JP5995088B2 - Control device for internal combustion engine - Google Patents

Description

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

  During deceleration of the internal combustion engine, the EGR valve that adjusts the amount of EGR gas that recirculates from the exhaust passage to the intake passage of the internal combustion engine is controlled to the closed side (see, for example, Patent Documents 1 and 2). At this time, due to a response delay of the EGR valve, the supply amount of EGR gas supplied to the cylinder becomes excessive, and there is a risk of misfire. Therefore, in the invention of Patent Document 1, at the time of deceleration, the control to the closing side of the throttle provided in the intake passage is synchronized with the control of the EGR valve, thereby preventing excessive supply of EGR gas and misfire. Trying to avoid.

  Further, in the invention of Patent Document 2, when the differential opening between the target opening of the EGR valve and the actual opening is larger than a predetermined value at the time of deceleration, misfire is caused by advancing the timing for performing the fuel cut control of the internal combustion engine. Trying to avoid.

JP-A-10-89130 Japanese Patent No. 4957692

  However, in the invention of Patent Document 1, since the control to the throttle closing side is delayed in accordance with the control of the EGR valve, the degree of deceleration differs from the driver's deceleration request, and the driver may feel uncomfortable. There is a feeling of slowing down. In the invention of Patent Document 2, the fuel cut control timing changes according to the situation at the time of deceleration, so the degree of deceleration changes according to the situation at the time of deceleration, and the driver may feel uncomfortable ( The feeling of deceleration becomes stronger.)

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for an internal combustion engine capable of avoiding the risk of misfire while suppressing variations in the feeling of deceleration given to the driver during deceleration of the internal combustion engine. .

In order to solve the above-described problems, an internal combustion engine control apparatus according to the present invention obtains a value that serves as an index of the amount of EGR gas supplied from the exhaust passage of the internal combustion engine to the intake passage and supplied to the internal combustion engine. A value acquisition means;
Excess determination means for determining whether or not the supply amount of the EGR gas during deceleration of the internal combustion engine is excessive based on the index value acquired by the index value acquisition means;
An injection control means for adjusting an injection amount of fuel supplied to the internal combustion engine according to an operating state of the internal combustion engine, and when the supply amount of the EGR gas is excessive during deceleration of the internal combustion engine, Injection control means for performing fuel injection with an injection amount that is corrected to decrease from a basic injection amount that is an injection amount when there is not,
Throttle control means for adjusting the opening of a throttle provided in the intake passage according to the operating condition of the internal combustion engine, and when the supply amount of the EGR gas is excessive during deceleration of the internal combustion engine, Throttle control means for correcting the throttle opening from the basic opening, which is the opening of the throttle when not excessive, to the open side;
It is characterized by providing.

  In the present invention, the above problem is solved by paying attention to the fact that the feeling of deceleration felt by the driver has a correlation with the sum of the output generated by combustion and the pumping loss that increases when the throttle is closed. That is, according to the present invention, if the supply amount of EGR gas is excessive during deceleration of the internal combustion engine, the injection amount reduction correction is performed, so the risk of misfire can be avoided. In addition, when the supply amount of EGR gas is excessive, the opening of the throttle is corrected to the open side, so that the pumping loss can be reduced as compared with the basic opening. And the output decrease due to the decrease in the injection amount can be compensated by the decrease in pumping loss due to the correction of the throttle, and the final output of the internal combustion engine (total output obtained by subtracting various losses such as pumping loss from the output due to combustion) , It can be equivalent to the case where the supply amount of the EGR gas is not excessive. Therefore, variation in the feeling of deceleration given to the driver during deceleration can be suppressed.

It is a block diagram of an engine system. It is the figure which showed the time change of the various parameters regarding the driving | operation of an engine. It is a flowchart of the process which ECU performs. 4 is a detailed flowchart of S13 in FIG. 3. It is the figure which compared the combustion output, the pumping loss, and the total output with the invention of the present invention and Patent Documents 1 and 2.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of an engine system 1 that is mounted on a vehicle and drives the vehicle. The engine system 1 includes a diesel engine 50 (hereinafter simply referred to as an engine) as an internal combustion engine and various configurations necessary for the operation of the engine 50.

