JP2001289095A - Fuel injection quantity control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection quantity control device for an internal combustion engine, capable of suppressing the generation of step difference in generated engine torque between uniform combustion operation and stratified combustion operation in the same engine operating state. SOLUTION: When ignition timing is corrected to the delay side by a delay quantity RTD to suppress knocking during uniform combustion operation, the output torque of the engine 11 during uniform combustion operation is lowered following the delay correction of the ignition timing. During stratified combustion operation in the same engine operating state, the fuel injection quantity is corrected to the decrease side by the portion corresponding to the delay quantity RD, and output torque during stratified combustion operation is also lowered corresponding to the output torque lowered during uniform combustion ration. Consequently, generated output torque is restrained from being different from each other between the stratified combustion operation and uniform combustion operation in the same engine operating state when the ignition timing is delay-corrected during the uniform combustion operation to suppress knocking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, in internal combustion engines for automobiles,
In order to achieve both improvement in fuel efficiency and obtaining required engine output, an internal combustion engine of a type that switches a combustion mode between homogeneous combustion and stratified combustion according to the engine operating state has been put to practical use. . When a high output is required, such a type of internal combustion engine performs a homogeneous combustion in which a homogeneous mixture in which fuel is evenly mixed with air is burned,
Ensure necessary engine output. On the other hand, when a very high output is not required, a stratified mixture is formed in which only the vicinity of the ignition plug becomes a combustible mixture, and the stratified mixture is burned to perform stratified combustion, thereby improving the fuel efficiency of the internal combustion engine. I try to plan.

In an internal combustion engine in which the combustion mode is switched, if a step occurs in the engine torque between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state,
Drivability is deteriorated due to the torque step. Therefore, during the stratified charge combustion operation in which the engine torque is controlled by controlling the fuel injection amount, the fuel injection amount is set so as not to cause the above-described torque step.

[0004]

Incidentally, even in an internal combustion engine of a type in which the combustion mode is switched, as shown in, for example, JP-A-10-61482 and JP-A-10-159624, knocking occurs during homogeneous combustion operation. When this occurs, the ignition timing is retarded and the knocking is suppressed. However, if the ignition timing is changed to the retard side to suppress knocking during the homogeneous combustion operation, the engine torque during the homogeneous combustion operation changes with the change in the ignition timing. As a result, the generated engine torque is different between the homogeneous combustion operation and the stratified combustion operation under the same engine operating state, and the above-described torque step occurs, which may cause deterioration in drivability. is there.

The present invention has been made in view of such circumstances, and has as its object to reduce the engine torque generated between homogeneous combustion operation and stratified combustion operation under the same engine operation state. An object of the present invention is to provide a fuel injection amount control device for an internal combustion engine that can suppress the occurrence of a step.

[0006]

The means for achieving the above object and the effects thereof will be described below. In order to achieve the above object, the invention according to claim 1 is applied to an internal combustion engine whose combustion mode is switched between homogeneous combustion and stratified combustion, and an injection amount command calculated based on the engine operating state during stratified combustion operation. In the fuel injection amount control device for the internal combustion engine that controls the fuel injection amount of the internal combustion engine based on the value and adjusts the engine torque, when knocking occurs during the homogeneous combustion operation, the engine control amount used for the operation control of the internal combustion engine is determined. Changing means for changing the direction in which knocking is suppressed; and the injection amount command so as to change the engine torque in the stratified combustion operation in response to the change in the engine torque in the homogeneous combustion operation accompanying the change in the engine control amount. Correction means for correcting the value.

[0007] According to the above configuration, when the engine control amount is changed to suppress knocking during the homogeneous combustion operation, the engine torque during the homogeneous combustion operation is changed in accordance with the change in the engine control amount. The engine torque when the stratified charge combustion operation is performed under the same engine operation state at this time also changes due to the correction of the injection amount command value. Therefore, between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state, it is possible to suppress the occurrence of a step in the generated engine torque, and to suppress the deterioration of the operability due to the torque step. be able to.

According to a second aspect of the present invention, in the first aspect of the present invention, the correction means determines the injection amount command value based on a change amount of the engine control amount during the homogeneous combustion operation changed by the change means. Correction was performed.

According to the above configuration, the stratified charge combustion operation is performed under the same engine operation state as the change in the engine torque according to the change in the engine control amount during the homogeneous combustion operation by the change means. The engine torque at the time of the occurrence can be accurately changed. Therefore, when the engine control amount is changed by the changing means, the occurrence of a step in the generated engine torque between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state is more accurately suppressed. be able to.

