JP2003193872A - Control device for self-igniting engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device with a variable compression ratio mechanism 10 allowing stable spark ignition combustion by preventing the occurrence of self ignition combustion during changing a combustion system from the self ignition combustion to the spark ignition combustion (during a compression ratio change) for establishing a high compression ratio in operation in a self ignition compression mode and a low compression ratio mode in operation in a spark ignition combustion mode. <P>SOLUTION: A variable valve mechanism 11 for changing the valve lift characteristic of an inlet valve 5 is used to correct the closing timing of the inlet valve to a delay side during changing the compression ratio to decrease an effective compression ratio. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a self-ignition engine that operates by switching between self-ignition combustion and spark ignition combustion depending on the operating condition.

[0002]

2. Description of the Related Art As a conventional self-ignition engine, there is one described in Japanese Patent Application Laid-Open No. 2000-220458. According to the operating state, the self-ignition combustion and the spark ignition combustion are switched to perform the operation, and when the two combustion methods are switched, the ignition timing and the intake air amount are controlled to smoothly burn the combustion. The system is being switched to improve fuel efficiency while ensuring drivability in the low load range.

However, when a low cetane number fuel such as gasoline is used, in order to carry out self-ignition combustion,
When it is necessary to significantly increase the compression ratio and only control the ignition timing and the intake air amount as disclosed in the above publication,
It is conceivable that the high load output in the case of performing spark ignition combustion is limited, and especially the maximum output is significantly reduced due to knocking at full load. On the other hand, if the compression ratio is lowered in order to secure the output, the region where self-ignition combustion is possible is limited to an extremely low rotation speed region, and there is a problem that a sufficient fuel efficiency improving effect cannot be obtained.

As one of means for solving the above-mentioned problem, a compression ratio variable means for changing the compression ratio at the time of self-ignition combustion and spark ignition combustion is provided, and self-ignition in a low load region is carried out for stable self-ignition combustion. It is conceivable to set the compression ratio high during ignition combustion and set it low to suppress knocking during spark ignition combustion in the high load region.

As a compression ratio changing means, for example, Japanese Patent Laid-Open No.
There is one disclosed in Japanese Unexamined Patent Publication No. 0-9005.
In Japanese Patent Laid-Open No. 10-9005, valve timing,
By controlling the compression ratio and intake pipe pressure, it is intended to improve the responsiveness during transition such as acceleration and deceleration. However, in Japanese Patent Laid-Open No. 10-9005, the purpose is to control the intake air amount and the intake resistance by adjusting the valve timing, the compression ratio, and the intake pipe pressure, and it is not always necessary to adjust the compression ratio during acceleration / deceleration. However, the control is insufficient when switching between the two combustion modes of self-ignition combustion and spark ignition combustion, and the gist of the present invention is obviously different.

Generally, when a means for changing the compression ratio is adopted, the changing speed, that is, the time required for the change is longer than that of the engine cycle, and the combustion occurs at a compression ratio intermediate between before and after the change in the compression ratio changing process. The cycle that takes place occurs. For example, considering switching from high compression ratio self-ignition combustion to low compression ratio spark ignition combustion, in the cycle immediately after the start of the compression ratio switching, the combustion cycle is at a slightly lower compression ratio, and self-ignition combustion is not possible. While stable, spark ignition combustion may cause severe knocking. Particularly, in the case of self-ignition combustion when the compression ratio is low, misfire easily occurs, and misfire and combustion occur randomly. Even if spark ignition combustion is possible by delaying the ignition timing and preventing knocking, in such a case, self-ignition combustion starts earlier than spark ignition combustion due to ignition, and self-ignition combustion occurs or self-ignition occurs. It is conceivable that there is a situation in which it is not possible to control whether or not spark ignition combustion is performed without the combustion being caused by misfire. In such a case, even if the fuel injection amount is the same, a difference occurs in the generated torque due to a large difference in the heat generation timing, so that the drivability is deteriorated.

