JP4648274B2 - 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 that includes a diesel particulate filter (hereinafter referred to as “DPF”) that collects particulates in exhaust gas in an exhaust system.

  2. Description of the Related Art A technique for providing a DPF that collects particulates in exhaust gas in an exhaust system of a diesel internal combustion engine to reduce the amount of particulate emissions is widely used. Since there is a limit to the amount of particulates that can be collected by the DPF, the amount of the particulates collected by the DPF is calculated, and the collected particulates are burned according to the calculated amount of collected particulates. The execution time of the process is determined.

  Patent Document 1 estimates the cetane number of the fuel in use, calculates the particulate emission amount per unit time according to the estimated cetane number and the engine operating state, and integrates the calculated particulate emission amount. Thus, a method for calculating the amount of collected particulates is shown.

JP 2005-48709 A

  However, after refueling, the cetane number of the refueled fuel may not be immediately estimated. Since Patent Document 1 does not disclose a countermeasure for such a case, for example, the actual particulate discharge amount per unit time becomes larger than the estimated value, and the execution time of the DPF regeneration process is delayed, so that the particulates May be discharged downstream of the DPF, or the DPF may be blocked.

  The present invention has been made paying attention to this point, and appropriately performs engine control immediately after refueling to reduce the amount of particulate discharged from the engine to prevent particulate leakage and DPF blockage. It is an object of the present invention to provide a control device for an internal combustion engine capable of performing the above.

  In order to achieve the above object, a first aspect of the present invention is directed to a fuel injection means (6) for injecting fuel into a combustion chamber of an internal combustion engine (1), and a particulate to collect particulates in exhaust gas in an exhaust system. A fuel for controlling fuel injection by the fuel injection means (6) in a control device for an internal combustion engine comprising a collection means (32) and an exhaust gas recirculation means (26, 27) for returning a part of exhaust gas to an intake system. Injection control means, pressure change detection means (2) for detecting a pressure change in the combustion chamber of the engine, and cetane for estimating the cetane number of the fuel in use based on the output of the pressure change detection means (2) The amount of particulates (QPT) collected by the value estimation means and the particulate collection means (32) is calculated using a collection amount map set according to the operating state of the engine. Calculation Means, regeneration means for executing regeneration processing of the particulate collection means (32) according to the calculated collection particulate quantity (QPT), and exhaustion when the estimation of the cetane number is not executed. An exhaust gas recirculation control means for reducing the recirculation amount, wherein the particulate quantity calculation means selects the collection amount map (DPT1 to DPT3) according to the estimated cetane number, and the estimation of the cetane number is performed When not executed, a collection amount map (DPT2) corresponding to an average cetane number fuel is selected.

  According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, the fuel injection control means is configured such that when the estimation of the cetane number is not completed, the average cetane number (CETAV The fuel injection control suitable for the fuel is performed.

  According to a third aspect of the present invention, in the control device for an internal combustion engine according to the first or second aspect, the fuel injection control means is configured to reduce the exhaust gas recirculation amount when the cetane number is not estimated. Fuel injection control suitable for GEGRNC) is performed.

  According to the first aspect of the present invention, when the cetane number estimation is performed, the collection amount map is selected according to the estimated cetane number. An accurate collection particulate quantity can be calculated using the collection map. On the other hand, when the estimation of the cetane number is not performed immediately after refueling, the collection amount map corresponding to the fuel having the average cetane number is selected and the exhaust gas recirculation amount is reduced. By using the collection amount map corresponding to the average cetane number fuel, the calculated collection particulate amount may be smaller than the actual particulate amount when using the refueled fuel. However, by reducing the exhaust gas recirculation amount, the particulate discharge amount can be reduced as compared with the case of performing normal exhaust gas recirculation. As a result, it is possible to prevent particulate leakage or blockage of the particulate collection means.

