4. The exhaust gas recirculation passage 9 and the EGR valve 20 constitute an exhaust gas recirculation mechanism. Further, a LAF sensor 29 that detects the oxygen concentration DO in the intake air in the intake pipe 7 is provided on the downstream side of the intake pipe 7 with respect to the joining position with the exhaust gas recirculation passage 9.

  Each cylinder of the engine 1 is provided with an in-cylinder pressure sensor 2 that detects an in-cylinder pressure (combustion pressure). In the present embodiment, the in-cylinder pressure sensor 2 is configured integrally with a glow plug provided in each cylinder. A detection signal from the in-cylinder pressure sensor 2 is supplied to the ECU 4. The detection signal of the in-cylinder pressure sensor 2 actually corresponds to a differential signal with respect to the crank angle (time) of the in-cylinder pressure PCYL, and the in-cylinder pressure PCYL is obtained by integrating the in-cylinder pressure sensor output. .

  The engine 1 is provided with a crank angle position sensor 3 that detects a rotation angle of a crankshaft (not shown). The crank angle position sensor 3 generates a pulse every crank angle, and the pulse signal is supplied to the ECU 4. The crank angle position sensor 3 further generates a cylinder identification pulse at a predetermined crank angle position of the specific prayer and supplies it to the ECU 4.

  The ECU 4 includes an accelerator sensor 21 that detects an operation amount AP of an accelerator pedal of a vehicle driven by the engine 1, a cooling water temperature sensor 22 that detects a cooling water temperature TW of the engine 1, and an intake air temperature that detects an intake air temperature TA of the engine 1. A sensor 23, an intake air flow rate sensor 24 for detecting the intake air amount flow rate GA of the engine 1, and a LAF sensor 29 for detecting the oxygen concentration DO in the intake air in the intake pipe 7 are connected. Detection of these sensors A signal is supplied to the ECU 4.

  The ECU 4 supplies a control signal for the fuel injection valve 6 provided in the combustion chamber of each cylinder of the engine 1 to the drive circuit 5. The drive circuit 5 is connected to the fuel injection valve 6, and supplies a drive signal corresponding to the control signal supplied from the ECU 4 to the fuel injection valve 6. Thus, at the fuel injection timing corresponding to the control signal output from the ECU 4, fuel is injected into the combustion chamber of each cylinder by the fuel injection amount corresponding to the control signal.

  The ECU 4 includes an amplifier 10, an A / D converter 11, a pulse generator 13, a CPU (Central Processing Unit) 14, a ROM (Read Only Memory) 15 that stores a program executed by the CPU 14, and a CPU 14. A RAM (Random Access Memory) 16 for storing calculation results and the like, an input circuit 17, and an output circuit 18 are provided. A detection signal of the in-cylinder pressure sensor 2 is input to the amplifier 10. The amplifier 10 amplifies an input signal. The signal amplified by the amplifier 10 is input to the A / D converter 11. The pulse signal output from the crank angle position sensor 3 is input to the pulse generator 13.

  The A / D conversion unit 11 includes a buffer 12, converts the in-cylinder pressure sensor output input from the amplifier 10 into a digital value (hereinafter referred to as “pressure change rate”) dpdθ, and stores the converted value in the buffer 12. More specifically, the A / D converter 11 is supplied with a pulse signal PLS1 (hereinafter referred to as “1 degree pulse”) PLS1 having a crank angle of 1 degree from the pulse generator 13, and this 1 degree pulse PLS1. The in-cylinder pressure sensor output is sampled at a period of ## EQU2 ## and converted into a digital value and stored in the buffer 12.

  On the other hand, the pulse signal PLS6 with a crank angle of 6 degrees is supplied from the pulse generator 13 to the CPU 14, and the CPU 14 performs a process of reading the digital value stored in the buffer 12 with the period of the 6 degrees pulse PLS6. . That is, in this embodiment, the A / D conversion unit 11 does not issue an interrupt request to the CPU 14, but the CPU 14 performs a reading process at a cycle of the 6-degree pulse PLS6.

