JP2002054542A - Control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In both a uniform combustion mode and a stratified combustion mode, a combustion parameter such as an ignition timing can be appropriately obtained according to an operation state or a combustion state, and thereby a stable combustion state can be obtained. To provide a control device for an in-cylinder injection type internal combustion engine that can ensure the above. SOLUTION: An ECU 2 of a control device 1 of an in-cylinder injection type internal combustion engine 3 is used for a uniform combustion mode and a stratified combustion mode in accordance with a load (an engine speed NE, a required torque PME, and an absolute intake pressure PBA) of the internal combustion engine 3 Target air-fuel ratio coefficient KCMD for combustion mode, target valve lift amount LCMD, fuel injection timing θinj, injection end timing IJLOGH, IJL
The OGH is determined (steps 13 to 15), the basic map value IGMAPm for the ignition timing for the uniform combustion mode is determined according to the load (steps 232 and 234), and the basic map value IGMAPm for the stratified combustion mode is determined. It is determined according to the injection end timing IJLOGD for combustion (step 235).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection system operated by switching a combustion mode between a uniform combustion mode in which fuel injection into a cylinder is performed during an intake stroke and a stratified combustion mode during a compression stroke. The present invention relates to a control device for an internal combustion engine that controls ignition timing, fuel injection amount, and the like of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as this type of control device, for example, a control device described in Japanese Patent Application Laid-Open No. H11-47111 is known. In this control device, the volumetric efficiency is obtained based on the intake air amount, and the engine load (target average effective pressure) is obtained.
Is obtained based on the accelerator opening and the engine speed, and the combustion mode is switched between the stratified combustion mode and the uniform combustion mode according to the engine speed and the load. In the stratified combustion mode, the combustion parameters of the target air-fuel ratio, the fuel injection timing, the ignition timing, and the target EGR amount are based on the engine speed and load. In the uniform combustion mode, the combustion parameters are based on the engine speed and volumetric efficiency. Respectively by searching the map.

[0003]

Generally, in an in-cylinder injection type internal combustion engine, in order to improve fuel efficiency and exhaust gas characteristics, the EGR amount is set to a larger value in the stratified combustion mode than in the uniform combustion mode. In addition to the control, the intake pipe internal pressure is controlled to a high value close to the atmospheric pressure. That is, E
The opening degree of the GR control valve and the opening degree of the throttle valve are controlled to large values. For this reason, when the combustion mode shifts from the stratified combustion mode to the uniform combustion mode, the target values of the EGR amount and the intake air amount may greatly change. Air becomes unstable. On the other hand, according to the above-described conventional control device, in the uniform combustion mode, each combustion parameter is calculated using the volumetric efficiency obtained based on the intake air amount. If the intake air becomes unstable, the above combustion parameters cannot be properly calculated. As a result, fuel efficiency, exhaust gas characteristics, and drivability may deteriorate.

In general, in the stratified combustion mode, fuel is inherently less liable to burn than in the uniform combustion mode.
Since the combustion state is likely to be unstable, it is necessary to set, for example, the ignition timing more appropriately than in the uniform combustion mode in order to secure a stable combustion state. On the other hand, according to the conventional control device, in the stratified combustion mode, the ignition timing is calculated based only on the accelerator opening and the engine speed, so that the ignition timing is set to an appropriate value that accurately reflects the combustion state and the operating state. Cannot be set.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to appropriately determine a combustion parameter such as an ignition timing in both a uniform combustion mode and a stratified combustion mode in accordance with an operation state and a combustion state. Accordingly, it is an object of the present invention to provide a control device for an in-cylinder injection type internal combustion engine capable of ensuring good fuel efficiency, operability and exhaust gas characteristics by ensuring a stable combustion state.

[0006]

In order to achieve this object, the invention according to claim 1 comprises a uniform combustion mode in which fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in which fuel is injected during a compression stroke. A control device 1 for an in-cylinder injection type internal combustion engine 3 operated by switching the combustion mode.
Load detecting means (ECU2, crank angle sensor 22, intake pipe absolute pressure sensor 24) for detecting the load (for example, required torque PME, intake pipe absolute pressure PBA, engine speed NE in the embodiment (hereinafter the same in this section)) , Accelerator opening sensor 30, step 1), and combustion parameters for the uniform combustion mode and the stratified combustion mode other than the ignition timing IG (final target air-fuel ratio coefficient KCMD, target valve lift amount LCMD, fuel injection timing θinj, injection end) Combustion parameter determining means (ECU2, steps 13 to 15) for determining the timings IJLOGH, IJLOGH) according to the detected load (required torque PME, intake pipe absolute pressure PBA, engine speed NE); Of the ignition timing IG (basic map value IGMAPm) of the detected load (request Torque PME, uniform combustion mode for the ignition timing determining means for determining in accordance with the engine rotational speed NE) (E
CU2, steps 232, 234, 250-259, 2
60 to 262), and the ignition timing IG for the stratified combustion mode.
(Basic map value IGMAPm) is determined in accordance with a stratified combustion mode combustion parameter (stratified combustion injection end timing IJLOGD) other than the determined ignition timing IG. 235, 270 to 275).

According to the control device for an internal combustion engine, the combustion parameters for the uniform combustion mode and the combustion parameters for the stratified combustion mode other than the ignition timing are determined according to the load. Is different from the conventional case, which is determined based on the intake air amount, even if the intake air becomes unstable immediately after the transition from the stratified combustion mode to the uniform combustion mode, The combustion parameters for the homogeneous combustion mode, including the timing, can be determined appropriately. Further, since the ignition timing for the stratified combustion mode is determined according to the combustion parameters for the stratified combustion mode other than the ignition timing determined according to the load, the ignition timing is appropriately determined while reflecting the operation state and the combustion state. Can be determined. As described above, by appropriately determining the combustion parameters including the ignition timing, a stable combustion state can be ensured in both the uniform combustion mode and the stratified combustion mode.

According to a second aspect of the present invention, in the control device 1 of the internal combustion engine 3 according to the first aspect, the combustion parameter used for determining the ignition timing IG (basic map value IGMAPm) for the stratified combustion mode is fuel. The injection timing θinj (injection end timing IJLOGD), and the combustion parameter determining means determines the final fuel injection amount (final fuel injection time Tout) injected into the cylinder during the stratified combustion mode by the load (engine speed NE, intake air Final fuel injection amount determining means (ECU 2, step 2) determined according to pipe absolute pressure PBA
0-30, 40-50, 60-70) and fuel injection timing determining means for determining the fuel injection timing θinj (injection end timing IJLOGD) according to the determined final fuel injection amount (final fuel injection time Tout). (ECU2, steps 270 to 275).

