JP2007239525A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent nonuniform deterioration of catalyst cells in an internal combustion engine performing an ignition retard control in returning from fuel cut, in a control device for an internal combustion engine. <P>SOLUTION: Under a condition where there is no extraneous NE changing factor and a forced return condition is not met, that is, under a condition where there is room for execution of F/C return from a desired cylinder as an initial explosion cylinder, a cylinder least frequently corresponding to the initial explosion cylinder is selected as an initial explosion cylinder. When there is any extraneous NE changing factor, or the acceleration request when the forced return condition is met is relatively high, a cylinder which can firstly start combustion after the F/C return condition is met is selected as an initial explosion cylinder, without any regard for the priority order of the initial explosion cylinder. Further, when the acceleration request when the forced return condition is met is relatively low, the selection of a cylinder most frequently corresponding to the initial explosion cylinder as an initial explosion cylinder is prohibited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device, and more particularly to an internal combustion engine control device suitable as a device for controlling an internal combustion engine that retards ignition timing when returning from a fuel cut.

  Conventionally, for example, Patent Document 1 discloses a control device for an internal combustion engine that performs fuel cut when a predetermined fuel cut condition is satisfied. In this conventional control device, the fuel supply is resumed from the cylinder having the largest volume of the connected exhaust passage when returning from the fuel cut.

JP 2005-180282 A JP-A-4-265444 JP 2001-73751 A JP-A-7-63088 JP 2001-152835 A Japanese Unexamined Patent Publication No. 6-1559046

  By the way, a technique for increasing the temperature of exhaust gas by performing retarded control of ignition timing when returning from a fuel cut is conventionally known. When such fuel cut return retardation control is executed, the exhaust gas temperature becomes very high in the first explosion cylinder at the time of return because the ignition delay amount is maximized. Exhaust gas discharged from the cylinder flows into the catalyst. In many cases, the catalyst is generally provided directly below the gathering portion of the exhaust manifold. For this reason, under the influence of the layout of the exhaust manifold, the catalyst cell through which the exhaust gas flows can be different depending on the cylinder. That is, the gas combusted in each cylinder when returning from the fuel cut passes through the same part of the catalyst cell each time. As a result, the deterioration of the catalyst becomes uneven depending on the part.

  The present invention has been made to solve the above-described problems. In an internal combustion engine that performs ignition delay control when returning from a fuel cut, an internal combustion engine that can prevent catalyst cells from being deteriorated unevenly. An object of the present invention is to provide an engine control device.

A first aspect of the present invention is a fuel cut means for performing a fuel cut during deceleration of an internal combustion engine;
Ignition retard execution means for retarding the ignition timing when returning from the fuel cut;
First-explosion cylinder setting means for setting the first-explosion cylinder so that the first-explosion cylinder at the time of fuel cut return does not concentrate on a specific cylinder;
It is characterized by providing.

  According to a second aspect of the present invention, in the first aspect, the first explosion cylinder setting means includes priority order setting means for setting a priority order for each cylinder when becoming the first explosion cylinder. .

  According to a third invention, in the first or second invention, the initial explosion cylinder setting means sets a cylinder having a relatively low frequency corresponding to the initial explosion cylinder as an initial explosion cylinder.

  According to a fourth aspect of the present invention, in the first or second aspect of the invention, the initial explosion cylinder setting means sets the cylinder having the lowest frequency corresponding to the initial explosion cylinder as the initial explosion cylinder.

Further, a fifth aspect of the present invention is the second aspect of the invention, further comprising an acceleration request level detecting means for detecting the driver's request for acceleration level.
The initial explosion cylinder setting means prohibits the prioritization of the initial explosion cylinder by the priority setting means when the driver's acceleration request is relatively high.

In addition, a sixth invention according to the second invention further comprises external load detection means for detecting an external load of the internal combustion engine,
The initial explosion cylinder setting means is configured to prohibit prioritization of initial explosion cylinders by the priority order setting means when an external load is detected.

The seventh invention is the second invention, further comprising an acceleration request level detection means for detecting the driver's acceleration request level,
The initial explosion cylinder setting means is characterized in that, when the driver's acceleration demand is relatively low, prohibiting the cylinder with the highest frequency corresponding to the initial explosion cylinder from becoming the initial explosion cylinder.

