JP4312651B2 - 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 a control device for an internal combustion engine provided with an exhaust purification device for purifying exhaust gas in an exhaust system.

  When the lean burn operation is performed in which the air-fuel ratio of the air-fuel mixture combusted in the combustion chamber of the engine is set to be leaner than the stoichiometric air-fuel ratio, the NOx emission tends to increase. Therefore, for example, Patent Document 1 discloses a technique for providing a NOx purification device in an exhaust system of an engine to reduce the NOx emission amount. In an engine equipped with an NOx purification device in the exhaust system, when only lean burn operation is continued for a long time, the amount of NOx absorbed in the NOx purification device is saturated. Therefore, in order to reduce the NOx absorbed in the NOx purification device, it is necessary to enrich the air-fuel ratio for a relatively short time.

  In the device shown in Patent Document 1, when the air-fuel ratio enrichment is performed, the amount of fuel supplied to the engine is increased, and the intake control valve of the engine is closed to a certain degree of opening, thereby reducing the intake amount. Further, the exhaust gas is recirculated to the intake system.

Japanese Patent No. 2845103

  Even if the intake control valve is closed, the intake air amount does not decrease immediately but decreases with a time delay. For this reason, in the control method shown in the above-described conventional apparatus, the fuel increase timing and the timing when the intake air amount actually decreases may deviate, resulting in fluctuations in engine output torque and deterioration in exhaust characteristics.

  The present invention has been made paying attention to this point, and improves the convergence of the intake air amount to the target value when the air-fuel ratio enrichment is performed. It is an object of the present invention to provide a control device for an internal combustion engine that can reduce the deviation and suppress the torque fluctuation and the deterioration of the exhaust characteristics.

In order to achieve the above object, an invention according to claim 1 is provided in an exhaust system (4) of an internal combustion engine (1) operated with an air-fuel ratio set to a leaner side than a stoichiometric air-fuel ratio, and purifies exhaust gas. Control of an internal combustion engine having exhaust purification means (16), a supercharger (8) provided in the intake system (2) of the engine, and an intake control valve (13) for controlling intake air flowing into the engine In the apparatus, a basic target opening degree setting means for setting a basic target opening degree (THMAP) of the intake control valve (3) according to an operating state of the engine, and the intake air control for regenerating the exhaust gas purification means. When the valve opening (TH) is decreased, the target opening (THCMD) is calculated by correcting the basic target opening (THMAP) by a set correction amount (ΔTH1) in the decreasing direction, and then the target opening Degree (THCMD) as the basic target And correcting means for returning to degrees (THMAP), the opening degree of the intake control valve (TH) comprises a driving means for driving the intake control valve such that the match with the target opening (THCMD), boost pressure (BPA ) For detecting the supercharging pressure , and the correction means according to a deviation (ΔBPA) between the target supercharging pressure (BPCMD) of the supercharger and the detected supercharging pressure (BPA). Te, characterized that you set the setting correction amount (? Th1).
Here, regeneration of the exhaust gas purification means means removal of NOx or SOx accumulated in the exhaust gas purification means.

According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, an exhaust gas recirculation passage (5) for recirculating exhaust gas of the engine to the intake system (2), and the exhaust gas recirculation passage (5) And an exhaust gas recirculation control means for controlling the opening degree (LACT) of the exhaust gas recirculation control valve, wherein the exhaust gas recirculation control means includes an opening degree of the intake control valve ( When decreasing (LACT), the control gain (GEGR) of the exhaust gas recirculation control valve opening (LACT) is increased from that during normal control.

According to a third aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, an intake air amount detecting means (21) for detecting an intake air amount (GAIR) of the engine, and an opening degree of the intake control valve. After the decrease, a convergence determining means for determining that the intake air amount (GAIR) detected by the intake air amount detecting means (21) has converged to a target intake air amount (GACMD), and a detected intake air amount ( A fuel supply amount control means for increasing the amount of fuel supplied to the engine when it is determined that (GAIR) has converged to the target intake air amount (GACMD).