According to the third aspect of the present invention, the first or second aspect is provided.
In the invention described in the description, even when knocking occurs during stratified combustion operation, the changing means changes the engine control amount in a direction in which knocking is suppressed, and the correction means performs the stratified combustion operation. When the engine control amount is changed to suppress knocking, the injection amount command value is corrected so as to suppress a change in engine torque during stratified combustion operation due to the change in the engine control amount.

[0011] Even when knocking occurs during stratified charge combustion operation, the engine control amount is changed to suppress the knocking. However, the engine torque during stratified charge combustion operation changes with this change in engine control amount, and the same engine There may be a step in the generated engine torque between the stratified combustion operation and the homogeneous combustion operation under the operating state. However, according to the above configuration, when the engine control amount is changed to suppress knocking during the stratified charge combustion operation, the change in the engine torque during the stratified charge combustion operation due to the change in the engine control amount is suppressed. It is possible to suppress the occurrence of the torque step as described above.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the correction means is configured to change the injection amount command value based on a change amount of the engine control amount during the stratified combustion operation changed by the change means. Correction was performed.

According to the above arrangement, the injection amount command value during stratified combustion operation is accurately corrected so as to suppress a change in engine torque due to a change in engine control amount during stratified combustion operation by the change means. Can be.

According to a fifth aspect of the present invention, in accordance with any one of the first to fourth aspects of the present invention, the intake air of the internal combustion engine when the homogeneous combustion operation is performed under the engine operation state during the stratified combustion operation. A calculation means is provided for estimating the amount and calculating an injection amount command value during stratified combustion operation based on the estimated intake air amount.

According to the above configuration, the injection amount command value during the stratified charge combustion operation is calculated based on the estimated intake air amount, and the fuel injection amount is controlled based on the injection amount command value, whereby the stratified charge combustion is controlled. The engine torque during operation is adjusted. Further, during the homogeneous combustion operation, the engine torque is adjusted by controlling the fuel injection amount according to the intake air amount of the internal combustion engine. As described above, in both the stratified combustion operation and the homogeneous combustion operation, the fuel injection amount is controlled in accordance with the intake air amount, and the engine torque is adjusted by controlling the fuel injection amount. Therefore, the parameters used for controlling the engine torque in the stratified combustion operation and the homogeneous combustion operation are the same, and the engine torque during the engine transition is changed between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state. It is possible to accurately adjust the torque including the change characteristics of the torque.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an in-cylinder spark ignition type automobile engine will be described below with reference to FIGS.

As shown in FIG. 1, in an engine 11, a piston 12 is connected to a crankshaft 14 via a connecting rod 13.
Is converted into rotation of the crankshaft 14 by the connecting rod 13. Signal rotor 1 having a plurality of protrusions 14b on crankshaft 14
4a is attached. And the signal rotor 1
A crank position sensor 14c that outputs a pulse signal corresponding to each of the protrusions 14b when the crankshaft 14 rotates is provided on the side of 4a.

An intake passage 32 and an exhaust passage 33 are connected to the combustion chamber 16 of the engine 11. Intake passage 32
And the combustion chamber 16, and between the exhaust passage 33 and the combustion chamber 16 are opened and closed by opening and closing the intake valve 19 and the exhaust valve 20. The opening and closing drive of the intake valve 19 and the exhaust valve 20 is performed by the rotation of the intake camshaft 21 and the exhaust camshaft 22 to which the rotation of the crankshaft 14 is transmitted. A cam position sensor 21b is provided on a side of the intake camshaft 21. Then, each time a protrusion 21a formed on the intake camshaft 21 passes by the side of the cam position sensor 21b with the rotation of the intake camshaft 21, a detection signal is output from the cam position sensor 21b.

In the intake passage 32, a throttle valve 23 for adjusting an intake air amount of the engine 11 is provided at an upstream portion thereof. The opening of the throttle valve 23 is adjusted by controlling the drive of a throttle motor 24 in accordance with the depression operation of an accelerator pedal 25 provided in the interior of the vehicle. The depression amount of the accelerator pedal 25 (acceleration depression amount) is detected by an accelerator position sensor 26. Further, a vacuum sensor 36 for detecting the pressure (intake pressure) in the intake passage 32 is provided downstream of the throttle valve 23 in the intake passage 32.

The engine 11 has a fuel injection valve 40 for directly injecting and supplying fuel into the combustion chamber 16 to form a mixture comprising fuel and air, and an ignition for igniting the mixture in the combustion chamber 16. A plug 41 is provided. The ignition timing of the air-fuel mixture by the ignition plug 41 is adjusted by an igniter 41 a provided above the ignition plug 41.
When the air-fuel mixture in the combustion chamber 16 is ignited and burns, the combustion energy at this time causes the piston 12 to reciprocate and the crankshaft 14 to rotate. In addition, the engine 11 sometimes includes a knock sensor 11c which detects knocking due to spontaneous ignition of the air-fuel mixture after ignition by the spark plug 41.

