JP4306004B2 - Engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a catalyst for purifying exhaust gas in the exhaust passage, and, for example, significantly retards the ignition timing at the time of cold start, and promotes activation of the catalyst by increasing the exhaust temperature due to afterburning. The present invention relates to an engine control device that suppresses combustion fluctuations by control.
[0002]
[Prior art]
In general, an automobile engine includes an exhaust gas purifying catalyst in an exhaust passage. And when the catalyst temperature is low, such as at the time of cold start, the catalyst has low catalytic activity and cannot fully exhibit the exhaust gas purification performance. Therefore, in an engine equipped with an exhaust gas purifying catalyst in the exhaust passage, when the engine is cold started, that is, when the engine is started from a cold state, the ignition timing is greatly retarded, and the exhaust temperature is rapidly increased by afterburning. It is necessary to promote the activation of the catalyst. However, if the ignition timing is greatly retarded in order to promote catalyst activation during cold start, the combustion characteristics of the engine will be reduced, and depending on the properties of gasoline as the fuel, especially when there are many heavy components The combustion state becomes extremely unstable. Therefore, conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 8-218995, in a predetermined low output region such as idling, when the catalyst temperature is low, the ignition timing is retarded to reduce the combustibility. At the same time, when the engine torque fluctuation exceeds a predetermined range, a control (roughness control) is performed in which the correction amount of the retardation correction is corrected to be small and the engine combustion fluctuation (roughness) is suppressed. Are known.
[0003]
[Problems to be solved by the invention]
As described above, combustion reduction control such as significantly retarding the ignition timing to promote catalyst activation during cold start is performed, and combustion fluctuations of the engine are suppressed in a predetermined low output region such as during idling. When performing roughness control by correcting the ignition timing, etc., the ignition timing etc. is controlled by the roughness control when the specific cylinder is continuously misfired due to failure of the ignition system such as disconnection of the high tension cord or disconnection of the ignition coil. If corrected to the flammability reduction side, in the situation where a large amount of raw gas was originally discharged due to misfire, the flammability will be reduced to other non-misfire cylinders. There is a possibility that the exhaust temperature rises excessively and the catalyst becomes overheated.
[0004]
Therefore, the problem is to prevent engine stall and catalyst overheating by performing roughness control in a state where a specific cylinder is misfiring continuously due to disconnection of a high tension cord or disconnection of an ignition coil. This is the object of the present invention.
[0005]
[Means for Solving the Problems]
In the present invention, a specific cylinder is continuously misfired due to disconnection of a high tension cord, disconnection of an ignition coil, etc., and roughness control is executed in a situation where a large amount of raw gas is originally discharged, and the ignition timing and the like are reduced in combustibility. If it is corrected to the side, it is due to the fact that the engine stalls as described above or that the catalyst may be in an overheated state, and prevents the engine stall and overheating of the catalyst in such a situation. The engine control device is configured as follows in order to achieve this.
[0006]
That is, the invention according to claim 1 includes a plurality of cylinders, and includes an exhaust gas purification catalyst in the exhaust passage, and when the catalyst is in an inactive state, By increasing the exhaust temperature by retarding the ignition timing To promote the activation of the catalyst Made An engine control apparatus, a combustion control means for controlling a combustion state of the engine, a combustion fluctuation detecting means for detecting a combustion fluctuation of the engine, The catalyst is in an inactive state, and the activation of the catalyst is promoted by increasing the exhaust temperature by retarding the ignition timing. Sometimes, the combustion fluctuation suppression correction means for setting the fluctuation suppression correction amount with respect to the control amount of the combustion control by the combustion control means so that the combustion fluctuation of the engine becomes a predetermined value or less, and the specification for detecting the continuous misfire of the specific cylinder A cylinder abnormality detecting means, and a stopping means for stopping the operation of the combustion fluctuation suppression correcting means when a continuous misfire of the specific cylinder is detected by the specific cylinder abnormality detecting means. In this case, when the exhaust purification catalyst is in an inactive state, such as during cold start. , The combustion property of the engine is reduced, the exhaust temperature is increased by afterburning, and the activation of the catalyst is promoted. In the meantime, roughness control is performed in which the fluctuation suppression correction amount is set so that the combustion fluctuation of the engine becomes a predetermined value or less and the control amount of the combustion control is corrected, thereby suppressing the combustion fluctuation (roughness), A decrease in engine output is suppressed by increasing the intake air amount. In addition, when continuous misfire in a specific cylinder is detected, the roughness control is stopped, so that the engine control is performed by executing the roughness control on the flammability lowering side in a situation where a large amount of raw gas is discharged due to misfire. And overheating of the catalyst is prevented.
[0007]
According to a second aspect of the invention, in the engine control apparatus according to the first aspect of the invention, the specific cylinder abnormality detecting means detects continuous misfire of one cylinder. In this case, if the engine is detected due to continuous misfire of one cylinder, the roughness control is stopped, thereby preventing overheating of the engine stall and the catalyst.
[0008]
According to a third aspect of the present invention, in the engine control device according to the first or second aspect, the specific cylinder abnormality detecting means is configured to continuously misfire a plurality of cylinders whose ignition plugs are energized and controlled by a common ignition coil. Is detected. In this case, when misfire (opposite misfire) of a plurality of cylinders sharing the ignition coil is detected, the roughness control is stopped, thereby preventing the engine stall and the catalyst from overheating.
[0009]
According to a fourth aspect of the present invention, in the engine control apparatus according to the first, second, or third aspect, the combustion fluctuation suppression correcting means is at least one of an ignition timing control means and an air-fuel ratio control means. There is. The correction for suppressing the combustion fluctuation can be performed by either the ignition timing control or the air-fuel ratio control in this way, and can also be performed by using both the ignition timing control means and the air-fuel ratio control means.