According to the control apparatus for the internal combustion engine, in the stratified charge combustion mode, the final fuel injection amount actually injected into the cylinder is determined according to the load, and the actual fuel injection amount is determined according to the final fuel injection amount. The timing is determined, and the ignition timing for the stratified combustion mode is determined according to the fuel injection timing. Therefore, the ignition timing for the stratified combustion mode can be determined to a value suitable for the actual final fuel injection amount and the actual fuel injection timing. Thereby, a more stable combustion state can be ensured.

According to a third aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the second aspect, the fuel injection timing determining means determines the fuel injection timing θinj of the combustion cycle.
After the (injection end timing IJLOGD) is determined,
The fuel injection timing θinj (injection end timing IJLOG) determined by the stratified combustion mode ignition timing determination means.
D), the ignition timing IG (basic map value IGMAPm) of the combustion cycle is determined (steps 220 to 220).
The ignition timing control process at 224 is executed after the execution of the fuel injection control process at steps 1 to 16).

According to this control device for an internal combustion engine, the ignition timing for the stratified combustion mode can be optimally determined according to the fuel injection timing in the same combustion cycle.

The invention according to claim 4 is the invention according to claims 1 to 3
In the control device 1 for the internal combustion engine 3 according to any one of
The load detecting means includes an engine speed detecting means (ECU2, crank angle sensor 22) for detecting the engine speed NE, and an accelerator opening detecting means (accelerator opening sensor 30) for detecting the accelerator opening AP. Required torque determining means (ECU2, step 1) for determining the required torque PME as a load according to the engine speed NE and the accelerator opening AP.

According to the control apparatus for an internal combustion engine, the ignition timing for the uniform combustion mode and the combustion parameters other than the ignition timing for the uniform combustion mode and the stratified combustion mode are set in accordance with the engine speed and the accelerator opening. It can be appropriately determined according to the determined required torque.

[0014] The invention according to claim 5 is the invention according to claims 1 to 4.
In the control device 1 for the internal combustion engine 3 according to any one of
A fuel injection valve 4 for injecting fuel into the cylinder is provided at the center of the top wall of the combustion chamber 3c of the cylinder, and is configured to inject fuel downward.

According to this control apparatus for an internal combustion engine, the above-described functions of claims 1 to 4 can be optimally obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for an internal combustion engine according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a control device of the present embodiment and an internal combustion engine to which the control device is applied. As shown in FIG. 1, the control device 1 includes an ECU 2.
Represents an internal combustion engine 3 (hereinafter referred to as “engine 3”)
), An ignition timing control process, a combustion mode shift determination process, and the like.

The engine 3 includes a vehicle serial 4 (not shown).
This is a cylinder (only one is shown) type gasoline engine, and a combustion chamber 3c is formed between a piston 3a and a cylinder head 3b of each cylinder. A recess 3d is formed in the center of the upper surface of the piston 3a. Further, a fuel injection valve 4 (hereinafter, referred to as “injector 4”) and a spark plug 5 are attached to the cylinder head 3b so as to face the combustion chamber 3c, and the fuel is directly injected into the combustion chamber 3c. That is, the engine 3 is of a direct injection type.

The injector 4 is disposed at the center of the top wall of the combustion chamber 3c, and is connected to a high-pressure pump 4b via a fuel pipe 4a. The fuel is boosted to a high pressure from a fuel tank (not shown) by the high-pressure pump 4b, and then supplied to the injector 4 in a state where the pressure is regulated by a regulator (not shown). The fuel is injected from the injector 4 toward the recess 3d side of the piston 3a, and collides with the upper surface of the piston 3a including the recess 3d to form a fuel jet. In particular, at the time of stratified combustion described later, most of the fuel injected by the injector 4 collides with the recess 3d to form a fuel jet.

On the other hand, a fuel pressure sensor 20 is attached to a portion near the injector 4 of the fuel pipe 4a. The fuel pressure sensor 20 detects the fuel pressure PF of the fuel injected by the injector 4 and outputs the detection signal to the ECU.
Send to 2. The injector 4 is connected to the ECU 2 and, as described later, receives a final fuel injection time Tout, which is a valve opening time, according to a drive signal from the ECU 2.
And the fuel injection timing θinj (valve opening timing and valve closing timing) are controlled.

The spark plug 5 is also connected to the ECU 2, and discharges when a high voltage is applied from the ECU 2 at a timing corresponding to the ignition timing IG, thereby burning the air-fuel mixture in the combustion chamber 3c.

Further, the engine 3 is of the DOHC type, and has an intake camshaft 6 and an exhaust camshaft 7.
It has. The intake and exhaust camshafts 6 and 7 have an intake cam 6a and an exhaust cam 7a for opening and closing the intake valve 8 and the exhaust valve 9, respectively. The intake and exhaust camshafts 6 and 7 are connected to a crankshaft 3e via a timing belt (not shown).
It makes one revolution for each revolution. A variable cam phase mechanism (hereinafter, referred to as “VTC”) 10 is provided at one end of the intake camshaft 6.

The VTC 10 operates by being supplied with a hydraulic pressure, and the intake cam 6 with respect to the crankshaft 3e.
By advancing or retarding the phase a (hereinafter referred to as “cam phase CAIN”) steplessly, the opening / closing timing of the intake valve 8 is advanced or delayed. Thereby, the intake valve 8
And increasing or decreasing the valve overlap of the exhaust valve 9 to increase or decrease the internal EGR amount and change the charging efficiency. In addition, this VTC1
0 is connected to the VTC electromagnetic control valve 10a. The VTC electromagnetic control valve 10a is driven by a drive signal from the ECU 2, and supplies a hydraulic pressure from a hydraulic pump (not shown) of the lubrication system of the engine 3 to the VTC 10 according to the duty ratio of the drive signal. Thereby, VTC1
A value of 0 advances or retards the cam phase CAIN of the intake cam 6a.

A cam angle sensor 21 is provided at an end of the intake camshaft 6 opposite to the cam phase variable mechanism 8. The cam angle sensor 21 is composed of, for example, a magnet rotor and an MRE pickup.
An M signal is output to the ECU 2 at every predetermined cam angle (for example, 1 °). The ECU 2 receives the CAM signal and a CR (described later).
The actual cam phase CAIN is obtained from the K signal.

Further, although not shown, each of the intake cam 6a and the exhaust cam 7a is composed of a low-speed cam and a high-speed cam having a cam nose higher than the low-speed cam.
The engine 3 is provided with a plurality of valve timing switching mechanisms (hereinafter, referred to as “VTEC (registered trademark)”) 11. Each VTEC 11 switches the intake cam 6a and the exhaust cam 7a between a low-speed cam and a high-speed cam, thereby setting the valve timing of the intake valve 8 and the exhaust valve 9 to a low-speed valve timing (hereinafter referred to as “Lo.V / T”).
And high-speed valve timing (hereinafter referred to as “Hi.V / T”). In this case, LO. VT. In the case of VT, the valve opening period of the intake valve 8 and the exhaust valve 9 and the valve overlap between them become longer, and the valve lift becomes larger, so that the charging efficiency is increased. This VTEC 11 is also the same as the VTC 1
0, the ECU 2 controls the VTEC electromagnetic control valve 11a.
The switching operation is performed by being supplied with hydraulic pressure via the.