  According to the first aspect of the invention, it is possible to avoid the initial explosion cylinders at the time of returning from the fuel cut from being concentrated on a specific cylinder. For this reason, it is possible to avoid high-temperature exhaust gas from locally flowing into some of the catalyst cells due to the initial explosion when the fuel cut is restored, and to prevent the catalyst from deteriorating unevenly.

  According to the second aspect of the invention, the priority order when becoming the first explosion cylinder is set for each cylinder, thereby avoiding the concentration of the first explosion cylinder at the time of fuel cut recovery to a specific cylinder. it can.

  According to the third aspect, the frequency corresponding to the initial explosion cylinder of each cylinder is leveled. For this reason, according to this invention, it can prevent effectively that a catalyst deteriorates unevenly.

  According to the fourth aspect of the invention, the initial explosion cylinder corresponding frequency of each cylinder is leveled more reliably than in the third aspect of the invention. For this reason, according to this invention, it can prevent effectively that a catalyst deteriorates unevenly.

  According to the fifth aspect of the present invention, when the driver's degree of acceleration request is relatively high, the fuel cut is promptly returned, so that it is possible to avoid slack during acceleration.

  According to the sixth aspect of the present invention, in the situation where a sudden decrease in the engine speed is expected due to the detection of the external load, the quick return from the fuel cut is performed. Thus, the return from the fuel cut can be ensured.

  According to the seventh aspect of the invention, when the driver's demand for acceleration is relatively low, the cylinder that is most inappropriate to be set as the first explosion cylinder is prohibited from becoming the first explosion cylinder. Therefore, it is possible to achieve both avoidance of slack and non-uniform catalyst deterioration.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining the configuration of the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine 10. Here, it is assumed that the internal combustion engine 10 has four cylinders. A combustion chamber 12 is formed in the cylinder of the internal combustion engine 10. An intake passage 14 and an exhaust passage 16 communicate with the combustion chamber 12.

  A throttle valve 18 is disposed in the intake passage 14. The throttle valve 18 is an electronically controlled valve that is driven by a throttle motor based on the accelerator opening. A throttle position sensor 20 for detecting the throttle opening degree TA is disposed in the vicinity of the throttle valve 18.

  The internal combustion engine 10 is a multi-cylinder engine having a plurality of cylinders, and FIG. 1 shows a cross section of one of the cylinders. Each cylinder included in the internal combustion engine 10 is provided with an intake port that communicates with the intake passage 14 and an exhaust port that communicates with the exhaust passage 16. A fuel injection valve 22 for injecting fuel into the intake port is disposed in the intake port. An ignition plug 24 is attached to the internal combustion engine 10 so that the tip of the internal combustion engine 10 protrudes into the combustion chamber 12. The intake port and the exhaust port are respectively provided with an intake valve 26 and an exhaust valve 28 for bringing the combustion chamber 12 and the intake passage 14 or the combustion chamber 12 and the exhaust passage 16 into a conductive state or a cut-off state. .

  The intake valve 26 and the exhaust valve 28 are driven by an intake variable valve operating (VVT) mechanism 30 and an exhaust variable valve operating (VVT) mechanism 32, respectively. The variable valve mechanisms 30 and 32 open and close the intake valve 26 and the exhaust valve 28 in synchronization with the rotation of the crankshaft, and change their valve opening characteristics (valve opening timing, operating angle, lift amount, etc.). can do.

  The internal combustion engine 10 includes a crank angle sensor 34 in the vicinity of the crankshaft. The crank angle sensor 34 is a sensor that reverses the Hi output and the Lo output each time the crankshaft rotates by a predetermined rotation angle. According to the output of the crank angle sensor 34, it is possible to detect the rotational position and rotational speed of the crankshaft, and further the engine rotational speed NE and the like.

  An upstream catalyst (SC) 36 and a downstream catalyst (UF) 38 for purifying exhaust gas are arranged in series in the exhaust passage 16 of the internal combustion engine 10. More specifically, the upstream catalyst 36 is provided at a position close to the collecting portion of the exhaust manifold. An air-fuel ratio sensor 40 for detecting the exhaust air-fuel ratio at that position is disposed upstream of the upstream catalyst 36. Further, an oxygen sensor 42 that generates a signal corresponding to whether the air-fuel ratio at that position is rich or lean is disposed between the upstream catalyst 36 and the downstream catalyst 38.