[0010]
The invention according to claim 5 is the engine control device according to claim 1, 2, 3 or 4, wherein the combustion fluctuation detecting means detects a combustion fluctuation for each cylinder, and the combustion fluctuation suppression correcting means. However, the fluctuation suppression correction amount is set for all cylinders based on the combustion fluctuation detected for each cylinder. In this way, combustion fluctuations are detected for each cylinder, and correction is performed uniformly for all cylinders to reduce the difference in output torque between the cylinders, and ignition is caused by rotational fluctuations caused by the torque difference. It is possible to prevent the time and the like from being diverged and becoming uncontrollable.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
1 to 18 relate to an example of the embodiment, FIG. 1 is an overall system diagram of the engine, FIGS. 2 to 7 are flowcharts of roughness control (ignition timing calculation), and FIG. 8 is an OBD misfire detection value calculation. FIG. 9 is a flowchart of setting a roughness correction value reset flag related to roughness control, FIG. 10 is a flowchart of shutter valve opening / closing determination related to roughness control, FIG. 11 is a flowchart of setting a prohibition timer immediately after start related to roughness control, and FIG. Is a time chart of master bag negative pressure recovery control relating to roughness control, FIG. 13 is a flowchart of setting a brake negative pressure ensuring flag relating to roughness control, FIG. 14 is a flowchart of setting a brake negative pressure ensuring control execution timer relating to roughness control, and FIG. 15 is a brake negative pressure securing control execution timer related to roughness control. FIG. 16 is a flowchart for changing the control gain of air-fuel ratio feedback control related to roughness control, FIG. 17 is a map for setting a water temperature correction advance value related to roughness control, and FIG. 18 is an ISC flow control related to roughness control. It is a flowchart of.
[0013]
An engine 1 shown in FIG. 1 is an in-line four-cylinder four-cycle engine using gasoline as fuel. The engine 1 has a cylinder block 3 having four cylinders 2 (only one is shown), and a cylinder head 4 assembled on the upper surface of the cylinder block 3, although the detailed structure is not shown. Yes. In each cylinder 2, a piston 5 is fitted so as to be capable of reciprocating, and a combustion chamber 6 is defined by the piston 5 and the cylinder head 4. In addition, spark plugs 7 are provided on the ceiling of each fuel chamber 6, and these spark plugs 7 are connected to an ignition circuit 8 including an igniter capable of electronically controlling the ignition timing.
[0014]
In addition, in order to supply air (intake air) to the combustion chamber 6 of each cylinder 2, the engine 1 has a single common intake passage 9 for taking in air from the atmosphere, and each air that receives air from the common intake passage 9. An independent intake passage 10 for each cylinder 2 is provided. The upstream end of the common intake passage 9 is connected to an air cleaner 11 that removes dust in the air, and the downstream end is connected to a surge tank 15 that stabilizes the air flow. The upstream end of each independent intake passage 10 is connected to a surge tank 15, and the downstream end is connected to the combustion chamber 6 via an intake valve 12.
[0015]
In the common intake passage 9, a hot wire type air flow sensor that detects an air flow rate (amount of intake air actually sucked into the engine 1) in order from the upstream side (the right end side in FIG. 1) in the air flow direction. 13 and a throttle valve 14 that is opened and closed according to the amount of depression of an accelerator pedal (not shown) to throttle the common intake passage 9. Each independent intake passage 10 is provided with an injector (fuel injection valve) 16 for injecting fuel in response to a fuel injection signal (injection pulse) from an ECU (engine control unit) 35 described later. . The air cleaner 11 is provided with an intake air temperature sensor 17 for detecting the intake air temperature (air temperature).
[0016]
Each independent intake passage 10 is branched into a first intake passage (intake port) and a second intake passage 10a (intake port) (not shown) in the vicinity of the respective downstream ends, and the first intake passage of each independent intake passage 10 and An on-off valve (shutter valve) 18 for reinforcing intake flow that is driven to open and close by an actuator 18a is disposed upstream of the branch portion of the second intake passage 10a and immediately upstream of the injector 16. The open / close valve 18 is notched on the upper end side when the valve is closed so that a gap is formed to allow intake air to flow to the injector 16 side when the valve is closed. When the on-off valve 18 is closed, air is substantially supplied to the combustion chamber 6 from the notched notched portion, and a strong tumble is generated in the combustion chamber 6 to improve the combustibility of the air-fuel mixture.
[0017]
The upstream side and the downstream side of the common intake passage 9 are connected to each other by an ISC (Idle Speed Control) bypass passage 20, and the ISC bypass passage 20 is driven to open and close by an actuator 21 a. An ISC valve 21 for opening and closing the ISC bypass passage 20 is provided. The ISC valve 21 controls the opening degree so that the idle speed of the engine 1 is controlled. Further, in the common intake passage 9, in the vicinity of the throttle valve 14, an idle switch 22 that detects the fully closed state of the throttle valve 14, and a throttle opening sensor 23 that detects the opening (throttle opening) of the throttle valve 14. Is provided.
[0018]
Further, the engine 1 is provided with an exhaust passage 25 for exhausting the exhaust gas into the atmosphere. The exhaust passage 25 has four passage portions on the upstream end side (the right end side in FIG. 1) in the exhaust gas flow direction. The branched passage portions are communicated with the combustion chambers 6 of the corresponding cylinders through exhaust valves 24, respectively. In the exhaust passage 25 downstream of the branch portion, an O2 sensor 26 that detects the oxygen concentration in the exhaust gas and a catalytic converter 27 that purifies the exhaust gas are disposed in order from the upstream side in the exhaust gas flow direction. . The O2 sensor 26 detects the air-fuel ratio in the combustion chamber 6 based on the oxygen concentration in the exhaust gas, and a λO2 sensor, a linear O2 sensor, or the like is used. The λO2 sensor is an O2 sensor that can detect whether the air-fuel ratio is substantially higher or lower than the stoichiometric air-fuel ratio by suddenly changing the output in the vicinity of the theoretical air-fuel ratio (λ = 1). The O2 sensor can detect the O2 concentration linearly, and the detection accuracy of the O2 concentration becomes high particularly in the vicinity of the theoretical air-fuel ratio (that is, the output change with respect to the change of the O2 concentration is large). The catalytic converter 27 uses a three-way catalyst capable of simultaneously purifying hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in the exhaust gas as a catalyst for exhaust gas purification. In other words, those having the ability to purify NOx even in a lean state are used.
[0019]
The engine 1 includes a crank angle sensor 30 made of an electromagnetic pickup or the like. But Is provided. The crank angle sensor 30 is disposed at a position corresponding to the outer periphery of the plate 31 to be detected that is attached to the end of the crankshaft (not shown), and the plate 31 to be detected rotates with the rotation of the crankshaft. Sometimes, a pulse signal is output with the passage of the four protrusions 31a on the outer periphery. Further, the engine 1 is provided with a water temperature sensor 32 for detecting the temperature of the cooling water (engine water temperature) in the water jacket.