  The engine 50 includes a cylindrical cylinder 51 and a piston 52 provided in the cylinder 51. An engine head 56 is provided above the cylinder 51 so as to close the cylinder 51. The engine head 56 is provided with an injector 53 that injects fuel (light oil) into the cylinder 51 (a space 511 (combustion chamber) between the upper surface of the piston 52 and the engine head 56). The engine head 56 is connected to an intake passage 21 through which air sucked into the combustion chamber 511 flows and an exhaust passage 22 through which exhaust gas discharged from the combustion chamber 511 communicates with the combustion chamber 511. An intake valve 54 that opens and closes the opening is provided at the opening of the intake passage 21 and the combustion chamber 511. An exhaust valve 55 that opens and closes the opening is provided at the opening of the exhaust passage 22 and the combustion chamber 511.

  The engine 50 generates power for reciprocating the piston 52 by combustion (spontaneous ignition) of the air sucked into the combustion chamber 511 and the fuel injected from the injector 53, and via a crank (not shown) connected to the piston 52. Drive the vehicle.

  The intake passage 21 includes, from the upstream side, an air cleaner 31 that removes dust and the like contained in air (fresh air) flowing through the intake passage 21, a supercharger compressor 32 that compresses air that has passed through the air cleaner 31, and compression An intercooler 33 that cools the generated air and a throttle 34 that adjusts the amount of air taken into the engine 50 are arranged in this order.

  The intake passage 21 is provided with an air flow meter 61 that detects the flow rate of air flowing through the intake passage 21. The air flow meter 61 is provided upstream of the throttle 34 (in the vicinity of the air cleaner 31 in FIG. 1). An intake manifold pressure sensor 62 that detects the pressure in the intake manifold and an intake manifold gas temperature sensor 63 that detects the gas temperature are provided downstream of the throttle 34 in the intake passage 21 (intake manifold).

  In the exhaust passage 22, from the upstream side, a turbocharger turbine 37 (variable nozzle turbo (VNT)) for recovering energy from the exhaust gas, an oxidation catalyst 38 for oxidizing and removing CO, HC, etc. in the exhaust gas, A DPF 39 for removing PM in exhaust gas and a muffler 40 for suppressing exhaust noise are arranged in this order. An exhaust manifold pressure sensor 64 for detecting the exhaust gas pressure is provided upstream of the turbocharger turbine 37 in the exhaust passage 22 (exhaust manifold). Further, the exhaust passage 22 is provided with an A / F sensor 65 that outputs a signal corresponding to the air-fuel ratio of the exhaust gas. The A / F sensor 65 is provided, for example, for calculating the oxygen concentration of the exhaust gas.

  The engine system 1 is provided with an EGR passage 23 for returning a part of the exhaust gas to the intake passage. One end of the EGR passage 23 is connected upstream (exhaust manifold) of the turbocharger turbine 37 of the exhaust passage 22, and the other end is connected downstream of the throttle 34 of the intake passage 21 (intake manifold). Yes. The EGR passage 23 is provided with an EGR valve 35 that adjusts the flow rate of EGR gas flowing through the EGR passage 23. Further, a passage 231 branched from the EGR passage 23 and joined again to the EGR passage 23 is provided, and an EGR cooler 36 for cooling the EGR gas flowing through the passage 231 is provided in the passage 231. Further, a valve 41 for adjusting the amount of EGR gas flowing through the passage 231 is provided. By adjusting the amount of EGR gas flowing through the passage 231 (the amount of EGR gas passing through the EGR cooler 36) by the valve 41, the temperature of the EGR gas can be adjusted.

  Further, the engine system 1 is provided with an accelerator pedal sensor 66 that detects the amount of depression of the accelerator pedal, and a rotation speed sensor 67 that detects the rotation speed of the engine 50. The rotation speed sensor 67 is, for example, a crank angle sensor that detects a crank angle.

  The engine system 1 includes an ECU 10 that controls the operation of the engine 50. The ECU 10 is mainly composed of a microcomputer composed of a CPU, a ROM, a RAM, and the like. The ECU 10 controls the injection timing and injection amount of the fuel injected by the injector 53 based on the detection signals of the sensors 61 to 67 described above, or EGR gas with respect to the total intake amount of the gas sucked into the combustion chamber 511. The target EGR rate, which is a ratio of the amount of, is set, and the valves such as the throttle 34 and the EGR valve 35 and the opening and closing of the valves are controlled. The ECU 10 includes a memory 11 such as an EEPROM. The memory 11 stores a processing program executed by the ECU 10 and various maps (such as a map for determining an injection amount).

