JP2007064033A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine having a supercharger which can accurately determine a cetan value of fuel on the basis of actual ignition timing. <P>SOLUTION: A cetan value estimation process for estimating a cetan value of fuel in use in accordance with an ignition delay angle DCAM which is the difference between a target main injection ignition timing map value CAFMM and actual ignition timing CAFM to be detected is executed in response to engine rotation speed NE and demand torque TRQ. The cetan value estimating process is executed when at least engine operating condition is in a premixtured fuel area and supercharging pressure PB falls within a predetermined range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  Patent Document 1 discloses a control apparatus for a compression ignition internal combustion engine that performs premixed combustion. According to this apparatus, the actual ignition timing of the fuel is detected during the premixed combustion, and the ignition timing error that is a difference from the preset standard fuel ignition timing and the variation in the ignition timing error are detected. The property of the fuel is determined.

JP-A-2005-171818

  In an internal combustion engine equipped with a supercharger, the supercharging pressure is controlled according to the engine operating state. However, when the deviation of the actual supercharging pressure from the target value increases, the ignition timing of the fuel changes. However, since this point is not taken into consideration in the conventional control device described above, when applied to an engine equipped with a supercharger, there is a possibility that a fuel property may be erroneously determined if there is a characteristic change or a malfunction of the supercharger. There was a problem of becoming higher.

  The present invention has been made paying attention to this point, and provides a control device for an internal combustion engine that can accurately determine the cetane number of fuel based on the actual ignition timing in an internal combustion engine equipped with a supercharger. The purpose is to provide.

  In order to achieve the above object, an invention according to claim 1 is provided in a combustion chamber of an internal combustion engine (1), a fuel injection means (6) for injecting fuel into the combustion chamber, a supercharging means (28), In the control device for an internal combustion engine, the operating state detecting means (3, 33) for detecting the operating state of the engine, the fuel injection timing (CAIMM) is determined according to the detected engine operating state, and the fuel injection means Fuel injection control means for executing fuel injection according to (6), and target ignition timing storage means for storing a target ignition timing (CAFMM) of fuel injected into the combustion chamber, which is set according to the operating state of the engine And a target ignition timing for calculating the target ignition timing (CAFMM) using an ignition timing detection means for detecting the actual ignition timing (CAFM) of the fuel injected into the combustion chamber and the target ignition timing storage means. And calculating an ignition delay (DCAM) of the actual ignition timing (CAFM) with respect to the calculated target ignition timing (CAFMM), and estimating the cetane number of the fuel according to the calculated ignition delay (DCAM) The cetane number estimating means, wherein the engine operating state is in a premixed combustion region, and a supercharging pressure (PB) pressurized by the supercharging means is within a predetermined range. In some cases, the estimation of the cetane number is performed.

  According to the first aspect of the present invention, the target ignition timing is calculated using the target ignition timing storage means that stores the target ignition timing of the fuel injected into the combustion chamber, which is set according to the operating state of the engine. In addition, the actual ignition timing is detected, and the ignition delay of the actual ignition timing with respect to the target ignition timing is calculated. Further, the cetane number of the fuel is estimated according to the calculated ignition delay. The estimation of the cetane number is executed when the engine operating state is in the premixed combustion region and the supercharging pressure pressurized by the supercharging means is within a predetermined range. Since the ignition timing of fuel is easily affected by changes in supercharging pressure, when the supercharging pressure is outside the specified range, the cetane number of fuel is incorrectly determined by not estimating the cetane number. It is possible to prevent this from happening and make an accurate determination.

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 one embodiment of the present invention. The following description will be given with reference to both figures together. An internal combustion engine (hereinafter simply referred to as “engine”) 1 having four cylinders 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 is provided downstream of the compressor 29 in the intake pipe 22.
An exhaust gas recirculation passage 26 that recirculates exhaust gas to the intake pipe 22 is provided between the upstream side of the turbine 30 in the exhaust pipe 24 and 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.

The intake pipe 22 is provided with an intake air flow rate sensor 31 for detecting the intake air flow rate GA, and a supercharging pressure sensor 32 for detecting an intake pipe internal pressure (supercharging pressure) PB on the downstream side of the supercharger 28. Detection signals from these sensors are supplied to the ECU 4.
Each cylinder of the engine 1 is provided with an in-cylinder pressure sensor 2 that detects an in-cylinder pressure (combustion pressure). In the present embodiment, the in-cylinder pressure sensor 2 is configured integrally with a glow plug provided in each cylinder. A detection signal from the in-cylinder pressure sensor 2 is supplied to the ECU 4. The detection signal of the in-cylinder pressure sensor 2 actually corresponds to a differential signal with respect to the crank angle (time) of the in-cylinder pressure PCYL, and the in-cylinder pressure PCYL is obtained by integrating the in-cylinder pressure sensor output. .