[0020]
The engine 1 is provided with an ECU (engine control unit) 35 composed of a microcomputer or the like in order to perform various controls. The ECU 35 receives various output signals from the air flow sensor 13, the intake air temperature sensor 17, the idle switch 22, the throttle opening sensor 23, the O2 sensor 26, the crank angle sensor 30, the water temperature sensor 32, and the like. On the other hand, the ECU 35 outputs a signal (pulse signal) for fuel injection control to the injector 16, and outputs a signal for ignition timing control to the ignition circuit 8, to the actuator 21 a of the ISC valve 21. In contrast, a signal (duty signal) for ISC control is output, and a signal for tumble control is output to the actuator 18a of the shutter valve 18.
[0021]
The outline of the control performed by the ECU 35 is as follows.
[0022]
That is, in the tumble control, the shutter valve 18 for each cylinder 2 is closed by controlling each actuator 18a in a predetermined low output region (low load / low rotation region). When the shutter valve 18 is closed, air is substantially supplied to the combustion chamber 6 through the notch, so that a strong tumble is formed in the combustion chamber 6 and the intake air flow is enhanced, whereby the combustion of the air-fuel mixture is performed. The characteristics are greatly improved. Further, the high-speed air flowing into the combustion chamber 6 through the notch portion of the shutter valve 18 promotes the vaporization and atomization of the fuel injected from the injector 16, thereby improving the combustibility of the air-fuel mixture. . On the other hand, when the operating state of the engine 1 is not within the predetermined low output region, the shutter valve 18 is opened, a sufficient amount of air is supplied to the combustion chamber 6, and the intake charge efficiency and thus the engine output is increased. .
[0023]
In the fuel injection control, basically, the air-fuel ratio of the air-fuel mixture supplied to each combustion chamber 6 is set to a predetermined target air-fuel ratio (for example, λ based on the intake air amount detected by the air flow sensor 13. = 1, A / F = 14.7), the amount of fuel injected from the injector 16 is controlled. Then, in a predetermined operating region, air-fuel ratio feedback control is performed by correcting the fuel injection amount based on the deviation of the O2 concentration in the exhaust gas detected by the O2 sensor 26, that is, the actual air-fuel ratio, from the target air-fuel ratio. As will be described later, during the roughness control, the control gain of the air-fuel ratio feedback control is reduced.
[0024]
In the ISC control, basically, a base flow rate is set based on the engine water temperature detected by the water temperature sensor 32 in a predetermined low output region such as when idling, and a target rotational speed is set based on the engine water temperature. The ISC valve 21 is duty-controlled so that the engine speed converges to the target speed by performing feedback correction based on the deviation of the engine speed calculated from the output of the crank angle sensor 30 with respect to the target speed. The flow rate of the bypass air flowing through the bypass passage 20 is controlled.
[0025]
In the control of the ignition timing, basically, for each cylinder, using the map of the engine speed and the intake charging efficiency, MBT, that is, the ignition timing at which the engine 1 outputs the maximum torque (for example, before top dead center) The basic ignition timing is set slightly retarded from 10 °. This basic ignition timing is individually set so as to be suitable for each operation state at the time of idling and at the time of non-idling (off idling). During idling, feedback control of ignition timing is performed so that the engine speed (idle speed) converges to the target idle speed. That is, the target idle speed is set with a characteristic that linearly decreases as the engine temperature rises in accordance with the engine water temperature (engine temperature), and when idling, the deviation of the engine speed (idle speed) from the target idle speed is set. Accordingly, the feedback correction amount in the retard direction or the advance direction is set.
[0026]
At the time of starting from the cold state, that is, at the time of cold starting, the ignition timing is greatly increased so as to promote the activation of the catalyst of the catalytic converter 27 by reducing the combustibility and raising the exhaust gas temperature by the afterburning ( (For example, 15 ° CA) A correction amount for retarding (water temperature advance correction amount) is set, and depending on the properties of gasoline, the combustion state becomes unstable, especially when there are many heavy components. Since combustion fluctuations (torque fluctuations), i.e., roughness, may occur and smooth operation of the engine 1 may be impaired, as a control for suppressing the roughness (roughness control), the retardation for promoting the catalyst activation described above. A roughness correction amount is set by correcting the amount in a direction to suppress torque fluctuation. Note that the engine torque fluctuation in this case is determined using an OBD misfire detection value (angular acceleration fluctuation value) as described later.
[0027]
Thus, based on the signal from the crank angle sensor 30, it is determined whether or not the ignition timing has been reached for each cylinder. When the ignition timing is reached, the ignition circuit 8 is turned on to energize the spark plug 7, The air-fuel mixture is ignited and burned for each cylinder.
[0028]
Hereinafter, based on the flowcharts shown in FIGS. 2 to 11, 13 to 16, and 18, and with reference to FIGS. 12 and 17, a specific control method of the roughness control will be described.
[0029]
(Ignition timing calculation)
The roughness control is based on ignition timing control. The processing flow is as shown in FIGS. 2 to 7. When the process starts, first, in step S101, the misfire detection value dac (i for intermittent / continuous misfire of OBD is performed. ) And the misfire detection value dac7c (i) for counter misfire. These OBD misfire detection values dac (i) and dac7c (i) are calculated by a known flow shown in FIG. 8, as will be described later.
[0030]
If it is determined that the OBD is continuous / intermittent or opposite complete misfire, the roughness control is prohibited. Therefore, in step S102, intermittent / continuous from a map of Ce (intake charging efficiency) and Ne (engine speed). The threshold value for the misfiring OBD misfire determination is searched. Similarly, in step S103, the OBD misfire determination threshold value for the counter misfire is searched from the Ce and Ne maps.
[0031]
Next, in step S104, the threshold value for roughness determination is searched first from the Ce and Ne map for the advance side threshold value (upper limit threshold value) corresponding to the stable combustion limit. In step S105, 0 (zero) is set as the retard threshold (lower threshold).
