JP7226205B2 - engine controller - Google Patents

Description

The technology disclosed herein relates to an engine control device.

Patent Literature 1 describes an engine that performs feedback control of ignition timing. This engine adjusts the ignition timing based on the output of the in-cylinder pressure sensor so that the crank angle at which the mass combustion ratio is 50% is the target timing.

Japanese Patent No. 3873580

In a multi-cylinder engine having a plurality of cylinders, it is preferable to adjust the ignition timing for each cylinder based on the output of the in-cylinder pressure sensor in consideration of the difference between the cylinders.

However, the inventors of the present application have found that feedback control of the ignition timing for each cylinder may result in a large response delay during a transient period in which the operating state of the engine changes, such as during acceleration. If the response delay becomes large, there is a risk that knocking will be caused by the ignition timing remaining advanced, or misfire will be caused by the ignition timing remaining retarded.

The technology disclosed herein enhances responsiveness to changes in engine operating conditions in an engine that feedback-controls ignition timing.

The technology disclosed herein relates to an engine control device. The control device of the engine is
an engine having four cylinders each forming a combustion chamber;
four igniters attached to the engine for each cylinder and each igniting a mixture in the combustion chamber;
four in-cylinder pressure sensors attached to the engine for each cylinder and each outputting a measurement signal corresponding to the pressure in the cylinder;
a control unit that determines a target ignition timing according to the operating state of the engine and sequentially outputs an ignition signal to the four ignition units so that the ignition unit performs ignition at the target ignition timing;
The control unit receives a measurement signal from the in-cylinder pressure sensor and, based on the combustion index obtained from the measurement signal, sets the target ignition timing for each cylinder so that the combustion index becomes a target combustion index. feedback correction to
The control unit also controls the target value of the one cylinder when the deviation between the feedback correction amount for one of the four cylinders and the feedback correction amount for the other cylinder exceeds a predetermined amount. Correct the ignition timing.

The control unit performs feedback control of the ignition timing based on the measurement signal of the in-cylinder pressure sensor. The air-fuel mixture in the combustion chamber burns such that the combustion index is the target combustion index. Combustion of the air-fuel mixture is optimized. The fuel efficiency of the engine is improved.

The engine is a four cylinder engine. The control unit performs feedback control for each cylinder. The combustion of the air-fuel mixture is optimized for each combustion chamber. Feedback control for each cylinder absorbs differences between cylinders.

While the engine is in steady operation, the state quantities in the cylinders do not change, or hardly change. Although the four cylinders fire sequentially, the state quantities in each cylinder are the same or nearly the same at the time of firing of each of the four cylinders. Therefore, the feedback correction amount is also the same or substantially the same for each of the four cylinders. While the engine is in steady operation, the deviation between the feedback correction amount for one of the four cylinders and the feedback correction amount for the other cylinders is small.

On the other hand, when the operating state of the engine changes, for example, when the vehicle in which the engine is installed accelerates or decelerates, the state quantity in the cylinder changes. The amount of fresh air and/or EGR gas introduced into the cylinder changes over time. The control unit must change the ignition timing of each cylinder to the retard side or the advance side so as to correspond to the change in the state quantity.

Here, in a multi-cylinder engine, a plurality of cylinders are sequentially combusted . In a four -cylinder engine, one cylinder burns once for every four total engine burns. The interval between combustions in one cylinder is wide.

During the transition, the amount of fresh air and/or EGR gas introduced into the cylinder changes from moment to moment between the previous combustion and the next combustion in one cylinder. When feedback control is performed for each cylinder, even if the control unit reflects the feedback correction amount determined for the previous combustion to the combustion to be performed from now on, it may not correspond to the state quantity in the cylinder. That is, the response delay of feedback control increases.

Therefore, the control unit obtains the deviation between the feedback correction amount for one cylinder and the feedback correction amount for the other cylinders, and determines whether or not the deviation exceeds a predetermined amount. Other cylinders include cylinders in which combustion precedes the one cylinder. In a state where the state quantity in the cylinder changes moment by moment, the state quantity in the cylinder that is newer than the feedback correction quantity for the one cylinder is reflected in the feedback correction quantity for the other cylinders. When the operating state of the engine changes, the deviation between the feedback correction amount of the other cylinder and the feedback correction amount of the one cylinder becomes large. The control unit can determine that it is in transition based on the fact that the deviation of the correction amount exceeds a predetermined amount.

If the deviation exceeds a predetermined amount, the controller modifies the target ignition timing of the one cylinder. Thereby, the control unit can set the target ignition timing corresponding to the state quantity in the cylinder during the transition. Response delay of feedback control is improved. As a result, the occurrence of knocking and misfiring during transients is suppressed. Improves engine reliability.

The control unit filters the feedback correction amount based on the measurement signal of the in-cylinder pressure sensor with a first first-order lag filter for each cylinder, and performs the target correction amount based on the filtered first correction amount. correct the ignition timing
The control unit also stores a second correction amount obtained by filtering feedback correction amounts for all cylinders including the one cylinder and the other cylinders with a second first-order lag filter,
The control unit also corrects the target ignition timing of the one cylinder when the first correction amount deviates from the second correction amount by a predetermined amount or more,
The first first-order lag filter has a stronger filter strength than the second first-order lag filter.

The control unit performs feedback correction for each cylinder based on the first correction amount filtered by the first first-order lag filter. The first first-order lag filter has a strong filter strength. Therefore, steady-state stability of feedback control of ignition timing is enhanced. Torque is suppressed from fluctuating when the engine is in steady operation. The drivability of automobiles is improved.

Feedback control for each cylinder improves steady-state stability, but because the strength of the first first-order lag filter is strong, this feedback control tends to increase the response delay during transients.

The controller stores the second correction amount. The second correction amount is a correction amount obtained by filtering the feedback correction amount for all cylinders with a second first-order lag filter. Since the feedback correction amount for all cylinders is included, the second correction amount reflects changes in the state quantities in the cylinders earlier than the first correction amount for each cylinder.

Also, the second first-order lag filter has a weaker filter strength than the first first-order lag filter. Therefore, the change in the state quantity in the cylinder is more likely to be reflected in the second correction amount than in the first correction amount.

As a result, the deviation between the first correction amount and the second correction amount exceeds the predetermined amount during a transient period when the operating state of the engine changes. When the deviation exceeds a predetermined amount, the target ignition timing is appropriately set by correcting the target ignition timing of one cylinder.