Further, the valve timing is set at LO.L during the lean combustion, the stratified combustion and the double injection combustion in the uniform combustion described later. VT, and in the case of stoichiometric combustion and rich combustion described later in the uniform combustion, the LO. V
T or HI. Switch to VT.

On the other hand, a magnet rotor 22a is attached to the crankshaft 3e. The magnet rotor 22a constitutes a crank angle sensor 22 together with the MRE pickup 22b. Crank angle sensor 22 (load detecting means, engine speed detecting means)
Output a CRK signal and a TDC signal, both of which are pulse signals, as the crankshaft 3e rotates.

One pulse is output as the CRK signal every predetermined crank angle (for example, 30 °). Based on the CRK signal, the ECU 2 determines the engine speed of the engine 3 (a parameter representing a load; hereinafter, referred to as “engine speed”) N
Find E. The TDC signal is a signal indicating that the piston 3a of each cylinder is at a predetermined crank angle position near TDC (top dead center) at the start of the intake stroke. One pulse is output. The engine 3 is provided with a cylinder discrimination sensor (not shown). The cylinder discrimination sensor sends a cylinder discrimination signal, which is a pulse signal for discriminating a cylinder, to the ECU 2. The ECU 2 determines a crank angle position for each cylinder based on the cylinder determination signal, the CRK signal, and the TDC signal.

A water temperature sensor 23 is attached to the main body of the engine 3. The water temperature sensor 23 is constituted by a thermistor, detects an engine water temperature TW which is a temperature of the cooling water circulating in the main body of the engine 3, and sends a detection signal to the ECU 2.

On the other hand, a throttle valve 13 is provided in the intake pipe 12 of the engine 3. This throttle valve 13
Is driven by the electric motor 13a connected thereto, so that the throttle valve opening TH changes. The throttle valve 13 has a throttle valve opening sensor 3.
2 is connected to the throttle valve opening sensor 32.
Detects the throttle valve opening TH and sends a detection signal to the ECU 2. The ECU 2 controls the throttle valve opening TH through the electric motor 13a according to the operating state of the engine 3.
, The amount of intake air to the engine 3 is controlled.

An intake pipe absolute pressure sensor 24 is disposed downstream of the throttle valve 13 in the intake pipe 12. This intake pipe absolute pressure sensor 24 (load detecting means)
Is composed of a semiconductor pressure sensor and the like, and the intake pipe 1
An intake pipe absolute pressure PBA (a parameter representing a load), which is an absolute pressure in the intake pipe 2, is detected, and a detection signal is sent to the ECU 2. Further, an intake air temperature sensor 25 is attached to the intake pipe 12. The intake air temperature sensor 25 is configured by a thermistor, and detects the intake air temperature TA in the intake pipe 12,
The detection signal is sent to the ECU 2.

An EGR pipe 15 is connected between the intake pipe 12 downstream of the throttle valve 13 and the exhaust pipe 14 upstream of a catalyst device (not shown). The EGR pipe 15 performs an EGR operation of recirculating exhaust gas of the engine 3 to the intake side and reducing NOx in the exhaust gas by lowering a combustion temperature in the combustion chamber 3c.

An EGR control valve 16 is attached to the EGR pipe 15. The EGR control valve 16 is a linear solenoid valve, and its valve lift changes linearly in response to a drive signal from the ECU 2, thereby opening and closing the EGR pipe 15. A valve lift sensor 26 is attached to the EGR control valve 16. The valve lift sensor 26 detects the actual valve lift LACT of the EGR control valve 16 and sends a detection signal to the ECU 2.

The ECU 2 calculates the target valve lift amount LCMD of the EGR control valve 16 in accordance with the operation state of the engine 3 and controls the actual valve lift amount LACT to be equal to the target valve lift amount LCMD. The EGR amount is controlled. This target valve lift amount LC
The calculation process of the MD (combustion parameter) will be described later.

An LAF sensor 27 is disposed upstream of the catalyst device in the exhaust pipe 14. The LAF sensor 27 is composed of zirconia and platinum electrodes, etc.
In a wide range of the air-fuel ratio A / F from a rich region richer than the stoichiometric air-fuel ratio to an extremely lean region, the oxygen concentration in the exhaust gas is linearly detected, and a detection signal proportional to the oxygen concentration is sent to the ECU 2. . Further, an O2 sensor (not shown) is arranged downstream of the catalyst device in the exhaust pipe 14. The O2 sensor sends a detection signal proportional to the oxygen concentration in the exhaust gas downstream of the catalyst device to the ECU 2. send.

Further, the engine 3 has an atmospheric pressure sensor 2
8 is attached. The atmospheric pressure sensor 28 includes a semiconductor pressure sensor or the like, detects the atmospheric pressure PA, and sends a detection signal to the ECU 2. Further, a battery voltage sensor 29 is connected to the ECU 2. The battery voltage sensor 29 detects a voltage value VB of a battery (not shown) that supplies a drive voltage to the injector 4, and outputs a detection signal thereof. Send to ECU2.

An accelerator opening sensor 30 is attached to a vehicle on which the engine 3 is mounted. The accelerator opening sensor 30 (load detecting means, accelerator opening detecting means) detects an accelerator opening AP (a parameter representing a load) which is an operation amount of an accelerator pedal (not shown),
The detection signal is sent to the ECU 2. Further, a gear position sensor 31 is attached to the automatic transmission (not shown) of the engine 3. The gear position sensor 31 detects a gear position NGAR of the automatic transmission and sends a detection signal to the ECU 2.

On the other hand, the ECU 2 (load detecting means, combustion parameter determining means, uniform combustion mode ignition timing determining means,
Stratified combustion mode ignition timing determining means, final fuel injection amount determining means, fuel injection timing determining means, engine speed detecting means,
The required torque determining means) includes a CPU 2a, a RAM 2b,
It is composed of a microcomputer (not shown) including the OM 2c and an input / output interface (not shown). The detection signals of the sensors 20 to 32 described above are respectively input to the ECU 2 and input to the input interface.
After being subjected to / D conversion and shaping, it is input to the CPU 2a. The CPU 2a responds to these input signals,
Various arithmetic processing is executed based on the control program stored in c, various tables and various maps described later, and the flag values and calculated values described later stored in the RAM 2b.

Specifically, the operating state of the engine 3 is determined from the various detection signals, and based on the determination result,
The combustion mode (combustion mode) of the engine 3 is switched to the stratified combustion mode at the time of extremely low load operation such as idle operation, and to the uniform combustion mode at the time of operation other than the extremely low load operation. Execute the injection combustion mode. Further, by controlling the final fuel injection time Tout and the fuel injection timing θinj of the injector 4 according to the combustion mode, the fuel injection control process including the air-fuel ratio feedback control process is executed,
The ignition timing IG of the ignition plug 5 is controlled.