[0032]
Next, misfire determination and roughness determination are performed. For example, for about 1 second immediately after start-up, a large angular velocity is generated even during normal combustion while the engine is starting up. During that time, OBD misfire determination is performed. I can't. Therefore, in step S106, it is determined whether or not a predetermined time (for example, 1 second) has elapsed after the start depending on whether or not the time timer after the start is 0 (zero). If the predetermined time has passed, the process proceeds to step S107, whether the misfire detection value dac (i) for intermittent / continuous misfire exceeds the threshold value, or the misfire detection value dac7c (i for counter misfire). ) Exceeds the threshold. If either dac (i) or dac7c (i) exceeds the threshold value, it is determined that the OBD is completely misfired, and at this time, roughness control is prohibited due to OBD misfire. In step S108, the roughness prohibition (OBD) F (flag) is set to 1, and the process proceeds to the next step S109. If dac (i) or dac7c (i) does not exceed the threshold value, it is not an OBD misfire, and the process directly proceeds to step S109. On the other hand, if it is determined in step S106 that the predetermined time has not elapsed after starting, the process proceeds to the next step S109 without doing anything.
[0033]
In steps S109 to S113, the misfire detection value dac (i) for intermittent / continuous misfire is compared with a threshold value to determine roughness.
[0034]
That is, in step S109, it is checked whether dac (i) is equal to or higher than the upper threshold value searched in step S104. If it is equal to or higher than the upper threshold value, the roughness large determination F (flag) is set to 1 in step S110. The roughness small determination F (flag) is set to 0, and the process proceeds to step S114. If dac (i) is smaller than the upper threshold value, it is checked in step S111 whether dac (i) is lower than the lower threshold value (0). Thus, the roughness large determination F (flag) is set to 0 and the roughness small determination F (flag) is set to 1, and the process proceeds to step S114. When dac (i) is not less than or equal to the lower threshold value (0), that is, when it is smaller than the upper threshold value and larger than the lower threshold value, in step S113, the roughness large determination F (flag) and the roughness smallness are small. Both judgments F (flags) are 0 When Then, the process proceeds to step S114.
[0035]
In steps S114 to S119, the dac (i) is returned to the retard side by roughness control depending on whether or not dac (i) is larger than the upper limit threshold value for roughness determination by a predetermined amount (for example, three times). A flag (retard prohibition continuation F) for continuing prohibition of correction is set. In other words, if the ignition timing is corrected to the retard side by roughness control when the combustion state has deteriorated due to smoldering of the ignition plug when left idle, such an ignition will occur because complete misfire will occur and emissions will deteriorate. Abnormalities due to plug smoldering, etc., for example, about three times the roughness judgment upper limit threshold (between the OBD misfire threshold (intermittent / continuous misfire) and the roughness judgment threshold (upper threshold)) If a large combustion fluctuation (dac (i)) exceeding (corresponding) occurs, the ignition timing retard is prohibited for a predetermined time in the subsequent step, and if an abnormality is detected again within the predetermined time, The retard is also prohibited for a predetermined time.
[0036]
That is, in step S114, it is checked whether or not the retard prohibition timer (time-counted down-counter) is 0 (zero). If the retard prohibition timer is 0, dac (i) is judged as roughness in step S115. It is determined whether or not the upper limit threshold is exceeded, for example, three times. If so, the retard prohibit timer is set to a predetermined time (for example, 5 seconds) in step S116, and the process proceeds to step S123. If dac (i) does not exceed, for example, three times the roughness determination upper limit threshold value, it is checked in step S117 whether the retard prohibition continuation F is 1. If retard retard continuation F is 1, In step S118, the retard prohibition timer is set to a predetermined time (for example, 5 seconds). In step S119, the retard prohibition continuation F is set to 0, and the process proceeds to step S123. If the retard prohibition continuation F is not 1 in step S117, the retard prohibition timer is set to 0 in step S120 because the retard prohibition is no longer continued.
[0037]
If the retard prohibition timer is not 0 (timer is running) in step S114, it is checked in step S121 whether dac (i) exceeds, for example, three times the upper threshold value. For example, the retard prohibition continuation F is set to 1 in step S122. Then, the process proceeds to step S123. If dac (i) does not exceed, for example, three times the upper threshold value, nothing is done and the process proceeds to step S123.
[0038]
In step S123, whether or not the condition for executing the roughness control by correcting the ignition timing is satisfied is determined as follows: roughness correction value reset F (flag), S / V (shutter valve) closed F (flag), idle F (flag), Vehicle speed 0 (zero) F (flag), gear-in F (flag), prohibition timer immediately after start, Br. (Brake) Negative pressure securing F (flag) and roughness prohibition (OBD) F are used for determination.
[0039]
The roughness correction value reset F is set based on the engine water temperature according to the flow shown in FIG. 9, as will be described later. The temperature condition for executing the roughness control is that the engine water temperature is 20 ° C to 60 ° C. At this time, the roughness correction value reset F is 0, and when the engine water temperature exceeds 60 ° C, or 20 ° C. When falling below C, the roughness correction value reset F is 1. At this time, roughness control is not performed.
[0040]
Further, the S / V closing F is set by the flow shown in FIG. 10, as will be described later. The roughness control is performed when the engine water temperature during idling is equal to or higher than a predetermined value (60 ° C). At this time, the S / V closing F is 1, and the engine water temperature falls below the predetermined value (60 ° C). At that time, S / Closed F is zero.
[0041]
Roughness control is executed when idling (idle F = 1), when the vehicle speed is 0 (vehicle speed 0F = 1), and when gear is off (gear-in F = 0).
[0042]
Further, as described later, the prohibition timer immediately after starting is set by the flow shown in FIG. 11, and is set to a predetermined value (for example, 1 second) immediately after starting when the engine speed is lower than a predetermined value (for example, 500 rpm). If the rotation speed is 500 rpm or more, the counter counts down, and the condition for executing the roughness control is that the timer value is zero.
[0043]
Also, Br. The negative pressure securing F is set by the flow shown in FIG. 12, as will be described later. The negative pressure securing F is set to 1 when the negative pressure of the brake master bag (vacuum booster) is reduced and the negative pressure needs to be secured. The condition for executing the roughness control is that the negative pressure securing F is zero.
[0044]
The roughness prohibition (OBD) F is set to 1 in the above-described step S108, and the condition for roughness control is that it is 0.