According to the first aspect of the present invention, when the basic target opening of the intake control valve is set according to the operating state of the engine and the opening of the intake control valve is decreased in order to regenerate the exhaust purification means. Then, the target opening is calculated by correcting the basic target opening in the decreasing direction by the set correction amount, and thereafter the target opening is controlled to return to the basic target opening. Then, the intake control valve is driven so that the opening degree of the intake control valve matches the target opening degree. Therefore, it is possible to improve the convergence to the target intake air amount when reducing the intake air amount, reduce the difference between the fuel increase timing and the intake air decrease timing, and suppress the torque fluctuation and the deterioration of the exhaust characteristics. it can. In addition, since the set correction amount is set according to the deviation between the target boost pressure of the turbocharger and the actual boost pressure, it is possible to correct the target opening appropriately according to the boost pressure deviation. it can. As a result, even when the boost pressure deviation is large, it is possible to prevent the convergence of the intake air amount to the target intake air amount from being deteriorated.

According to the second aspect of the present invention, when the opening degree of the intake control valve is decreased, the control gain of the exhaust gas recirculation control valve opening degree is higher than that during normal control, so that the exhaust gas recirculation amount that affects the intake air amount. And the convergence of the intake air amount to the target intake air amount can be further improved.

According to the third aspect of the present invention, the fuel supplied to the engine is increased when it is determined that the detected intake air amount has converged to the target intake air amount after the opening degree of the intake control valve is decreased. Therefore, it is possible to reliably match the fuel increase timing and the intake air decrease timing.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an overall configuration of an internal combustion engine (hereinafter referred to as “engine”) and a control device thereof according to an embodiment of the present invention. The engine 1 is a diesel engine that directly injects fuel into a cylinder, and a fuel injection valve 12 is provided in each cylinder. The fuel injection valve 12 is electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 20, and the valve opening timing and valve opening time of the fuel injection valve 12 are controlled by the ECU 20.

  The engine 1 includes an intake pipe 2, an exhaust pipe 4, and a turbocharger 8. The turbocharger 8 includes a turbine 10 driven by exhaust kinetic energy, and a compressor 9 that is rotationally driven by the turbine 10 and compresses intake air.

  The turbine 10 includes a plurality of variable vanes (not shown), and the turbine rotational speed (rotational speed) can be changed by changing the opening of the variable vane (hereinafter referred to as “vane opening”). It is configured. The vane opening degree of the turbine 10 is electromagnetically controlled by the ECU 20. More specifically, the ECU 20 supplies a control signal with a variable duty ratio to the turbine 10 to control the vane opening. Increasing the vane opening improves the efficiency of the turbine 10 and increases the turbine speed. As a result, the supercharging pressure increases.

  A throttle valve 13 for controlling the intake air amount is provided in the intake pipe 2 downstream of the compressor 9. The throttle valve 13 is driven by an actuator 14, and the actuator 14 is connected to the ECU 20. The opening degree TH of the throttle valve 13 is controlled by the ECU 20.

The intake pipe 2 is branched corresponding to each cylinder on the downstream side of the throttle valve 13, and each of the branched intake pipes 2 is branched into two intake ports 2A and 2B. FIG. 1 shows only the configuration corresponding to one cylinder.
Each cylinder of the engine 1 is provided with two intake valves (not shown) and two exhaust valves (not shown). An intake port (not shown) that is opened and closed by two intake valves is connected to each of the intake ports 2A and 2B.

  In addition, a swirl control valve (hereinafter referred to as “SCV”) 15 that generates a swirl in the combustion chamber of the engine 1 by limiting the amount of air sucked through the intake port 2B is provided in the intake port 2B. Yes. SCV15 is a butterfly valve driven by an electric motor (not shown), and the valve opening degree is controlled by ECU20.

  Between the exhaust pipe 4 and the downstream side of the throttle valve 13 of the intake pipe 2, an exhaust recirculation passage 5 for returning the exhaust gas to the intake pipe 2 is provided. The exhaust gas recirculation passage 5 is provided with an exhaust gas recirculation control valve (hereinafter referred to as “EGR valve”) 6 for controlling the exhaust gas recirculation amount. The EGR valve 6 is an electromagnetic valve having a solenoid, and the valve opening degree is controlled by the ECU 20. The EGR valve 6 is provided with a lift sensor 7 for detecting the valve opening degree (valve lift amount) LACT, and the detection signal is supplied to the ECU 20. An exhaust gas recirculation mechanism is configured by the exhaust gas recirculation passage 5 and the EGR valve 6. The EGR valve 6 is controlled by a control signal having a variable duty ratio so that the valve opening degree LACT coincides with the valve opening degree command value LCMD set according to the engine operating state.