  The system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50. In addition to the various sensors described above, the ECU 50 is connected to an accelerator position sensor 52 for detecting the accelerator opening and the various actuators described above. The ECU 50 can control the operating state of the internal combustion engine 10 based on those sensor outputs. The ECU 50 also receives an air conditioner signal 54 and a steering angle 56 of a vehicle steering wheel.

[Ignition retarding control when returning from fuel cut]
In the system of the present embodiment configured as described above, for example, when the throttle opening degree TA is set to the idle opening degree during the operation of the internal combustion engine 10, a process of stopping fuel injection, that is, a fuel cut ( F / C) is executed. In order to increase the temperature of the catalyst 36 or the like that has decreased during F / C, there is a case where control is performed to retard the ignition timing when returning from F / C.

  FIG. 2 is a timing chart for explaining the operation of ignition retard control at the time of fuel cut return. More specifically, FIG. 2A shows a waveform indicating the success or failure of the F / C execution flag, FIG. 2B shows a waveform showing the change in the actual ignition timing, and FIG. 2C shows the upstream catalyst 36. Waveforms representing temperature changes of the inflowing exhaust gas (catalyst containing gas) are shown. As shown in FIG. 2A, when a predetermined return condition from F / C is satisfied, as shown in FIG. 2B, the ignition timing is retarded by a predetermined amount over a predetermined period. When the F / C is restored, combustion is started from any of the # 1 to # 4 cylinders. Here, the cylinder in which combustion is first started when the F / C is restored is referred to as “first explosion cylinder”.

  When the ignition timing is retarded, the combustion timing is delayed and the in-cylinder gas temperature when the exhaust valve 28 is opened increases, so that the exhaust gas flowing into the upstream catalyst 36 as shown in FIG. The gas temperature rises. For this reason, according to such retard control of the ignition timing, the temperature of the catalyst 36 and the like can be raised when returning from the F / C.

[Characteristics of Embodiment 1]
As described above with reference to FIG. 2 (B), at the time of return from F / C, the ignition timing is controlled so that the retard amount becomes maximum in the first explosion cylinder, and thereafter the operation is started. It is gradually returned to the ignition timing corresponding to the state. Therefore, when returning from F / C, the exhaust gas temperature at the first explosion is the highest.

  When returning from F / C, basically, at the time when the return condition is satisfied, the cylinder with the first explosion timing (the first explosion cylinder) is selected, and fuel is supplied to the selected cylinder. By restarting, combustion is restarted. The return condition is satisfied when the current engine speed NE reaches a predetermined natural return speed or when an acceleration request is detected by the driver depressing the accelerator pedal. That is, when the return condition is satisfied, it is not specified uniformly. Therefore, in the internal combustion engine 10 of this embodiment having four cylinders, the number of times corresponding to the first explosion cylinder may vary among the cylinders.

  The upstream catalyst 36 is often arranged on the upstream side of the exhaust passage 16 as much as possible, that is, directly below the collection portion of the exhaust manifold, from the viewpoint of achieving early warm-up at the start of the internal combustion engine 10. As a result, under the influence of the exhaust manifold layout, the catalyst cell through which the exhaust gas passes may vary from cylinder to cylinder. For this reason, when a situation occurs in which the first explosion cylinder concentrates on a specific cylinder when returning from F / C, the catalyst cell that receives the high-temperature exhaust gas at the time of the first explosion is biased, and the upstream The deterioration of the catalyst 36 becomes uneven depending on the part.

  Therefore, in the system of the present embodiment, the first explosion cylinder is determined from all the cylinders so that the first explosion cylinder at the time of return from F / C does not concentrate on a specific cylinder. More specifically, the order of priority when the cylinders become the first explosion cylinders is set for each cylinder based on the frequency corresponding to the past first explosion cylinder of each cylinder.