In the stratified combustion mode, fuel is injected from the injector 4 into the combustion chamber 3c during the compression stroke, and most of the injected fuel collides with the recess 3d to form a fuel jet. An air-fuel mixture is generated by the fuel jet and the flow of the air flowing in from the intake pipe 12, and the air-fuel mixture is moved to the vicinity of the ignition plug 5 by the piston 3 a being located near the top dead center of the compression stroke. While being unevenly distributed, an air-fuel ratio A / F that is extremely leaner than the stoichiometric air-fuel ratio (for example, 27 to
Burn in 60).

In the uniform combustion mode, the fuel is injected into the combustion chamber 3c during the intake stroke, and the mixture formed by the fuel jet and the flow of the air is dispersed uniformly in the combustion chamber 3c while stratified combustion. A / F richer than mode
(For example, 12 to 22), uniform combustion is performed.

Further, in the double injection combustion mode, the fuel is injected twice at intervals in one cycle, and the air-fuel ratio A / F (for example, 12 to 22) richer than in the stratified combustion mode.
Then, combustion is performed. The two fuel injections in this case are executed during the intake stroke and during the compression stroke.

Hereinafter, the fuel injection control process including the air-fuel ratio feedback control process executed by the ECU 2 will be described with reference to FIGS. FIG. 2 shows a main routine of this control processing.
The interrupt is executed in synchronization with the input of the TDC signal. As described later, in this process, the combustion mode monitor S_EMO
D is determined (step 1), various correction coefficients are calculated (steps 2 to 9), the combustion mode transition flag F_CMOD and the combustion mode monitor S_EMO are determined.
Each combustion mode control process is executed according to the value of D (steps 10 to 16).

First, in step 1 (abbreviated as S1 in the figure, the same applies hereinafter), the combustion mode is determined as follows, and the value of the combustion mode monitor S_EMOD representing the combustion mode is set. That is, the engine speed NE and the accelerator opening A
By searching a map (not shown) based on P,
A required torque PME (a parameter representing a load) is obtained, and a combustion mode is determined by searching a map shown in FIG. 3 based on the required torque PME and the engine speed NE, and a combustion mode monitor S_EMOD representing the determined combustion mode is determined. Is set. Specifically, in the same map, the required torque PME and the engine speed N
In the stratified combustion region where both E are low, the stratified combustion mode is determined, and the combustion mode monitor S_EMOD is set to “2”. In addition, the required torque PME and the engine speed NE
In the lean combustion region of the uniform combustion higher than the stratified combustion region, the lean combustion mode is determined, and the combustion mode monitor S
_EMOD is set to “1”. Further, in the stoichiometric combustion region of the uniform combustion in which the required torque PME and the engine speed NE are higher than the lean combustion region, the stoichiometric combustion mode is determined, and the combustion mode monitor S_EMO
D is set to “0”. Note that the stoichiometric combustion region in this map includes a rich combustion region in which the air-fuel mixture is burned at an air-fuel ratio A / F richer than the stoichiometric air-fuel ratio, in addition to a region in which the air-fuel mixture is mainly burned at the stoichiometric air-fuel ratio. It is referred to as stoichiometric combustion, including rich combustion.

Next, the routine proceeds to step 2, where an initial value of the starting correction coefficient KAST is calculated. This starting correction coefficient KA
ST is for performing an increase correction of the fuel injection amount when the engine 3 is started.

Next, the routine proceeds to step 3, where the correction coefficient KO
Initialize the BSV. This correction coefficient KOBSV is used for an A / F feedback control process (steps 26 and 4).
6, 66, 86).

Next, the process proceeds to a step 4, wherein a subtraction process of the starting correction coefficient KAST obtained in the step 2 is executed. This is because, after the engine 3 is started, the degree of the increase correction of the fuel injection amount by the start-time correction coefficient KAST is reduced with time.

Next, the routine proceeds to step 5, where a basic fuel injection time Tist for starting is calculated.

Next, the routine proceeds to step 6, where the engine coolant temperature T
A water temperature correction coefficient KTW is determined by searching a map (not shown) based on W and the intake pipe absolute pressure PBA.

Then, the process proceeds to a step 7, wherein an atmospheric pressure correction coefficient KPA is obtained by searching a table (not shown) based on the atmospheric pressure PA.

Then, the program proceeds to a step S 8, wherein a KPF calculation process is executed to obtain a fuel pressure correction coefficient KPF. The fuel pressure correction coefficient KPF is obtained by searching a table (not shown) based on the pressure difference ΔPF between the fuel pressure PF and the in-cylinder pressure PCYL. In this case, the cylinder pressure PCYL is estimated by searching a table (not shown) based on the crank angle position of each cylinder.

Next, the routine proceeds to step 9, where an F / C operation determination process is executed. In this process, the engine 3 determines whether the engine speed is F / F according to the engine speed NE and the throttle valve opening TH.
It is determined whether or not the vehicle is in the C (fuel cut) operation state, and a flag indicating the determination result is set.

Next, the routine proceeds to step 10, where it is determined whether or not the combustion mode transition flag F_CMOD is "1". The combustion mode transition flag F_CMOD is set to “1” in the double injection combustion mode and “0” in the other combustion modes in a combustion mode transition determination process (FIG. 27 or 28) described later. Is set to The double injection combustion mode is executed when the combustion mode shifts between the lean combustion mode and the stratified combustion mode.

When the result of this determination is NO, that is, when the combustion mode is other than the double injection combustion mode, the routine proceeds to step 11, where it is determined whether or not the combustion mode monitor S_EMOD obtained in step 1 is "0". Determine. If the result of this determination is YES, the process proceeds to step 13, where a stoichiometric combustion mode control process described later is executed, and this process ends.

On the other hand, if the decision result in the step 11 is NO, that is, if it is a combustion mode other than the stoichiometric combustion mode, the process proceeds to a step 12, and the combustion mode monitor S_
It is determined whether the EMOD is “1”. If the result of this determination is YES, that is, if the engine is in the lean combustion mode, the routine proceeds to step 14, where a lean combustion mode control process described later is executed, and this process ends.

On the other hand, if the decision result in the step 12 is NO, that is, in the stratified combustion mode, the step 15 is executed.
To perform a stratified combustion mode control process described later,
This processing ends.

On the other hand, if the result of the determination in step 10 is YE
In the case of S, that is, when F_CMOD = 1, the process proceeds to step 16, where a two-injection combustion mode control process described later is executed, and this process ends.

Next, the stoichiometric combustion mode control process in step 13 of FIG. 2 will be described with reference to FIG. As shown in the figure, in this process, first, in step 20, a Tibase calculation process is executed to calculate a basic fuel injection time Tibase. The specific contents of this processing will be described later.

Next, the routine proceeds to step 21, where an LCMD calculation process is executed. In this process, the target valve lift amount LCMD is calculated as described later.