The intake pipe 2 includes an intake air amount sensor 21 that detects an intake air amount GAIR (an amount of air sucked into the engine 1 per unit time), and a supercharging pressure sensor 22 that detects a supercharging pressure BPA downstream of the compressor 9. These detection signals are supplied to the ECU 20.
A particulate matter filter 11 and a NOx purification device 16 are provided downstream of the turbine 10 in the exhaust pipe 4. The particulate matter filter 11 collects soot which is a particulate matter whose main component is carbon contained in the exhaust gas. The NOx purification device 16 contains a NOx absorbent that absorbs NOx and a catalyst for promoting oxidation and reduction. The NOx purification device 16 has an air-fuel ratio of the air-fuel mixture in the combustion chamber set to a lean side with respect to the stoichiometric air-fuel ratio, an exhaust gas lean having a relatively high oxygen concentration and a reducing agent (HC and CO) concentration lower than the oxygen concentration. In the state, while absorbing NOx, the air-fuel ratio of the air-fuel mixture in the combustion chamber is set to be richer than the stoichiometric air-fuel ratio, and the exhaust gas has a relatively low oxygen concentration and a reducing agent concentration higher than the oxygen concentration. In the rich state, the absorbed NOx is reduced by a reducing agent and discharged as nitrogen gas, water vapor, and carbon dioxide.

  If NOx is absorbed up to the limit of the NOx absorption capacity of the NOx absorbent, that is, the maximum NOx absorption amount, no more NOx can be absorbed. Therefore, enrichment of the air-fuel ratio is executed to reduce NOx in a timely manner. The enrichment of the air-fuel ratio is performed by increasing the amount of fuel injected from the fuel injection valve 12 and mainly decreasing the intake amount by the throttle valve 13. In this embodiment, the adjustment of the intake air amount when enriching the air-fuel ratio is performed by using not only the throttle valve 13 but also the opening degree of the EGR valve 6, the supercharging pressure control, and the SCV 15 control.

  Further, on the upstream side of the particulate matter filter 11, a proportional air-fuel ratio sensor (hereinafter referred to as “LAF sensor”) 23 and an exhaust pressure sensor 24 for detecting the exhaust pressure PEX are provided. The LAF sensor 23 supplies a detection signal to the ECU 20 that is substantially proportional to the oxygen concentration (air-fuel ratio) in the exhaust gas. The exhaust pressure sensor 24 supplies a detection signal indicating the exhaust pressure PEX to the ECU 20.

  Further, an accelerator sensor 25 for detecting an operation amount (hereinafter referred to as “accelerator pedal operation amount”) AP of an accelerator pedal (not shown) of a vehicle driven by the engine 1 and rotation of a crankshaft (not shown) of the engine 1. A crank angle position sensor 26 for detecting the angle is provided. Detection signals from these sensors are supplied to the ECU 20.

  The crank angle position sensor 26 is a cylinder discrimination sensor that outputs a pulse (hereinafter referred to as “CYL pulse”) at a predetermined crank angle position of a specific cylinder of the engine 1, and relates to a top dead center (TDC) at the start of the intake stroke of each cylinder. A TDC sensor that outputs a TDC pulse at a crank angle position before a predetermined crank angle (every crank angle of 180 degrees in a four-cylinder engine), and a CRK that generates a CRK pulse at a constant crank angle period shorter than the TDC pulse (for example, a period of 30 degrees) The sensor is composed of a CYL pulse, a TDC pulse, and a CRK pulse. These pulses are used for fuel injection control and detection of engine speed (engine speed) NE.

  The ECU 20 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, a central processing unit (hereinafter referred to as “CPU”). A storage circuit for storing various calculation programs executed by the CPU, calculation results, and the like, an output circuit for supplying control signals to the fuel injection valve 12, the EGR valve 6, the turbine 10, the actuator 14, and the like.