The control unit calculates the first correction amount and the second correction amount based on the measurement signal of the in-cylinder pressure sensor without directly determining whether the operating state of the engine is a steady state or a transient state. , it can be quickly and accurately determined that the operating state of the engine is in transition.

The ignition unit receives the ignition signal and ignites the air-fuel mixture, whereby a part of the air-fuel mixture begins to burn with flame propagation, and then the remaining unburned air-fuel mixture burns by self-ignition. , may be

This combustion is SPCCI (SPark Controlled Compression Ignition) combustion, which is a combination of SI (Spark Ignition) combustion and CI (Compression Ignition) combustion. SPCCI combustion is excellent in engine fuel efficiency and clean exhaust gas. By adjusting the amount of SI combustion, it is possible to absorb temperature variations in the cylinder before the start of compression. By adjusting the amount of SI combustion, the unburned air-fuel mixture self-ignites at the target timing. The combustion amount of SI combustion can be adjusted by adjusting the ignition timing by the controller. Therefore, CI combustion starts at the target timing by adjusting the ignition timing by the control unit.

The combustion index may be a crank angle at which the mass combustion ratio of the air-fuel mixture becomes a predetermined ratio.

SPCCI combustion varies in duration from ignition to onset of auto-ignition depending on conditions within the cylinder. In SPCCI combustion, even if the ignition timing is the same, the timing at which self-ignition starts may change. If the timing to start self-ignition changes, the combustion waveform of SPCCI combustion will change.

In order to obtain a desired combustion waveform for SPCCI combustion, the controller determines the mass combustion ratio as an index for ignition control. If the control unit adjusts the ignition timing so that the crank angle at which the mass fraction burned reaches a predetermined rate, for example, the crank angle at which the mass fraction burned (mfb50: mass fraction burned) reaches 50%, becomes the target crank angle, The combustion waveform of SPCCI combustion can be made into a desired waveform. By using the crank angle at which the mass combustion ratio reaches a predetermined ratio as the combustion index, the control unit can appropriately control the SPCCI combustion.

The control unit feedback-corrects the target ignition timing of the one cylinder based on a modified feedback correction amount obtained by adding a correction amount corresponding to the deviation to the feedback correction amount for the one cylinder. good too.

The control unit can appropriately set the target ignition timing by considering feedback correction amounts for other cylinders during transition.

The control unit may set the target ignition timing for the one cylinder based on a feedback correction amount for the one cylinder and feedback correction amounts for all cylinders.

The control unit can appropriately set the target ignition timing by considering feedback correction amounts for other cylinders during transition.

As described above, the engine control device can improve the responsiveness to changes in the operating state of the engine.

FIG. 1 is a configuration diagram illustrating an engine. FIG. 2 is a block diagram illustrating an engine control device. The upper diagram in FIG. 3 is a diagram illustrating the waveform of SPCCI combustion, and the lower diagram is a diagram illustrating changes in heat release. FIG. 4 is a block diagram illustrating the configuration of an engine ignition control device. FIG. 5 is a diagram illustrating a combustion cycle of multiple cylinders. FIG. 6 is a flow chart for setting the target ignition timing for each cylinder. FIG. 7 is a flowchart relating to setting of correction amounts for all cylinders. FIG. 8 is a time chart for setting the target ignition timing during transition. FIG. 9 is a time chart illustrating the amount of feedback correction during transition.

Hereinafter, embodiments of an engine control device will be described with reference to the drawings. The engine control system described here is an example.

FIG. 1 is a diagram illustrating an engine. FIG. 2 is a block diagram illustrating an engine control device.

The engine 1 has a combustion chamber 17 . The combustion chamber 17 repeats an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke. Engine 1 is a four-stroke engine. The engine 1 is installed in a four-wheeled vehicle. The automobile runs as the engine 1 operates. The fuel of the engine 1 is gasoline in this configuration example. The fuel may be liquid fuel containing at least gasoline. The fuel may be gasoline, including, for example, bioethanol.

(Engine configuration)
The engine 1 has a cylinder block 12 and a cylinder head 13 . The cylinder head 13 is mounted on the cylinder block 12 .

A plurality of cylinders 11 are formed in the cylinder block 12 . The engine 1 is a multi-cylinder engine. The illustrated engine 1 has four cylinders 11, #1, #2, #3, and #4, as shown in FIG. Note that only one cylinder 11 is shown in FIG.

A piston 3 is inserted in each cylinder 11 . Piston 3 is connected to crankshaft 15 via connecting rod 14 . The piston 3 reciprocates inside the cylinder 11 . The piston 3 , cylinder 11 and cylinder head 13 form a combustion chamber 17 . The "combustion chamber" means a space formed by the piston 3, the cylinder 11 and the cylinder head 13 regardless of the position of the piston 3.

The geometric compression ratio of the engine 1 is set to 10 or more and 30 or less. The engine 1 performs SPCCI combustion, which is a combination of SI (Spark Ignition) combustion and CI (Compression Ignition) combustion, in some operating ranges. The engine 1 performs SI combustion in an operating range other than the operating range in which SPCCI combustion is performed.

SPCCI combustion controls CI combustion through heat generation and/or pressure increase due to SI combustion. The engine 1 is a compression ignition engine. This engine 1 does not need to raise the temperature of the combustion chamber 17 when the piston 3 reaches the compression top dead center. Engine 1 has a low geometric compression ratio. A low geometric compression ratio favors reduced cooling losses and reduced mechanical losses. The geometric compression ratio of the engine 1 may be 14-17 for regular specifications and 15-18 for high-octane specifications. The regular fuel is low octane fuel with an octane number of about 91. A high-octane fuel is a high-octane fuel with an octane number of about 96.

An intake port 18 is formed in the cylinder head 13 for each cylinder 11 . The intake port 18 communicates with the combustion chamber 17 . Although detailed illustration is omitted, the intake port 18 is a so-called tumble port. That is, the intake port 18 has a shape that generates a tumble flow in the combustion chamber 17 .

An intake valve 21 is arranged in the intake port 18 . The intake valve 21 opens and closes the intake port 18 . The valve mechanism opens and closes the intake valve 21 at predetermined timings. The valve mechanism may be a variable valve mechanism that varies valve timing and/or valve lift. As shown in FIG. 2, the valve mechanism has an electric intake S-VT (Sequential-Valve Timing) 23 . The electric intake S-VT 23 continuously changes the rotation phase of the intake camshaft within a predetermined angle range. The opening angle of the intake valve 21 does not change. The valve mechanism may have a hydraulic S-VT instead of the electric S-VT.

An exhaust port 19 is formed in the cylinder head 13 for each cylinder 11 . The exhaust port 19 communicates with the combustion chamber 17 .