  The input circuit 17 converts detection signals from various sensors into digital values and supplies them to the CPU 14. The engine speed NE is calculated from the cycle of the 6-degree pulse PLS. Further, the required torque TRQ of the engine 1 is calculated according to the accelerator pedal operation amount AP.

  The CPU 14 calculates a target EGR rate according to the engine operating state, calculates a duty ratio of a control signal for controlling the EGR valve 20 with an opening degree corresponding to the target EGR rate, and outputs the duty control signal to the output circuit 18. The EGR valve 20 is supplied via Here, the target EGR rate is the sum of the total EGR amount that is the sum of the exhaust amount recirculated into the cylinder and the amount of burned gas remaining in the cylinder, and the sum of the total EGR amount and the amount of fresh air sucked into the cylinder. This is a target value of a value (EGR rate) representing the ratio to the total gas amount.

  FIG. 3 is a block diagram showing a configuration of a module for calculating the main injection timing CAIM by the fuel injection valve 6. The function of this module is realized by processing executed by the CPU 14. Note that illustration and detailed description of the configuration of the module for calculating the duty control signal are omitted.

  The module shown in FIG. 3 includes a main injection timing calculation unit 32 that calculates a main injection timing CAIM and a main injection timing correction amount calculation unit 33 that calculates a fuel injection timing correction amount CAD.

  The main injection timing calculation unit 32 includes a main injection timing map value calculation unit 51 and an addition unit 52. The main injection timing map value calculation unit 51 searches a CAIMM map set in advance according to the engine speed NE and the required torque TRQ, and calculates a target main injection timing map value CAIMM. The CAIMM map is set based on a fuel having a predetermined cetane number (for example, an average cetane number in the market). The adding unit 52 calculates the main injection timing CAIM by adding the fuel injection timing correction amount CAD calculated by the main injection timing correction amount calculating unit 33 to the target main injection timing map value CAIMM.

  The main injection timing correction amount calculation unit 33 includes a target main injection ignition timing map value calculation unit 61, an ignition timing detection unit 62, a target ignition timing correction unit 63, a subtraction unit 64, and a PID control unit 65. ing.

  The target main injection ignition timing map value calculation unit 61 searches a CAFMM map set in advance according to the engine speed NE and the required torque TRQ, and calculates a target main injection ignition timing map value CAFMM. The CAFMM map is set based on a fuel having a predetermined cetane number (for example, an average cetane number in the market).

  The ignition timing detection unit 62 includes a heat generation rate calculation unit 71 and an ignition timing determination unit 72, and detects the main injection ignition timing CAFM according to the in-cylinder pressure PCYL detected by the in-cylinder pressure sensor 2. The heat generation rate calculation unit 71 calculates a heat generation rate dQdθ, which is a heat generation amount for each crank angle, based on the crank angle detected by the crank angle position sensor 3 and the in-cylinder pressure PCYL detected by the in-cylinder pressure sensor 2. To do.

  Based on the heat generation rate dQdθ calculated by the heat generation rate calculation unit 71, the ignition timing determination unit 72 detects a pilot injection ignition timing CAFP corresponding to pilot injection and a main injection ignition timing CAFM corresponding to main injection. To do. Specifically, the ignition timing determination unit 72 integrates the heat generation rate dQdθ calculated by the heat generation rate calculation unit 71 corresponding to each of the pilot injection and the main injection, and the combustion mass ratio becomes 50%. The crank angle positions are determined as pilot injection ignition timing CAFP and main injection ignition timing CAFM, respectively. In the present embodiment, only the main injection ignition timing CAFM is used for calculating the fuel injection timing correction amount CAD.

  The target ignition timing correction unit 63 includes a target EGR rate map value calculation unit 81, an actual EGR rate calculation unit 82, a subtraction unit 83, an ignition timing correction amount calculation unit 84, and an addition unit 85, and includes a target main injection. The target main injection ignition timing map value CAFMM calculated by the ignition timing map value calculation unit 61 is corrected to calculate the target ignition timing CAFMCC.