  The engine 1 is normally operated with the air-fuel ratio set leaner than the stoichiometric air-fuel ratio. When the air-fuel ratio enrichment is performed, the air-fuel ratio is set richer than the stoichiometric air-fuel ratio.

  2 and 3 are flowcharts of processing for controlling the intake air amount of the engine 1. This process is executed by the CPU of the ECU 5 in synchronization with the TDC pulse.

  Steps S10 to S17 in FIG. 2 correspond to supercharging pressure control (VNT control) for controlling the vane opening of the turbine 10, and steps S21 to S27 are exhaust gas recirculation control (EGR control) for controlling the opening of the EGR valve 6. ), Steps S31 to S38 in FIG. 3 correspond to throttle valve opening control (DBW control) for controlling the opening of the throttle valve 13, and steps S41 to S45 are SCV opening for controlling the opening of the SCV15. This corresponds to control (SCV control).

  In step S10, a deviation ΔBPA (= BPA−BPCMD) between the detected boost pressure BPA and the target boost pressure BPCMD is calculated. The target boost pressure BPCMD is calculated by searching a map set in accordance with the accelerator pedal operation amount AP and the engine speed NE. In step S11, a correction coefficient KBPA is calculated according to the deviation ΔBPA. The correction coefficient KBPA is set to a smaller value as the deviation ΔBPA increases.

  In step S12, it is determined whether or not the enrichment flag FRSP is “1”. The enrichment flag FRSP is set to “1” when air-fuel ratio enrichment is performed. When FRSP = 0 and normal operation is being performed, the first vane opening map value VNTMAP1 is calculated according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE (step S13). ), The vane opening basic value VNTMAP is set to the first vane opening map value VNTMAP1 (step S14). Thereafter, the process proceeds to step S17. Thereby, the vane opening basic value VNTMAP is set to a value suitable for normal operation.

  In step S12, when FRSP = 1 and the air-fuel ratio enrichment operation is being performed, the second vane opening map value is determined according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE. VNTMAP2 is calculated (step S15), and the vane opening basic value VNTMAP is set to the second vane opening map value VNTMAP2 (step S16). Thereafter, the process proceeds to step S17. The second vane opening degree map value VNTMAP2 is set to a value smaller than the first vane opening degree map value VNTMAP1 (a value for reducing the supercharging pressure) in the same engine operating state. Thereby, the vane opening basic value VNTMAP is set to a value suitable for the air-fuel ratio enrichment operation.

In step S17, the vane opening command value VNTCMD is calculated by multiplying the vane opening basic value VNTMAP by the correction coefficient KBPA.
The vane opening of the turbine 10 is controlled so as to coincide with the vane opening command value VNTCMD.

  In step S21, it is determined whether or not the enrichment flag FRSP is “1” as in step S12. When FRSP = 0, the first control gain GEGR1 of EGR control is calculated according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE (step S23), and the control gain GEGR is calculated. The first control gain GEGR1 is set (step S24). Thereafter, the process proceeds to step S27. Thereby, the control gain GEGR for EGR control is set to a value suitable for normal operation.

  If FRSP = 1 in step S21, it is determined whether or not the detected intake air amount GAIR has converged to the target intake air amount GACMD (step S22). Specifically, it is determined whether or not the absolute value of the deviation ΔGAIR between the intake air amount GAIR and the target intake air amount GACMD is equal to or smaller than the convergence determination threshold value ΔGATH. If the answer to step S22 is affirmative (YES), the process proceeds to step S23. If the answer is negative (NO), the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE are selected. Then, the second control gain GEGR2 for EGR control is calculated (step S25), and the control gain GEGR is set to the second control gain GEGR2 (step S26). Thereafter, the process proceeds to step S27. The second control gain GEGR2 is set to a value larger than the first control gain GEGR1 in the same operating state. Thereby, the control gain GEGR of EGR control is set to a value suitable for the air-fuel ratio enrichment operation.

  In step S27, the valve opening command value LCMD of the EGR valve 6 is set according to the intake air amount GAIR, and the EGR valve 6 is controlled so that the actual valve opening LACT coincides with the valve opening command value LCMD. . The control gain GEGR set in steps S23 to S26 is applied as the control gain of this feedback control.