  According to the second aspect of the present invention, when the estimation of the cetane number is not executed, the fuel injection control suitable for the fuel having the average cetane number is performed, so that the deviation from the actual cetane number of the fuel The expected value of is minimized, and the influence of the cetane number shift can be minimized.

  According to the third aspect of the present invention, when the estimation of the cetane number is not executed, the fuel injection control suitable for the reduced exhaust gas recirculation amount is performed. The combustion state can be maintained.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 and FIG. 2 are diagrams showing the configuration of an internal combustion engine and its control device according to an embodiment of the present invention. The following description will be made with reference to both figures together. An internal combustion engine (hereinafter simply referred to as “engine”) 1 is a diesel engine that directly injects fuel into a cylinder, and a fuel injection valve 6 is provided in 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 are controlled by the ECU 4.

The engine 1 includes an intake pipe 22, an exhaust pipe 24, and a supercharger 28. The supercharger 28 includes a turbine 30 that is driven by exhaust kinetic energy, and a compressor 29 that is rotationally driven by the turbine 30 and compresses intake air.
The turbine 30 includes a plurality of variable vanes (not shown), and is configured to change the turbine rotational speed (rotational speed) by changing the opening degree of the variable vanes. The vane opening degree of the turbine 30 is electromagnetically controlled by the ECU 4.

  An intercooler 25 for cooling the pressurized air and an intake shutter (throttle valve) 23 for controlling the amount of intake air are provided in the intake pipe 22 downstream of the compressor 29. The intake shutter 23 is controlled to be opened and closed by the ECU 4 via an actuator (not shown).

  An exhaust gas recirculation passage 26 is provided between the upstream side of the turbine 30 in the exhaust pipe 24 and the downstream side of the intake shutter 23 in the intake pipe 22 to recirculate exhaust gas to the intake pipe 22. The exhaust gas recirculation passage 26 is provided with an exhaust gas recirculation control valve (hereinafter referred to as “EGR valve”) 27 for controlling the exhaust gas recirculation amount. The EGR valve 27 is a solenoid valve having a solenoid, and the valve opening degree is controlled by the ECU 4.

On the downstream side of the turbine 30 of the exhaust pipe 24, a catalytic converter 31 for purifying exhaust and a DPF 32 are provided in this order from the upstream side.
The catalytic converter 31 incorporates an oxidation catalyst for promoting the oxidation of hydrocarbons and carbon monoxide contained in the exhaust gas. Note that the catalytic converter 31 may be added with a NOx adsorbent that adsorbs NOx and a NOx reduction action.

  When the exhaust gas passes through the fine holes in the filter wall, the DPF 32 deposits soot, which is a particulate mainly composed of carbon (C) in the exhaust gas, on the surface of the filter wall and the holes in the filter wall. Collect by letting. As a constituent material of the filter wall, for example, ceramics such as silicon carbide (SiC) or a porous metal body is used.

  If soot is collected to the limit of the soot collecting ability of the DPF 32, the exhaust pressure rises (blocking of the DPF 32), so that it is necessary to perform a regeneration process for burning the soot at an appropriate time. In this regeneration process, post injection is performed in order to raise the temperature of the exhaust gas to the combustion temperature of the soot. Post-injection is fuel injection performed in the exhaust stroke by the fuel injection valve 6. The fuel injected by the post injection is mainly burned by the catalytic converter 31 and raises the temperature of the exhaust gas flowing into the DPF 32.

  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 (pressure fluctuation) with respect to the crank angle (time) of the in-cylinder pressure PCYL. The in-cylinder pressure PCYL integrates the output of the in-cylinder pressure sensor. Can be obtained.

  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 cylinder and supplies it to the ECU 4.

  The ECU 4 includes an accelerator sensor 37 that detects an operation amount AP of an accelerator pedal of a vehicle driven by the engine 1, a cooling water temperature sensor 38 that detects a cooling water temperature TW of the engine 1, and a vehicle speed sensor 39 that detects a vehicle speed VP of the vehicle. An oxygen concentration sensor (not shown) for detecting the oxygen concentration in the exhaust and an intake air temperature sensor (not shown) for detecting the intake air temperature TA of the engine 1 are connected, and the detection signals of these sensors are It 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 normally executes pilot injection and main injection for one cylinder.