Therefore, in the self-ignition engine having the variable compression ratio mechanism, when the combustion system is switched from the self-ignition combustion to the spark ignition combustion, the self-ignition combustion is promptly prevented from occurring and the spark ignition combustion is stably performed. It is necessary to take measures to do so. In addition, even after the compression ratio is reduced to a level where self-ignition combustion does not occur, it is necessary to perform control so as to perform stable spark ignition combustion while avoiding knocking and reducing thermal efficiency as much as possible.

[0008]

SUMMARY OF THE INVENTION In view of the above situation, the present invention has a variable compression ratio and a high compression ratio in order to widen the operating range in which self-ignition combustion is possible, which has low fuel consumption and low exhaust gas. Operating conditions for self-ignition combustion and spark-ignition combustion in a self-ignition engine that achieves high output by realizing self-ignition combustion in a wide range and performing compression ignition combustion with a compression ratio lower than that during self-ignition combustion. The switching of the combustion method should be performed smoothly during the transition when switching according to the above, especially when the combustion method is switched from self-ignition combustion to spark ignition combustion, self-ignition combustion does not occur immediately and is stable. The purpose is to enable spark ignition combustion.

[0009]

Therefore, in the invention of claim 1, the self-ignition combustion is provided with the variable valve mechanism for changing the valve lift characteristic of the intake valve and the variable compression ratio mechanism for changing the compression ratio. High compression ratio when operating according to the form,
In a control device for a self-ignition engine that provides a low compression ratio when operating in the spark ignition combustion mode, the variable compression ratio mechanism changes from a high compression ratio state for the self-ignition combustion mode to a low compression ratio for the spark ignition combustion mode. In the compression ratio switching process changing toward the ratio state, the variable valve mechanism is controlled to correct the intake valve closing timing to the retard side.

According to a second aspect of the present invention, the correction of the intake valve closing timing is started at the same time when the state change of the variable compression ratio mechanism starts. The invention of claim 3 is characterized in that the retard amount of the intake valve closing timing is reduced as the compression ratio state approaches the low compression ratio state for the spark ignition combustion mode.
In the invention of claim 4, in the compression ratio switching process,
It is characterized in that the intake valve closing timing is corrected to the retard side and the ignition timing is corrected to the retard side.

According to a fifth aspect of the present invention, in the compression ratio switching process, the higher the compression ratio, the larger the retard amount of the ignition timing. In the invention of claim 6, in the compression ratio switching process, the intake valve closing timing is corrected to the retard side and the fuel injection amount is increased and corrected. In the invention of claim 7, in the compression ratio switching process, the intake valve closing timing is corrected to the retard side, and the throttle valve is closed by a predetermined amount.

[0012]

According to the first aspect of the present invention, when switching from self-ignition combustion to spark ignition combustion, the variable valve mechanism is controlled in the compression ratio switching process from the high compression ratio state to the low compression ratio state. By correcting the intake valve closing timing to the retard side, the effective compression ratio is lowered at the intermediate compression ratio in the switching process, so that the self-ignition combustion can be promptly ended, and the spark ignition combustion is smoothly performed. It becomes possible to make a transition.

According to the second aspect of the present invention, the correction of the intake valve closing timing is started at the same time when the state change of the variable compression ratio mechanism starts, so that the self-ignition combustion is promptly performed at the compression ratio in the middle of the switching process. It is possible to prevent deterioration of drivability at the time of switching the combustion method by shifting from spark ignition combustion to avoid knocking. According to the invention of claim 3,
By setting the intake valve closing timing optimally according to the compression ratio so that the retard amount of the intake valve closing timing becomes smaller as it approaches the low compression ratio state for spark ignition combustion mode, the intake valve closing timing is significantly delayed. Combustion deterioration due to corners can be prevented, and operation can be performed without significantly deteriorating thermal efficiency.

According to the fourth aspect of the present invention, in the compression ratio switching process, the intake valve closing timing is retarded and the ignition timing is retarded, so that knocking is reliably avoided at the compression ratio in the middle of the switching process. It becomes possible to do. According to the invention of claim 5, in the process of switching the compression ratio, the intake valve closing timing is retarded, the ignition timing is retarded, and the retard amount of the ignition timing is increased as the compression ratio is higher. At a compression ratio in the middle of the process, knocking can be reliably avoided, and combustion instability and thermal efficiency deterioration due to an ignition retard more than necessary can be prevented.