  The target EGR rate map value calculation unit 81 searches a GEGRM map set in advance according to the engine speed NE and the required torque TRQ, and calculates a target EGR rate map value GEGRM. The EGR rate calculation unit 82 calculates a real EGR rate GEGR that is an actual EGR rate by searching a predetermined map according to the oxygen concentration DO detected by the LAF sensor 29. The subtraction unit 83 calculates the deviation ΔGEGRM by subtracting the target EGR rate map value GEGRM from the actual EGR rate GEGR.

  The ignition timing correction amount calculation unit 84 calculates the target ignition timing correction amount CAFMC according to the deviation ΔGEGRM calculated by the subtraction unit 83. Specifically, the ignition timing correction amount calculation unit 84 advances the ignition timing when more exhaust gas is recirculated than the target EGR rate map value GEGRM, that is, when the deviation ΔGEGRM is positive. Then, the target ignition timing correction amount CAFMC is calculated. Further, when the exhaust gas smaller than the target EGR rate map value GEGRM is recirculated, that is, when the deviation ΔGEGRM is negative, the target ignition timing correction amount CAFMC is calculated so that the ignition timing is retarded. More specifically, for example, when ΔGEGRM is about + 3%, the ignition timing is advanced by 1 to 2 degrees, and when ΔGEGRM is about −3%, the ignition timing is 1-2. The target ignition timing correction amount CAFMC is calculated so as to retard the degree.

  The subtracting unit 64 calculates the deviation ΔCAM by subtracting the main injection ignition timing CAFM from the target ignition timing CAFMCC corrected by the target ignition timing correcting unit 63. The PID control unit 65 calculates the fuel injection timing correction amount CAD by PID (proportional integral derivative) control so that the deviation ΔCAM is “0”. That is, when the deviation ΔCAM is a positive value (CAFMCC> CAFM), the fuel injection timing correction amount CAD is decreased. Conversely, when the deviation ΔCAM is a negative value (CAFMCC <CAFM), the fuel injection timing correction is performed. Increase the amount CAD.

  FIG. 4 is a time chart showing the pressure change rate dpdθ and the Pmi fluctuation rate in the internal combustion engine 1 of the present embodiment configured as described above. Specifically, FIG. 4 is a graph showing the pressure change rate dpdθ and the Pmi fluctuation rate when the actual EGR rate changes as indicated by the solid line with respect to the target EGR rate indicated by the broken line with the horizontal axis as time. It is.

  In FIG. 4, solid lines D1 and P1 indicate the pressure change rate dpdθ and Pmi variation rate in the internal combustion engine 1 of the present embodiment, respectively, and alternate long and short dash lines D2 and P2 indicate the pressure change rate dpdθ in the conventional internal combustion engine, respectively. And Pmi variation rate. Here, the conventional internal combustion engine indicates that the target ignition timing map value CAFMM is not corrected by the target ignition timing correction unit 63. That is, the conventional internal combustion engine is one that does not correct the target main injection ignition timing map value CAFMM according to the deviation ΔGEGRRM of the EGR rate.

As shown in FIG. 4, the deviation ΔGEGRM between the target EGR rate and the actual EGR rate is substantially “0” from time t = 0 to t ₁ . For this reason, the influence of the correction of the target main injection ignition timing map value CAFMM by the target ignition timing correction unit 63 is small, and the pressure change rate dpdθ and the Pmi variation rate in this embodiment and the conventional example are substantially equal.

On the other hand, at the time _{t 1} and later, deviation ΔGEGRM between the target EGR rate and the actual EGR rate swings greatly to the positive and negative. For this reason, the influence of the correction of the target main injection ignition timing map value CAFMM by the target ignition timing correction unit 63 becomes large. In other words, in the internal combustion engine 1 of the present embodiment, by correcting the target main injection ignition timing map value CAFMM in accordance with the EGR rate deviation ΔGEGRRM, the pressure change rate dpdθ and the Pmi change rate are increased compared to the conventional example. Can be suppressed.