  In step S31 of FIG. 3, it is determined whether or not the enrichment flag FRSP is “1”. When FRSP = 0, the target opening degree THCMD of the throttle valve 13 is set to the full opening degree THMAX (step S32). When FRSP = 1, the target opening degree map value THMAP for the air-fuel ratio enrichment operation is calculated according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE. The target opening degree map value THMAP is set to a value smaller than the fully opened opening degree.

  In step S34, as in step S22, it is determined whether or not the intake air amount GAIR has converged to the target intake air amount GACMD. When the answer to step S34 is negative (NO), the difference ΔBPA (= BPA−BPCMD) between the detected boost pressure BPA and the target boost pressure BPCMD is calculated (step S10), similarly to step S10. S35).

In step S36, a correction amount ΔTH1 is calculated according to the deviation ΔBPA. The correction amount ΔTH1 is calculated by searching a ΔTH1 map set in advance according to the deviation ΔBPA and the intake air amount GAIR, or by the following equation (1). That is, the correction amount ΔTH1 is set to a larger value as the deviation ΔBPA increases and the intake air amount GAIR increases.
ΔTH1 = Kth × ΔBPA × GAIR (1)
Here, Kth is a flow rate correction coefficient determined by the shape of the throttle valve 13.

  In step S37, the target opening degree THCMD is calculated by subtracting the correction amount ΔTH1 from the target opening degree map value THMAP. That is, when the air-fuel ratio enrichment operation is performed, the target opening degree THCMD corrects the target opening degree map value THMAP in a decreasing direction by the correction amount ΔTH1 within a period until the intake air amount GAIR converges to the target intake air amount GACMD. Is set to the specified value.

If the answer to step S34 is affirmative (YES) and the intake air amount GAIR converges to the target intake air amount GACMD, the target opening degree THCMD is calculated by the following equation (2) (step S38).
THCMD = (1−α) × THCMD (n−1) + α × THMAP (2)
Here, α is a predetermined coefficient set to a value between 0 and 1, and THCMD (n−1) is a previously calculated value of the target opening.

From equation (2), the target opening THCMD is set so as to gradually approach the target opening map value THMAP.
The opening TH of the throttle valve 13 is controlled so as to coincide with the target opening THCMD.

  In step S41, it is determined whether or not the enrichment flag FRSP is “1”. When FRSP = 0, the first target SCV opening map value SCVMAP1 is calculated according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE (step S42), and the target SCV opening is calculated. The degree SCVCMD is set to the first target SCV opening map value SCVMAP1 (step S43). Thereby, the target SCV opening SCVCMD is set to a value suitable for normal operation.

If FRSP = 1 in step S41, a second target SCV opening map value SCVMAP2 is calculated according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE (step S44). Then, the target SCV opening SCVCMD is set to the second target SCV opening map value SCVMAP2 (step S45). The second target SCV opening map value SCVMAP2 is set to a value smaller than the first target SCV opening map value SCVMAP1 in the same engine operating state. Thereby, the target SCV opening SCVCMD is set to a value suitable for the air-fuel ratio enrichment operation.
The opening degree of the SCV 15 is controlled so as to coincide with the target SCV opening degree SCVCMD.

FIG. 4 is a flowchart of the fuel supply control process. This process is executed by the CPU of the ECU 5 in synchronization with the generation of the TDC pulse.
In step S51, it is determined whether or not the enrichment flag FRSP is “1”. When FRSP = 0, the fuel control parameter for normal control is calculated according to the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE (step S53). The fuel control parameters include the number of fuel injections NINJ1, the fuel injection timing TINJ1, and the fuel injection amount QINJ1 within one TDC period (TDC pulse generation interval).

  If FRSP = 1 in step S51, it is determined whether or not the intake air amount GAIR has converged to the target intake air amount GACMD (step S52). If the answer is negative (NO), the process proceeds to step S53. If the answer is affirmative (YES), the process proceeds to step S54, and the engine operating state, specifically, the accelerator pedal operation amount AP and the engine speed NE are set. Accordingly, the fuel control parameters for the air-fuel ratio enrichment operation, that is, the fuel injection number NINJ2, the fuel injection timing TINJ2, and the fuel injection amount QINJ2 are calculated. The fuel injection amount QINJ2 is set to a larger value than the fuel injection amount QINJ1 for normal control in the same engine operating state.