Then, the program proceeds to a step S22, wherein a KEGR calculation process is executed to obtain an EGR correction coefficient KEGR. In this process, the required torque obtained in step 1, the engine speed NE, the target valve lift LCMD obtained in step 22, the actual valve lift LACT detected by the valve lift sensor 26, and the intake pipe absolute pressure PB
An EGR correction coefficient KEGR is obtained by searching three maps (not shown) based on A and the map value PBAm of the intake pipe absolute pressure PBA. The EGR correction coefficient KEGR is for compensating for a change in the intake air amount due to a change in the EGR amount.

Next, the process proceeds to a step 23, wherein a KCMD calculation process is executed to calculate a final target air-fuel ratio coefficient KCMD (combustion parameter). Specifically, first, a basic target air-fuel ratio coefficient KBS is obtained by searching a map (not shown) based on the required torque PME and the engine speed NE obtained in step 1. Then, the final target air-fuel ratio coefficient KCMD is calculated by multiplying this by the water temperature correction coefficient KTW obtained in step 6. These basic target air-fuel ratio coefficient KBS and final target air-fuel ratio coefficient K
CMD is expressed as an equivalence ratio proportional to the reciprocal of the air-fuel ratio A / F.

That is, in this KCMD calculation process, the final target air-fuel ratio coefficient KCMD for stoichiometric combustion, that is, for uniform combustion, is calculated based on the engine speed NE and the required torque PME representing the load. Unlike the conventional case, even after the transition from the stratified combustion mode to the uniform combustion mode, even when the intake air is in an unstable state, the final target air-fuel ratio coefficient KCMD is appropriately obtained without being affected by the unstable state. be able to.

Next, the routine proceeds to step 24, where the total correction coefficient K
A KTOTAL calculation process for calculating TOTAL is executed. Specifically, the total correction coefficient KTOT is calculated by the following equation (1).
Ask for AL. KTOTAL = KAST / KTA / KPA / KEGR / KETC (1) Here, KTA is an intake air temperature correction coefficient obtained by searching a table (not shown) based on the intake air temperature TA. Target air-fuel ratio coefficient KCMD
Is a filling efficiency correction coefficient obtained by searching a table (not shown) based on

Next, the process proceeds to a step 25, wherein a KOBSV calculation process is executed. In this process, the next step 26 is performed by estimating the air-fuel ratio for each cylinder by the observer.
KOBSV is calculated.

Next, the routine proceeds to step 26, where an A / F feedback control process is executed. In this process, the estimated air-fuel ratio feedback control is executed for each cylinder using the final target air-fuel ratio coefficient KCMD and the correction coefficient KOBSV calculated in steps 23 and 26, respectively.

Next, the process proceeds to a step 27, wherein a KSTR calculation process is executed to calculate a feedback correction coefficient KSTR. In this process, based on the detection signal of the LAF sensor 27, a feedback correction coefficient KSTR is obtained by a Self Tuning Regulator type adaptive controller (not shown). This feedback correction coefficient KSTR is applied to the basic fuel injection time Tibase, and dynamically compensates for the time required for the actual air-fuel ratio to reach the target air-fuel ratio due to the response delay of the fuel injection system. This is for improving the convergence of.

Next, the routine proceeds to step 28, where a DB compensation process is executed. In this process, when the fluctuation of the engine speed NE is large, the correction value TiD for compensating the fluctuation is large.
B is calculated. This correction value TiDB is calculated as a positive or negative value.

Then, the process proceeds to a step 29, wherein a calculation process of the direct rate Ae and the carry-out rate Be is executed. In this process, the direct rate Ae and the carry-out rate Be, which are fuel behavior parameters, are calculated based on the engine speed NE, the intake pipe absolute pressure PBA, and parameters representing various operating states.

Next, the routine proceeds to step 30, where a calculation process of the final fuel injection time Tout is executed. Specifically, first, the basic fuel injection time Tibase determined as described above
To the total correction coefficient KTOTAL and the final target air-fuel ratio coefficient KCM
The required fuel injection time Tcyl (i) for each cylinder is calculated by adding a correction value TiDB to a value obtained by multiplying D and the feedback correction coefficient KSTR (Tcyl).
(I) = Tibase, KTOTAL, KCMD, KS
TR + TiDB). Note that the required fuel injection time Tcyl
The symbol i in (i) represents the cylinder number.

Next, using the fuel pressure correction coefficient KPF, the direct rate Ae and the carry-out rate Be obtained as described above, the final fuel injection time Tout for each cylinder is calculated by the following equation (2).
(I) is calculated. These final fuel injection times Tout
(I) is the valve opening time of the injector 4 for each cylinder, and represents the fuel injection amount actually injected into each cylinder.

Tout (i) = ((Tcyl (i) −Be · TWP (i)) / Ae) · KPF + TiVB (2) where TiVB is an invalid correction time, TWP obtained based on the battery voltage. (I) is an attached fuel amount equivalent value (time) corresponding to the attached fuel amount for each cylinder. This TWP
(I) is obtained by the following equation (3) in the TWP (i) calculation processing executed separately from this processing.

TWP (i) n = ((Tout (i) −TiVB) / KPF) · (1−Ae) + (1−Be) · TWP (i) n−1 (3) where TWP (I) n and TWP (i) n-1 are the current value and the previous value of the attached fuel amount equivalent value TWP (i), respectively.

Next, the routine proceeds to step 31, where the fuel injection timing θinj is calculated in the injection timing calculation processing. The details of the injection timing calculation processing will be described later.

Then, the process proceeds to a step 32, wherein a purge control process is executed, and the process is terminated. In this process, the evaporated fuel temporarily adsorbed in the canister of the purge system is sent to the intake pipe 12, and the purge amount, which is the flow rate, is controlled.

On the other hand, FIG. 5 and FIG.
4 and 15 show the lean combustion mode control process and the stratified combustion mode control process, respectively. As shown in both figures, the procedures of steps 40 to 52 and steps 60 to 72 of these processes are the same as those of the stoichiometric combustion described above. Since the steps are the same as steps 20 to 32 of the mode control processing, a specific description is omitted. In the KCMD calculation process in step 43, the final target air-fuel ratio coefficient KCMD for lean combustion is determined based on the engine speed NE and the required torque PME in the same manner as in the procedure in step 23 described above. Thus, even after the transition from the stratified combustion mode to the uniform combustion mode, even when the above-described intake air is in an unstable state, the final target air-fuel ratio coefficient KCMD can be appropriately determined without being affected. it can.

FIG. 7 shows the two-injection combustion mode control process of the step 16. As shown in FIG. 7, each procedure of the steps 80 to 92 of this process is performed by the KCMD calculation process of the step 84. Are the same as those in steps 20 to 32 of the stoichiometric combustion mode control process described above, and thus a specific description is omitted. Note that K in step 84
The details of the CMD calculation process will be described later.