An exhaust valve 22 is arranged in the exhaust port 19 . The exhaust valve 22 opens and closes the exhaust port 19 . The valve mechanism opens and closes the exhaust valve 22 at predetermined timings. The valve mechanism may be a variable valve mechanism that varies valve timing and/or valve lift. As shown in FIG. 2, the valve train has an electric exhaust S-VT 24 . The electric exhaust S-VT 24 continuously changes the rotation phase of the exhaust camshaft within a predetermined angle range. The opening angle of the exhaust valve 22 does not change. The valve mechanism may have a hydraulic S-VT instead of the electric S-VT.

The electric intake S-VT 23 and the electric exhaust S-VT 24 adjust the length of the overlap period during which both the intake valve 21 and the exhaust valve 22 are open. Internal EGR (Exhaust Gas Recirculation) gas is introduced into the combustion chamber 17 by adjusting the length of the overlap period.

An injector 6 is attached to the cylinder head 13 for each cylinder 11 . Injector 6 injects fuel directly into combustion chamber 17 . Although the detailed illustration is omitted, the injector 6 is of a multiple injection hole type having a plurality of injection holes. The injector 6 injects fuel radially and obliquely downward from the center of the ceiling of the combustion chamber 17 .

A fuel supply system 61 is connected to the injector 6 . The fuel supply system 61 includes a fuel tank 63 that stores fuel and a fuel supply path 62 . A fuel supply path 62 connects the fuel tank 63 and the injector 6 to each other. A fuel pump 65 and a common rail 64 are interposed in the fuel supply path 62 . Fuel pump 65 delivers fuel to common rail 64 . The fuel pump 65 is a plunger pump driven by the crankshaft 15 in this configuration example. Common rail 64 stores fuel sent from fuel pump 65 . The voltage inside the common rail 64 is high voltage. Injector 6 is connected to common rail 64 . When the injector 6 opens, the high-pressure fuel in the common rail 64 is injected into the combustion chamber 17 through the nozzle hole of the injector 6 . Note that the configuration of the fuel supply system 61 is not limited to the configuration described above.

A spark plug 25 is attached to the cylinder head 13 for each cylinder 11 (see also FIG. 4). A spark plug 25 forcibly ignites the air-fuel mixture in the combustion chamber 17 . The spark plug 25 is an example of an ignition section. Electrodes of the ignition plug 25 face the inside of the combustion chamber 17 .

An intake passage 40 is connected to one side surface of the engine 1 . The intake passage 40 communicates with the intake port 18 of each cylinder 11 . Intake gas introduced into the combustion chamber 17 flows through the intake passage 40 . An air cleaner 41 is arranged at the upstream end of the intake passage 40 . A surge tank 42 is arranged near the downstream end of the intake passage 40 . The intake passage 40 downstream of the surge tank 42 branches for each cylinder 11 .

A throttle valve 43 is arranged between the air cleaner 41 and the surge tank 42 in the intake passage 40 . The throttle valve 43 adjusts the amount of fresh air introduced into the combustion chamber 17 by changing the opening of the valve.

A supercharger 44 is also arranged in the intake passage 40 downstream of the throttle valve 43 . The supercharger 44 increases the pressure of intake gas introduced into the combustion chamber 17 . In this configuration example, the supercharger 44 is driven by the engine 1 . The supercharger 44 may be of the Roots, Lysholm, vane, or centrifugal type.

An electromagnetic clutch 45 is interposed between the supercharger 44 and the engine 1 . The electromagnetic clutch 45 switches between a state in which driving force is transmitted from the engine 1 to the supercharger 44 and a state in which transmission of the driving force is interrupted. The turbocharger 44 is turned on or off by outputting a control signal to the electromagnetic clutch 45 from the ECU 10, which will be described later.

An intercooler 46 is arranged downstream of the supercharger 44 in the intake passage 40 . The intercooler 46 cools the intake gas compressed by the supercharger 44 . The intercooler 46 is water cooled or oil cooled.

A bypass passage 47 is connected to the intake passage 40 . The bypass passage 47 connects the upstream portion of the supercharger 44 and the downstream portion of the intercooler 46 in the intake passage 40 to each other. A bypass passage 47 bypasses the supercharger 44 and the intercooler 46 . An air bypass valve 48 is arranged in the bypass passage 47 . The air bypass valve 48 adjusts the flow rate of gas flowing through the bypass passage 47 .

The ECU 10 fully opens the air bypass valve 48 when the supercharger 44 is off. Intake gas flowing through the intake passage 40 bypasses the supercharger 44 and the intercooler 46 and reaches the combustion chamber 17 of the engine 1 . The engine 1 operates in a non-supercharged state, that is, in a naturally aspirated state.

When the supercharger 44 is on, the engine 1 operates in a supercharged state. The ECU 10 adjusts the opening degree of the air bypass valve 48 when the supercharger 44 is on. Part of the intake gas that has passed through the supercharger 44 and the intercooler 46 returns to the upstream of the supercharger 44 through the bypass passage 47 . When the ECU 10 adjusts the opening of the air bypass valve 48, the pressure of the intake gas introduced into the combustion chamber 17 changes. "Supercharging" is defined as a state in which the pressure in the surge tank 42 exceeds the atmospheric pressure, and "non-supercharging" is defined as a state in which the pressure in the surge tank 42 is below the atmospheric pressure. You may

The engine 1 has a swirl generator that generates a swirl flow within the combustion chamber 17 . Although not shown in detail, the swirl generator has a swirl control valve 56 attached to the intake passage 40 . The swirl control valve 56 is an opening control valve. When the opening degree of the swirl control valve 56 is small, the swirl flow inside the combustion chamber 17 becomes strong. When the opening of the swirl control valve 56 is large, the swirl flow in the combustion chamber 17 becomes weak. When the swirl control valve 56 is fully opened, no swirl flow occurs.

An exhaust passage 50 is connected to the other side surface of the engine 1 . The exhaust passage 50 communicates with the exhaust port 19 of each cylinder 11 . Exhaust gas discharged from the combustion chamber 17 flows through the exhaust passage 50 . The upstream portion of the exhaust passage 50 branches for each cylinder 11, although detailed illustration is omitted.

An exhaust gas purification system having a plurality of catalytic converters is arranged in the exhaust passage 50 . Although not shown, these catalytic converters are arranged in the engine room. The upstream catalytic converter has a three-way catalyst 511 and a GPF (Gasoline Particulate Filter) 512 . The downstream catalytic converter has a three-way catalyst 513 . It should be noted that the exhaust gas purification system is not limited to the configuration of the illustrated example. For example, GPF may be omitted. Also, the catalytic converter is not limited to having a three-way catalyst. Furthermore, the order in which the three-way catalyst and GPF are arranged may be changed as appropriate.