In step S55, air-fuel ratio feedback control for correcting the fuel injection amount QINJ2 is performed so that the air-fuel ratio AFACT detected by the LAF sensor 23 matches the target air-fuel ratio AFCMD.
Based on the fuel control parameter calculated in this way, drive control of the fuel injection valve 12 is performed.

  FIG. 5 shows the target opening THCMD of the throttle valve 13 (FIG. 5A), the opening LACT of the EGR valve 6 (FIG. 5B), and the intake air amount GAIR (when the air-fuel ratio enrichment operation is started. It is a time chart which shows transition of the figure (c)) and fuel injection quantity QINJ (the figure (d)). In this figure, the broken line corresponds to the conventional control method, and the solid line corresponds to the control method of the present embodiment. When the air-fuel ratio enrichment operation is started at time t1, the target intake air amount GACMD is changed from the first value GACMD1 to the second value GACMD2, and a map for calculating the target opening degree map value THMAP is: The map is switched to the air-fuel ratio enrichment operation map. Accordingly, the map value THMAP changes from the first value THMAP1 to the second value THMAP2 in steps. At this time, in the present embodiment, the target opening degree THCMD is set to a value smaller than the map value THMAP by a correction amount ΔTH1. After it is determined that the intake air amount GAIR converges to the target intake air amount GACMD at time t2, the target opening degree THCMD gradually approaches the second value THMAP2 and coincides with time t3.

  Further, as shown in FIG. 5B, at time t1, the valve opening command value LCMD of the EGR valve 6 is changed from the first value LCMD1 to the second value LCMD2. In the present embodiment, since the control gain GEGR for EGR control is set to the second control gain GEGR2 that is larger than the first control gain GEGR1 for normal control, the actual valve opening LACT is the first valve gain command value LCMD. Overshoot with respect to the value LCMD2 of 2 converges to the second value LCMD2. In FIG. 5B, the control gain GEGR is set to the second control gain GEGR2 during the period TFBH from time t1 to t2.

By performing the DBW control and the EGR control as shown in FIGS. 5A and 5B, the intake air amount GAIR is earlier than the conventional intake air amount as shown by the solid line in FIG. 5C. It converges to GACMD2 (time t2).
Further, as shown in FIG. 5D, the fuel injection amount QINJ is increased at time t2 when the intake air amount GAIR converges to the target intake air amount GACMD2. Therefore, the fuel supply amount is increased in accordance with the time when the intake air amount GAIR actually decreases. On the other hand, in the conventional control method, since the increase in the fuel supply amount is started from time t1, more fuel must be injected to realize the necessary rich air-fuel ratio. That is, in the present embodiment, the fuel supply amount is increased in accordance with the time when the intake air amount GAIR actually decreases, so that the increase amount can be reduced compared to the conventional case. As described above, according to the present embodiment, the convergence to the target intake air amount GACMD when the intake air amount GAIR is decreased is improved, the deviation between the fuel increase timing and the intake air decrease timing is eliminated, and the torque fluctuation In addition, deterioration of exhaust characteristics can be prevented.

  FIG. 6 is a time chart showing the transition of the target intake air amount GACMD (broken line) and the detected intake air amount GAIR (solid line). Time t1 in FIG. 6 corresponds to time t1 in FIG. 6A corresponds to the case where the conventional control method is applied, and FIG. 6C corresponds to the case where the control method of the present embodiment is applied. In the example shown in this figure, the air-fuel ratio enrichment operation ends at time t4, and the lean burn operation is resumed. FIG. 6B corresponds to the case where only the EGR control is applied to the conventional control method. Comparing FIG. 6B and FIG. 6C, it can be confirmed that the convergence in the A part is improved in FIG. 6C. That is, the convergence of the intake air amount GAIR can be further improved by increasing the control gain GEGR of EGR control.