  Here, a basic control mode of the engine 50 by the ECU 10 will be described with reference to FIG. FIG. 2 exemplifies changes over time in various parameters relating to the operation of the engine 50. Specifically, FIG. 2A shows the engine speed, FIG. 2B shows the accelerator pedal depression amount, and FIG. 2) shows the fuel injection amount, FIG. 2D shows the target EGR rate, FIG. 2E shows the opening of the throttle 34, and FIG. 2F shows the opening of the EGR valve 35. The engine speed in FIG. 2A is a parameter detected by the speed sensor 67, and the depression amount of the accelerator pedal in FIG. 2B is a parameter detected by the accelerator pedal sensor 66. FIG. (C) to FIG. 2 (F) are parameters adjusted by the ECU 10. In FIG. 2, the value of each parameter is constant before time t0 when the accelerator pedal is loosened, but it actually varies depending on the situation.

  The ECU 10 determines the injection amount shown in FIG. 2C or FIG. 2 according to the operating state of the engine 50, specifically, for example, the engine speed shown in FIG. 2A and the accelerator pedal depression amount shown in FIG. The target EGR rate of (D) is set. As shown in FIG. 2 (B), when the accelerator pedal is loosened at time t0, that is, when the engine 50 is decelerated, the ECU 10 takes the line 101 (line when there is no risk of misfire) in FIG. 2 (C). As shown, the injection amount is decreased in accordance with a decrease in the depression amount of the accelerator pedal. Then, at time t2 slightly delayed from time t1 when the accelerator pedal is completely released (depression amount is zero), the injection amount is zero, that is, the fuel is cut.

  FIG. 2C also shows an injection amount line 103 according to the invention of Patent Document 2 as a comparative example. As shown by the line 103, in the invention of Patent Document 2, when there is a risk of misfire, the fuel cut time is advanced. That is, the fuel cut time is advanced from the time t2 to the time t3 before the time t2.

  Further, as shown in FIG. 2D, the ECU 10 decreases the target EGR rate in accordance with the release of the accelerator pedal (in accordance with the injection amount in FIG. 2C). Then, the target EGR rate is set to zero at the time t2 when the fuel cut is performed. The ECU 10 sets a target opening degree of the EGR valve 35 according to the set target EGR rate, and controls the opening and closing of the EGR valve 35 so as to be the target opening degree. However, as shown by the actual opening line in FIG. 2F, a response delay occurs in the EGR valve 35, and until the time t5 after the time t2 when the target EGR rate is set to zero, the EGR valve 35 May continue to open.

  Further, when the engine 50 is decelerated (when the accelerator pedal is loosened), the ECU 10 reduces the amount of gas sucked into the combustion chamber 511 and quickly decelerates the line 104 (FIG. 2E). As shown by the line when there is no risk of misfire, the throttle 34 is controlled to the closed side. When a response delay occurs in the EGR valve 35, the time t4 when the opening of the throttle 34 becomes the target value on the closing side is earlier than the time t5 when the opening of the EGR valve 35 becomes zero. In this case, the supply amount of EGR gas supplied to the engine 50 becomes excessive, and there is a risk of misfire. In Patent Document 1, as shown by the line 106 in FIG. 2 (E), the control to the closing side of the throttle 34 is synchronized with the control to the closing side of the EGR valve 35 (line in FIG. 2 (F)). This avoids an excessive state of EGR gas.

  Note that misfire at the time of deceleration (excessive EGR gas) occurs due to a response delay of the EGR valve 35, and even when there is no response delay of the EGR valve 35, a large amount of, for example, during high-load operation of the engine 50 It may also occur when the EGR gas is supplied and suddenly shifts to a light load operation (for example, idle operation).

  In the present invention, when there is a risk of misfire when the engine 50 is decelerated, as shown in FIG. 2C, a normal injection amount (basic injection amount, injection amount of the line 101) when there is no risk of misfire. From this, fuel injection is performed with the injection amount (line 102) corrected to decrease. In addition, as shown in FIG. 2E, the throttle opening (line 105) corrected from the normal throttle opening (basic opening, throttle opening of line 104) to the open side when there is no risk of misfire. Thus, the opening degree of the throttle 34 is controlled. Hereinafter, with reference to the flowchart of FIG. 3, processing relating to correction of the fuel injection amount and the throttle opening will be described. FIG. 3 is a flowchart of processing executed by the ECU 10. The process of FIG. 3 starts at the start of the engine 50, for example, and is repeatedly executed at regular intervals until the engine 50 stops.