  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”) dp / dθ, 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. The in-cylinder pressure PCYL is calculated by integrating the pressure change rate dp / dθ.

  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 the target exhaust gas recirculation amount GEGR according to the engine operating state (specifically, the engine speed NE and the required torque TRQ), and the duty for controlling the opening degree of the EGR valve 27 according to the target exhaust gas recirculation amount GEGR. A control signal is supplied to the EGR valve 27 via the output circuit 18. Further, the CPU 14 executes processing for estimating the cetane number of the fuel in use as described below, and performs fuel injection control according to the estimated cetane number. Further, according to the estimated cetane number, a particulate amount collected in the DPF 32 (hereinafter referred to as “collected particulate amount”) QPT is calculated, and when the collected particulate amount QPT reaches a predetermined amount, the DPF 32 is regenerated. Execute the process.

FIG. 3 is a flowchart showing a processing procedure for estimating the cetane number of the fuel in use.
In step S11, it is determined whether or not the fuel tank (not shown) that supplies fuel to the engine 1 has just been refueled. Immediately after refueling is determined based on an increase in the fuel meter instruction value, opening / closing of the filler cap, and a change from OFF to ON of the engine switch.

  When it is immediately after refueling, the system waits for a predetermined time TWAIT (for example, 2 minutes) required for the fuel in the path from the fuel tank to the fuel injection valve 6 to be replaced (step S12). Thereafter, the cetane number learning value CETLRN is set to the average cetane number CETAV (for example, 50) of the fuel distributed in the market (step S13), and the DPT map used for calculating the collected particulate quantity QPT is A 2DPT map is selected (step S14).

  The DPT map is a map used to calculate a particulate amount (hereinafter referred to as “unit time discharge amount”) DPT discharged from the engine 1 per unit time in the DPF regeneration control described later. It is preset according to NE and the required torque TRQ. The second DPT map is a map set on the basis of fuel having an average cetane number CET2 (= CETAV), and in addition to this, a first DPT map set on the basis of fuel having a low cetane number CET1 (for example, 45), In addition, a third DPT map set based on fuel having a high cetane number CET3 (for example, 55) is provided (see FIG. 11). If the engine operating states (NE, TRQ) are the same, assuming that the set values of the first to third DPT maps are DPT1, DPT2, and DPT3, a relationship of DPT3> DPT2> DPT1 is established.

  In step S15, the target exhaust gas recirculation amount GEGR is decreased. Specifically, the target exhaust gas recirculation amount is calculated using a GEGRNC map in which the target exhaust gas recirculation amount GEGRNC for use immediately after refueling used when cetane number learning is not executed. The target exhaust gas recirculation amount GEGRNC immediately after refueling is set to a value smaller than the normal target exhaust gas recirculation amount GEGR if the engine operating state is the same. As a result, the amount of particulates discharged from the engine 1 is reduced, and the amount of collected particulates calculated using the second DPT map until the learning of the cetane number is completed is the actual amount collected. It becomes the same level or more, and blockage of the DPF 32 or leakage of particulates can be prevented.

  In step S16, the value of the counter N for counting the number of executions of the cetane number learning process in the idle state is set to “0”, and the learning completion flag FLC is set to “0” (step S16). The learning completion flag FLC is set to “1” in step S23 described later when learning of the cetane number after refueling is completed.

  After executing Step S16, the process proceeds to Step S17. If it is not immediately after refueling in step S11, the process immediately proceeds to step S17. Steps S13 to S16 are executed only once immediately after refueling.