In the engine 11 configured as described above, the combustion mode is switched between homogeneous combustion and stratified combustion in accordance with the operating state of the engine. That is, during a high rotation and a high load where a high output is required, the combustion chamber 1
6 to form a homogeneous mixture in which fuel is evenly mixed with air, and the homogeneous mixture is burned to perform high-output homogeneous combustion. Is done. In such a homogeneous combustion operation, the air-fuel ratio of the air-fuel mixture is set to the stoichiometric air-fuel ratio.

At the time of low rotation and low load, which does not require a very high output, by injecting fuel toward the combustion chamber 16 during the compression stroke, a stratified layer in which only the periphery of the ignition plug 41 becomes a combustible mixture. A stratified combustion is executed by forming an air-fuel mixture and burning the same stratified air-fuel mixture. In such a stratified combustion operation, combustion of the air-fuel mixture is performed in a state where the air-fuel ratio of the entire stratified air-fuel mixture is significantly leaner than the stoichiometric air-fuel ratio. Therefore, the throttle opening can be controlled to the opening side as compared with the homogeneous combustion operation, and the pumping loss of the engine 11 can be reduced.

Next, the electrical configuration of the fuel injection amount control device according to the present embodiment will be described with reference to FIG. This fuel injection amount control device includes an electronic control unit (hereinafter, referred to as an ECU) 92 for controlling the operation state of the engine 11 such as throttle opening control, fuel injection control, and ignition timing control. This ECU 92 has a ROM 9
3, CPU 94, RAM 95, and backup RAM
It is configured as an arithmetic and logic operation circuit having 96 or the like.

Here, the ROM 93 is a memory that stores various control programs and maps that are referred to when the various control programs are executed.
The arithmetic processing is executed based on various control programs and maps stored in the OM 93. The RAM 95 is a CPU
94 is a memory for temporarily storing the calculation result at 94, data input from each sensor, and the like.
Reference numeral 6 denotes a non-volatile memory for storing data and the like stored when the engine 11 is stopped. And ROM9
3. CPU 94, RAM 95 and backup RAM 9
6 are connected to each other via a bus 97, and are also connected to an external input circuit 98 and an external output circuit 99.

The external input circuit 98 includes a knock sensor 11
c, a crank position sensor 14c, a cam position sensor 21b, an accelerator position sensor 26, a vacuum sensor 36, and the like. The external output circuit 99 is connected to the throttle motor 24, the fuel injection valve 40, the igniter 41a, and the like.

The ECU 92 configured as described above determines the accelerator depression amount ACCP based on the detection signal from the accelerator position sensor 26, and controls the drive of the throttle motor 24 based on the accelerator depression amount ACCP to open the throttle valve 23. Perform control. By such throttle opening control, under the same accelerator depression amount ACCP, the throttle opening during the stratified combustion operation becomes an open value compared to the throttle opening during the homogeneous combustion operation.

The ECU 92 determines the engine speed N based on a detection signal from the crank position sensor 14c.
E is obtained, and the intake pressure PM is obtained based on the detection signal from the vacuum sensor 36. This intake pressure PM is
As described above, the value changes in accordance with the throttle opening controlled based on the accelerator depression amount ACCP, and becomes a value corresponding to the amount of air (the amount of intake air) drawn into the combustion chamber 16 through the intake passage 32. .

During the homogeneous combustion operation, the fuel injection amount is controlled on the basis of the load factor KL and the engine speed NE, whereby the output torque of the engine 11 is adjusted. The load factor KL is calculated as a value indicating the current load ratio with respect to the maximum engine load by referring to a map or the like based on the intake pressure PM and the engine speed NE. Therefore, during the homogeneous combustion operation, the output torque of the engine 11 changes as the intake pressure PM changes according to the depression operation of the accelerator pedal 25.

Also, during the stratified charge combustion operation, the fuel injection amount is controlled based on the load factor KL and the engine speed NE, whereby the output torque of the engine 11 is adjusted. However, during the stratified combustion operation, the intake pressure PM (intake air amount) when the homogeneous combustion operation is performed with the accelerator depression amount ACCP during the stratified combustion operation is estimated. Then, the estimated intake pressure PM is set as a virtual intake pressure PMv, and the virtual intake pressure P
Based on Mv and the engine speed NE, the load factor KL is calculated with reference to the map. Therefore, during the stratified charge combustion operation, the output torque of the engine 11 changes as the virtual intake pressure PMv changes according to the depression operation of the accelerator pedal 25.