  When the processing of FIG. 3 starts, first, the values of parameters necessary for the operation of the engine 50 such as the commanded fuel injection amount, the injection timing, the throttle opening degree, the target EGR rate, etc. according to the current operating state of the engine 50 are obtained. Calculate (S11). Specifically, for example, the command injection amount corresponding to the engine rotation speed detected by the rotation speed sensor 67 (see FIG. 1) and the accelerator pedal depression amount detected by the accelerator pedal sensor 66 (see FIG. 1) is stored in the memory. 11 is set based on the injection amount map stored in No. 11. When the engine 50 is decelerating, the injection amount of the line 101 in FIG. 2C is set in S11. Similarly, the throttle opening corresponding to the engine speed and the depression amount of the accelerator pedal is set based on the throttle opening map stored in the memory 11. When the engine 50 is in a deceleration state, the throttle opening of the line 104 in FIG. Further, in S11, for example, a target EGR rate corresponding to the engine speed and the command injection amount is set based on the target EGR rate map stored in the memory 11. And the target opening degree of the EGR valve 35 according to the set target EGR rate is set.

  Next, based on the detection signal of the accelerator pedal sensor 66, it is determined whether or not the engine 50 is in a decelerating state (S12). Specifically, the engine 50 is in a decelerating state when the accelerator pedal is moving to the closing side, or when the accelerator pedal is completely released (the amount of depression is zero) and the engine speed is decreasing. In other cases (the accelerator pedal depression amount is kept constant or the accelerator pedal is moved to the open side), it is determined that the vehicle is not in a deceleration state.

  When the engine 50 is not in a decelerating state (S12: No), the injector 53, the EGR valve 35, etc. according to the values (command injection amount, injection timing, throttle opening, EGR valve opening) of each parameter set in S11. Is controlled (S21). Then, the process of the flowchart of FIG. 3 is complete | finished.

  When the engine 50 is decelerating (S12: Yes), the supply amount of EGR gas supplied to the engine 50 (combustion chamber 511) is calculated (S13). Specifically, for example, the supply amount of EGR gas is calculated according to the processing of the flowchart of FIG. When the process proceeds to FIG. 4, first, the amount of gas flowing into the combustion chamber 511 (hereinafter referred to as cylinder inflow gas amount) is calculated (S31). Since the intake of the air of the engine 50 is performed in synchronization with the engine rotation, the cylinder inflow gas amount depends on the number of engine cycles. Specifically, as the engine speed increases, the amount of suction per rotation increases. On the other hand, when the engine speed changes, the time during which the intake valve 54 is open changes (the higher the engine speed, the shorter the time during which the intake valve 54 is open), so that the combustion chamber 511 is changed according to the engine speed. The filling efficiency of the sucked air changes. The cylinder inflow gas amount depends on the pressure in the intake manifold detected by the intake manifold pressure sensor 62 (see FIG. 1). Specifically, when the pressure increases, the gas is easily sucked into the combustion chamber 511. . The amount of gas flowing into the cylinder depends on the pressure in the exhaust manifold detected by the exhaust pressure sensor 64 (see FIG. 1). Specifically, when the pressure increases, the gas is not easily discharged from the combustion chamber 511. The gas remaining in the combustion chamber 511 is increased, and as a result, the gas is hardly sucked into the combustion chamber 511. Therefore, in S31, for example, the cylinder inflow gas amount is calculated based on the engine speed, the pressure in the intake manifold, and the pressure in the exhaust manifold.

  Next, the amount of fresh air passing through the throttle 34 (hereinafter referred to as throttle passing gas amount) is calculated based on the detection signal of the air flow meter 61 (see FIG. 1) (S32). The cylinder inflow gas amount obtained in S31 can be considered as the sum of the throttle passage gas amount and the EGR gas amount from the EGR passage 23. Therefore, next, the difference between the cylinder inflow gas amount and the throttle passage gas amount is calculated as the supply amount of the EGR gas supplied to the combustion chamber 511 (S33). Thereby, even if a sensor for directly detecting the supply amount of EGR gas (a sensor for detecting the amount of gas flowing through the EGR passage 23) is not provided, the EGR gas supply amount can be calculated. When a sensor that directly detects the supply amount of EGR gas is provided, the EGR gas supply amount may be calculated based on the detection signal of the sensor. In this case, the process of FIG. 4 can be omitted. After S33, the process of the flowchart of FIG. 4 is terminated, and the process returns to the process of FIG.