[Specific Processing in Embodiment 1]
FIG. 3 is a flowchart of a routine executed by the ECU 50 in the first embodiment to realize the above function. Note that this routine is periodically executed at predetermined time intervals. In the routine shown in FIG. 3, first, the recommended return cylinder priority order is set (step 100). The ECU 50 stores the frequency corresponding to the initial explosion cylinder of each cylinder as shown in FIG. 4 in the RAM. Specifically, in step 100, the recommended return cylinder priority order is set based on the initial explosion cylinder corresponding frequency as shown in FIG. Here, the recommended return cylinder refers to a cylinder that has the lowest frequency in the past for the first explosion cylinder.

  In the example shown in FIG. 4, the initial explosion cylinder corresponding frequencies are # 4 cylinder, # 2 cylinder, # 1 cylinder, and # 3 cylinder, in order of decreasing frequency. Therefore, when the initial explosion cylinder corresponding frequency of each cylinder is the example shown in FIG. 4, when setting the initial explosion cylinder from now on, the most recommended cylinder is the # 4 cylinder. The cylinder that is inappropriate for the first explosion cylinder is the # 3 cylinder. In other words, the priority order of the recommended return cylinder is set so that a cylinder with a lower frequency corresponding to the first explosion cylinder is given priority.

  Note that when counting the number of initial explosion cylinders in each cylinder, the ECU 50 takes into account the RAM capacity limitation, for example, when the number of initial explosions of a certain cylinder reaches the upper limit guard value shown in FIG. For that cylinder, the accumulation of the number of first explosions beyond that is stopped. Based on the equation | ((Σ # 1 to #n) / n) − # n) | <C, the deviation between the average value of all cylinders for the number of first explosions and the number of first explosions for each cylinder is all When the cylinder becomes smaller than a certain value C, it is determined that the frequency corresponding to the first explosion cylinder of each cylinder has been leveled, and the RAM is cleared.

  Next, it is determined whether or not F / C is being executed (step 102). As a result, if it is determined that the F / C is not being executed, the process at the time of starting this time is immediately terminated, whereas if it is determined that the F / C is being executed, the return NE, that is, The natural return rotational speed for determining the natural return timing from the F / C is updated (step 104). Here, the return NE is updated to a value corresponding to the current operating state of the internal combustion engine 10 such as the coolant temperature.

  Next, a deviation ξ between the current engine speed NE and the return NE is calculated (step 106). Next, it is determined whether or not the deviation ξ is smaller than 200 (step 108). If it is determined that the deviation ξ <200 is established, whether there is an external NE change factor, that is, the engine speed NE. It is determined whether or not an external load that causes a drastic decrease in the load is detected (step 110). The external load is mainly caused by the driving of auxiliary machines (such as an air conditioner compressor and a power steering pump) of the internal combustion engine 10, and the ECU 50 drives the compressor by detecting the air conditioner signal 54, and the steering wheel. By detecting an increase in the driving load of the power steering pump by detecting the steering angle 56, it is determined that an external NE change factor has occurred.

  If it is determined in step 100 that there is an external NE change factor, the current crank angle is acquired (step 112). Then, the fastest cylinder return is selected (step 114). More specifically, based on the crank angle information acquired in step 112, the cylinder that can start combustion first after the F / C return condition is satisfied is selected as the first explosion cylinder. That is, in this case, the control for selecting the recommended return cylinder based on the frequency corresponding to the initial explosion cylinder as the initial explosion cylinder is prohibited. As a result, fuel is first supplied to the cylinder that can be returned at the fastest speed. Next, the cylinder selected in step 114 is stored in the RAM as the first explosion cylinder (step 116).

  On the other hand, if it is determined in step 108 that the deviation ξ <200 is not satisfied, or if it is determined in step 110 that there is no external NE change factor, it is determined whether or not the deviation ξ <20 is satisfied. (Step 118). The 20 rpm used in this step is a hysteresis for obtaining a preparatory period for returning any cylinder as the first-explosion cylinder while avoiding engine stall before the engine speed NE actually reaches the natural return speed. It is.

  FIG. 5 shows an example of a map in which the hysteresis used in this step 118 is determined in relation to the decrease speed ΔNE of the engine speed NE during F / C execution. According to the map shown in FIG. 5, the hysteresis is set to increase as the decrease rate ΔNE increases. According to such a setting, when the decrease rate ΔNE of the engine speed NE during F / C execution is high, the preparation period can be secured longer than when it is low.