[0045]
Then, the roughness correction value reset F = 0, S / V closed F = 1, idle F = 1, vehicle speed 0F = 1, gear-in F = 0, immediately after start prohibition timer = 0, Br. When all of the conditions of negative pressure securing F = 0 and roughness prohibition (OBD) F = 0 are satisfied, the roughness control is executed. After setting the roughness execution F (flag) to 1 in step S124, the step In S125, whether the large roughness determination F is 1 or not is 1. If it is 1, ignition advance processing as roughness control is performed in steps S128 to 133 as described later. That is, the ignition timing fluctuation suppression correction amount (roughness IG correction value) is set to the advance side. If the large roughness determination F is not 1, it is checked in step S126 if the small roughness determination F is 1 and the retard prohibition timer is 0, and the roughness small determination F is 1 and the retard is detected. When the prohibit timer (set in steps S114 to 122) is 0, in steps S134 to 136, ignition retard processing is performed as roughness control, and the roughness IG correction value is set to the retard side. Further, when the roughness small determination F is not 1, or when the retard prohibition timer is not 0, the process proceeds to step S137 described later. In step S123, the roughness correction value reset F = 0, S / V closed F = 1, idle F = 1, vehicle speed 0F = 1, gear-in F = 0, immediately after start prohibition timer = 0, Br. When either of the conditions of securing negative pressure F = 0 and roughness prohibition (OBD) F = 0 is not satisfied, the roughness control is not executed. In step S127, after the roughness execution F is set to 0, Steps S138 to 147 are performed.
[0046]
When the roughness large determination F is 1 and the processing of steps S128 to 133 is started, first, in step S128, the deviation of the OBD misfire detection value dac (i) with respect to the upper limit threshold value of the roughness determination is multiplied by a proportionality constant Kp. A basic advance amount ΔIGAD is calculated. Then, as basic advance amount limiter processing, in step S129, it is checked whether or not ΔIGAD exceeds a predetermined value (for example, 1 ° of crank angle), and if it exceeds, ΔIGAD is set to a predetermined value (for example, crank angle of 1) in step S130. )), The process proceeds to step S131. If not, the process proceeds to step S131. In step S131, ΔIGAD is added to the previous roughness IG correction value (i−1) to set a new roughness correction value (i). In step S132, the new roughness IG correction value (i) is obtained. Whether or not it exceeds a certain amount (for example, a crank angle of 20 °), if so, in step S133, the roughness IG correction value (i) is clipped to a predetermined value (for example, a crank angle of 20 °) to be described later. The process proceeds to S148 to 152, and if not exceeded, the process proceeds to steps S148 to 152 as it is.
[0047]
Further, when the roughness small determination F is 1 and the retard prohibition timer is 0 and the processing of steps S134 to 136 is started, in step S134, a predetermined value (for example, crank angle) is determined from the previous roughness IG correction value (i-1). To 0.1 °) to set a new roughness IG correction value (i). In step S135, the new roughness IG correction value (i) falls below a predetermined value (for example, −20 ° of the crank angle). When the rotation is reduced, the roughness IG correction value (i) is clipped to a predetermined value (for example, −20 ° of crank angle) in step S136, and the process proceeds to steps S148 to 152 again. If not, the process proceeds to steps S148 to 152 as it is.
[0048]
When the small roughness determination F is not 1 in step S126 or when the retard prohibition timer is not 0, the roughness IG correction value (i) is fixed to the previous roughness IG correction value (i-1) in step S137. .
[0049]
If the execution conditions of the roughness control are not satisfied and the processing of steps S138 to 147 is started, first, in step S138, the roughness correction value reset F (set based on the engine water temperature by the flow shown in FIG. 9) is performed. Whether the roughness correction value reset F is 0 or whether the roughness prohibition (OBD) F is 0 is determined by checking whether the roughness prohibition (OBD) F (set in step S108) is 0 or not. If it is 0, the roughness IG correction value (i) is fixed to the previous roughness IG correction value (i−1) in step S139, and the process proceeds to steps S148 to 152.
[0050]
If the determination in step S138 is NO and the roughness correction value reset F and the roughness prohibition (OBD) F are not 0, in step S140, the previous roughness IG correction value (i-1) is a positive value (> 0), if it is a positive value, in step S141, a predetermined value (for example, 0.01 ° of the crank angle) is subtracted from the previous roughness IG correction value (i-1) to obtain a new value. The roughness IG correction value (i) is set, and whether or not the new roughness IG correction value (i) falls below 0 is determined in step S142. When the roughness IG correction value (i) falls below 0, the roughness IG correction value is determined in step S143. (I) is clipped to 0, and the process proceeds to steps S148 to 152 again. If it is not a negative value, the process proceeds to steps S148 to 152 as it is.
[0051]
If the previous roughness IG correction value (i−1) is not a positive value (> 0) in step S140, the previous roughness IG correction value (i−1) is a negative value (<0) in step S144. If it is a negative value, in step S145, a predetermined value (for example, 0.01 ° of crank angle) is added to the previous roughness IG correction value (i-1) to obtain a new roughness IG correction value. (I) is set, and whether or not the new roughness IG correction value (i) exceeds 0 in step S146, and if it exceeds 0, the roughness IG correction value (i) is set in step S147. Clip to 0 and proceed to steps S148 to 152 as well. If the value is not a negative value, proceed to steps S148 to 152 as it is.
[0052]
If the previous roughness IG correction value (i-1) is neither a positive value nor a negative value, that is, 0, the process proceeds to steps S148 to 152 as it is.
[0053]
In steps S148 to 152, the basic ignition timing during idling is set according to the map. The basic ignition timing is when the roughness control is performed or not performed when the shutter valve (S / V) 18 is open and when the shutter valve 18 is closed, and when the shutter valve 18 is closed. And the settings are different. First, in step S148, whether or not S / V closed F is 1 (S / V closed F is set by the flow shown in FIG. 10), and if S / V closed F is 1, In step S149, whether or not the roughness correction value reset F (set by the flow shown in FIG. 9) due to the engine water temperature is 1, and if the roughness correction value reset F is 1, then in step S150, the intake charge efficiency ( The basic ignition timing (idle basic advance angle (i)) at idling is set by searching the basic IG map for idling, S / V closing, and roughness non-operation set by Ce) and engine speed (Ne). Then, the process proceeds to step S153 for setting the final ignition timing. Further, when the roughness correction value reset F is not 1, that is, while the roughness control is being executed, in step S151, the idling value S / S / having a constant setting regardless of changes in the engine speed (Ne) and the intake charging efficiency (Ce). Using the basic IG map for V closing / roughness operation, the basic idle angle (i) is set to a constant value, and the process proceeds to step S153. If the S / V closing F is not 1 in step S148, the idle basic advance angle (i) is set by the basic IG map for idling / S / V opening in step S152, and the process proceeds to step S153. .