  As described above in detail, in the present embodiment, the target main injection timing map value CAIMM is calculated according to the engine speed NE and the required torque TRQ, and the target main injection is determined according to the engine speed NE and the required torque TRQ. An ignition timing map value CAFMM is calculated. Further, the target main injection ignition timing map value CAFMM is corrected according to the deviation ΔGEGRM between the target EGR rate map value GEGRM and the actual EGR rate GEGR, and the deviation ΔCAM between the corrected target ignition timing CAFMCC and the main injection ignition timing CAFM. The fuel injection timing correction amount CAD is calculated so as to decrease. Further, the target main injection timing map value CAIMM is corrected by the fuel injection timing correction amount CAD, and fuel injection is executed in accordance with the corrected main injection timing CAIM. The target main injection ignition timing map value CAFMM is appropriately corrected according to the deviation ΔGEGRRM between the target EGR rate map value GEGRM set in advance according to the engine speed NE and the required torque TRQ and the detected actual EGR rate GEGR. As a result, it is possible to prevent the pressure change rate dpdθ in the cylinder from increasing to generate a large noise and vibration, or the Pmi fluctuation rate to deteriorate and misfire.

  In this embodiment, the fuel injection valve 6 constitutes a fuel injection means, the exhaust gas recirculation passage 9 and the EGR valve 20 constitute an exhaust gas recirculation mechanism, and the crank angle position sensor 3 and the accelerator sensor 21 constitute an operation state detection means. The ECU 4 includes fuel injection control means, fuel injection timing storage means, ignition timing storage means, part of ignition timing detection means, part of exhaust gas recirculation rate calculation means, target ignition timing correction means, and fuel injection timing correction amount calculation means. Constitute. More specifically, the CAIMM map corresponds to the fuel injection timing storage means, the CAFMM map corresponds to the ignition timing storage means, the in-cylinder pressure sensor 2 and the ignition timing detection unit 62 correspond to the ignition timing detection means, and the target main The injection ignition timing map corresponds to the ignition timing storage means, the target EGR rate map corresponds to the exhaust gas recirculation rate control value storage means, the actual EGR rate calculation unit 82 corresponds to the exhaust gas recirculation rate calculation means, and the target ignition timing correction unit. 63 corresponds to the target ignition timing correction means, and the main injection timing correction amount calculation unit 33 corresponds to the fuel injection timing correction amount calculation means.

  The present invention is not limited to the embodiment described above, and various modifications can be made. In the present embodiment, the LAF sensor 29 is provided in order to calculate the actual EGR rate GEGR, and the actual EGR rate is calculated based on the oxygen concentration DO detected by the LAF sensor 29. However, the present invention is not limited to this. For example, an EGR sensor that detects the opening degree of the EGR valve may be provided, and the actual EGR rate may be calculated based on the opening degree of the EGR valve detected by the EGR sensor. Further, the actual EGR rate may be calculated based on the amount of fresh air flowing through the intake pipe 7 detected by the intake air flow rate sensor 24 provided in the intake pipe 7.

  In the present embodiment, the ignition timing determination unit 72 integrates the heat generation rate dQdθ and determines the crank angle position at which the combustion mass ratio is 50% as the ignition timing. The ignition timing may be determined at a certain crank angle position.

  Further, when the EGR distribution ratio is different for each cylinder, the target main injection ignition timing map value calculation unit provides a CAFMM map different for each cylinder and calculates a different target main injection ignition timing map value CAFMM for each cylinder. May be.

  In the present embodiment, the target ignition timing correction unit 63 calculates the target ignition timing CAFMCC by correcting the target main injection ignition timing map value CAFMM based on the EGR rate. However, the present invention is not limited to this. For example, the target ignition timing CAFMCC may be calculated by correcting the target main injection ignition timing map value CAFMM based on the amount of fresh air flowing through the intake pipe. In addition, the target main injection ignition timing map value CAFMM is corrected based on the in-cylinder indicated mean effective pressure (IMEP) detected by the in-cylinder pressure sensor, the air-fuel ratio of the exhaust gas, the supercharging pressure, etc. The time CAFMCC may be calculated.