As described above, in both the homogeneous combustion operation and the stratified combustion operation, the fuel injection amount is controlled using the same parameter as the intake pressure (intake air amount), and the control of the engine 11 is performed by controlling the fuel injection amount. The output torque is adjusted. Therefore, the engine 11 is switched between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state such as the accelerator depression amount ACCP and the engine speed NE.
Can be accurately adjusted, including the output torque change characteristics during excessive engine operation.

Next, a procedure for calculating the target ignition timing SAt used for controlling the ignition timing of the engine 11 will be described with reference to a flowchart of FIG. 3 showing an ignition timing calculation routine. The ignition timing calculation routine is executed by the ECU 92 at, for example, an angle interruption every predetermined crank angle.

The target ignition timing SAt is obtained by the following equation (1) based on a basic ignition timing SAbse, a retard amount RTD, and other correction amounts B, which will be described later, in step S111 in the ignition timing calculation routine. Is calculated.

SAt = SAbse−RTD + B (1) In the equation (1), the basic ignition timing SAbse is obtained by the processing in step S102 or the processing in step S105.
It is calculated based on the engine operating state for each combustion mode of the engine 11. The retard amount RTD is used to correct the target ignition timing SAt to a value on the retard side when knocking occurs.
Alternatively, it is calculated in the processing of steps S106 and S107. The ECU 92 determines the target ignition timing SAt, the crank position sensor 14c and the cam position sensor 2
The drive of the igniter 41a is controlled based on the detection signal from 1b, and the ignition timing of the air-fuel mixture by the ignition plug 41 is controlled.

In the ignition timing calculation routine, the ECU 9
2 judges whether or not stratified charge combustion is being executed as the process of step S101. If it is determined in step S101 that homogeneous combustion operation is being performed instead of stratified combustion operation, the process proceeds to step S105, and a basic ignition timing SAbse for homogeneous combustion is calculated based on the engine speed NE and the load factor KL. . This load factor KL is calculated based on the engine speed NE and the intake pressure PM.

Subsequently, the ECU 92 performs the process of step S106, based on the detection signal (knock signal) from the knock sensor 11c, for the retard amount RTD of the ignition timing for homogeneous combustion.
Calculate S. The ignition timing retard amount RTDS is determined by the target ignition timing SAt for homogeneous combustion when knocking occurs.
Is corrected to a value on the retard side. When it is determined that knocking has occurred based on the knock signal, a predetermined value a is added to the retard amount RTDS stored so far. As a result, the retard amount RTDS changes by the predetermined value a in the direction of changing the target ignition timing SAt for homogeneous combustion to a value on the retard side. When it is determined based on the knock signal that knocking has not occurred, a predetermined value a is subtracted from the previously stored retard amount RTDS. As a result, the retard amount RTDS changes by the predetermined value a in a direction in which the homogeneous ignition target ignition timing SAt is changed to a value on the advance side.

Therefore, when knocking occurs, the retard amount R
The TDS increases by a predetermined value a every predetermined period, and the target ignition timing SAt gradually changes to a value on the retard side. By gradually changing the target ignition timing SAt to the retard side in this way, the ignition timing is retarded and knocking is suppressed. When knocking has not occurred, the retard amount RTDS decreases by a predetermined value a at predetermined intervals, and the target ignition timing SAt gradually changes to a value on the advance side. By gradually changing the target ignition timing SAt to the advance side in this way, the correction of the ignition timing to the retard side becomes gradually smaller.

In the processing of step S105, the retard amount RTDS
After the change, the process proceeds to step S107. ECU 92
Performs a guard process of the retard amount RTDS so that the retard amount RTDS does not become excessively large or small as the process of step S107, and stores and updates the retard amount RTDS after the guard process. Proceed to step S108.

On the other hand, if it is determined in step S101 that the stratified combustion operation is being performed, step S101 is executed.
Proceed to 102. The ECU 92 calculates the basic ignition timing SAbse for stratified combustion based on the engine speed NE and the load factor KL as the process of step S102. This load factor KL is calculated based on the engine speed NE and the virtual intake pressure PMv.