  If it is determined in step 118 that the deviation ξ <20 is satisfied, the recommended return cylinder set in step 100 is selected as the initial explosion cylinder (# 4 cylinder in the example shown in FIG. 4). Is selected) (step 120). As a result, when the engine speed NE reaches the return NE, the natural return is executed with the recommended return cylinder as the first explosion cylinder. Next, the cylinder selected in step 118 is stored in the RAM as the first explosion cylinder (step 122).

  If it is determined in step 118 that the deviation ξ <20 is not satisfied, it is then determined whether or not a forced return condition from F / C is satisfied (step 124). When the accelerator pedal leaves the idle position during execution of F / C, an acceleration request is detected and it is determined that the condition for forced return from F / C is satisfied.

  If it is determined in step 124 that the forced return condition is not satisfied, the process at the time of starting this time is immediately terminated. On the other hand, if it is determined that the forced return condition is satisfied, the Δ pedal That is, it is determined whether or not the accelerator pedal depression amount (accelerator pedal depression speed) per unit time is smaller than a predetermined determination value α (step 126).

  If it is determined in step 126 that Δpedal <α is not satisfied, that is, it can be determined that the accelerator pedal depression speed when the forced return condition is satisfied is relatively high and the driver's acceleration request is relatively high. Then, in order to give priority to avoiding the acceleration after the F / C return over the return from the recommended return cylinder, the processing of the above step 112 to step 116 (the fastest cylinder return) is executed.

  On the other hand, if it is determined in step 126 that Δ pedal <α is satisfied, that is, it can be determined that the accelerator pedal depression speed when the forced return condition is satisfied is relatively low and the driver's acceleration request is relatively low. If so, then the current crank angle is obtained (step 128).

  Next, rapid cylinder return is selected (step 130). More specifically, based on the crank angle information acquired in step 128 above, it is possible to perform a quick F / C return while avoiding the cylinder with the highest frequency corresponding to the first explosion cylinder from being the first explosion cylinder. The first explosion cylinder is selected. For example, when the cylinder that can start combustion first after establishment of the F / C return condition is the cylinder with the highest frequency corresponding to the initial explosion cylinder (# 3 cylinder in the example shown in FIG. 4), the # 3 cylinder is Avoiding the first explosion cylinder, the # 4 cylinder whose explosion timing comes after the # 3 cylinder is selected as the first explosion cylinder. Further, when the cylinder that can start combustion first after establishment of the F / C return condition is a cylinder other than the # 3 cylinder, the cylinder is selected as the first explosion cylinder. Next, the cylinder selected in step 130 is stored in the RAM as the first explosion cylinder (step 132).

  According to the routine shown in FIG. 3 described above, there is no room for changing the external NE, and there is a margin in which F / C return can be executed with the desired cylinder as the first explosion cylinder under the condition that the forced return condition is not satisfied. Under the circumstances that are recognized, the cylinder with the lowest frequency corresponding to the first explosion cylinder is selected as the first explosion cylinder. According to such a method, it is possible to avoid the concentration of the initial explosion cylinders at the time of F / C return to the specific cylinder, in other words, the frequency corresponding to the initial explosion cylinder of each cylinder can be leveled. For this reason, it is possible to avoid high temperature exhaust gas from locally flowing into some of the catalyst cells due to the initial explosion at the time of F / C recovery, and to prevent the catalyst from deteriorating unevenly.

  In addition, according to the above routine, when it is recognized that there is an external NE change factor, the cylinder that can start combustion first after the F / C return condition is satisfied without considering the priority order of the first explosion cylinder. Selected as the first explosion cylinder. According to such a method, in a situation where a sudden decrease in the engine speed NE is expected, it is possible to achieve a reliable return from F / C with the highest priority given to avoiding engine stall.

  Further, according to the above routine, when the forced return condition is satisfied, basically, the cylinder having the highest priority of the recommended return cylinder is prohibited from being selected as the first explosion cylinder. More specifically, when the acceleration request when the forced return condition is satisfied is relatively high, the cylinder that can start combustion first after the F / C return condition is satisfied is selected as the first explosion cylinder. For this reason, when rapid acceleration is required, it is possible to give the highest priority to avoiding rattling. Further, when the acceleration request when the forced return condition is satisfied is relatively low, it is prohibited to select the cylinder having the highest frequency corresponding to the first explosion cylinder as the first explosion cylinder. For this reason, when slow acceleration is required, it is possible to avoid returning to the cylinder that is most inappropriate as the first explosion cylinder at the present time, and to achieve both acceleration avoidance and uniform catalyst deterioration. be able to.