An EGR passage 52 is connected between the intake passage 40 and the exhaust passage 50 . The EGR passage 52 is a passage that recirculates part of the exhaust gas to the intake passage 40 . An upstream end of the EGR passage 52 is connected between the two catalytic converters in the exhaust passage 50 . A downstream end of the EGR passage 52 is connected to an upstream portion of the supercharger 44 in the intake passage 40 .

A water-cooled EGR cooler 53 is arranged in the EGR passage 52 . The EGR cooler 53 cools the exhaust gas. An EGR valve 54 is also arranged in the EGR passage 52 . The EGR valve 54 adjusts the flow rate of exhaust gas flowing through the EGR passage 52 . The EGR valve 54 adjusts the amount of recirculated external EGR gas.

(Configuration of engine control device)
The engine control device includes an ECU (Engine Control Unit) 10 . The ECU 10 is an example of a control section. The ECU 10 includes a microcomputer 101, a memory 102, and an I/F circuit 103, as shown in FIG. The microcomputer 101 executes programs. Memory 102 stores programs and data. The memory 102 is, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory). The I/F circuit 103 inputs and outputs electrical signals.

Various sensors SW1-SW11 are connected to the ECU 10 as shown in FIGS. The sensors SW1-SW11 output signals to the ECU 10. FIG. The sensors include the following sensors.

The airflow sensor SW1 measures the flow rate of fresh air flowing through the intake passage 40 . The airflow sensor SW1 is arranged downstream of the air cleaner 41 in the intake passage 40. The first intake air temperature sensor SW2 measures the temperature of fresh air flowing through the intake passage 40. FIG. The first intake air temperature sensor SW2 is arranged downstream of the air cleaner 41 in the intake passage 40. The second intake air temperature sensor SW3 measures the temperature of the intake gas introduced into the combustion chamber 17. FIG. The second intake air temperature sensor SW3 is attached to the surge tank 42. The intake air pressure sensor SW4 measures the pressure of the intake gas introduced into the combustion chamber 17. FIG. The intake pressure sensor SW4 is attached to the surge tank 42. The in-cylinder pressure sensor SW5 measures the pressure inside each combustion chamber 17. FIG. The in-cylinder pressure sensor SW5 is attached to the cylinder head 13 for each cylinder 11, and the water temperature sensor SW6 measures the temperature of the cooling water. A water temperature sensor SW6 is attached to the engine 1. A crank angle sensor SW7 measures the rotation angle of the crankshaft 15. FIG. The crank angle sensor SW7 is attached to the engine 1. The accelerator opening sensor SW8 measures the accelerator opening corresponding to the operation amount of the accelerator pedal. The accelerator opening sensor SW8 is attached to the accelerator pedal mechanism. The intake cam angle sensor SW9 measures the rotational position of the intake cam. An intake cam angle sensor SW9 is attached to the engine 1. An exhaust cam angle sensor SW10 measures the rotational position of the exhaust cam. The exhaust cam angle sensor SW10 is attached to the engine 1. The SCV position sensor SW11 measures the opening of the swirl control valve 56. The SCV position sensor SW11 is attached to the swirl control valve 56.

The ECU 10 determines the operating state of the engine 1 based on the signals from these sensors SW1-SW11. The ECU 10 also calculates the control amount of each device according to predetermined control logic. The control logic is stored in memory 102 .

The ECU 100 transmits electric signals related to the control amount to the injector 6, the spark plug 25, the electric intake S-VT 23, the electric exhaust S-VT 24, the fuel supply system 61, the throttle valve 43, the EGR valve 54, and the electromagnetic clutch of the supercharger 44. 45 , air bypass valve 48 and swirl control valve 56 .

(SPCCI combustion concept)
The main purpose of the engine 1 is to improve fuel consumption and exhaust gas performance. If the temperature in the combustion chamber 17 before the start of compression varies, the timing of self-ignition changes greatly. Therefore, the engine 1 performs SPCCI combustion, which is a combination of SI combustion and CI combustion.

SPCCI combustion is the following form of combustion. That is, after all the fuel to be injected in one cycle has been injected into the combustion chamber 17, the spark plug 25 forces the mixture in the combustion chamber 17 to ignite. This causes the air-fuel mixture to initiate SI combustion through flame propagation. After the start of SI combustion, (1) the temperature in the combustion chamber 17 increases due to the heat generated by the SI combustion, and (2) the pressure in the combustion chamber 17 increases due to flame propagation. CI combustion is performed by self-ignition.

Fig. 31 in the upper part of Fig. 3 shows the change in the heat release rate dq/dθ with respect to the crank angle when the combustion is SPCCI combustion (solid line), and when the mixture does not self-ignite and the combustion is SI combustion. change in heat release rate dq/dθ with respect to crank angle (solid line and dashed line). The lower graph 32 in FIG. 3 shows the change in heat release Q with respect to the crank angle when the combustion is SPCCI combustion (solid line), and the change in heat release Q with respect to the crank angle when the combustion is SI combustion (solid line and one point dashed line) and are exemplified.

In the SPCCI combustion, after combustion by flame propagation is started by ignition, the air-fuel mixture self-ignites at θci, and combustion by self-ignition is performed. As shown in FIG. 31 above, the waveform of the heat release rate (dq/dθ) in SPCCI combustion has a shape in which a peak of heat release due to SI combustion and a peak of heat release due to CI combustion are stacked. As shown in FIG. 32 below, the change in heat release in SPCCI combustion changes in slope before θci and after θci.

By adjusting the amount of SI combustion, it is possible to absorb temperature variations in the combustion chamber 17 before the start of compression. The amount of SI combustion is adjusted by the ECU 10 adjusting the ignition timing. If the ECU 10 adjusts the ignition timing, the air-fuel mixture self-ignites at the target timing. In SPCCI combustion, the amount of SI combustion controls the start timing of CI combustion.

(engine ignition control)
FIG. 4 illustrates the configuration of an ignition control device 100 related to ignition control of the engine 1. As shown in FIG. The ignition control device 100 includes an estimation section 111 , an ignition timing setting section 112 , a correction amount calculation section 113 , an own cylinder F/B filter section 114 and an all cylinder F/B filter section 115 . These are all functional blocks of the ECU 10 .