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

  The ECU 4 includes an accelerator sensor 33 that detects an operation amount AP of an accelerator pedal of a vehicle driven by the engine 1, a cooling water temperature sensor 34 that detects a cooling water temperature TW of the engine 1, and a vehicle speed sensor 35 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 the ECU 4. To be supplied.

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

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

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

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

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

  The CPU 14 calculates the target exhaust gas recirculation amount GEGR according to the engine operating state, and supplies a duty control signal for controlling the opening degree of the EGR valve 27 according to the target exhaust gas recirculation amount GEGR to the EGR valve 27 via the output circuit 18. To do.

  FIG. 3 is a block diagram showing the configuration of a module for calculating the target exhaust gas recirculation amount (hereinafter referred to as “target EGR amount”) GEGR and the main injection timing CAIM by the fuel injection valve 6. The function of this module is realized by processing executed by the CPU 14.

  The module shown in FIG. 3 estimates a target EGR amount calculation unit 36 that calculates a target EGR amount GEGR, a main injection timing calculation unit 37 that calculates a main injection timing CAIM, and a cetane number CET of fuel in use. The correction coefficient calculation unit 38 calculates a correction coefficient KCET according to the cetane number CET.

  The target EGR amount calculation unit 36 includes a target EGR amount map value calculation unit 41, an EGR correction amount map value calculation unit 42, a multiplication unit 43, switch units 44 and 46, and an addition unit 45. The target EGR amount map value calculation unit 41 searches a GEGRM map set in advance according to the engine speed NE and the required torque TRQ, and calculates a target EGR amount map value GEGRM. The GEGRM map is set based on a first cetane number, for example, a fuel having a high cetane number of about cetane number “57”.

  The EGR correction amount map value calculation unit 42 searches for a GCM map set in advance according to the engine speed NE and the required torque TRQ, and calculates an EGR correction amount map value GCM. The GCM map is set so as to correct, for example, about 15% per cetane number based on the second cetane number, for example, a low cetane number fuel of about 40 cetane number. The multiplying unit 43 calculates the EGR correction amount GC by multiplying the EGR correction amount map value GCM by the correction coefficient KCET calculated by the correction coefficient calculating unit 38 and corresponding to the cetane number CET of the fuel in use. .

  The adding unit 45 calculates the target EGR amount GEGR by adding the EGR correction amount GC to the target EGR amount map value GEGRM. The switch units 44 and 46 are supplied with a switching control signal SCTL. When the switching control signal SCTL is at a low level (“0”), the switch unit 44 is kept on as shown in the figure, and the switch unit 46 selects the output of the adder unit 45. The switching control signal SCTL is set to “1” when executing the cetane number estimation process of the fuel being used, and set to “0” otherwise. Therefore, when executing the cetane number estimation process, the switch unit 44 is turned off, and the switch unit 46 selects the input “0” (meaning that the EGR valve is fully closed). Thus, when the cetane number estimation process is executed, the exhaust gas recirculation is stopped.

  In step S11 of FIG. 4, it is determined whether or not a failure of the sensors (crank angle position sensor 3, accelerator sensor 21, and in-cylinder pressure sensor 2) necessary for the cetane number estimation process has been detected. If the answer is affirmative (YES), the switching control signal SCTL is set to “0” (step S17). If no sensor failure is detected, it is determined whether or not the vehicle driven by the engine 1 is in steady travel (step S12). When the vehicle is in steady running, it is determined whether or not the operating state of the engine 1 is in the premixed combustion region (step S13). Premixed combustion refers to combustion in which the fuel burns after a lapse of a delay time from the time when the fuel is injected. For example, the hatched area in FIG. 60 Nm) or less and the region where the engine speed NE is in the range from the first predetermined rotational speed NE1 (for example, 1200 rpm) to the second predetermined rotational speed NE2 (for example, 2300 rpm) is the premixed combustion region. In the premixed combustion region, the difference in the ignition timing due to the difference in the cetane number of the fuel becomes large, so that the estimation of the cetane number based on the ignition delay can be performed accurately.