According to the sixth aspect of the present invention, in the compression ratio switching process, the intake valve closing timing is delayed and the fuel injection amount is increased. Therefore, it is possible to prevent the output reduction due to the actual compression ratio reduction. The combustion method can be switched without deteriorating the drivability. According to the invention of claim 7, in the process of switching the compression ratio, the intake valve closing timing is delayed and the throttle valve is closed by a predetermined amount, so that the self-ignition combustion can be completed more quickly, and the self-ignition combustion can be completed. By more quickly supplying the air-fuel mixture having a combustible air-fuel ratio to the lean air-fuel ratio at the time of ignition combustion, it becomes possible to perform more stable combustion by spark ignition combustion.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a self-ignition engine showing a first embodiment of the present invention. In the intake system,
A throttle valve 1, a collector 2, and a fuel injection valve 4 are further provided in an intake port 3, and a mixture of intake air and injected fuel is sucked into a combustion chamber 6 via an intake valve 5. Although the intake port injection type engine is shown here, a cylinder direct injection type engine may be used.

The air-fuel mixture in the combustion chamber 6 is compressed by the piston 7 and combusted by compression self-ignition or spark ignition by the spark plug 8, and the exhaust gas after combustion is discharged from the exhaust valve 9. Here, low fuel consumption due to self-ignition combustion
In order to achieve both low exhaust and high output by spark ignition combustion, a variable compression ratio mechanism 10 that can change the compression ratio and variable valve operating mechanisms 11 and 12 for the intake valve 5 and the exhaust valve 9 are provided.

As the variable compression ratio mechanism 10, a multi-link type piston-crank mechanism is used to change the piston stroke (proposed in Japanese Patent Application No. 2000-71381), and the relative position between the piston pin and the piston is changed. It is possible to use the one that changes the relative position between the cylinder head and the cylinder block, or the like. It suffices for the variable valve operating mechanisms 11 and 12 to be able to change at least the intake valve closing timing, and a mechanism for changing the phases of the crankshaft and the camshaft is used to set the valve timing (as shown in FIG. 2A). That changes the lift center phase),
A mechanism for transmitting the rotational movement of the valve drive shaft, which rotates in synchronization with the crankshaft, to the valve by a plurality of links, and changing the operating angle and lift amount as shown in FIG. 2B can be used. .

Engine control unit (ECU)
13 is a crank angle sensor (engine speed sensor)
14, based on information from the accelerator opening sensor 15, etc., the combustion system, compression ratio, valve timing (in particular, intake valve closing timing), fuel injection amount, throttle opening, ignition timing, etc. are set and controlled. FIG. 3 shows an engine rotation-load map of the combustion method and the compression ratio.

In the low rotation / low load region, for example, a high compression ratio of about 18 is set for self-ignition combustion, and in the high rotation / high load region, for example, a compression ratio of 11
Spark ignition combustion is performed at a low compression ratio. In the high rotation speed range, the crank angle change with respect to real time becomes large, and basically in compression self-ignition caused by a chemical reaction governed by real time, the crank angle required for combustion becomes large, and therefore, before and after compression top dead center. The piston goes down before the combustion starts in the entire cylinder, and the flame is extinguished, and combustion is not completely performed.In addition, in the high load region, the amount of fuel injection increases, so compression self-ignition occurs. The combustion starts relatively faster, the combustion pressure increases significantly due to the synergistic effect with the compression of the piston, and the combustion noise increases.Therefore, the self-ignition combustion area is limited to the low rotation and low load area. In consideration of combustion noise and the like, it is practically difficult to operate the entire operation region by self-ignition combustion.

As described above, the self-ignition combustion at a high compression ratio and the spark ignition combustion at a low compression ratio are switched according to the operating state. At such a switching of the combustion system, a particularly high compression ratio is selected. Since it takes time to change the compression ratio when switching from the self-ignition combustion in the above to the spark ignition combustion with a low compression ratio, it is possible to prevent the self-ignition combustion from occurring in the switching process, and to stabilize the combustion. It is necessary to make spark ignition combustion. Therefore, in the present invention, the intake valve closing timing is controlled during the switching process.