The estimation unit 111 estimates the period from ignition to crank angle (mfb50) at which the mass combustion ratio becomes 50% in the combustion to be performed from now on, based on the measurement signals of various sensors. Here, the mass combustion ratio is the ratio of the burned mass to the mass of fuel supplied to the combustion chamber 17 per one combustion cycle, and is calculated for each crank angle. mfb50 is a crank angle at which 0.5Q is obtained when Q is heat generation at the time of completion of combustion, as shown in the lower diagram 32 of FIG.

The ignition control device 100 performs ignition control using mfb50 as a combustion index. This is because in SPCCI combustion, the period from ignition to the start of self-ignition varies depending on the state in the cylinder. In SPCCI combustion, even if the ignition timing is the same, the timing at which self-ignition starts may change. If the timing to start self-ignition changes, the combustion waveform of SPCCI combustion will change. Therefore, the ignition control device 100 adjusts the ignition timing so that mfb50 becomes the target crank angle. Thereby, the combustion waveform of SPCCI combustion can be made into a desired waveform. The ignition controller 100 can appropriately control SPCCI combustion.

The estimator 111 has a combustion period model. The combustion duration model estimates the crank angle duration from ignition to mfb50 from various parameters. Parameters used for estimation are, as shown in FIG. number and SCV opening.

The external EGR rate and the internal EGR rate are calculated based on measurement signals from the airflow sensor SW1 and the intake pressure sensor SW4. The target φ is a target value set by the ECU 10 .

The injection mode relates to the timing of fuel injection, and corresponds to, for example, an injection set that injects fuel during the intake stroke or an injection set that injects fuel during the compression stroke. The injection mode is a set value determined by the ECU 10 .

The charging efficiency is calculated based on the measurement signal of the intake pressure sensor SW4. The intake valve opening timing and the exhaust valve opening timing are calculated based on measurement signals from the intake cam angle sensor SW9 and the exhaust cam angle sensor SW10, respectively. The water temperature is calculated based on the measurement signal of the water temperature sensor SW6. The engine speed is calculated based on the measurement signal of the crank angle sensor SW7. The SCV opening is calculated based on the measurement signal of the SCV position sensor SW11.

Ignition timing setting unit 112 sets the target ignition timing based on the combustion period estimated by estimating unit 111, that is, the estimated value of mfb50, and target mfb50 so that mfb50 becomes target mfb50. The target mfb50 is set by the ECU 10 based on the operating state of the engine 1 . The ignition timing setting unit 112 can set the target ignition timing by open loop control.

The ignition timing setting unit 112 sets target ignition timing for each cylinder 11 . More specifically, the ignition timing setting unit 112 corrects the target ignition timing set by open loop control for each cylinder 11 based on the feedback correction amount for each cylinder 11 . Calculation of the feedback correction amount will be described in detail later. The ignition timing setting unit 112 outputs an ignition signal to the ignition plug 25 of each cylinder 11 according to the target ignition timing set for each cylinder 11 (instruction IG). A plurality of spark plugs 25 ignite in order. FIG. 5 shows the combustion cycle for each of the four cylinders 11. FIG. As illustrated in FIG. 5, in this engine 1, the air-fuel mixture in each cylinder 11 is combusted in order of #1, #3, #4, and #2.

The correction amount calculator 113 calculates the feedback correction amount of the target ignition timing for each cylinder 11 . Correction amount calculator 113 receives the measurement signal of in-cylinder pressure sensor SW5. Correction amount calculator 113 calculates actual mfb50 based on the measurement signal of in-cylinder pressure sensor SW5. Correction amount calculator 113 also calculates a feedback correction amount based on the difference between mfb50 estimated by estimator 111 and actual mfb50 and the ignition timing set by ignition timing setter 112 . The correction amount calculator 113 increases the feedback correction amount as the difference between the estimated mfb50 and the actual mfb50 increases. The calculated feedback correction amount may be used to correct the ignition timing to the advance side or to correct the ignition timing to the retard side.

The self-cylinder F/B filter unit 114 filters the correction amount calculated by the correction amount calculation unit 113 for each cylinder 11 . Own-cylinder F/B filter section 114 filters the feedback correction amount with a first first-order lag filter. The first first-order lag filter has a higher filter strength than a second first-order lag filter of all-cylinder F/B filter section 115, which will be described later. The self-cylinder F/B filter unit 114 performs filter processing using the first first-order lag filter having a high filter strength, so that steady-state stability can be enhanced. In other words, the measurement signal of the in-cylinder pressure sensor SW5 tends to contain errors and noise. However, the own-cylinder F/B filter unit 114 filters the feedback correction amount using a strong filter, so that the influence of error and noise on the feedback correction amount can be reduced. As a result, hunting of the ignition timing can be suppressed. Fluctuations in the torque of the engine 1 can be suppressed during steady operation, and the drivability of the automobile is improved.

Own-cylinder F/B filter section 114 outputs the feedback correction amount after filtering, that is, the first correction amount, to ignition timing setting section 112 . The ignition timing setting unit 112 corrects the target ignition timing set by open loop control based on the filtered feedback correction amount set for each cylinder 11 . The target ignition timing is changed to the advance side or the retard side. Feedback control brings mfb50 closer to the target mfb50. SPCCI combustion and SI combustion are optimized. The fuel consumption performance of the engine 1 is improved while suppressing combustion noise. The ignition control device 100 can absorb the difference between the cylinders by feedbacking the ignition timing for each cylinder 11 .

The all-cylinder F/B filter unit 115 reads the feedback correction amount of each cylinder 11 calculated by the correction amount calculation unit 113 . The all-cylinder F/B filter unit 115 filters the read feedback correction amounts of all the cylinders 11 using a second first-order lag filter. The second first-order lag filter has a weaker filter strength than the first first-order lag filter.

The self-cylinder F/B filter unit 114 aims at stabilizing the feedback control when the engine 1 is in steady operation, as described above. On the other hand, the all-cylinder F/B filter unit 115 is intended to suppress the response delay of the feedback control when the operating state of the engine 1 changes.

In the multi-cylinder engine 1, a plurality of cylinders 11 sequentially combust. Therefore, as shown in FIG. 5, the interval between combustions in one cylinder 11 is wide. In a four-cylinder engine 1, one cylinder 11 burns once while the engine 1 burns four times.