[0054]
In step S153, the idle basic advance angle (i), roughness IG correction value (i), Br. Add the negative pressure ensuring correction value (i), the water temperature advance angle correction value (i), and various other advance angle correction values (e.t.c.) during normal idling to obtain the final ignition timing. Set the idle advance angle (i) that is and return. The water temperature advance angle correction value (i) is set by a map shown in FIG. 17, as will be described later.
[0055]
(OBD misfire detection value calculation)
FIG. 8 is a flowchart of the known OBD misfire detection value calculation. When started, in S201, the crank angle pulse time of ATDC 80 ° to ATDC 260 ° corresponding to the crank angle range of 180 ° from the latter half of the expansion stroke to the first half of the exhaust stroke is shown. The measured value T (i) is input. In step S202, the angular velocity av (i) is calculated by multiplying the value obtained by dividing 180 ° (360 ° / 2) by T (i) by the tolerance correction coefficient mscf, and then in step S203, this time The angular acceleration ca (i) is calculated by dividing the difference between the previous angular velocity av (i) and the previous angular velocity av (i−1) by T (i).
[0056]
In the next step S204, the angular acceleration (measured values) ca (i) to ca (i-4) of the five points before and after the ignition order including the current time, and the median value camd5 (i) of the five points in the ignition order including the current time. The median value camd7 (i) of the angular accelerations (measured values) ca (i) to ca (i-6) of the points is calculated. Then, in step S205, the angular accelerations ca (i) to ca (i) of the five points are calculated. -4) Calculate the deviation dac (i) of the angular acceleration ca (i-2) at the middle measurement point in the middle with respect to the median value camd5 (i). Is the OBD misfire detection value for the continuous / intermittent fire for the middle cylinder, and the angular acceleration ca (i−) at the middle measurement point of the seven angular accelerations ca (i) to ca (i-6). 3) calculating the deviation dac7 (i) with respect to the median value camd7 (i) Is calculated as the OBD misfire detection value for counter misfire for the cylinder in which the ignition order is the middle of the seven times before and after this time. Here, the continuous misfire refers to the case where a specific cylinder continuously misfires, and the intermittent fire refers to the case where an unspecified cylinder intermittently misfires. The counter misfire refers to misfire of a plurality of cylinders in which the ignition coil is energized and controlled by a common ignition coil.
[0057]
Then, the process is returned and the above process is repeated, and the OBD misfire detection value dac (i) for continuous / intermittent fire and the OBD misfire detection value dac7 (i) for counterfire are calculated for every cylinder.
[0058]
(Roughness correction value reset flag setting)
FIG. 9 is a flowchart for setting a roughness correction value reset flag. When started, it is checked in S301 whether the engine water temperature is higher than 60 ° C. or lower than 20 ° C. If the engine water temperature is higher than 60 ° C. or lower than 20 ° C., the roughness correction value reset F (flag) is set to 1 in step S302. If the engine water temperature is neither higher than 60 ° C. nor lower than 20 ° C., the roughness correction value reset F is set to 0 in step S303.
[0059]
(Shutter valve open / close judgment)
FIG. 10 is a flowchart for determining whether the shutter valve is open or closed. When started, it is checked in step S401 whether the idle F (flag) is “1”. When the idling F is 1 (during idling), it is determined in step 402 whether the engine water temperature is lower than a predetermined value (for example, 60 ° C.), and the engine water temperature is lower than the predetermined value (for example, 60 ° C.). At this time, the S / V (shutter valve) closing flag is set to 1, and when the engine water temperature is equal to or higher than a predetermined value (for example, 60 ° C.), the S / V closing flag is set to 0.
[0060]
When the idle F is not 1 (off-idle), in step S405, the shutter valve (S / V) closed region is set based on the intake charging efficiency (Ce), the engine speed (Ne), and the engine water temperature. Search for Ce (S / V closed Ce) as a threshold value of the S / V closed region (which becomes narrower as the engine water temperature becomes higher) according to the engine water temperature from the map (S / V closed Ce map). In S406, it is checked whether the measured Ce is smaller than S / V closed Ce. If Ce is smaller than S / V closed Ce, the S / V closed flag is set to 1 in step S407, and Ce is If it is equal to or greater than S / V closing Ce, the S / V closing flag is set to 0 in step S408.
[0061]
(Prohibit timer setting immediately after starting)
FIG. 11 is a flowchart of setting a prohibit timer immediately after starting. When starting, in S501, immediately after starting the engine, it is checked whether the engine speed (Ne) is lower than 500 rpm, for example, and when Ne is lower than 500 rpm, for example. Immediately after the prohibit timer is set to a predetermined value (for example, 1 second), if Ne becomes 500 rpm or more, the prohibit timer immediately after starting is counted down and clipped at 0.
[0062]
(Master bag negative pressure recovery control)
FIG. 12 is a time chart of the master bag negative pressure recovery control. The execution timer (Br. Negative pressure ensuring control execution timer) is set to an initial set value (for example, 20 seconds) for a predetermined time (for example, 1 to 20 seconds) after the engine is started. ) And is counted down after the predetermined time has elapsed. Meanwhile, Br. When the negative pressure ensuring correction value is 0 and the execution timer becomes 0, the execution timer is clipped to 0, and Br. The negative pressure securing correction value is gradually increased. And Br. When the negative pressure securing correction value becomes a value that cancels the roughness IG correction value, the execution timer setting F (flag) is set to 1, the execution timer is set again to the setting value (for example, 20 seconds), and Br. The negative pressure securing correction value is gradually reduced to zero. Br. For stopping roughness control. The negative pressure securing F (flag) is set to 1 when the execution timer reaches 0, and Br. While the negative pressure securing correction value exceeds 0, the value of Br. When the negative pressure securing correction value becomes zero, it returns to zero.
[0063]
FIG. 13 is a flowchart for setting a brake negative pressure securing flag. When started, in step S601, Br. Check whether the negative pressure securing control execution timer is 0 or not. And Br. If the negative pressure ensuring control execution timer is 0, in step S602, the previous Br. Add a predetermined amount (for example, 0.3 ° of the crank angle) to the negative pressure ensuring correction value (i−1) to obtain a new Br. The negative pressure securing correction value (i) is set, and in step S603, Br. Seeing whether the negative pressure securing correction value (i) exceeds 0, Br. If the negative pressure securing correction value (i) exceeds 0, in step S604, Br. Negative pressure securing F (flag) is set to 1, Br. If the negative pressure securing correction value (i) does not exceed 0, in step S605, Br. The negative pressure securing F (flag) is set to zero.