  After calculating the EGR gas supply amount in S13 of FIG. 3, the process proceeds to S14, and the amount of O2 sucked into the combustion chamber 511 (hereinafter referred to as intake O2 amount) is calculated based on the EGR gas supply amount calculated in S13. (S14). Specifically, the O2 concentration of exhaust gas (EGR gas) (hereinafter referred to as exhaust O2 concentration) is calculated based on the detection signal of the A / F sensor 65. Then, the intake O2 amount is calculated based on the EGR gas supply amount, the exhaust O2 concentration, the throttle passage gas amount (fresh air amount), and the fresh air O2 concentration (theoretical value). If the EGR gas supply amount becomes excessive due to a response delay of the EGR valve 35 or the like, the ratio of EGR gas to the gas (fresh air + EGR gas) sucked into the combustion chamber 511 increases. In comparison, the intake O2 amount becomes smaller.

  Next, a fuel injection amount (hereinafter, referred to as misfire avoidance injection amount) that can avoid misfire (can be reliably burned) is calculated based on the intake O2 amount obtained in S14 (S15). Specifically, for example, an injection amount that becomes stoichiometric (theoretical air-fuel ratio) with respect to the obtained intake O2 amount is calculated as a misfire avoidance injection amount. An injection amount that is slightly smaller than the stoichiometric injection amount (for example, an injection amount obtained by subtracting a predetermined ratio from the stoichiometric injection amount) may be calculated as the misfire avoidance injection amount. Thereby, the injection quantity which can avoid misfire more reliably can be obtained.

  Next, based on the comparison between the command injection amount calculated in S11 and the misfire avoidance injection amount calculated in S15, it is determined whether or not there is a risk of misfire when fuel injection is performed with the command injection amount in S11. (S16). Specifically, if the command injection amount is smaller than the misfire avoidance injection amount, it is determined that there is no risk of misfire, and if the command injection amount is larger, it is determined that there is a risk of misfire.

  If there is no risk of misfire (S16: No), it is assumed that the EGR gas is normally supplied, and the values of the parameters set in S11 (command injection amount, injection timing, throttle opening, EGR valve open) The normal control according to (degree) is performed (S21). That is, fuel injection is performed at the injection amount indicated by the line 101 in FIG. 2C, and the throttle 34 is controlled by the throttle opening indicated by the line 104 in FIG.

  On the other hand, when there is a risk of misfire (S16: Yes), the process proceeds to S17. When the amount of intake O2 is small, if fuel injection is performed at the injection timing set on the assumption of a normal intake O2 amount, an ignition delay (misfire) is likely to occur and the risk of misfire increases, but a certain amount of intake O2 can be secured. In some cases, misfire can be avoided by advancing the injection timing. Therefore, in S17, if the fuel injection timing is advanced (advanced with respect to the injection timing calculated in S11), whether or not misfire can be avoided even if fuel injection is performed with the command injection amount in S11. Judgment is made (S17). Specifically, for example, when the command injection amount is larger than the misfire avoidance injection amount reduced by a predetermined rate than the stoichiometric injection amount obtained in S15, but less than the predetermined threshold value than the stoichiometric injection amount In addition, it is determined that misfire can be avoided by the advance angle of the injection timing, and it is determined that misfire cannot be avoided even if the injection timing is advanced if it is equal to or greater than the threshold.

  If misfire can be avoided by the advance angle of the injection timing (S17: Yes), the injection timing calculated in S11 is advanced and fuel injection is performed with the command injection amount of S11 (S22). For example, the advance amount of the injection timing that can avoid misfire is obtained in advance by experiment and stored in the memory 11, and in S22, the injection timing may be advanced by the advance amount. In S22, the throttle 34 is controlled with the throttle opening set in S11. Thus, misfire can be avoided without reducing the command injection amount and the throttle opening, and variations in the feeling of deceleration can be suppressed. After S22, the process of the flowchart of FIG.

  If misfire cannot be avoided at the advance angle of the injection timing (S17: No), a decrease correction is performed on the command injection amount of S11 (S18). Specifically, the command injection amount is reduced and corrected by the difference between the command injection amount and the misfire avoidance injection amount calculated in S15. Then, fuel injection is performed with the injection amount after the reduction correction, that is, the misfire avoidance injection amount. In this case, fuel injection is performed with the injection amount (misfire avoidance injection amount) indicated by the line 102 in FIG. Thereby, misfire due to an excessive supply amount of EGR gas can be avoided.