The control will be described below. Figure 4
Is a flow chart of control in the first embodiment, and this control is executed in the ECU at predetermined time intervals (for example, 10 ms). In S1, the engine rotation speed Ne is read from the output signal of the engine rotation speed sensor, and the accelerator opening APO is read from the output signal of the accelerator opening sensor.

At S2, the actual compression ratio rε is obtained from the output signal of the compression ratio sensor included in the variable compression ratio mechanism, and the actual intake valve closing timing rIV is obtained from the output signal of the valve operating sensor included in the variable valve mechanism.
Read C respectively. The compression ratio sensor is a potentiometer that detects the operating position of the actuator that the variable compression ratio mechanism is accelerating. From the operating position of the actuator, the current compression ratio (= cylinder volume at intake bottom dead center / cylinder content at compression top dead center) Product). The valve operating sensor is a potentiometer that detects the operating position of an actuator included in the variable valve operating mechanism, and detects the current intake valve closing timing from the operating position of the actuator. The value of rIVC indicates the crank angle from the intake bottom dead center to the intake valve closing timing. The intake valve closing timings in this embodiment are all defined similarly.

In S3, based on the engine rotation speed Ne and the accelerator opening APO read in S1, the engine rotation-load map of FIG. 3 is referred to, and whether the current operating condition is in the self-ignition combustion region or not. To judge. If the current operating condition is in the self-ignition combustion region, the routine proceeds to S4, where the target intake valve closing timing tIVC is the intake valve closing timing IV for self-ignition combustion.
Cse. IVCse may be a single predetermined value, or an optimum value may be read from a control map prepared for self-ignition combustion based on the engine speed Ne and the accelerator opening APO. Good.

When it is determined in S3 that the ignition timing is not in the self-ignition combustion region (when the operating condition is in the spark ignition combustion region), the process proceeds to S5, where the actual compression ratio rε read in S2 and the compression ratio εL for spark ignition combustion are set. The deviation dε = rε−εL is calculated. εL is a value indicating a low compression ratio (for example, about 11). In S6, it is determined whether the deviation dε is smaller than the predetermined plant a.
The predetermined value a is a value close to 0. If the deviation dε is smaller than the predetermined value a, that is, if the actual compression ratio rε is the compression ratio εL for spark ignition combustion, the routine proceeds to S7, where the target intake valve closing timing tIVC is set to the intake valve closing for spark ignition combustion. Period IV
Csp. IVCsp may be a single value or may be read from a control map prepared for spark ignition combustion based on the engine speed Ne and the accelerator opening APO.

When the deviation dε is not smaller than the predetermined value a in the determination of S6, the process proceeds to S8, and the intake valve closing timing retard correction amount c
Calculate IVC. Specifically, the retardation correction amount cIVC = k × dε is obtained by multiplying the deviation dε of the compression ratio by the coefficient k. In S9, the intake valve closing timing 1VCs for spark ignition combustion
p is corrected by the retard correction amount cIVC, and the target intake valve closing timing t
Calculate IVC. Here, cIVC is added to IVCsp to calculate tIVC = IVCsp + cIVC because the intake valve closing timing is represented by the crank angle from the intake bottom dead center to the intake valve closing timing. .

In S10, a control command for the actuator of the variable valve mechanism is based on the target intake valve closing timing tIVC calculated in any of S4, S7 and S9 and the actual intake valve closing timing rIVC read in in S2. Calculate the value. For example, the target intake valve closing timing tIVC and the actual intake valve closing timing rIV
The control command value is calculated by multiplying the deviation from C by a predetermined control gain.

FIG. 5 is a time chart showing the state of control according to the first embodiment, and shows a case where the operating condition shifts from the self-ignition combustion region to the spark ignition combustion region at time t0. The target compression ratio tε indicated by the broken line on the lower side of FIG. 5 is εH for the self-ignition combustion mode at time t0.
(High compression ratio) is changed stepwise from εL (low compression ratio) for spark ignition combustion, and at the same time the actual compression ratio rε also begins to change toward εL, but the control response speed of the variable compression ratio mechanism Is not so large, it takes some time (t1−t0) until the actual compression ratio rε reaches εL. Note that the variable compression ratio mechanism is a mechanism that changes the specifications of the main motion system that moves while receiving a large combustion pressure and changes the overall height of the engine itself, and it is difficult to give this mechanism a high control response speed. Is.