  If the answer to step S13 is affirmative (YES), it is determined whether or not the supercharging pressure PB is within a predetermined range (for example, within a range of ± 5% of the target pressure value). If the answer is affirmative (YES), it is determined whether or not the other engine operating parameters are within a predetermined range determined for each parameter. For example, a swirl valve (not shown) determines whether the detected fresh air flow rate GA is within ± 5% of the target value, and whether the air-fuel ratio AF detected by the oxygen concentration sensor is within ± 5% of the target value. It is determined whether or not the opening of the fuel is within ± 5% of the target value and whether the fuel pressure PF is within ± 5% of the target value. When all the operating parameters are within the predetermined range, it is determined that the cetane number estimation execution condition is satisfied, and the switching control signal SCTL is set to “1” (step S16). When the switching control signal SCTL is set to “1”, the switch unit 64 is turned on as described above, and the cetane number estimation process is executed. The switch units 44 and 54 are turned off, and the switch unit 46 selects the input “0”.

  When the answer to any of steps S12 to S15 is negative (NO), the process proceeds to step S17, and the switching control signal SCTL is set to “0”.

  According to the process of FIG. 4, when the operating state of the engine 1 is in the premixed combustion region and the supercharging pressure PB is within a predetermined range, other conditions (steps S11, S12, and S15) are also satisfied. The execution of the cetane number estimation process is permitted. When the engine operating condition is in the premixed combustion region, the difference in the ignition timing due to the difference in the cetane number of the fuel becomes large, and the cetane number can be accurately estimated based on the ignition delay. Further, since the ignition timing of the fuel is easily affected by the change in the supercharging pressure, when the supercharging pressure PB is outside the predetermined range, the estimation of the cetane number is not performed so that the supercharger 28 It is possible to prevent erroneous determination of the cetane number of the fuel due to the characteristic change or malfunction.

  Returning to FIG. 3, the main injection timing calculation unit 37 includes a main injection timing map value calculation unit 51, an ignition delay correction map value calculation unit 52, a multiplication unit 53, a switch unit 54, and an addition unit 55. Yes. The main injection timing map value calculation unit 51 searches a CAIMM map set in advance according to the engine speed NE and the required torque TRQ, and calculates the main injection timing map value CAIMM. The CAIMM map is set based on the fuel having the first cetane number.

  The ignition delay correction map value calculation unit 52 searches a CADM map set in advance according to the engine speed NE and the required torque TRQ, and calculates an ignition delay correction map value CADM. The CADM map is set so as to correct, for example, about 0.15 degrees per cetane number based on the second cetane number fuel. The multiplier 53 multiplies the ignition delay correction map value CADM by the correction coefficient KCET calculated by the correction coefficient calculator 38 to calculate the ignition delay correction amount CAD. Similarly to the switch unit 44, the switch unit 54 is ON / OFF controlled by a switching control signal SCTL.

  The adder 55 calculates the main injection timing CAIM by adding the ignition delay correction amount CAD to the main injection timing map value CAIMM (advance the ignition delay correction amount CAD by the advance amount).

  The correction coefficient calculation unit 38 includes a target main injection ignition timing map value calculation unit 61, an ignition timing detection unit 62, a subtraction unit 63, a switch unit 64, a filter processing unit 65, a cetane number estimation unit 66, and a KCET. And a calculating unit 67. The target main injection ignition timing map value calculation unit 61 searches a CAFMM map set in advance according to the engine speed NE and the required torque TRQ, and calculates a target main injection ignition timing map value CAFMM. The CAFMM map is set based on the fuel having the first cetane number. The ignition timing detection unit 62 detects the main injection ignition timing CAFM according to the pressure change rate dpdθ obtained by converting the output signal of the in-cylinder pressure sensor 2 into a digital value. This detection method will be described later with reference to FIGS.

  The subtracting unit 63 calculates the ignition delay angle DCAM by subtracting the main injection ignition timing CAFM detected from the target main injection ignition timing map value CAFMM. The switch unit 64 is switch-controlled by a switch control signal SCTL, but is turned on / off opposite to the switch unit 44 or 54, and is in an off state when the switch control signal SCTL is “0”, and in an on state when “1”. It becomes. The filter processing unit 65 filters data of the ignition delay angle DCAM obtained over a relatively long time (10 to 60 seconds) by a least square method calculation or a moving average calculation. Let it be the ignition delay angle DCAMF after filtering.