  Next, the output reduction amount due to the injection amount reduction correction is calculated (S19). Specifically, for example, a map of the output decrease amount with respect to the decrease in the injection amount is obtained and stored in the memory 11. Then, an output decrease amount with respect to the current decrease in the injection amount may be calculated based on the map.

  Next, the throttle opening calculated in S11 is corrected to the open side by the amount that compensates for the output decrease calculated in S19 (S20). Specifically, for example, the relationship between the correction amount to the opening side of the throttle opening and the pumping loss reduction amount (output increase amount) is obtained in advance through experiments and stored in the memory 11. Then, based on the relationship, the correction amount of the throttle opening that gives the pumping loss reduction amount to compensate for the output reduction amount obtained in S19 is calculated. Then, the throttle 34 is corrected to the open side by the correction amount. In this case, the throttle 34 is controlled at the throttle opening indicated by the line 105 in FIG. As a result, the pumping loss is reduced by an amount corresponding to the correction of the throttle 34 to the open side, and the output reduction due to the reduction in the injection amount can be compensated. As a result, the feeling of deceleration given to the driver can be made equal when the injection amount and the throttle opening are corrected or not. Note that there is no risk of misfire after the time point when the injection amount (line 102) in FIG. 2 (C) becomes zero (the time when fuel cut), but the output decreases until the time point when line 101 becomes zero. In this embodiment, the throttle opening is corrected until that time, and the throttle 34 is controlled so as to return to the normal throttle opening after that time. That is, the line 105 in FIG. 2E is the same as the line 104 having a normal opening degree in the middle (after the fuel cut time). After S20, the process of the flowchart of FIG.

  Here, FIG. 5 is a diagram for explaining the effect of the present invention. Specifically, the combustion output by fuel injection, the pumping loss due to the throttle opening, and the total output obtained by subtracting the pumping loss from the combustion output. Is shown. FIG. 5A shows an assumed output (output when the supply of EGR gas is normal), FIG. 5B shows the output of the invention of Patent Document 1, and FIG. 5C shows Patent Document 2. FIG. 5 (D) shows the output of the present invention. In the present invention, as shown in FIG. 5D, when the supply of EGR gas is excessive and there is a risk of misfire, the injection amount is reduced, so that the combustion output is higher than the combustion output of FIG. Decreases. However, in this case, since the throttle opening is corrected to the open side, the pumping loss is lower than the pumping loss in FIG. The total output is substantially the same as the total output in FIG.

  On the other hand, in the invention of Patent Document 1, as a result of synchronizing the throttle opening with the EGR valve opening at the time of deceleration, as shown by the line 106 in FIG. Operates on the open side. As a result, as shown in FIG. 5B, the pumping loss is reduced, but since the injection amount is not corrected, the total output is larger than the total output of FIG. In other words, the feeling of deceleration is weaker than expected (the engine braking is weak and the driver feels free running).

  Further, in the invention of Patent Document 2, when there is a risk of misfire, as shown by the line 103 in FIG. 2 (C), the time for performing the fuel cut is advanced, so that it is shown in FIG. 5 (C). As described above, the combustion output is lower than the assumed combustion output in FIG. In Patent Document 2, since the throttle opening is not corrected, the total output is smaller than the total output of FIG. In other words, the feeling of deceleration is stronger than expected (the engine brake feels strong). In the present invention, the problems as in Patent Documents 1 and 2 can be avoided.

  As described above, in the present embodiment, misfire in the transient state of the EGR gas supply during engine deceleration can be avoided while suppressing the variation in the feeling of deceleration.

  The control device for an internal combustion engine according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the claims. For example, in S16 of FIG. 3, the risk of misfire is determined based on the comparison between the command injection amount and the misfire avoidance injection amount. However, the EGR gas supply amount calculated in S13 or the intake O2 amount calculated in S14 The risk of misfire may be determined based on the magnitude of the. Specifically, it may be determined that there is a risk of misfire when the EGR gas supply amount exceeds a predetermined threshold or when the intake O2 amount is less than the predetermined threshold. According to this, the risk of misfire can be easily determined.