Next, referring to FIG. 8, the Tibase calculation processing of the steps 20, 40, 60 and 80 will be described. As shown in the figure, in this processing, first, in step 100, it is determined whether or not the VTEC permission flag F_VTEC is “1”. The VTEC permission flag F_VTEC indicates that the valve timing is set to HI. When set to VT, it is set to "1" and L
O. When it is set to VT, it is set to "0". In the lean combustion mode, the stratified combustion mode, and the double injection combustion mode, the valve timing is set to LO. By setting to VT, F_VT
EC = 0.

If the decision result in the step 100 is YES, that is, if the valve timing is HI. When it is set to VT, the routine proceeds to step 101, where a map (not shown) is searched based on the engine speed NE and the actual cam phase CAIN, thereby obtaining the HI. The multiplication term Ati for VT is obtained.

Then, the program proceeds to a step 102, wherein a map (not shown) is searched based on the engine speed NE and the actual cam phase CAIN, thereby obtaining a HI. An addition term Bti for VT is obtained.

Next, the routine proceeds to step 103, where HI. Basic fuel injection time Tiba for VT
After calculating “se”, the present process ends. Tibase = Ati · PBA + Bti (4)

On the other hand, if the decision result in the step 100 is NO, that is, if the valve timing is LO. If it is set to VT, the process proceeds to step 104, and the LO. V
A multiplication term Ati for T is obtained.

Then, the process proceeds to a step 105, wherein the LO. V
An addition term Bti for T is obtained.

Next, the routine proceeds to step 103, where L
O. The basic fuel injection time Tibase for VT is calculated, and the process ends.

Next, the calculation process (steps 21, 41, 61, 81) of the target valve lift amount LCMD in each combustion mode control process described above will be described with reference to FIG. As shown in the figure, in this process, first, in step 110, the EGR permission flag F_EGR is set to "1".
Is determined. This EGR permission flag F_E
GR is set to “1” when EGR is performed by opening the EGR pipe 15 by the EGR control valve 16, and is set to “0” when EGR is not performed by closing the EGR pipe 15. It is.

If the decision result in the step 110 is NO,
That is, when the EGR is not executed, the present process is terminated, while when the determination result is YES, that is, when the EG
When R is being executed, proceed to step 111,
It is determined whether or not the combustion mode monitor S_EMOD is “0”. When the result of this determination is YES, that is, when the engine is in the stoichiometric combustion mode, the routine proceeds to step 112, where VT
It is determined whether or not the EC permission flag F_VTEC is “1”.

When the result of this determination is YES, that is, when the valve timing is HI. If it is set to VT, the routine proceeds to step 113, where a map (not shown) is searched based on the engine speed NE and the required torque PME to obtain stoichiometric combustion, HI. A map value LMAP for VT is obtained. Next, proceed to step 114,
The map value LMAP obtained in step 113 is set as the target valve lift amount LCMD, and the process ends.

On the other hand, if the decision result in the step 112 is NO, that is, if the valve timing is LO. When it is set to VT, the routine proceeds to step 115, and similarly to step 113, a map (not shown) is searched based on the engine speed NE and the required torque PME to obtain the stoichiometric combustion, LO. Map value LMAP for VT
Ask for. Next, the above step 114 is executed, and the present process ends.

On the other hand, if the decision result in the step 111 is NO, that is, if not in the stoichiometric combustion mode, the process proceeds to a step 116, in which it is determined whether or not S_EMOD is "1". When the result of this determination is YES, that is, when the engine is in the lean combustion mode, the routine proceeds to step 117, and
A map value LMAP for lean combustion is obtained by the same method as in steps 113 and 115 described above. Next, the above step 114 is executed, and the present process ends.

On the other hand, if the decision result in the step 116 is NO, that is, if the stratified combustion mode is set, the step 1
Proceeding to 18, it is determined whether or not the idle flag F_IDLE is "1". This idle flag F_IDLE
Is set to "1" when the engine 3 is in the idling operation mode, and is set to "0" otherwise.

When the result of this determination is YES, that is, when the engine is in the idling operation mode, the routine proceeds to step 119, where
A map value LMAP for stratified combustion and idling operation is obtained by the same method as in step 113. Next, the step 114 is executed, and the present process ends.

If the decision result in the step 118 is NO,
That is, when the engine is not in the idling operation mode, the process proceeds to step 120, and the map value LMAP for stratified combustion and non-idling operation is obtained by the same method as in step 113. Next, the step 114 is executed, and the present process ends. In the LCMD calculation process in step 81 in the double injection combustion mode, each flag F_EGR, F_VETC,
The target valve lift amount LCMD is obtained based on the values of F_IDLE and the combustion mode monitor S_EMOD.

As described above, in the LCMD calculation process as well, the target valve lift amount LCMD for uniform combustion and stratified combustion is, like the final target air-fuel ratio coefficient KCMD, the engine speed NE and the required torque PME as loads.
Is calculated based on Therefore, even when the intake air is in an unstable state after the transition from the stratified combustion mode to the uniform combustion mode, the target valve lift amount LCMD can be appropriately obtained without being affected by the unstable state.

Next, the injection timing calculation processing (steps 31, 51, 71, 91) of each combustion mode control processing described above will be described with reference to FIGS. In this process, as described below, the injection end timing (combustion parameter) and the injection start timing of the fuel injection timing θinj (combustion parameter) for each combustion mode are calculated for each cylinder. As shown in the figure, first, in step 130, the combustion mode transition flag F_CMOD
Is "0". The result of this determination is YE
When S, that is, when F_CMOD = 0 and the mode is not the double injection combustion mode, the routine proceeds to step 131,
It is determined whether or not the combustion mode monitor S_EMOD is “0”.

When the result of this determination is YES, that is, when S
If _EMOD = 0 and the engine 3 is in the stoichiometric combustion mode, the routine proceeds to step 132, where an injection end timing calculation process for stoichiometric combustion is executed. Although details will be described later, in this process, an injection end timing IJLOGH (fuel injection timing for uniform combustion mode, combustion parameter) for stoichiometric combustion is calculated.

Next, the routine proceeds to step 133, where an injection start timing calculation process for uniform combustion is executed, and this process is ended. In this process, the injection start timing for stoichiometric combustion is calculated backward from the final fuel injection time Tout (final fuel injection amount) calculated in step 30 and the injection end timing IJLOGH calculated in step 132. The injection start timing and the injection end timing IJLOGH are calculated as crank angle positions based on the TDC position in the intake stroke.

On the other hand, if the decision result in the step 131 is NO, that is, if it is not the stoichiometric combustion mode, the routine proceeds to a step 134, where it is determined whether or not the combustion mode monitor S_EMOD is "1". This determination result is YES
In this case, that is, when the engine 3 is in the lean combustion mode, the routine proceeds to step 135, where the lean end injection end timing IJLOGH is calculated in the lean end injection end timing calculation process described later.