The ECU 92 calculates the retardation amount RTDT of the ignition timing for stratified charge combustion based on the knock signal as the process of the subsequent step S103. This ignition timing retard amount RT
DT is for correcting the target ignition timing SAt for stratified combustion to a value on the retard side when knocking occurs,
When it is determined based on the knock signal that knocking has occurred, a predetermined amount b is added to the previously stored retard amount RTDT. As a result, the retard amount RTDT changes by the predetermined value b in a direction to change the target ignition timing SAt for stratified combustion to a value on the retard side. When it is determined that knocking has not occurred based on the knock signal, a predetermined value b is subtracted from the retard amount RTDT stored so far. As a result, the retard amount RTDT changes by the predetermined value b in a direction to change the target ignition timing SAt for stratified combustion to a value on the advance side.

Therefore, when knocking occurs, the retard amount R
The TDT increases by a predetermined value b every predetermined period, and the target ignition timing SAt gradually changes to a value on the retard side. By gradually changing the target ignition timing SAt to the retard side in this way, the ignition timing is retarded and knocking is suppressed. When knocking has not occurred, the retard amount RTDT decreases by a predetermined value b at predetermined intervals, and the target ignition timing SAt gradually changes to a value on the advance side. By gradually changing the target ignition timing SAt to the advance side in this way, the correction of the ignition timing to the retard side becomes gradually smaller.

Subsequently, the ECU 92 performs a guard process for the retard amount RTDT so that the retard amount RTDT does not become excessively large or small as the process of step S104, and the retard amount RTDT after the guard process. Then, the process proceeds to step S108.

The ECU 92 determines whether or not stratified charge combustion is being performed as the process of step S108. If the stratified combustion operation is being performed, the retard amount RTDT at that time is set as the retard amount RTD in the process of step S109, and thereafter, the process proceeds to step S111. If the stratified combustion operation is not being performed, the retard amount RTDS at that time is set as the retard amount RTD in the process of step S110, and thereafter, the process proceeds to step S111. The ECU 92 determines in step S
In step 111, the target ignition timing S is calculated based on the above equation (1).
After calculating At, the ignition timing calculation routine is temporarily terminated.

If the ignition timing is corrected based on the retard amount RTD to suppress knocking during the homogeneous combustion operation, the output torque of the engine 11 during the homogeneous combustion operation decreases. Become. as a result,
The output torque generated by the engine 11 is different between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state, and the torque step between the combustion modes under the same engine operation state is different. Occurs and driving performance deteriorates.

Therefore, in the present embodiment, during stratified charge combustion operation, the fuel injection amount is reduced and corrected on the basis of the retard amount RTD during the homogeneous combustion operation, and during the homogeneous combustion operation accompanying the retard correction of the ignition timing by the same delay amount RTD. Corresponding to the decrease in output torque of
Reduce output torque during stratified combustion operation. As a result, a step is prevented from occurring in the output torque generated by the engine 11 between the homogeneous combustion operation and the stratified combustion operation under the same engine operating state, and the operability is deteriorated due to the torque step. Can be suppressed.

Further, the retard correction of the ignition timing for suppressing the occurrence of knocking is performed not only during the homogeneous combustion operation but also during the stratified combustion operation. RT during the stratified combustion operation
When the ignition timing is retarded based on D, the output torque of the engine 11 during the stratified combustion operation decreases accordingly. As a result, a step occurs in the generated output torque between the homogeneous combustion operation and the stratified combustion operation under the same engine operating state, and the operability deteriorates.

Therefore, in the present embodiment, during the stratified charge combustion operation, the fuel injection amount is increased and corrected based on the retard amount RTD during the stratified charge combustion operation, and the stratification accompanying the ignition timing retard correction based on the retarded amount RTD is performed. Suppress a decrease in output torque during combustion operation. As a result, a step is prevented from occurring in the output torque generated by the engine 11 between the homogeneous combustion operation and the stratified combustion operation under the same engine operating state, and the operability is deteriorated due to the torque step. Can be suppressed.

Next, a procedure for calculating the final fuel injection amount Qfin used for controlling the fuel injection amount of the engine 11 will be described with reference to a flowchart of FIG. 4 showing a fuel injection amount calculation routine. The fuel injection amount calculation routine is executed by the ECU 9
2 through, for example, an angle interrupt for each predetermined crank angle.

The final fuel injection amount Qfin is determined by the following formula based on a basic fuel injection amount Qbse, a correction amount h2, a correction coefficient h1, and other correction amounts A, which will be described later, in step S210 in the fuel injection amount calculation routine. It is calculated using (2).

Qfin = (Qbse + h2) * h1 (2) In the equation (2), the basic fuel injection amount Qbse is determined by the processing in steps S202 and S203 or step S20.
6. In the processing of S207, it is calculated based on the engine operating state for each combustion mode of the engine 11. The correction coefficient h1
Is for correcting the final fuel injection amount Qfin to a value on the decrease side based on the retard amount RTD during the homogeneous combustion operation. Further, the correction amount h2 is the retardation amount RT during the stratified combustion operation.
This is for correcting the final fuel injection amount Qfin to a value on the increasing side based on D. The ECU 92 controls the drive of the fuel injection valve 40 based on the final fuel injection amount Qfin, and
6 is controlled.