  In the above-described embodiment, an example of a four-cylinder diesel internal combustion engine has been described. However, the present invention is not limited to this, and a diesel internal combustion engine having a different number of cylinders, an outboard motor having a crankshaft in a vertical direction, or the like. The present invention can also be applied to the control of such marine propulsion engine.

1 is a diagram illustrating an internal combustion engine and a control device thereof according to an embodiment of the present invention. FIG. 2 is a diagram more specifically showing a partial configuration of the control device shown in FIG. 1. It is a block diagram which shows the structure of the module which calculates main injection time (CAIM). It is a time chart which shows pressure change rate dpd (theta) and Pmi fluctuation rate in an internal combustion engine. It is a figure which shows the relationship between the crank angle and in-cylinder pressure in PCCI combustion. It is a figure which shows the relationship between the crank angle and in-cylinder pressure in PCCI combustion. It is a figure which shows the relationship between the pressure change rate in a cylinder, and a Pmi fluctuation rate when changing an exhaust gas recirculation rate from 0% to -30%. It is a figure which shows the relationship between the pressure change rate in a cylinder when changing an exhaust gas recirculation rate from 0% to + 30%, and Pmi fluctuation rate.

Explanation of symbols

1 Internal combustion engine 2 In-cylinder pressure sensor (ignition timing detection means)
3 Crank angle position sensor (operating state detection means)
4 Electronic control unit 6 Fuel injection valve (fuel injection means)
9 Exhaust gas recirculation passage (exhaust gas recirculation mechanism)
20 EGR valve (exhaust gas recirculation mechanism)
21 Accelerator sensor (operating state detection means)
32 Main injection timing calculation unit 33 Main injection timing correction amount calculation unit (fuel injection timing correction amount calculation means)
51 Main injection timing map value calculation unit (fuel injection control means)
52 Adder (fuel injection control means)
62 Ignition timing detector (Ignition timing detection means)
63 Target ignition timing correction unit (target ignition timing calculation means)
82 Real EGR rate calculation unit (exhaust gas recirculation rate calculation means)

Claims (1)

In a control apparatus for an internal combustion engine, provided with a fuel injection means for injecting fuel into the combustion chamber of the internal combustion engine, and an exhaust gas recirculation mechanism for recirculating exhaust gas of the internal combustion engine to an intake system,
Fuel injection timing storage means for storing fuel injection timing by the fuel injection means set according to the operating state of the internal combustion engine;
An operating state detecting means for detecting an operating state of the internal combustion engine;
A fuel injection control means for determining the fuel injection timing by searching the fuel injection timing stored in the fuel injection timing storage means according to the detected engine operating state, and executing the fuel injection by the fuel injection means;
Ignition timing storage means for storing a target ignition timing of the fuel injected into the combustion chamber, which is set according to the operating state of the internal combustion engine;
Ignition timing detection means for detecting the actual ignition timing of the fuel injected into the combustion chamber;
An exhaust gas recirculation rate control value storage means storing an exhaust gas recirculation rate control value set by the exhaust gas recirculation mechanism, which is set according to the operating state of the internal combustion engine;
An exhaust gas recirculation rate calculating means for calculating an actual exhaust gas recirculation rate by the exhaust gas recirculation mechanism;
A deviation is calculated by subtracting the control value of the exhaust gas recirculation rate from the actual exhaust gas recirculation rate, and when the calculated deviation is positive, the target ignition timing is corrected to the advance side, and when it is negative Is a target ignition timing correction means for correcting the target ignition timing to the retard side ,
Fuel injection timing correction amount calculation means for calculating a fuel injection timing correction amount so as to reduce a deviation between the target ignition timing corrected by the target ignition timing correction means and the actual ignition timing;
The control apparatus for an internal combustion engine, wherein the fuel injection control means corrects the fuel injection timing by the fuel injection timing correction amount, and executes fuel injection according to the corrected fuel injection timing.

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