Next, proceeding to step 133, the injection start timing for lean combustion is calculated based on the injection end timing IJLOGH and the final fuel injection time Tout calculated in step 135 and step 50, respectively. finish. These injection start timing and injection end timing IJL for lean combustion
The OGH is calculated as a crank angle position based on the TDC position of the intake stroke as in the case of the stoichiometric combustion.

On the other hand, if the decision result in the step 134 is NO, that is, if the engine 3 is in the stratified charge combustion mode, the routine proceeds to a step 136, where in the stratified charge combustion end timing calculation processing to be described later, the stratified charge combustion end is calculated. The timing IJLOGD (combustion parameter) is calculated.

Next, proceeding to step 137, the injection end timing IJLOG calculated in step 136 and step 70, respectively, as in step 133.
The injection start timing for stratified charge combustion is calculated based on D and the final fuel injection time Tout, and this processing ends. Both the injection start timing and the injection end timing IJLOGD are different from those for the stoichiometric combustion and the lean combustion described above.
It is calculated as a crank angle position based on the position.

On the other hand, if the decision result in the step 130 is NO, that is, if the engine 3 is in the double injection combustion mode, the routine proceeds to a step 138, wherein the engine speed NE
NE-Toutdb, an example of which is shown in FIG.
By searching the D table, the compression stroke injection time T
outdbD is determined.

This compression stroke injection time ToutdbD is:
The fuel injection time (second injection time) in the compression stroke of the two fuel injections in the double injection combustion mode,
The reason for this is as follows. That is, in the two-injection combustion mode in which fuel is injected in both the intake stroke and the compression stroke, the fuel injection amount in the intake stroke is increased as much as possible in order to secure combustion stability, and at the same time, good fuel economy and exhaust gas characteristics It is preferable to limit the fuel injection amount in the compression stroke to the minimum ignitable fuel injection amount in order to secure the respective values. Furthermore, the minimum ignitable fuel injection amount in the compression stroke fluctuates as the state of air flow in the cylinder changes in accordance with the engine speed NE. Therefore, it is necessary to compensate for this fluctuation. is there. Accordingly, by obtaining the compression stroke injection time ToutdbD based on the engine speed NE as described above, it is possible to ensure the stability of combustion and the like. NE-T
In the outdbD table, the compression stroke injection time ToutdbD is set to be smaller as the engine speed NE is higher. This is because the higher the engine speed NE, the more easily the air-fuel mixture burns due to the relationship between the in-cylinder flow, so that the minimum ignitable fuel injection amount in the compression stroke can be reduced.

Next, the routine proceeds to step 139, where the final fuel injection time Tout calculated in step 90 is set to the compression stroke injection time ToutdbD and the predetermined time X_Toutdb.
It is determined whether the sum is greater than the sum of. The result of this determination is N
When O, ie, Tout ≦ ToutdbD + X_T
In the case of outdb, steps 136 and 137 are executed, and this processing ends. That is, even when the double injection combustion mode is determined, when the fuel injection amount is small, only the fuel injection in the compression stroke is executed as in the stratified combustion mode without performing injection twice in one cycle. I do. This is because, since the final fuel injection time Tout is short, only the minimum ignitable injection amount can be secured as the fuel injection amount in the compression stroke, and it is difficult to perform the fuel injection in the intake stroke.

On the other hand, if the decision result in the step 139 is YES.
, Ie, Tout> ToutdbD + X_To
In the case of utdb, the routine proceeds to step 140, and in the later-described injection end timing calculation processing for double injection combustion, using the final fuel injection time Tout and the compression stroke injection time ToutdbD calculated in step 90 and step 138, respectively, 2 for double injection combustion
Injection end timings IJLOGH and IJLOGD are calculated respectively (during the intake stroke and during the compression stroke).

Next, the routine proceeds to step 141, where the first injection end timing IJLOGH (during the intake stroke) and a first injection time ToutH, which will be described later, and the second injection end timing IJLOGD (during the compression stroke), and which will be described later Based on the second injection time ToutD, two injection start timings for double injection combustion are calculated, and the process ends.

Next, the processing for calculating the injection end timing for stoichiometric combustion in step 132 will be described with reference to FIG. In this process, as described below, the injection end timing IJLOGH for stoichiometric combustion
Is calculated.

In this process, first, at step 150, a water temperature correction term IJTW is obtained. This water temperature correction term I
More specifically, the JTW is determined by searching a TW-IJTW table, an example of which is shown in FIG. 13, based on the engine coolant temperature TW. As shown in FIG.
In the −IJTW table, the water temperature correction term IJTW is set to a smaller value as the engine water temperature TW is higher.
This is because the higher the engine coolant temperature TW, the more easily the fuel injected into the combustion chamber 3c is ignited and the more efficient the uniform combustion is performed. Therefore, the earlier the injection end timing IJLOGH of the fuel injection timing θinj is, the more the generated torque is reduced. To get better.

Next, the routine proceeds to step 151, where it is determined whether or not the VTEC permission flag F_VTEC is "1". When the result of this determination is YES, that is, when the valve timing is HI. When it is set to VT, the routine proceeds to step 152, where the EGR permission flag F_EGR is set to “1”.
Is determined.

When the result of this determination is YES, that is, when E
When the GR is being executed, the routine proceeds to step 153, where a map (not shown) is searched based on the engine speed NE and the final fuel injection time Tout obtained in step 30 to obtain the HI. The basic injection end timing INJMAPF for VT and EGR is obtained.

Next, the routine proceeds to step 155, where the basic injection termination timing INJMAPF is set to the above-mentioned step 1
The value obtained by adding the water temperature correction term IJTW obtained in step 50 is set as the injection end timing IJLOGH, and this processing ends.

On the other hand, if the decision result in the step 152 is NO, that is, if the EGR is not executed, the process proceeds to a step 154, and the HI. The basic injection end timing INJMAPF for VT and non-EGR is obtained. Next, step 15
5 and HI. Injection end timing I for VT, non-EGR
JLOGH is calculated, and this processing ends.

On the other hand, if the decision result in the step 151 is NO, that is, if the valve timing is LO. When it is set to VT, the routine proceeds to step 156, where it is determined whether or not the EGR permission flag F_EGR is "1".

When the result of this determination is YES, that is, when E
When the GR is being executed, the process proceeds to step 157, and the LO. V
Basic injection end timing INJMAPF for T, EGR
Ask for. Next, at step 155, the LO. VT,
The injection end timing IJLOGH for EGR is calculated, and this processing ends.

On the other hand, if the decision result in the step 156 is NO, that is, if the EGR is not executed, the process proceeds to a step 158, and the LO. The basic injection end timing INJMAPF for VT and non-EGR is obtained. Next, step 15
5 to LO. The injection end timing IJLOGH for VT and non-EGR is calculated, and this processing ends.

Next, the processing for calculating the injection end timing for lean combustion in step 135 will be described with reference to FIG. In this process, first, in step 16
At 0, a water temperature correction term IJTW is retrieved from the TW-IJTW table shown in FIG. 3 based on the engine water temperature TW as in step 150.