From time t0 onward, spark ignition combustion is performed for control purposes, but in the case of several combustions immediately after t0, unintended self-ignition combustion may occur due to a high actual compression ratio rε, which deteriorates drivability. In particular, when self-ignition combustion occurs in the operating region where the spark ignition combustion should be originally performed, the pressure rise rate in the cylinder becomes excessively high, which causes a problem of generating large combustion noise.

Therefore, the effective compression ratio (= cylinder volume at the intake valve closing timing / compression top dead center at the intake valve closing timing is corrected by retarding the intake valve closing timing IVC until the actual compression ratio rε reaches εL. The in-cylinder volume) is rapidly reduced to prevent unintended self-ignition combustion. Since this retard correction has no meaning unless it exerts an effect on several combustions immediately after t0, at the same time as the transition from the self-ignition combustion region to the spark ignition combustion region, that is, the actual compression ratio rε
It is desirable to start at the same time as starts to change toward εL.

In the present embodiment, the retard correction amount cIVC is defined as the deviation dε between the actual compression ratio rε and the compression ratio εL for spark ignition combustion.
It is calculated according to. Therefore, the retard correction amount cIVC
Becomes maximum at time t0 and becomes smaller as the actual compression ratio rε approaches εL. As a result, the effective compression ratio becomes substantially constant, and knocking or unstable combustion does not occur in spark ignition combustion.

It should be noted that increasing the control response speed of the variable valve actuation mechanism is relatively easier than increasing the control response speed of the variable compression ratio mechanism, and is simply feedback controlled (target intake valve closing timing tIVC and actual intake valve closing timing). It is possible to reduce the effective compression ratio quickly just by calculating the command value according to the deviation from the timing rIVC. However, if you want to more surely prevent self-ignition combustion immediately after the transition to the region, To the target intake valve closing timing tIV, and the actual intake valve closing timing rIVC is set to the target intake valve closing timing tIV.
It is also possible to send a special command to the actuator so that the retard angle correction is performed at the maximum speed on the mechanism until C is reached.

Next, a second embodiment of the present invention will be described. The system configuration is the same as that of the first embodiment, and only the control is different. FIG. 6 is a flow chart of control in the second embodiment. First, based on a signal from the accelerator opening sensor, it is determined whether or not the transient operation is performed (S101). Specifically, if the absolute value of the amount of change in the accelerator opening | ΔAPO | is less than a predetermined value, it is considered to be steady operation, and if it is more than a predetermined value, it is considered to be transient operation. If it is regarded as the steady operation, the combustion method switching control ends, and the parameters are set according to the required load during the steady operation.

If it is regarded as a transient operation, the required load is calculated based on the accelerator opening APO at that time (S1).
02). As a result, it is determined whether the combustion mode needs to be switched based on the current engine speed and load (S10).
3). If the combustion method switching is not required, the combustion method switching control ends, and the parameters are set according to the required load during steady operation.

When it is necessary to switch the combustion method, first, Δ
It is determined from the sign of APO or from the combustion method flag at the start of control whether acceleration or deceleration (S104). In the case of acceleration, that is, in the case of switching from self-ignition combustion (CI) to spark ignition combustion (SI), control is performed to reduce the compression ratio ε (S105). At the same time, until the compression ratio ε reaches the low compression ratio εL for spark ignition combustion (S106),
The intake valve closing timing, throttle opening, ignition timing, and fuel injection amount are set / changed to predetermined values (S108-S111).

FIG. 7 shows a schematic diagram of a method of controlling each parameter. The compression ratio is changed from a high compression ratio for compression self-ignition combustion to a low compression ratio for spark ignition combustion by switching combustion modes. At that time, since the change cannot be performed instantaneously, combustion is performed at an intermediate compression ratio in the process of change. At the same time that the compression ratio starts to decrease, the variable valve mechanism immediately changes the valve timing, delaying the intake valve closing timing. The valve timing change for changing the intake valve closing timing may be either of the two methods shown in FIG. It may be difficult to avoid knocking and obtain sufficient torque only with the intake valve closing timing, and the ignition timing is retarded by a predetermined amount. The retard amount of the ignition timing shown in FIG. 7 is the retard amount with respect to the optimum ignition timing when the compression ratio is a low compression ratio for spark ignition combustion.