  In step S17, it is determined whether or not the learning completion flag FLC is “1”. Since this answer is negative (NO) at first, the process proceeds to step S18 to determine whether or not the operating state of the engine 1 is an idle state. When not in an idle state, this process is immediately terminated. Therefore, since the cetane number learning process is not executed when the engine is not in the idle state immediately after refueling, the average cetane number CETAV set in step S13 is used as the cetane number learned value for engine control.

  When the answer to step S18 is affirmative (YES), that is, when the engine operating state is an idle state, it is determined whether or not the value of the counter N is equal to a predetermined value N0 (for example, 10). Since this answer is negative (NO) at first, the process proceeds to step S20, and the fuel injection mode of a specific cylinder determined in advance is changed. Specifically, the pilot injection is stopped, only the main injection is executed, and the execution timing of the main injection is advanced from the normal time. In this state, the cetane number learning process shown in FIG. 4 is executed to calculate a cetane number learned value CETLRN.

  In step S22, the counter N is incremented by “1”. Next, a DPT map corresponding to the cetane number learning value CETLRN is selected (step S24). That is, immediately after refueling, the second DPT map corresponding to the average cetane number CETAV (= CET2) is selected, but when the cetane number learning is executed once, the cetane number learned value CETLRN is the low cetane number CET1. When it is close to (for example, 45) or high cetane number CET3 (for example, 55), it is changed to the first or third DPT map. When the cetane number learning value CETLRN is close to the average cetane number CET2, the second DPT map is continuously used.

In step S25, the target EGR flow rate GEGR is calculated by using the normal control GEGR map. .
When the value of the counter N reaches the predetermined value N0, the process proceeds from step S19 to step S23, and the learning completion flag FLC is set to “1”.

  When the learning completion flag FLC is set to “1”, the answer to step S17 becomes affirmative (YES), and this process is immediately terminated.

FIG. 4 is a flowchart of the cetane number learning process executed in step S21 of FIG.
In step S41, a CAFMM map (not shown) is searched according to the engine speed NE and the required torque TRQ to calculate a reference ignition timing CAFMM. The CAFMM map is set based on, for example, an average cetane number CET2 fuel. In step S42, the ignition delay angle DCA is calculated by subtracting the actual ignition timing CAFM from the reference ignition timing CAFMM. When the cetane number of the fuel in use is higher than the cetane number CET2, the ignition delay angle DCA becomes a negative value.

  FIG. 5 is a block diagram showing a configuration of an ignition timing calculation module that calculates (detects) the actual ignition timing CAFM. The function of the ignition timing calculation module is realized by arithmetic processing by the CPU 14. The ignition timing calculation module includes a band pass filter unit 71, a phase delay correction unit 72, and an ignition timing determination unit 73. The band change filter unit 71 receives the pressure change rate dp / dθ output from the in-cylinder pressure sensor 2. The bandpass filter unit 71 removes a noise component included in the pressure change rate dp / dθ. Since the phase delay occurs in the band pass filter unit 71, the phase delay correction unit 72 corrects this delay.

  The ignition timing determination unit 73 determines the crank angle position at which the pressure change rate dp / dθ has a peak value as the actual ignition timing CAFM, corresponding to the fuel injection. Specifically, as shown in FIG. 6B, the crank angle at which the pressure change rate dp / dθ output from the phase delay correction unit 72 exceeds the detection threshold DPP is determined as the actual ignition timing CAFM.

  FIG. 6A shows an injection pulse INJM starting from the crank angle CAIM, and FIG. 6B shows an angle range RDET (for example, 10 degrees) for detecting the actual ignition timing CAFM. Yes. Thus, by limiting the detection angle range RDET to a relatively narrow range, it is possible to accurately determine the ignition timing without increasing the calculation load on the CPU 14.

  Returning to FIG. 4, in step S43, the ignition delay angle DCA is converted into the ignition delay time TDFM using the engine speed NE, the CET table shown in FIG. 7 is searched according to the ignition delay time TDFM, and the cetane number CET Is calculated.