During the transient, the amount of fresh air and/or EGR gas introduced into the cylinder 11 changes from moment to moment. The amount of fresh air and/or EGR gas introduced into the cylinder 11 also changes between the previous combustion and the next combustion in one cylinder 11 . Therefore, if the correction amount calculation unit 113 determines the feedback correction amount for each cylinder, the feedback correction amount determined during the previous combustion does not correspond to the state quantity in the cylinder during the combustion to be performed from now on. There is

In particular, the self-cylinder F/B filter unit 114 filters the feedback correction amount with a strong first-order lag filter. Therefore, even if the amount of fresh air and/or EGR gas introduced into the cylinder 11 changes, the change is less likely to be reflected in the feedback correction amount. As a result, if the feedback control of the ignition timing is performed based only on the first correction amount by the self-cylinder F/B filter 114 at the transient time, the response delay becomes large.

The feedback correction amount filtered by the all-cylinder F/B filter section 115, that is, the second correction amount, is obtained by reading the feedback correction amount of all the cylinders 11. FIG. Therefore, the updating frequency is higher than the post-filtering feedback correction amount calculated for each cylinder by own cylinder F/B filter unit 114 . The feedback correction amount filtered by the all-cylinder F/B filter unit 115 is a state quantity in the cylinder that is newer than the feedback correction amount after filtering calculated for each cylinder by the self-cylinder F/B filter unit 114. reflected. As shown in FIG. 5, when the correction amount calculator 113 calculates the feedback correction amount based on the signal measured by the in-cylinder pressure sensor SW5 in the #1 cylinder 11, the feedback correction amount is equal to the target ignition timing of the #2 cylinder 11. can be reflected when setting The second correction amount can be reflected in correction of the ignition timing after four ignitions. Note that the first correction amount can be reflected only in the correction of the ignition timing after five ignitions.

Also, the strength of the second first-order lag filter in all-cylinder F/B filter section 115 is weak. The feedback correction amount filtered by the all-cylinder F/B filter unit 115 increases as the state quantity of the cylinder 11 changes significantly. The feedback correction amount filtered by the all-cylinder F/B filter unit 115 is greater than the feedback correction amount after filtering calculated for each cylinder by the self-cylinder F/B filter unit 114. and/or changes in the amount of EGR gas are likely to be reflected.

All-cylinder F/B filter section 115 outputs the filtered feedback correction amount to ignition timing setting section 112 .

Ignition timing setting unit 112 compares the feedback correction amount after filtering from self-cylinder F/B filter unit 114 and the feedback correction amount after filtering from all-cylinder F/B filter unit 115 . While the engine 1 is in steady operation, changes in the state quantities in the cylinders 11 are small. The correction amount is the same or substantially the same. Therefore, the feedback correction amount after filtering from own-cylinder F/B filter section 114 and the feedback correction amount after filtering from all-cylinder F/B filter section 115 are the same or substantially the same. While the engine 1 is in steady operation, the feedback correction amount after filtering from the self-cylinder F/B filter unit 114 and the feedback correction amount after filtering from the all-cylinder F/B filter unit 115 Deviation is small.

On the other hand, during transition, the change in the state quantity in the cylinder 11 is large, so the feedback correction amount for one cylinder 11 and the feedback correction amount for the other cylinders 11 are not the same. Therefore, the difference between the feedback correction amount after filtering from the self-cylinder F/B filter section 114 and the feedback correction amount after filtering from the all-cylinder F/B filter section 115 becomes large. Ignition timing setting unit 112 determines whether or not the deviation of the feedback correction amount exceeds a predetermined threshold value. When the deviation of the feedback correction amount exceeds the threshold value, the ignition timing setting unit 112 can determine that the operating state of the engine 1 is in a transient state.

When the deviation of the feedback correction amount exceeds the threshold value, the ignition timing setting unit 112 corrects the feedback correction amount after filtering from the self-cylinder F/B filter unit 114 . More specifically, the ignition timing setting unit 112 converts the correction amount corresponding to the difference between the deviation of the feedback correction amount described above and the threshold value to the feedback correction amount after filtering from the own cylinder F/B filter unit 114. add to Since the feedback correction amount for one cylinder 11 is corrected in consideration of the feedback correction amount for the other cylinders 11, the delay in feedback control response during transition is suppressed.

Next, the ignition control executed by the ignition control device 100 will be described with reference to the flow charts of FIGS. 6 and 7. FIG. FIG. 6 is a flow chart showing the procedure for calculating the feedback correction amount for each cylinder 11. As shown in FIG. In step S1 after the start, the estimating unit 111 of the ignition control device 100 estimates the combustion period using the combustion period model, and the ignition timing setting unit 112 sets the open time based on the estimated combustion period and the target mfb50. A target ignition timing is calculated by loop control.

In each of subsequent steps S11, S21, S31, and S41, the ignition timing setting unit 112 corrects the target ignition timing for each cylinder 11. FIG. As described above, the ignition timing setting unit 112 corrects the target ignition timing for each cylinder 11 based on the filtered feedback correction amount.

In each of steps S12, S22, S32, and S42, the ignition timing setting unit 112 instructs the ignition plug 25 of each cylinder 11 to ignite. The four cylinders 11 fire in order #1, #3, #4, #2.

In each of steps S13, S23, S33, and S43, the in-cylinder pressure sensor SW5 of each cylinder 11 measures the pressure inside the cylinder 11 . In each of subsequent steps S14, 24, 34, and 44, the correction amount calculator 113 calculates the feedback correction amount based on the measured pressure. The correction amount calculator 113 outputs the calculated feedback correction amount to the all-cylinder F/B filter section (see (A), (B), (C), and (D) in FIGS. 6 and 7).

In each of steps S15, S25, S35, and S45, the self-cylinder F/B filter unit 114 performs filtering of the feedback correction amount for each cylinder 11. FIG. As described above, the self-cylinder F/B filter unit 114 performs filtering using the first first-order lag filter.

In each of steps S16, S26, S36, and S46, the ignition timing setting unit 112 sets the feedback correction amount after filtering from the self-cylinder F/B filter unit 114 and the Calculate the deviation between the feedback correction amount after filtering. Ignition timing setting unit 112 then determines whether or not the deviation exceeds the threshold value. If the determination in step S16 is YES, the process proceeds to step S17, otherwise the process proceeds to step S18. Similarly, if the determination in step S26 is YES, the process proceeds to step S27, and if NO, the process proceeds to step S28. If the determination in step S36 is YES, the process proceeds to step S37, and if NO, the process proceeds to step S38. If the determination in step S46 is YES, the process proceeds to step S47, otherwise the process proceeds to step S48.