Further, the throttle opening is controlled so as to be closed after the self-ignition combustion. Self-ignition combustion is possible even in a lean air-fuel mixture concentration, and combustion is performed with a lean air-fuel mixture in order to achieve low fuel consumption and low exhaust gas. Therefore, in order to quickly and stably perform spark ignition combustion at the time of switching the combustion system, it is necessary to adjust the throttle opening degree for supplying the air-fuel mixture with the combustible air-fuel ratio at the fuel injection amount according to the required load. By closing the throttle opening, it is possible to obtain the effect of promptly reducing the in-cylinder pressure and immediately ending the self-ignition combustion immediately after reducing the compression ratio from the self-ignition combustion.

On the other hand, since the intake valve closing timing is retarded and the ignition timing is retarded, a torque decrease occurs when the combustion system is switched. Therefore, the intake valve closing timing is retarded and the ignition timing is retarded. The fuel injection amount is set so as to prevent the torque from decreasing. Then, as the compression ratio decreases, the intake valve closing timing is gradually advanced, the ignition timing retard amount is decreased, and the throttle opening is closed. At the same time, when the amount of increase in fuel is moderated and the compression ratio reaches a predetermined value, the combustion mode switching control is terminated and normal spark ignition combustion control is performed to set parameters according to the required load.

When it is determined that the vehicle is decelerating as a result of the transient determination and the acceleration / deceleration determination, that is, when the spark ignition combustion (SI) is switched to the self-ignition combustion (CI), the compression ratio ε is controlled to be increased and ( S112) until the compression ratio ε reaches the high compression ratio εH for self-ignition combustion (S11).
3) The intake valve closing timing, the throttle opening, the ignition timing, and the fuel injection amount are controlled in the opposite directions with the same guidance as in the case of acceleration shown in FIG. 7 (S115 to S118).

The control of each parameter in the second embodiment is instantaneously switched when the compression ratio variable mechanism is not performed, and the variable valve mechanism is instantaneously switched, for example, when an electromagnetic valve is used. This is the case. Even when the valve timing is mechanically changed, the variable valve mechanism can generally switch faster than the compression ratio changing mechanism, but the valve timing may not be switched instantaneously. . As a control method in such a case, a method like the third embodiment shown in the flowchart of FIG. 8 and the time chart of FIG. 9 can be considered.

The control parameter and its control direction in the third embodiment are the same as those in the second embodiment, but the control in the valve timing changing process during the compression ratio switching process is added to the second embodiment. Specifically, in the case of acceleration, that is, when switching from self-ignition combustion (CI) to spark ignition combustion (SI), the compression ratio ε is reduced (S105), and the compression ratio ε is low compression for spark ignition combustion. Until the ratio εL is reached (S106), the intake valve closing timing, the throttle opening, the ignition timing, and the fuel injection amount are set and changed to predetermined values (S108 to S111), but before that, S10.
The step 7 is added, and the degree of setting / change is changed depending on whether the compression ratio ε has decreased to the compression ratio εc at which self-ignition combustion does not occur. In the case of deceleration, the same step S11
4 has been added.

That is, the variable valve mechanism switches the combustion system,
That is, the intake valve closing timing is delayed as soon as the compression ratio is changed, and the intake valve closing timing is delayed until the compression ratio εc at which self-ignition combustion does not occur (Tc). Further, while the valve timing is being changed (Tc), the throttle opening is set so as to be closed more than in the second embodiment.
The ignition timing is retarded greatly so that knocking of spark ignition combustion does not occur. Since the torque is further reduced, the fuel injection amount is increased. The fuel injection amount is increased in the period Tc more than during the change of the compression ratio other than Tc.