[0064]
In step S601, Br. When the negative pressure ensuring control execution timer is not 0, in step S606, the previous Br. By subtracting a predetermined amount (for example, 0.3 ° of crank angle) from the negative pressure ensuring correction value (i−1), a new Br. The negative pressure securing correction value (i) is set, and in step S607, Br. Seeing whether the negative pressure securing correction value (i) has fallen below 0, Br. When the negative pressure securing correction value (i) falls below 0, in step S608, Br. Clip the negative pressure securing correction value (i) to 0. In step S603, Br. Seeing whether the negative pressure securing correction value (i) exceeds 0, Br. If the negative pressure ensuring correction value (i) exceeds 0, in step S604, Br. Negative pressure securing F (flag) is set to 1, Br. If the negative pressure securing correction value (i) does not exceed 0, in step S605, Br. The negative pressure securing F (flag) is set to zero.
[0065]
FIG. 14 is a flowchart for setting a brake negative pressure ensuring control execution timer. Check whether the negative pressure ensuring correction value (i) is equal to or greater than the value obtained by multiplying the roughness IG correction value (i) by a constant Kc (for example, -0.8) (a value that substantially cancels the roughness IG correction value). If the secured correction value (i) is not less than the value obtained by multiplying the roughness IG correction value (i) by a constant Kc (for example, -0.8), in step S702, Br. The negative pressure securing control execution timer setting F (flag) is set to 1. If the negative pressure ensuring correction value (i) is not equal to or greater than the value obtained by multiplying the roughness IG correction value (i) by a constant Kc (for example, -0.8), in step S703, Br. It is checked whether the negative pressure ensuring control execution timer (i) is a value exceeding 0, and if it exceeds 0, in step S704, Br. The negative pressure securing control execution timer setting F is set to 0, and if it does not exceed 0, the process returns as it is.
[0066]
FIG. 15 is a flowchart for setting a brake negative pressure ensuring control execution timer setting flag. One of the following conditions is satisfied: negative pressure securing control execution timer setting F is 1, post-start prohibition timer is 0 or more, roughness correction value reset F is 1, idle F is 0, vehicle speed 0F is 1, and gear-in F is 1 If any of the above conditions is satisfied, in step S802, Br. The negative pressure ensuring control execution timer is set to a predetermined value (for example, 20 seconds). When none of the above conditions is satisfied, Br. The negative pressure securing control execution timer is counted down and clipped at 0.
[0067]
(Air-fuel ratio feedback control gain change)
FIG. 16 is a flowchart for changing the control gain of the air-fuel ratio feedback control. When starting, it is checked in step S901 whether the idle F is 1. When the idle F is 1 (during idle), it is checked in step S902 whether the roughness execution F is 1. When the roughness execution F is 1, the proportional term OKP, the integral term OKI and others are in step S903. The control gain of (differential term, etc.) is a control gain dedicated to roughness control, and when the roughness execution F is not 1, in step S904, the control gain is set as a normal control gain during idling. When the idle F is not 1 (non-idle), in step S905, the control gain is set to the control gain during traveling. The control gain dedicated to roughness control, the normal control gain during idling, and the control gain during driving increase in the order of the control gain dedicated for roughness control, the normal control gain during idling, and the control gain during driving. .
[0068]
(Water temperature advance angle correction value setting)
The water temperature correction advance value is set according to the map shown in FIG. 17. When the engine water temperature is 20 ° C. to 40 ° C., it is set to the retard side, and when the engine water temperature falls below 20 ° C., it is gradually increased. Also, when the temperature exceeds 40 ° C, it is gradually advanced to 60 ° C.
[0069]
(ISC flow control)
FIG. 18 is a flowchart of ISC flow rate control. When started, in step S1001, the base flow rate Ceb is set by a map of engine water temperature and ignition advance angle. In this case, the base flow rate Ceb decreases as the engine water temperature increases, and the advance angle decreases as the advance side increases.
[0070]
Next, in step S1002, the target rotational speed No (i) is set according to the engine water temperature map. In this case, the target rotational speed No (i) is set to a higher value as the engine water temperature is lower.
[0071]
In step S1003, a deviation ΔNe (i) of the current engine speed Ne (i) with respect to the target speed No (i) is calculated. In step S1004, an integral constant K1 is set to the deviation ΔNe (i). The current feedback correction value Cefb (i) is calculated by multiplying and adding to the previous feedback correction value Cefb (i-1).
[0072]
In step S1005, the feedback correction value Cefb (i) is added to the current base flow rate Ceb (i) to calculate a total flow rate Cetal. In step S1006, the duty is converted and output.
[0073]
FIG. 19 shows a part of the flow of the ignition timing calculation for the roughness control shown in another example of the embodiment (the part corresponding to steps S114 to 127 of the flow of the ignition timing calculation in the roughness control of the previous embodiment) ). In the ignition timing calculation in the roughness control of the previous embodiment, the roughness control after the OBD misfire detection value dac (i) becomes a value that exceeds a predetermined amount (for example, three times) larger than the upper limit threshold value of the roughness determination. In the flow of FIG. 19, the OBD misfire detection value dac (i) is set to a predetermined amount (for example, the roughness determination upper limit threshold value). After the prohibition of the roughness control, the shift to the high load operation is performed, and the prohibition of the roughness is canceled when the state of the high load operation continues for a predetermined period.
[0074]
That is, step S1101 in FIG. 19 is processing corresponding to step S115 in FIG. 3, and checks whether the retard inhibition F (flag) is 1. If retard prohibition F is not 1, in step S1102, it is checked whether dac (i) exceeds, for example, three times the roughness determination upper limit threshold. If so, retard prohibition is performed in step S1103. Set F to 1 and proceed to Step S1110. On the other hand, when dac (i) does not exceed, for example, three times the roughness determination upper limit threshold value, the process proceeds to step S1110 as it is.