  Further, in S13, the EGR gas supply amount itself is calculated, but a value serving as an index of the EGR gas supply amount, specifically, for example, as shown in Patent Document 2, the target opening and the actual opening of the EGR valve The deviation may be calculated. Based on the deviation, the presence or absence of misfire risk and the misfire avoidance injection amount may be calculated. When judging the risk of misfire based on the deviation, for example, it is judged that there is a risk of misfire when the deviation exceeds a predetermined threshold. When calculating the misfire avoidance injection amount from the deviation, the relationship between the deviation and the intake O2 amount is obtained in advance by experiment, and the intake O2 amount with respect to the current deviation is calculated based on the relationship. Then, the misfire avoidance injection amount may be calculated based on the intake O2 amount. Further, the present invention may be applied to a gasoline engine system.

1 Engine system 10 ECU
50 Diesel engine 21 Intake passage 22 Exhaust passage 23 EGR passage 34 Throttle 35 EGR valve

Claims (8)

Index value acquisition means (S13) for acquiring a value serving as an index of the supply amount of EGR gas that is recirculated from the exhaust passage (22) of the internal combustion engine (50) to the intake passage (21) and supplied to the internal combustion engine;
Excess determination means (S14 to S16) for determining whether or not the supply amount of the EGR gas during deceleration of the internal combustion engine is excessive based on the index value acquired by the index value acquisition means;
An injection control means for adjusting an injection amount of fuel supplied to the internal combustion engine according to an operating state of the internal combustion engine, and when the supply amount of the EGR gas is excessive during deceleration of the internal combustion engine, Injection control means (S18) for performing fuel injection with an injection amount that is corrected to decrease from a basic injection amount that is an injection amount when there is not,
Throttle control means for adjusting the opening of a throttle (34) provided in the intake passage according to the operating condition of the internal combustion engine, and when the supply amount of the EGR gas is excessive during deceleration of the internal combustion engine Throttle control means (S19, S20) for correcting the throttle opening from the basic opening, which is the opening of the throttle when not excessive, to the open side;
A control device (10) for an internal combustion engine, comprising: An injection amount calculation means (S14, S15) for calculating a misfire avoidance injection amount, which is a fuel injection amount expected to burn without injecting the injected fuel, based on the index value;
The injection control means, wherein when the supply amount of the EGR gas during deceleration of the internal combustion engine is excessive, characterized in that the fuel injection by the misfire avoidance injection amount as reduced corrected injection amount from the previous SL basic injection amount The control apparatus for an internal combustion engine according to claim 1.
  If the supply amount of the EGR gas is excessive during deceleration of the internal combustion engine, the throttle control means sets the throttle opening to the amount corresponding to the amount of decrease in the output of the internal combustion engine due to injection amount reduction correction. The control apparatus for an internal combustion engine according to claim 2, wherein the correction is made from the basic opening to the opening side.   4. The injection amount calculation means calculates an intake O2 amount sucked into the internal combustion engine based on the index value, and calculates the misfire avoidance injection amount with respect to the intake O2 amount. The control apparatus of the internal combustion engine described in 1.   The excessive determination means (S16) determines that the supply amount of the EGR gas is excessive when the basic injection amount to be injected by the injection control means is larger than the misfire avoidance injection amount, and is small. 5. The control device for an internal combustion engine according to claim 2, wherein it is determined that the supply amount of the EGR gas is not excessive.   The control apparatus for an internal combustion engine according to claim 1, wherein the index value acquisition unit acquires the supply amount of the EGR gas itself as the index value. The EGR gas is returned to the intake passage downstream of the throttle,
The index value acquisition means
First gas amount estimating means (S31) for estimating the amount of gas flowing into the internal combustion engine;
Second gas amount estimating means (S32) for estimating the amount of gas passing through the throttle;
EGR gas amount estimating means (S33) for estimating the supply amount of the EGR gas based on the gas amount estimated by the first gas amount estimating means and the gas amount estimated by the second gas amount estimating means. The control apparatus for an internal combustion engine according to claim 6, further comprising: An avoidance judging means (S17) for judging whether misfire can be avoided by advancing the fuel injection timing when the supply amount of the EGR gas is excessive during deceleration of the internal combustion engine;
When the avoidance determination unit determines that the misfire can be avoided by the advance of the injection timing, the injection control unit stops the injection amount reduction correction and advances the injection timing with the basic injection amount. 8. The control apparatus for an internal combustion engine according to claim 1, wherein fuel injection is performed.

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