In step S44, the calculated cetane number CET is applied to the following equation (1) to calculate the cetane number learned value CETLRN.
CETLRN = α × CET + (1−α) × CETLRN (1)
Here, α is an annealing coefficient set to a value between 0 and 1, and CETLRN on the right side is a previously calculated value.

  FIG. 8 is a graph showing the transition of the heat release rate HRR in a specific cylinder of the engine 1, where the solid line corresponds to a high cetane number (for example, 57) fuel and the broken line represents a low cetane number (for example, 41) fuel. Correspond. The horizontal axis is the crank angle CA (when the piston is at the compression top dead center, it is set to “0” degree). FIG. 6A corresponds to the case where pilot injection and main injection are performed. In this case, fuel injection is performed in the vicinity of a crank angle of 0 degrees (compression top dead center), and 5 to 10 after top dead center. The heat release rate HRR reaches a peak at a degree. The difference in peak position due to the difference in cetane number is about 1 degree. FIG. 6B corresponds to the case where only the main injection is executed by advancing the fuel injection timing. In this case, the fuel injection is performed near a crank angle of −20 degrees (20 degrees before compression top dead center). The heat release rate HRR reaches a peak at 5 to 10 degrees before top dead center. The difference in peak position due to the difference in cetane number is about 8 degrees. That is, by making the fuel injection only the main injection (single injection) and advancing the injection timing, the difference in the ignition timing due to the difference in cetane number becomes more remarkable, and the calculation accuracy of the cetane number CET can be improved. .

  FIG. 9 is a frequency distribution diagram of the cetane number CET calculated by the first cetane number learning process using fuel having a cetane number of 42.8. In this example, the measurement is performed 50 times or more, and the distribution of the measurement results can be regarded as a normal distribution. From this measurement result, there is an error of about ± 2 cetane number in one measurement result. Assuming that the maximum value of the error due to one measurement is eMAX, the maximum error en when the measurement is performed n times is given by the following equation (2).

en = eMAX / sqr (n) (2)
Here, sqr is a square root arithmetic symbol.
Assuming that n = 10, the maximum error en is 2 / 3.16≈0.63, and therefore, at least 10 measurements are required. Therefore, in the present embodiment, the predetermined value N0 is set to “10”.

FIG. 10 is a flowchart of regeneration control of the DPF 32. This process is executed by the CPU 14 every predetermined time.
In step S61, the DPT map selected in the process of FIG. 3 is searched according to the engine speed NE and the required torque TRQ, and the unit time emission amount DPT is calculated. That is, the unit time emission amount DPT is calculated using one selected from the first to third DPT maps shown in FIG.

  In step S62, the collection particulate quantity QPT is calculated by integrating the unit time discharge quantity DPT. Next, it is determined whether or not the collected particulate amount QPT is equal to or greater than a predetermined amount QPTH (step S63). If the answer is negative (NO), the process is immediately terminated, and if the answer is affirmative (YES), the reproduction process is executed (step S64).

  In step S65, it is determined whether or not the reproduction process has been completed. If the reproduction process has not been completed, this process is immediately terminated. When the regeneration process is completed, the collected particulate quantity QPT is returned to “0” (step S66).

  FIG. 12 is a diagram showing the relationship between the collected particulate quantity QPT and the vehicle travel time TRUN (or the vehicle travel distance DRUN). The line L1 corresponds to fuel having a cetane number of 45, and the line L2 is cetane number 55. Corresponding to the fuel. Thus, as the cetane number increases, the unit time discharge amount DPT increases, and the time at which the collected particulate amount QPT reaches the predetermined amount QPTH is advanced.

FIG. 13 is a flowchart of the fuel injection control process executed by the CPU 14.
In step S71, a main injection amount map, a pilot injection amount map, a main injection timing map, and a pilot interval map (not shown) are searched according to the engine speed NE and the required torque TRQ, and the basic main injection amount QIMMAP, Basic pilot injection amount QIPMAP, basic main injection timing CAIMMAP (defined as an advance amount from the crank angle position corresponding to the top dead center), and basic pilot interval ICPMAP (defined as an advance amount from the main injection timing) ) Is calculated. The main injection amount map, the pilot injection amount map, the main injection timing map, and the pilot interval map are set on the basis of fuel having an average cetane number CET2.