[0075]
Next, if the retard prohibition F is 1 in step S1101, it is determined in step S1104 whether the high load operation state (high load is being used). If the high load is being used, the high load is determined in step S1105. Count up the timer by one. In step S1106, it is determined whether the high load timer has exceeded a predetermined time. If the predetermined time is exceeded, the roughness prohibition is canceled. In step S1107, the retard prohibition F is reset to 0, and step S1108 is performed. The high load timer is reset to zero. Then, the process proceeds to step S1110. If it is determined in step S1104 that the high load is not being used, the high load timer is set to 0 in step S1109, and the process proceeds to step S1110.
[0076]
Then, in step S1110, whether or not the condition for executing the roughness control by correcting the ignition timing is satisfied, the roughness correction value reset F, S / V closed F, idle F, vehicle speed 0F, gear-in F, and prohibition immediately after starting. Timer, Br. Judgment is made by negative pressure securing F and roughness prohibition (OBD) F. That is, roughness correction value reset F = 0, S / V closed F = 1, idle F = 1, vehicle speed 0F = 1, gear-in F = 0, immediately after start prohibition timer = 0, Br. When all of the conditions of negative pressure securing F = 0 and roughness prohibition (OBD) F = 0 are satisfied, the roughness control is executed. In step S1111, the roughness execution F is set to 1, and then in step S1112, When it is determined whether the roughness large determination F is 1, the process proceeds to step S128 in FIG. If the large roughness determination F is not 1, it is determined in step S1113 whether the small roughness determination F is 1 and the retard prohibition F is 0. The small roughness determination F is 1 and the retard When the prohibition F is not 0, the process proceeds to step S134 in FIG. Further, when the roughness small determination F is not 1, or when the retard prohibition F is not 0, the process proceeds to step S137 in FIG. In step S1110, the roughness correction value reset F = 0, S / V closed F = 1, idle F = 1, vehicle speed 0F = 1, gear-in F = 0, immediately after start prohibition timer = 0, Br. When either of the conditions of securing negative pressure F = 0 and roughness prohibition (OBD) F = 0 is not satisfied, the roughness control is not executed, so that the roughness execution F is set to 0 in step S1114, and then FIG. The process proceeds to step S138.
[0077]
【The invention's effect】
According to the present invention, it is possible to prevent engine stall and catalyst overheating by performing roughness control in a state where a specific cylinder is continuously misfired due to disconnection of a high tension cord or disconnection of an ignition coil.
[Brief description of the drawings]
FIG. 1 is an overall system diagram of an engine according to an example of an embodiment of the present invention.
FIG. 2 is a part (part 1) of a flowchart of ignition timing calculation in the roughness control of the embodiment.
FIG. 3 is a part (part 2) of the flowchart of the ignition timing calculation in the roughness control of the embodiment.
FIG. 4 is a part (part 3) of a flowchart of ignition timing calculation in the roughness control of the embodiment.
FIG. 5 is a part (No. 4) of the flowchart of the ignition timing calculation in the roughness control of the embodiment.
FIG. 6 is a part (No. 5) of the flowchart of the ignition timing calculation in the roughness control of the embodiment.
FIG. 7 is a part (No. 6) of the flowchart of the ignition timing calculation in the roughness control of the embodiment.
FIG. 8 is a flowchart of OBD misfire detection value calculation according to the embodiment.
FIG. 9 is a flowchart for setting a roughness correction value reset flag according to the roughness control of the embodiment.
FIG. 10 is a flowchart of shutter valve opening / closing determination relating to roughness control according to the embodiment.
FIG. 11 is a flowchart for setting a prohibit timer immediately after start according to the roughness control of the embodiment.
FIG. 12 is a time chart of master bag negative pressure recovery control according to roughness control of the embodiment.
FIG. 13 is a flowchart for setting a brake negative pressure securing flag according to the roughness control of the embodiment.
FIG. 14 is a flowchart for setting a brake negative pressure ensuring control execution timer according to the roughness control of the embodiment.
FIG. 15 is a flowchart for setting a brake negative pressure ensuring control execution timer setting flag according to the roughness control of the embodiment.
FIG. 16 is a flowchart of control gain change of air-fuel ratio feedback control according to roughness control of the embodiment.
FIG. 17 is a map for setting a water temperature advance angle correction value according to the roughness control of the embodiment.
FIG. 18 is a flowchart of ISC flow control related to roughness control of the embodiment.
FIG. 19 is a part of a flowchart of ignition timing calculation showing another example of roughness control according to the embodiment of the present invention.
[Explanation of symbols]
1 engine
7 Spark plug
8 Ignition circuit
13 Air flow sensor
16 Injector
18 On-off valve (shutter valve)
20 ISC bypass passage
21 ISC valve
22 Idle switch
26 O2 sensor
27 Catalytic converter
30 Crank angle sensor
35 ECU

Claims (5)

Composed of a plurality of cylinders and equipped with an exhaust gas purification catalyst in the exhaust passage, and when the catalyst is in an inactive state, the ignition timing is retarded to increase the exhaust temperature and promote the activation of the catalyst. An engine control device adapted to
Combustion control means for controlling the combustion state of the engine;
Combustion fluctuation detecting means for detecting the combustion fluctuation of the engine;
When the catalyst is in an inactive state and the exhaust temperature is increased by retarding the ignition timing to promote the activation of the catalyst , the engine combustion fluctuation is reduced to a predetermined value or less. Combustion fluctuation suppression correction means for setting a fluctuation suppression correction amount with respect to a control amount of combustion control by the combustion control means;
Specific cylinder abnormality detection means for detecting continuous misfire of the specific cylinder;
An engine control device comprising: a stopping means for stopping the operation of the combustion fluctuation suppression correcting means when the specific cylinder abnormality detecting means detects a continuous misfire of the specific cylinder. The engine control apparatus according to claim 1, wherein the specific cylinder abnormality detection means detects continuous misfire of one cylinder. The engine control apparatus according to claim 1 or 2, wherein the specific cylinder abnormality detection means detects a continuous misfire of a plurality of cylinders whose ignition plugs are energized and controlled by a common ignition coil. 4. The engine control device according to claim 1, wherein the combustion fluctuation suppression correction means is at least one of an ignition timing control means and an air-fuel ratio control means. The combustion fluctuation detection means detects combustion fluctuation for each cylinder, and the combustion fluctuation suppression correction means sets the fluctuation suppression correction amount for all cylinders based on the combustion fluctuation detected for each cylinder. The engine control device according to 2, 3 or 4.

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