  Further, in the present embodiment, the correction amount ΔTH1 of the target opening THCMD of the throttle valve 13 is set according to the supercharging pressure deviation ΔBPA, so that the supercharging pressure BPA does not match the target supercharging pressure BPCMD. Even in this case, appropriate correction according to the supercharging pressure deviation ΔBPA can be performed. In particular, even when the supercharging pressure deviation ΔBPA is large, it is possible to prevent the convergence of the intake air amount GAIR from being deteriorated.

  In the present embodiment, the NOx purification device 16 corresponds to the exhaust purification means, the throttle valve 13 corresponds to the intake control valve, the actuator 14 corresponds to the drive means, the intake air amount sensor 21 corresponds to the intake air amount detection means, The supercharging pressure sensor 22 corresponds to supercharging pressure detection means. Further, the ECU 20 constitutes a target opening setting means, a correction means, an exhaust gas recirculation control means, a convergence judgment means, and a fuel supply amount control means. Specifically, step S33 in FIG. 3 corresponds to the target opening setting means, steps S34 to S38 correspond to the correction means, and steps S21 to S27 in FIG. 2 correspond to the exhaust gas recirculation control means. Step S52 of FIG. 4 corresponds to convergence determination means, and step S54 of FIG. 4 corresponds to fuel supply amount control means.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the example in which the present invention is applied when performing the air-fuel ratio enrichment operation to reduce the NOx absorbed by the NOx purification device 16 has been described. In the case of poisoning, the present invention may be applied when performing an air-fuel ratio enrichment operation in order to remove SOx.

  The present invention can also be applied to control of a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a flowchart of the process which performs intake air amount control of the internal combustion engine shown in FIG. It is a flowchart of the process which performs intake air amount control of the internal combustion engine shown in FIG. It is a flowchart of the process which performs fuel supply control of the internal combustion engine shown in FIG. It is a time chart for demonstrating the process shown to FIGS. FIG. 4 is a time chart for explaining control characteristics by an intake air amount control process shown in FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 4 Exhaust pipe 5 Exhaust gas recirculation passage 6 Exhaust gas recirculation control valve 8 Supercharger 12 Fuel injection valve 13 Throttle valve (intake control valve)
14 Actuator (drive means)
16 NOx purification device (exhaust gas purification means)
22 Supercharging pressure sensor (Supercharging pressure detection means)

Claims (3)

An exhaust gas purifying means for purifying exhaust gas, a supercharger provided in the intake system of the engine, provided in an exhaust system of an internal combustion engine that is operated with an air-fuel ratio set to a lean side of the stoichiometric air-fuel ratio; and the engine An internal combustion engine control device having an intake control valve for controlling intake air flowing into the engine,
Basic target opening setting means for setting a basic target opening of the intake control valve according to the operating state of the engine;
When reducing the opening of the intake control valve to regenerate the exhaust purification means, the target opening is calculated by correcting the basic target opening in a decreasing direction by a set correction amount, and then the target Correction means for returning the opening to the basic target opening;
Drive means for driving the intake control valve so that the opening of the intake control valve matches the target opening ;
A supercharging pressure detecting means for detecting the supercharging pressure ,
It said correction means, wherein the target supercharging pressure of the supercharger, in accordance with the deviation between the detected boost pressure control apparatus for an internal combustion engine, characterized in that you set the setting correction amount. An exhaust gas recirculation passage for recirculating exhaust gas from the engine to an intake system; an exhaust gas recirculation control valve provided in the exhaust gas recirculation passage; and an exhaust gas recirculation control means for controlling an opening degree of the exhaust gas recirculation control valve. recirculation control means is operated to reduce the opening degree of the intake control valve, the control apparatus for an internal combustion engine according to claim 1, characterized in that to increase the control gain of the exhaust gas recirculation control valve opening than normal control .   Intake amount detection means for detecting the intake amount of the engine, and convergence for determining that the intake amount detected by the intake amount detection means has converged to a target intake amount after reducing the opening of the intake control valve And a fuel supply amount control unit configured to increase the amount of fuel supplied to the engine when it is determined by the convergence determination unit that the detected intake air amount has converged to a target intake air amount. Item 2. A control device for an internal combustion engine according to Item 1.

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