  In step S72, it is determined whether or not the exhaust gas recirculation amount is being reduced. When this answer is negative (NO), that is, when the cetane number learning process is executed at least once in the idle operation state, the main injection amount correction value QIMC, the pilot injection amount, according to the cetane number learned value CETLRN Correction value QIPC, main injection timing correction value CAIMC, and pilot interval correction value ICPC are calculated (step S73). Thereafter, the process proceeds to step S75. The main injection timing correction value CAIMC is set to decrease (the corrected injection timing is retarded) as the cetane number learning value CETLRN increases, and the main injection injection amount correction value QIMC and the pilot injection amount correction value QIPC are set. Is also set to decrease. The correction of the fuel injection timing is performed to make the actual ignition timing appropriate, and the correction of the fuel injection amount is made to make the heat generation amount due to combustion appropriate. Since the pilot injection timing is retarded together with the main injection timing CAINJM, the pilot interval correction value ICPC is set to a value in the vicinity of “0”, for example.

  If the answer to step S72 is affirmative (YES) and the exhaust gas recirculation amount is decreasing, that is, if the engine operating state has not been in the idle state even after refueling, the main injection amount correction value QIMC, the main injection amount The timing correction value CAIMC and the pilot interval correction value ICPC are all set to “0”, the pilot injection amount correction value QIPC is set to a negative predetermined correction value QIPCE (step S74), and the process proceeds to step S75. Therefore, during the reduction of the exhaust gas recirculation amount, only the pilot injection amount QINJP is corrected for reduction.

In step S75, the main injection amount QINJM, the pilot injection amount QINJP, the main injection timing CAINJM, and the pilot interval ICAINJP are calculated by the following equations (3) to (6).
QINJM = QIMMAP + QIMC (3)
QINJP = QIPMAP + QIPC (4)
CAINJM = CAIMMAP + CAIMC (5)
ICAINJP = ICPMAP + ICPC (6)

  The CPU 14 drives the fuel injection valve 6 according to the calculated main injection amount QINJM, pilot injection amount QINJP, main injection timing CAINJM, and pilot interval ICAINJP.

  As described above in detail, in the present embodiment, the cetane number of the fuel in use is estimated by the process of FIG. 3, and one of the three DPT maps is selected according to the estimated cetane number. Therefore, when the cetane number estimation is executed, an accurate collection particulate quantity QPT can be calculated using a DPT map suitable for the cetane number of the fuel during use. On the other hand, when the cetane number is not estimated immediately after refueling, the second DPT map corresponding to the average cetane number CET2 is selected, and the exhaust gas recirculation amount is reduced. As a result, the particulate discharge amount can be reduced as compared with the case where the normal exhaust gas recirculation is performed, and the leakage of the particulates or the blockage of the DPF 32 can be prevented.

  When cetane number estimation is not performed, the cetane number learning value CETLRN is set to the average cetane number CETAV (= CET2) (FIG. 3, step S13), which is suitable for the fuel having the average cetane number. Fuel injection control is performed. Therefore, the expected value of the deviation between the cetane number learning value CETLRN used for control and the actual cetane number of the fuel is minimized, and the influence of the cetane number deviation can be minimized.

  Further, when the cetane number learning is not executed and the exhaust gas recirculation amount is reduced, a correction value suitable for the reduced exhaust gas recirculation amount is calculated and fuel injection control is performed in step S74 of FIG. It is possible to reduce the particulate emission amount and maintain a good combustion state.