By performing the control as described above, even if the valve timing cannot be changed instantaneously, it is possible to avoid deterioration of drivability due to random self-ignition combustion and its misfire, and knocking due to spark ignition combustion. While
It becomes possible to switch the combustion method, and it is possible to achieve both low fuel consumption, low exhaust and high output by selecting and switching the optimum combustion method.

[Brief description of drawings]

FIG. 1 is a system diagram of a self-ignition engine showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a method for controlling valve timing (intake valve closing timing).

FIG. 3 is a diagram showing an engine rotation-load map of a combustion system and a compression ratio.

FIG. 4 is a flowchart of control according to the first embodiment.

FIG. 5 is a time chart according to the first embodiment.

FIG. 6 is a flowchart of control according to the second embodiment.

FIG. 7 is a time chart according to the second embodiment.

FIG. 8 is a flowchart of control according to the third embodiment.

FIG. 9 is a time chart according to the third embodiment.

[Explanation of symbols]

1 Throttle valve 4 Fuel injection valve 5 intake valve 6 Combustion chamber 7 pistons 8 spark plugs 9 Exhaust valve 10 Compression ratio variable mechanism 11,12 Variable valve mechanism 13 ECU 14 Engine speed sensor 15 Accelerator position sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 15/02 F02D 15/02 C 41/02 351 41/02 351 41/04 360 360/04/04 360A 370 370 43/00 301 43/00 301A 301B 301K 301S 301Z F02P 5/15 F02P 5/15 B (72) Inventor Atsushi Terachi 2 Takaracho, Kanagawa-ku, Kanagawa Prefecture Nissan Motor Co., Ltd. F-term (reference) 3G022 DA02 DA04 EA02 EA07 GA01 GA08 3G023 AA06 AB06 AC02 AF01 3G084 AA00 BA05 BA13 BA16 BA17 BA23 DA11 DA38 EB08 FA10 FA38 3G092 AA01 AA05 AA11 AA12 AB02 BA09 BA10 DA01 DA03 DA04 DA05 DC01 DD04 DD05 DD06 DD07 DE01S EA01 EA04 EA11 EC09 FA07 FA16 HA06X HA13X HA14X HB01X HB01Z HC09X HE01Z HE03Z 3G301 HA01 HA19 JA03 JA04 JA11 JA21 JA22 KA12 KA15 KA16 KA19 KB10 L A01 LA07 LC08 MA11 NE01 NE12 PA11A PA11Z PB03A PC08A PE01Z PE09A PE09Z PE10A PE10Z

Claims (7)

[Claims] 1. A variable valve mechanism for changing a valve lift characteristic of an intake valve, and a variable compression ratio mechanism for changing a compression ratio, wherein a high compression ratio is provided when operating in a self-ignition combustion mode, and spark ignition is performed. In a control device for a self-ignition engine having a low compression ratio when operating in a combustion mode, the variable compression ratio mechanism changes from a high compression ratio state for self-ignition combustion mode to a low compression ratio state for spark ignition combustion mode. A control device for a self-ignition engine, wherein the variable valve mechanism is controlled to correct the intake valve closing timing to a retard side during a compression ratio switching process that is changing toward. 2. The control apparatus for the self-ignition engine according to claim 1, wherein the correction of the intake valve closing timing is started at the same time when the state change of the variable compression ratio mechanism starts. 3. The self-ignition engine according to claim 1, wherein the retard amount of the intake valve closing timing is reduced as the compression ratio state approaches the low compression ratio state for spark ignition combustion mode. . 4. The method according to claim 1, wherein in the compression ratio switching process, the intake valve closing timing is corrected to the retard side and the ignition timing is corrected to the retard side. Of the self-ignition engine according to item 1. 5. The control apparatus for a self-ignition engine according to claim 4, wherein in the compression ratio switching process, the ignition timing retard amount is increased as the compression ratio is higher. 6. The method according to claim 1, wherein in the compression ratio switching process, the intake valve closing timing is corrected to the retard side and the fuel injection amount is increased and corrected.
Of the self-ignition engine according to item 1. 7. The method according to claim 1, wherein in the compression ratio switching process, the intake valve closing timing is corrected to the retard side and the throttle valve is closed by a predetermined amount. Self-ignition engine controller.