In each of steps S17, S27, S37, and S47, the ignition timing setting unit 112 corrects the feedback correction amount because it can be determined that the operating state of the engine 1 is changing. As described above, the correction amount corresponding to the difference between the deviation of the feedback correction amount and the threshold value is added to the feedback correction amount of each cylinder 11 . Then, in each of steps S18, S28, S38, and S48, the ignition timing setting section 112 updates the feedback correction amount. When the feedback correction amount is corrected in steps S17, S27, S37, and S47, the corrected feedback correction amount is used at the next ignition. If the feedback correction amount is not corrected, the feedback correction amount filtered in steps S15, S25, S35, and S45 is used at the next ignition (see the dashed-dotted arrow in FIG. 6).

FIG. 7 is a flow chart showing a procedure for all-cylinder F/B filter section 115 to calculate the feedback correction amount. In step S51 after the start, the all-cylinder F/B filter section 115 determines an initial value. The initial value may be zero. The initial value can also be set to an appropriate value.

In step S52, the all-cylinder F/B filter section 115 determines whether or not the feedback correction value for the #1 cylinder 11 has been calculated. If the determination in step S52 is YES, the process proceeds to step S53; otherwise, the process proceeds to step S54. In step S<b>53 , the all-cylinder F/B filter section 115 reads the feedback correction value of the #1 cylinder 11 .

In step S54, the all-cylinder F/B filter section 115 determines whether or not the feedback correction value for the #3 cylinder 11 has been calculated. If the determination in step S54 is YES, the process proceeds to step S55; otherwise, the process proceeds to step S56. In step S55, the all-cylinder F/B filter section 115 reads the feedback correction value of the #3 cylinder 11. As shown in FIG.

In step S56, the all-cylinder F/B filter section 115 determines whether or not the feedback correction value for the #4 cylinder 11 has been calculated. If the determination in step S56 is YES, the process proceeds to step S57; otherwise, the process proceeds to step S58. In step S57, the all-cylinder F/B filter unit 115 reads the feedback correction value of the #4 cylinder 11.

In step S58, the all-cylinder F/B filter section 115 determines whether or not the feedback correction value for the #2 cylinder 11 has been calculated. If the determination in step S58 is YES, the process proceeds to step S59; otherwise, the process proceeds to step S510. In step S59, the all-cylinder F/B filter unit 115 reads the feedback correction value of the #4 cylinder 11.

In step S510, the all-cylinder F/B filter unit 115 performs filtering processing of the feedback correction amount. As described above, the all-cylinder F/B filter unit 115 filters the feedback correction amount using the second first-order lag filter. The all-cylinder F/B filter unit 115 outputs the filtered feedback correction amount to the ignition timing setting unit 112 (see (E) in FIGS. 6 and 7).

Next, changes in each parameter during ignition control executed by the ignition control device 100 will be described with reference to the time chart of FIG. The horizontal axis of FIG. 8 indicates time, and time progresses as it moves to the right of the paper surface. A chart 81 shows changes in fuel injection amount. At time t1, the fuel injection amount is increasing. Chart 82 shows the change in charging efficiency. At time t1, the charging efficiency is high. FIG. 8 corresponds to an example in which the automobile is accelerating. That is, before time t1, the engine 1 is in steady operation. After time t1, the engine 1 transitions to a transient state.

A chart 83 indicates the combustion period estimated by the estimation unit 111 . Before time t1, when the load on the engine 1 is relatively low, the combustion period is relatively long. That is, the period from ignition to mfb50 is long. A chart 84 indicates the target ignition timing set by the ignition timing setting section 112 . The target ignition timing is set to the advance side. Note that the dashed line exemplifies the target ignition timing when feedback correction is not performed. In the example of FIG. 8, the target ignition timing is feedback-corrected to advance.

A chart 86 shows the feedback correction amount for #3 cylinder 11 . This is the feedback correction amount after filtering. In the example of FIG. 8, the feedback correction amount is set to the advance side. As described above, the target ignition timing is feedback-corrected to advance.

Chart 85 shows mfb50. As a result of setting the target ignition timing to the advanced side, mfb50 is advanced. By adjusting the ignition timing, the actual mfb50 shown by the solid line matches or nearly matches the target mfb50 shown by the dashed line.

A chart 87 indicates feedback correction amounts for all cylinders. During steady operation of the engine 1 before time t1, the feedback correction amount for #3 cylinder 11 in the chart 86 substantially matches the feedback correction amount for all cylinders. A chart 88 shows the deviation between the feedback correction amount for #3 cylinder 11 and the feedback correction amount for all cylinders. The deviation is zero or nearly zero and less than the threshold. A chart 89 shows the correction amount determined by the deviation between the feedback correction amount of #3 cylinder 11 and the feedback correction amount of all cylinders. The amount of correction is zero because the deviation is less than the threshold.

After time t1, when the charging efficiency increases and the fuel injection amount increases, the estimated combustion period shortens (chart 83). The target mfb50 is changed to the retarded side as indicated by the dashed line in the chart 85 in response to the shortening of the estimated combustion period. Therefore, the target ignition timing is retarded (chart 84).

As described above, the feedback correction amount set for each cylinder 11 is delayed as indicated by the dashed line in the chart 86 due to the wide combustion interval and the high strength of the first first-order lag filter. The timing of the change to the corner side is delayed (time t3), and the amount of change is also small. If the feedback correction for each cylinder 11 is continued during the transition, the target ignition timing gradually shifts to the retarded side as indicated by the dashed line in the chart 84 . As a result, the actual mfb50 gradually shifts to the retard side as indicated by the dashed line in chart 85 . It takes time for the actual mfb50 to reach the target mfb50. That is, the responsiveness of feedback control is delayed during transition.

A dashed line (that is, no filter) in the chart 86 indicates the feedback correction amount without filtering. That is, the dashed line in chart 86 corresponds to the feedback correction amount calculated by correction amount calculation section 113 . If filtering is not performed, the feedback correction amount is greatly changed to the retard side. However, if the filter processing is not performed, there is a problem that the feedback control is not stabilized during steady operation of the engine 1 .

As shown in the chart 87, the feedback correction amount of all cylinders 11 is changed to the retard side earlier (time t2), and the change amount is large. As a result, the deviation of the feedback correction amount exceeds the threshold (see chart 88). Ignition timing setting unit 112 calculates a correction amount based on the deviation and the threshold value. The correction amount Δa is the difference between the deviation and the threshold (see charts 88 and 89). The ignition timing setting unit 112 corrects the feedback correction amount for each cylinder 11 using the correction amount. As indicated by the solid line in the chart 86, the feedback correction amount for the #3 cylinder 11 is the amount obtained by adding the correction amount Δa to the retard side to the feedback correction amount indicated by the one-dot chain line.