In the fuel injection amount calculation routine, the ECU
92 determines whether or not stratified combustion is being executed as the process of step S201. When it is determined that the engine is in the homogeneous combustion operation instead of the stratified combustion operation, the process proceeds to step S206. The ECU 92 calculates the load factor KL based on the intake pressure PM and the engine speed NE in the process of step S206. The ECU 92 proceeds to step S20.
In the process of 7, the basic fuel injection amount Q for homogeneous combustion is referred to with reference to a map based on the load factor KL and the engine speed NE.
Calculate bse.

Subsequently, the ECU 92 sets the correction coefficient h1 to "1.0" in step S208,
In step 209, the correction amount h2 is set to “0”. Thereafter, the process proceeds to step S210. The ECU 92 calculates the final fuel injection amount Qfin based on the above equation (2) as the process of step S210, and then temporarily ends the fuel injection amount calculation routine. During the homogeneous combustion operation, the correction coefficient h1
Becomes "1.0" and the correction amount h2 becomes "0", so that the final fuel injection amount Qfin is not corrected according to the retard amount RTD.

On the other hand, if it is determined in step S201 that the stratified charge combustion operation is being performed, the routine proceeds to step S201.
Proceed to 202. The ECU 92 calculates the load factor KL based on the virtual intake pressure PMv as the intake pressure when the homogeneous combustion operation is performed in the engine operating state at this time (at the time of stratified combustion operation) and the engine speed NE as the process of step S202. I do. The ECU 92 calculates the basic fuel injection amount Qbse for stratified combustion with reference to a map based on the load factor KL and the engine speed NE as the process of the subsequent step S203.

The map for calculating the basic fuel injection amount Qbse for stratified combustion is based on the basic fuel injection amount Qbs for homogeneous combustion.
A different map from that used to calculate e is used.
Under the condition that the load factor KL and the engine speed NE are the same, the basic fuel injection amount Qbse for stratified combustion becomes smaller than the basic fuel injection amount Qbse for homogeneous combustion. This is because in the stratified combustion operation, pump loss and cooling loss are reduced and the combustion efficiency is increased as compared with the homogeneous combustion operation, and the fuel injection amount required to obtain a predetermined output torque is smaller than in the homogeneous combustion operation. It is because it becomes.

After calculating the basic fuel injection amount Qbse for stratified combustion in the process of step S203, the process proceeds to step S204. The ECU 92 performs the process of step S204 as follows:
Based on the retard amount RTDS (the retard amount RTD during the homogeneous combustion operation), a correction coefficient h1 for correcting the fuel injection amount to decrease is calculated. For example, as shown in FIG. 5, the correction coefficient h1 calculated in this manner changes to a value smaller than "1.0" as the retard amount RTDS becomes a value that retards the ignition timing.

Accordingly, as the retard amount RTDS becomes a value that retards the ignition timing and the output torque during the homogeneous combustion operation decreases, the fuel injection amount (final fuel injection amount Qfin) during the stratified combustion operation decreases. The output torque is corrected to the decrease side, and the output torque during the stratified combustion operation also decreases. That is, when the ignition timing is corrected for retarding the ignition timing to suppress knocking during the homogeneous combustion operation, the output torque during the homogeneous combustion operation decreases, but the output when the stratified combustion operation is performed in the engine operating state at this time is reduced. The torque also decreases as the output torque during the homogeneous combustion operation decreases.

After calculating the correction coefficient h1 in the process of step S204, the process proceeds to step S205. The ECU 92
In step S205, a correction amount h2 for increasing and correcting the fuel injection amount is calculated based on the retard amount RTD at that time (at the time of stratified combustion operation). The correction amount h2 calculated in this way is, for example, as shown in FIG.
The value becomes larger than “0” as the value on the side that retards the ignition timing is increased.

Therefore, the fuel injection amount (final fuel injection amount Qfin) during the stratified charge combustion operation is corrected to a larger increase as the retard amount RTD during the stratified charge combustion operation becomes a value that retards the ignition timing. Become like As a result, when the ignition timing is corrected to retard knocking during the stratified charge combustion operation, the output torque during the stratified charge combustion operation decreases due to this.
The fuel injection amount during the stratified charge combustion operation is accurately suppressed by the increase correction.