  By the way, in the first embodiment described above, the selection of the first explosion cylinder is changed based on the comparison result between the magnitude of the Δ pedal and the determination value α. However, the selection of the first explosion cylinder based on the degree of acceleration demand is not limited to the above method. For example, when a slow acceleration request is made, the cylinder that can start combustion first is the cylinder immediately before the cylinder with the lowest frequency corresponding to the first explosion cylinder (the cylinder that is most suitable as the first explosion cylinder). Even if the cylinder that can start combustion first is not the cylinder with the highest frequency of initial explosion cylinders (the cylinder that is inappropriate for the first explosion cylinder), it waits for return execution to the cylinder with the lowest frequency of initial explosion cylinders You may do it.

  In the first embodiment described above, the ECU 50 executes F / C when the internal combustion engine decelerates, so that the “fuel cut means” in the first aspect of the invention is ignited when returning from F / C. By retarding the timing, the “ignition retarding execution means” in the first invention performs the processing of 100 to 108, 118, and 120, and “initial explosion cylinder setting means” in the first invention. Are realized. Further, the “priority setting means” in the second aspect of the present invention is realized by the ECU 50 executing the processing of steps 100, 116, 122, and 132. Further, the “acceleration request level detecting means” in the fifth or seventh aspect of the present invention is realized by the ECU 50 executing the processing of steps 124 and 126 described above. Further, the “external load detecting means” in the sixth aspect of the present invention is realized by the ECU 50 executing the processing of step 110 described above.

It is a figure for demonstrating the structure of Embodiment 1 of this invention. It is a timing chart for demonstrating the operation | movement of the ignition retard control at the time of a fuel cut return. It is a flowchart of the routine performed in Embodiment 1 of the present invention. FIG. 2 is a diagram showing an example of the frequency corresponding to the initial explosion cylinder of each cylinder stored in the RAM of the ECU shown in FIG. 1. FIG. 4 is a diagram showing an example of a map in which hysteresis used in the routine shown in FIG. 3 is defined in relation to a decrease rate ΔNE of engine speed NE during execution of F / C.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 22 Fuel injection valve 24 Spark plug 36 Upstream catalyst 38 Downstream catalyst 50 ECU (Electronic Control Unit)
52 Accelerator position sensor 54 Air conditioner signal 56 Steering angle

Claims (7)

Fuel cut means for performing fuel cut during deceleration of the internal combustion engine;
Ignition retard execution means for retarding the ignition timing when returning from the fuel cut;
First-explosion cylinder setting means for setting the first-explosion cylinder so that the first-explosion cylinder at the time of fuel cut return does not concentrate on a specific cylinder;
A control device for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the first explosion cylinder setting means includes priority order setting means for setting a priority order for becoming the first explosion cylinder for each cylinder.   The control device for an internal combustion engine according to claim 1 or 2, wherein the initial explosion cylinder setting means sets a cylinder having a relatively low frequency corresponding to the initial explosion cylinder as an initial explosion cylinder.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the first explosion cylinder setting means sets the cylinder having the lowest frequency corresponding to the first explosion cylinder as the first explosion cylinder. Acceleration request degree detection means for detecting the driver's acceleration request degree is further provided,
3. The internal combustion engine according to claim 2, wherein the initial explosion cylinder setting means prohibits prioritization of the initial explosion cylinder by the priority setting means when the driver's acceleration demand is relatively high. Control device. An external load detecting means for detecting an external load of the internal combustion engine;
3. The control device for an internal combustion engine according to claim 2, wherein the initial explosion cylinder setting means prohibits the prioritization cylinder prioritization by the priority setting means when an external load is detected. Acceleration request degree detection means for detecting the driver's acceleration request degree is further provided,
3. The initial explosion cylinder setting means, when the acceleration demand of the driver is relatively low, prohibits the cylinder having the highest frequency corresponding to the initial explosion cylinder from becoming the initial explosion cylinder. Control device for internal combustion engine.

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