  In this embodiment, the fuel injection valve 6 corresponds to the fuel injection means, the DPF 32 corresponds to the particulate collection means, the exhaust gas recirculation passage 26 and the EGR valve 27 correspond to the exhaust gas recirculation means, and the in-cylinder pressure sensor 2 is the pressure. This corresponds to change detection means. The ECU 4 constitutes a fuel injection control means, a cetane number estimation means, a particulate amount calculation means, a regeneration means, and an exhaust gas recirculation control means. More specifically, the process in FIG. 13 corresponds to the fuel injection control means, step S21 in FIG. 3 corresponds to the cetane number estimation means, steps S14 and S24 in FIG. 3, and steps S61, S62 in FIG. S65 and S66 correspond to the particulate quantity calculating means, steps S63 and S64 in FIG. 10 correspond to the regeneration means, and steps S15 and S25 in FIG. 3 correspond to the exhaust gas recirculation control means.

The present invention is not limited to the embodiment described above, and various modifications can be made. For example, although three DPT maps are used corresponding to three cetane numbers CET1 to CET3, two or four or more DPT maps may be used.
The present invention can also be applied to control of a marine vessel propulsion engine such as an outboard motor having a crankshaft as a vertical direction.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. FIG. 2 is a diagram specifically illustrating a configuration of a part of the control device illustrated in FIG. 1. It is a flowchart which shows the process for estimating the cetane number of the fuel in use. It is a flowchart of the 1st cetane number learning process performed by the process of FIG. It is a block diagram which shows the structure of an ignition timing calculation module. It is a time chart for demonstrating the detection method of ignition timing. It is a figure which shows the table for calculating a cetane number (CET) from ignition delay time (TDFM). It is a figure which shows transition of the heat release rate (HRR) in a specific cylinder. It is a figure which shows the frequency distribution of the estimation result of a cetane number. It is a flowchart of the process which performs reproduction | regeneration of DPF. It is a figure which shows the DPT map referred by the process of FIG. It is a figure which shows the relationship between the travel time (TRUN) of a vehicle, and the amount of collection particulates (QPT). It is a flowchart of the process which performs fuel injection control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 In-cylinder pressure sensor (pressure change detection means)
4 Electronic control unit (fuel injection control means, cetane number estimation means, particulate amount calculation means, regeneration means, exhaust gas recirculation control means)
6 Fuel injection valve (fuel injection means)
26 Exhaust gas recirculation passage (exhaust gas recirculation means)
27 Exhaust gas recirculation control valve (exhaust gas recirculation means)
32 Diesel particulate filter (particulate collecting means)

Claims (3)

Fuel injection means for injecting fuel into a combustion chamber of an internal combustion engine, particulate collection means for collecting particulates in the exhaust in an exhaust system, and exhaust gas recirculation means for returning a part of the exhaust to the intake system In a control device for an internal combustion engine,
Fuel injection control means for controlling fuel injection by the fuel injection means;
Pressure change detection means for detecting a pressure change in the combustion chamber of the engine;
Cetane number estimation means for estimating the cetane number of the fuel in use based on the output of the pressure change detection means;
Particulate amount calculation means for calculating the amount of particulates collected by the particulate collection means using a collection amount map set according to the operating state of the engine;
Regenerating means for performing regeneration processing of the particulate collection means according to the amount of collected particulates calculated;
An exhaust gas recirculation control means for reducing the exhaust gas recirculation amount when the estimation of the cetane number is not executed,
The particulate amount calculating means selects the collection amount map according to the estimated cetane number, and when the estimation of the cetane number is not completed, the particulate amount calculation means corresponds to an average cetane number fuel. A control device for an internal combustion engine, wherein a collection map is selected.   2. The internal combustion engine according to claim 1, wherein the fuel injection control unit performs fuel injection control suitable for the fuel having the average cetane number when the estimation of the cetane number is not executed. Control device.   The internal combustion engine control according to claim 1 or 2, wherein the fuel injection control means performs fuel injection control suitable for the reduced exhaust gas recirculation amount when the estimation of the cetane number is not executed. apparatus.

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