After calculating the correction amount h2 in the process of step S205, the process proceeds to step S210. The ECU 92 calculates the final fuel injection amount Qfin based on the above equation (2) as the process of step S210, and then temporarily ends the fuel injection amount calculation routine.

According to the present embodiment in which the processing described in detail above is performed, the following effects can be obtained. (1) In the stratified charge combustion operation, the final fuel injection amount Qfin is corrected to the decreasing side by the correction coefficient h1 by an amount corresponding to the ignition timing retard amount RTD (retard amount RTDS) in the homogeneous combustion operation. Therefore, when the ignition timing is retarded to suppress knocking during the homogeneous combustion operation, the same engine operation is performed in response to the decrease in the output torque during the homogeneous combustion operation accompanying the retardation of the ignition timing. The output torque when the stratified charge combustion operation is executed in this state is reduced by the correction for decreasing the final fuel injection amount Qfin. Therefore, when the ignition timing is retarded for suppressing knocking during the homogeneous combustion operation, the output torque generated between the homogeneous combustion operation and the stratified combustion operation under the same engine operating condition is mutually different. Being different is suppressed. Therefore, it is possible to suppress the occurrence of a step in the output torque generated between the combustion modes under the same engine operating state, and to suppress the deterioration in operability due to the torque step.

(2) The correction coefficient h1 is determined by the retard amount RTD.
As S becomes a value that retards the ignition timing, the retard amount R becomes larger.
The final fuel injection amount Qfin becomes a value on the side of decreasing the amount according to the TDS. Therefore, in response to the decrease in the output torque during the homogeneous combustion operation corresponding to the retard amount RTD of the ignition timing, the output torque at the time of performing the stratified combustion operation in the same engine operating state at this time is used as the fuel injection amount. Can be accurately reduced by the weight reduction correction.

(3) In the stratified charge combustion operation, the final fuel injection amount Qfin is increased by the correction amount h2 by an amount corresponding to the retard amount RTD of the ignition timing in the stratified charge combustion operation. Therefore, when the ignition timing is retarded to suppress knocking during the stratified charge combustion operation, a decrease in output torque during the stratified charge combustion operation due to the retardation correction of the ignition timing is suppressed by increasing the fuel injection amount. . Therefore, when the ignition timing is retarded for suppressing knocking during the stratified charge combustion operation, the output torque generated between the homogeneous combustion operation and the stratified charge combustion operation under the same engine operating condition is mutually different. Being different is suppressed. for that reason,
It is possible to suppress the occurrence of a step in the output torque generated between the combustion modes under the same engine operating state, and to suppress the deterioration of the operability due to the torque step.

(4) The correction amount h2 increases the final fuel injection amount Qfin in accordance with the retard amount RTD as the retard amount RTD during the stratified charge combustion operation becomes a value that retards the ignition timing. Side value. Therefore, the ignition timing retard amount RT
The decrease in the output torque during the stratified charge combustion operation corresponding to D can be accurately suppressed by increasing the fuel injection amount during the stratified charge combustion operation.

(5) In the homogeneous combustion operation, the final fuel injection amount Qfin (basic fuel injection amount Qbse) is calculated based on the intake pressure PM that changes according to the accelerator depression amount ACCP (throttle opening). The output torque is adjusted by controlling the fuel injection amount based on the injection amount Qfin. Further, during the stratified combustion operation, the intake pressure P when the homogeneous combustion operation is executed with the accelerator depression amount ACCP at that time.
M is calculated as the virtual intake pressure PMv, and the accelerator depression amount A
Based on the virtual intake pressure PMv and the like that changes according to the CCP,
The final fuel injection amount Qfin (basic fuel injection amount Qbse) is calculated. Then, by controlling the fuel injection amount based on the final fuel injection amount Qfin, the output torque of the engine 11 during the stratified charge combustion operation is adjusted. As described above, in both the homogeneous combustion operation and the stratified combustion operation, the fuel injection amount is controlled according to the intake pressure (intake air amount), and the output torque is controlled by controlling the fuel injection amount. Therefore, the parameters used for controlling the output torque in the homogeneous combustion operation and the stratified combustion operation become the same,
The output torque can be accurately adjusted between the homogeneous combustion operation and the stratified combustion operation under the same engine operation state, including the change characteristic of the torque during engine transition.

The present embodiment can be modified, for example, as follows. In the present embodiment, during the stratified charge combustion operation, the basic fuel injection amount Qbse is calculated based on the virtual intake pressure PMv and the like, so that there is no step in the output torque between the combustion modes in the same engine operating state. It is not always necessary to use the virtual intake pressure PMv for calculating the fuel injection amount Qbse. For example, between the stratified charge combustion operation and the homogeneous charge combustion operation under the same engine operation state, the accelerator pedal depression amount ACCP or the like is referred to by referring to a map that is set in advance so that a step does not occur in the generated output torque. Based on the above, the basic fuel injection amount Qbse may be calculated.