The cetane number estimation unit 66 converts the ignition delay angle DCAMF into the ignition delay time TDFM using the engine speed NE, searches the CET table shown in FIG. 8 according to the ignition delay time TDFM, and calculates the cetane number CET. To do. The cetane number estimation unit 66 further applies the cetane number CET to the following formula (1) to calculate a cetane number learning 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.
When refueling is performed, the cetane number learning value CETLRN is initialized to the minimum value CET0 (for example, 40) among the cetane numbers of fuels traded in the market, and the fuel in use is subsequently learned. Converges to a value indicating the cetane number. By initializing to the minimum value CET0, when used for the control of the fuel injection timing described below, it is possible to reliably ignite even the most difficult-to-ignite fuel when the engine is cold started.

  The cetane number learning value CETLRN described above is calculated using all the cylinder pressure sensor outputs of the four cylinders. Therefore, the cetane number CET detected for each cylinder and the cetane number CET with different detection timings are averaged by the above equation (1). When the cetane number estimation process is not executed, the latest stored cetane number learning value CETLRN is output from the cetane number estimation unit 66.

The KCET calculation unit 67 calculates the correction coefficient KCET by applying the cetane number learned value CETLRN to the following equation (2).
KCET = (CETH-CETLRN) / (CETH-CETO) (2)
Here, CETH is the cetane number (for example, 57) of the high cetane number fuel used as a reference for setting the CAIMM map and the CADM map described above. Therefore, when the cetane number learning value CETLRN is equal to the reference high cetane number CETH, the correction coefficient KCET is “0”, and when it is equal to the reference low cetane number CET0, the correction coefficient KCET is “1.0”.

  FIG. 6 is a block diagram illustrating a configuration of the ignition timing detection unit 62. The ignition timing detection unit 62 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 dpdθ output from the in-cylinder pressure sensor 2. A waveform W1 shown in FIG. 7 indicates an input waveform, and a waveform W2 indicates an output waveform. 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 corresponds to the pilot injection, the crank angle position where the pressure change rate dpdθ exhibits a peak value (hereinafter referred to as “pilot injection ignition timing”) CAFP, and the pressure change rate dpdθ corresponding to the main injection. Is determined as a crank angle position (hereinafter referred to as “main injection ignition timing”) CAFM indicating a peak value. Specifically, as shown in FIG. 8C, the crank angle at which the pressure change rate dpdθ output from the phase delay correction unit 72 exceeds the pilot detection threshold DPP is determined as the pilot injection ignition timing CAFP, and the pressure The crank angle at which the change rate dpdθ exceeds the main detection threshold value DPM is determined as the main injection ignition timing CAFM. In the present embodiment, only the main injection ignition timing CAFM is used for estimating the cetane number CET.

  FIGS. 8A and 8B show a pilot injection pulse INJP starting from the crank angle CAIP and a main injection pulse INJM starting from the crank angle CAIM. FIG. 8C shows ignition. An angle range RDET (for example, 10 degrees) for detecting the times CAFP and CAFM is shown. 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.

  As described above in detail, in the present embodiment, the target main injection ignition timing map value CAFMM is calculated according to the engine speed NE and the required torque TRQ, the main injection ignition timing CAFM is detected, and the target main injection ignition is detected. An ignition delay angle DCAM of the main injection ignition timing CAFM with respect to the timing map value CAFMM is calculated. Further, the cetane number CET of the fuel is estimated according to the calculated ignition delay angle DCAM, and the learning value CETLRN is calculated. Further, a target EGR amount map value GEGRM is calculated according to the engine speed NE and the required torque TRQ, and the target EGR amount map value GEGRM is corrected by a correction coefficient KCET set according to the cetane number learning value CETLRN. Then, the exhaust gas recirculation amount is controlled using the corrected target EGR amount GEGR. Therefore, appropriate exhaust gas recirculation according to the cetane number of the fuel to be used can be performed, and good combustion state and exhaust characteristics can be maintained.

  Further, the cetane number estimation process is executed when an execution condition including that the engine operating state is in the premixed combustion region and the supercharging pressure PB is within a predetermined range is satisfied. The difference in ignition timing due to the difference increases, the cetane number can be accurately estimated based on the ignition delay, and the cetane number of the fuel is erroneously determined due to the characteristic change or malfunction of the supercharger 28. Can be prevented.