The target ignition timing is rapidly retarded as indicated by the solid line in chart 84 , and the actual mfb50 quickly approaches the target mfb50 as indicated by the solid line in chart 85 . Responsiveness of feedback control is enhanced during transition.

After the operating state of the engine 1 changes, as the operating state of the engine 1 transitions to a steady state, the deviation between the feedback correction amount for each cylinder 11 and the feedback correction amount for all cylinders becomes smaller. After time t4, when the deviation becomes smaller than the threshold value, the aforementioned correction of the feedback correction amount is not performed.

As shown in FIG. 8, when the vehicle is accelerating, the correction direction of the target ignition timing is reversed from the advance side to the retard side. When the automobile decelerates, the correction direction of the target ignition timing is reversed from the retard side to the advance side. When the correction direction is reversed, the feedback correction amount for all cylinders is reversed earlier than the feedback correction amount for each cylinder 11, and the correction amount is also large. As a result, the deviation between the feedback correction amount for each cylinder 11 and the feedback correction amount for all cylinders becomes large. Conversely, when the engine 1 is in steady operation, the deviation of the feedback correction amount becomes small. The ignition control device 100 accurately and accurately determines whether the operating state of the engine 1 is in a steady state or a transient state based on the deviation between the feedback correction amount for each cylinder 11 and the feedback correction amount for all cylinders. can be determined quickly.

Next, changes in the feedback correction amount for all cylinders and the feedback correction amount for each cylinder 11 will be compared with reference to the time chart of FIG. Chart 91 shows the change in filling efficiency. As in FIG. 8, the charging efficiency changes from low to high at time t1. This corresponds to acceleration of the automobile.

A chart 92 indicates the feedback correction amounts for all cylinders. The dashed line in chart 92 is the feedback correction amount before filtering. The solid line is the feedback correction amount after filtering. A comparison between the solid line and the dashed line shows that the second first-order lag filter of all-cylinder F/B filter section 115 has a weak filter strength.

Charts 93, 94, 95 and 96 show the feedback correction amounts of #1, #3, #4 and #2 cylinders 11, respectively. Broken lines in charts 93, 94, 95, and 96 are feedback correction amounts before filtering. A dashed-dotted line is the feedback correction amount after filtering for each cylinder 11 . The solid line is the feedback correction amount obtained by correcting the feedback correction amount after filtering for each cylinder 11 based on the feedback correction amount of all cylinders (that is, multi-cylinder consideration). A comparison between the solid line and the one-dot chain line indicates that the first first-order lag filter of own-cylinder F/B filter section 114 has a high filter strength. Immediately after time t1, the feedback correction amount is corrected in each of the #1, #3, #4, and #2 cylinders 11 . When time elapses from time t1, the difference between the feedback correction amount after filtering for each cylinder 11 and the feedback correction amount after filtering for all cylinders becomes small, so the feedback correction amount is no longer corrected.

In the above configuration, the correction amount based on the feedback correction amount for all cylinders is added to the feedback correction amount for each cylinder 11, but correction of the target ignition timing is not limited to correction of the feedback correction amount. If the deviation between the feedback correction amount for each cylinder 11 and the feedback correction amount for all cylinders exceeds the threshold value, the ignition timing setting unit 112 adjusts the feedback correction amount for each cylinder 11 and the feedback correction amount for all cylinders based on the , the target ignition timing may be corrected.

Further, the combustion index used for ignition timing control is not limited to mfb50. The ignition timing setting unit 112 can use the mass combustion ratio of any ratio as the combustion index. Further, in controlling the ignition timing of SPCCI combustion, the ignition timing setting unit 112 can use θci (see FIG. 3) at which the air-fuel mixture starts to self-ignite as a combustion index.

It should be noted that the engine control device disclosed herein is not limited to application to the engine 1 having the configuration described above. The engine may be an engine that does not use SPCCI combustion, eg, only SI combustion by flame propagation.

1 engine 10 ECU (control unit)
100 ignition control device 112 ignition timing setting unit 113 correction amount calculation unit 114 self-cylinder F/B filter unit 115 all-cylinder F/B filter unit 11 cylinder 17 combustion chamber 25 spark plug (ignition unit)
SW5 In-cylinder pressure sensor

Claims (6)

an engine having four cylinders each forming a combustion chamber;
four igniters attached to the engine for each cylinder and each igniting a mixture in the combustion chamber;
four in-cylinder pressure sensors attached to the engine for each cylinder and each outputting a measurement signal corresponding to the pressure in the cylinder;
a control unit that determines a target ignition timing according to the operating state of the engine and sequentially outputs an ignition signal to the four ignition units so that the ignition unit performs ignition at the target ignition timing;
The control unit receives a measurement signal from the in-cylinder pressure sensor and, based on the combustion index obtained from the measurement signal, sets the target ignition timing for each cylinder so that the combustion index becomes a target combustion index. feedback correction to
The control unit filters the feedback correction amount based on the measurement signal of the in-cylinder pressure sensor with a first first-order lag filter for each cylinder, and performs the target correction amount based on the filtered first correction amount. correct the ignition timing
The control unit also stores a second correction amount obtained by filtering feedback correction amounts for all cylinders including one of the four cylinders and the other cylinders with a second first-order lag filter,
The control unit also corrects the target ignition timing of the one cylinder when a deviation between the first correction amount and the second correction amount exceeds a predetermined amount,
The engine control device , wherein the first first-order lag filter has a stronger filter strength than the second first-order lag filter . In the engine control device according to claim 1,
The ignition unit receives the ignition signal and ignites the air-fuel mixture, whereby a part of the air-fuel mixture begins to burn with flame propagation, and then the remaining unburned air-fuel mixture burns by self-ignition. Engine controller. In the engine control device according to claim 2,
A control device for an engine, wherein the combustion index is a crank angle at which a mass combustion ratio of the air-fuel mixture is a predetermined ratio. In the engine control device according to any one of claims 1 to 3 ,
The control unit performs feedback correction of the target ignition timing of the one cylinder based on a modified feedback correction amount obtained by adding a correction amount corresponding to the deviation to the feedback correction amount of the one cylinder. Control device. In the engine control device according to any one of claims 1 to 3 ,
The control unit for an engine, wherein the control unit sets the target ignition timing of the one cylinder based on a feedback correction amount for the one cylinder and a feedback correction amount for all cylinders. In the engine control device according to any one of claims 1 to 5 ,
The engine control device, wherein the deviation exceeds the predetermined amount when the operating state of the engine changes.

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