In the present embodiment, the correction coefficient h1 for reducing the fuel injection amount during the stratified combustion operation is calculated based on the ignition timing retard amount RTD (retard amount RTDS) during the homogeneous combustion operation. However, the present invention is not limited to this. For example, the amount of decrease in output torque due to the ignition timing retard correction during the homogeneous combustion operation may be determined, and the correction coefficient h1 may be calculated based on the amount of decrease in output torque.

In the present embodiment, the fuel injection amount during the stratified combustion operation is increased and corrected by the correction amount h2 calculated based on the retard amount RTD during the stratified combustion operation. It is not always necessary to carry out the increase correction.

In the present embodiment, the knocking during the homogeneous combustion operation is suppressed by the retard correction of the ignition timing. Instead, the fuel injection amount is increased and the air-fuel ratio is made richer than the stoichiometric air-fuel ratio (for example, The knocking may be suppressed by setting “12”). In this case, by increasing and correcting the fuel injection amount during the stratified charge combustion operation to increase the output torque, it is possible to suppress the occurrence of a step in the output torque between the combustion modes under the same engine operation state. This is because, when the fuel injection amount is increased and corrected to suppress knocking during the homogeneous combustion operation, the output torque during the homogeneous combustion operation increases, and the output torque during the homogeneous combustion operation increases. This is because it is necessary to increase the output torque when performing the stratified combustion operation in the operating state.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an entire engine to which a fuel injection amount control device according to an embodiment is applied.

FIG. 2 is a block diagram showing an electrical configuration of the fuel injection amount control device.

FIG. 3 is a flowchart showing a procedure for calculating a target ignition timing SAt.

FIG. 4 is a flowchart showing a procedure for calculating a final fuel injection amount Qfin.

FIG. 5 is a graph showing a transition tendency of a correction coefficient h1 with respect to a change in a retard amount RTDS.

FIG. 6 is a graph showing a transition tendency of a correction amount h2 with respect to a change in a retard amount RTD.

[Explanation of symbols]

11: engine, 11c: knock sensor, 14c: crank position sensor, 21b: cam position sensor, 26: accelerator position sensor, 36: vacuum sensor, 40: fuel injection valve, 41: spark plug, 41
a: igniter, 92: electronic control unit (ECU).

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Takayuki Demura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G084 AA04 BA13 BA17 DA11 FA10 FA11 FA25 FA33 FA38 3G301 HA01 HA04 HA16 JA04 LA00 LA03 LB04 PA07Z PC08Z PE01Z PE03Z PF03Z

Claims (5)

[Claims] The present invention is applied to an internal combustion engine in which a combustion mode is switched between homogeneous combustion and stratified combustion. During a stratified combustion operation, a fuel injection amount of the internal combustion engine is determined based on an injection amount command value calculated based on an engine operating state. In a fuel injection amount control device for an internal combustion engine that controls and adjusts engine torque, when knocking occurs during homogeneous combustion operation, the engine control amount used for operation control of the internal combustion engine is changed in a direction to suppress knocking Means, and correction means for correcting the injection amount command value so that the engine torque in the stratified combustion operation changes in response to the change in the engine torque in the homogeneous combustion operation accompanying the change in the engine control amount. A fuel injection amount control device for an internal combustion engine, comprising: 2. The fuel injection amount for an internal combustion engine according to claim 1, wherein said correction means corrects said injection amount command value based on a change amount of an engine control amount during the homogeneous combustion operation changed by said change means. Control device. 3. The striking means changes the engine control amount in a direction in which knocking is suppressed even when knocking occurs during stratified charge combustion operation. 3. The injection amount command value is corrected so that, when the engine control amount is changed to suppress knocking, a change in engine torque during stratified combustion operation accompanying the change in the engine control amount is suppressed. Control device for an internal combustion engine. 4. The fuel injection amount of an internal combustion engine according to claim 3, wherein the correction means corrects the injection amount command value based on a change amount of the engine control amount during the stratified combustion operation changed by the change means. Control device. 5. A fuel injection amount control apparatus for an internal combustion engine according to claim 1, wherein the intake of the internal combustion engine when the homogeneous combustion operation is performed under the engine operation state during the stratified combustion operation. A fuel injection amount control device for an internal combustion engine, comprising: calculation means for estimating an air amount and calculating an injection amount command value during stratified combustion operation based on the estimated intake air amount.