  In the present embodiment, the fuel injection valve 6 constitutes a fuel injection means, the crank angle position sensor 3 and the accelerator sensor 33 constitute an operating state detection means, and the ECU 4 is a fuel injection control means, an ignition timing storage means, a target ignition timing. A calculation means, a part of the ignition timing detection means, and a cetane number estimation means are configured. More specifically, the CAFMM map corresponds to the ignition timing storage unit, the in-cylinder pressure sensor 2 and the ignition timing detection unit 62 correspond to the ignition timing detection unit, the subtraction unit 63, the switch 64, the filter processing unit 65, and the cetane. The price estimation unit 66 corresponds to a cetane number estimation unit, and the main injection timing map value calculation unit 51 and the addition unit 55 correspond to a fuel injection control unit.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, the cetane number is estimated based on the main injection ignition timing CAFM corresponding to the main injection, but the cetane number estimation may be performed based on the pilot injection ignition timing CAFP corresponding to the pilot injection. Further, the pilot injection timing may be corrected according to the estimated cetane number.

  In the above-described embodiment, the GEGRM map and the CAIMM map are set based on the high cetane number fuel, and the GCM map and the CADM map are set based on the low cetane number fuel, but conversely, the GEGRM map and the CAIMM map are set. The low cetane number fuel may be set as a reference, and the GCM map and CADM map may be set based on the high cetane number fuel.

  In the above-described embodiment, the in-cylinder pressures of all the cylinders are detected and the cetane number learning value CETLRN is calculated. However, the in-cylinder pressure sensor is provided only in one specific cylinder and is detected by the in-cylinder pressure sensor. The cetane number learning value CETLRN may be calculated based on the in-cylinder pressure.

  Further, the ignition delay time TDFM changes not only with the cetane number of the fuel but also with the deterioration of the fuel injection valve 6. Therefore, it is desirable to correct the ignition delay time TDFM according to the travel distance of the vehicle or the integrated value of the operation time of the engine 1.

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

1 is a diagram illustrating an internal combustion engine and a control device thereof according to an embodiment of the present invention. FIG. 2 is a diagram more specifically showing a partial configuration of the control device shown in FIG. 1. It is a block diagram which shows the structure of the module which calculates target exhaust gas recirculation amount (GEGR) and main injection timing (CAIM). It is a flowchart of the process which performs the setting of the switching control signal (SCTL) supplied to the switch part shown in FIG. It is a figure for demonstrating a premix combustion area | region. It is a block diagram which shows the structure of the ignition timing detection part shown in FIG. It is a time chart for demonstrating the band pass filter process of a cylinder pressure sensor output. 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).

Explanation of symbols

1 Internal combustion engine 2 In-cylinder pressure sensor (ignition timing detection means)
3 Crank angle position sensor (operating state detection means)
4 Electronic control unit 6 Fuel injection valve (fuel injection means)
28 Supercharger (supercharger)
33 Accelerator sensor (operating state detection means)
51 Main injection timing map value calculation unit (fuel injection control means)
55 Adder (fuel injection control means)
61 Target main injection ignition timing map value calculation unit (target ignition timing calculation means)
62 Ignition timing detector (Ignition timing detection means)
63 Subtraction part (cetane number estimation means)
64 Switch part (cetane number estimation means)
65 Filter processing unit (cetane number estimation means)
66 Cetane number estimation part (cetane number estimation means)

Claims (1)

In a control device for an internal combustion engine, provided in a combustion chamber of an internal combustion engine, comprising a fuel injection means for injecting fuel into the combustion chamber, and a supercharging means.
Operating state detecting means for detecting the operating state of the engine;
Fuel injection control means for determining fuel injection timing according to the detected engine operating state and executing fuel injection by the fuel injection means;
A target ignition timing storage means for storing a target ignition timing of the fuel injected into the combustion chamber, which is set according to the operating state of the engine;
Ignition timing detection means for detecting the actual ignition timing of the fuel injected into the combustion chamber;
Target ignition timing calculation means for calculating the target ignition timing using the target ignition timing storage means;
Cetane number estimating means for calculating an ignition delay of the actual ignition timing with respect to the calculated target ignition timing, and estimating the cetane number of the fuel according to the calculated ignition delay,
The cetane number estimating means performs the estimation of the cetane number when the operating state of the engine is in a premixed combustion region and the supercharging pressure pressurized by the supercharging means is within a predetermined range. A control device for an internal combustion engine.

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