Next, the routine proceeds to step 161, where it is determined whether or not the EGR permission flag F_EGR is "1". When the result of this determination is YES, that is, when EGR is being executed, the routine proceeds to step 162, where a map (not shown) is searched based on the engine speed NE and the final fuel injection time Tout obtained in step 50, and Basic injection end timing INJMA for EGR
Find the PF.

Next, the routine proceeds to step 163, where the basic injection end timing INJMAPF is set to step 160.
The value obtained by adding the water temperature correction term IJTW obtained in step (1) is set as the injection end timing IJLOGH, and this processing ends.

On the other hand, if the decision result in the step 161 is NO, that is, if the EGR is not executed, the process proceeds to a step 164, and the basic injection end timing INJMAP for non-EGR is performed by the same method as the step 162.
Find F. Next, in step 163 described above, the non-EG
The injection end timing IJLOGH for R is calculated, and this processing ends.

Next, the processing for calculating the injection end timing for stratified combustion in step 136 will be described with reference to FIG. In this processing, the injection end timing I
JLOGD is different from that for stoichiometric combustion and lean combustion, and is calculated as the crank angle position after TDC in the compression stroke.

In this process, first, at step 170, it is determined whether or not the EGR permission flag F_EGR is "1". When the result of this determination is YES, that is, when EGR is being executed, the routine proceeds to step 171, in which a map (not shown) is searched based on the engine speed NE and the final fuel injection time Tout obtained in step 70, and A basic injection end timing INJMAPF for EGR is obtained.

Next, the routine proceeds to step 172, where the basic injection end timing INJMAPF is set to the EGR injection end timing IJLOGD, and this processing ends.

On the other hand, if the decision result in the step 170 is NO, that is, if the EGR is not executed, the process proceeds to a step 173, and the non-EGR basic injection end timing INJM is performed in the same manner as the step 171.
Find APF. Next, in step 172 described above, the non-EGR injection end timing IJLOGD is calculated, and this processing ends.

Next, the processing for calculating the injection end timing for double injection combustion in step 140 will be described with reference to FIG. In this process, two injection end timings IJLOGH and IJLOGD of the fuel injection timing θinj for the double injection combustion are calculated as described below. In this case, the first injection end timing IJLO
GH is calculated as the crank angle position after TDC in the intake stroke, and the second injection end timing IJLOGD
Is calculated as the crank angle position after TDC in the compression stroke.

In this process, first, in step 180, a water temperature correction term IJTW is retrieved from the TW-IJTW table based on the engine water temperature TW, as in steps 150 and 160.

Next, the routine proceeds to step 181, where the final fuel injection time To for the two-injection combustion obtained in step 90 is set.
ut to the value obtained by subtracting the compression stroke injection time ToutdbD obtained in step 138 from the first injection time To.
utH (injection time during the intake stroke).

Next, the routine proceeds to step 182, where the compression stroke injection time ToutdbD is changed to the second injection time ToutD.
(Injection time during the compression stroke).

Next, the routine proceeds to step 183, where it is determined whether or not the combustion mode monitor S_EMOD is "0". When the result of this determination is YES, that is, when the combustion mode before the transition to the two-injection combustion mode is the stoichiometric combustion mode, the following steps are performed in the same manner as in steps 156 to 158 of the injection end timing calculation processing for stoichiometric combustion described above. 184 to 186 are executed.

That is, if the determination result of step 184 is Y
If it is ES and EGR is being executed, the routine proceeds to step 185, where the map used in step 157 is searched based on the engine speed NE and the first injection time ToutH obtained in step 181. , Basic injection end timing INJMAPF for stoichiometric combustion and EGR.

On the other hand, if the decision result in the step 184 is NO, that is, if the EGR is not executed, the process proceeds to a step 186, and the map used in the step 158 is searched by the same method as in the step 185, thereby obtaining the stoichiometric value. A basic injection end timing INJMAPF for combustion and non-EGR is obtained.

On the other hand, if the decision result in the step 183 is NO, that is, if the combustion mode before the transition to the double injection combustion mode is not the stoichiometric combustion mode, the step 16 of the above-described lean-combustion injection end timing calculation processing
1, 162, 164, the following steps 187-
189 is executed.

That is, if the decision result in the step 187 is Y
If it is ES and EGR is being executed, the routine proceeds to step 188, where the map used in step 162 is searched by the same method as in step 185 to obtain the basic injection end timing INJMAPF for lean combustion and EGR. Ask for.

On the other hand, if the decision result in the step 187 is NO, that is, if the EGR is not executed, the process proceeds to a step 189, and the map used in the step 164 is searched by the same method as the step 185. The basic injection end timing INJMAPF for lean combustion and non-EGR is obtained.

The above steps 185, 186, 188,
189, the routine proceeds to step 190, in which the basic injection end timing INJMAPF is set to step 1
A value obtained by adding the water temperature correction term IJTW obtained at 80 is set as the first injection end timing IJLOGH.

Next, the following steps 191 to 194 are performed.
This is executed in the same manner as in steps 170 to 173 of the above-described stratified charge combustion end timing calculation processing. That is, when the determination result in step 191 is YES and EGR is being executed, the process proceeds to step 192, and based on the engine speed NE and the second injection time ToutD obtained in step 182, the routine proceeds to step 171. By searching the used map, stratified combustion, EGR
Basic injection end timing INJMAPF is obtained.
Next, the routine proceeds to step 193, where the basic injection end timing INJMAPF for stratified charge combustion and EGR is set as the second injection end timing IJLOGD, and this processing ends.

On the other hand, if the decision result in the step 191 is NO, that is, if the EGR is not executed, the process proceeds to a step 194, and the map used in the step 173 is searched by the same method as that in the step 192. After obtaining the basic injection end timing INJMAPF for stratified charge combustion and non-EGR, the routine proceeds to step 193, where the basic injection end timing INJMAPD is determined as the second injection end timing IJLOGD.
And the process ends.

As described above, in the processing of steps 180 to 193, the injection end timing in the intake stroke of the double injection combustion mode is set to the uniform combustion injection end timing IJLOGH retrieved from the map for uniform combustion. The injection end timing for the stratified combustion is the injection end timing for the stratified combustion IJLOG retrieved from the map for the stratified combustion.
D is set. For this reason, it is not necessary to prepare a map for double injection combustion separately from the maps for uniform combustion and stratified combustion, and the number of ROMs 2c can be reduced accordingly.

Next, the KCMD calculation process in step 83 of the double injection combustion mode control process will be described with reference to FIG. First, in step 200,
It is determined whether or not the combustion mode monitor S_EMOD is “0”. When the result of this determination is YES, that is, when the combustion mode before the transition to the two-injection combustion mode is the stoichiometric combustion mode, the routine proceeds to step 201, where the previous value of the final target air-fuel ratio coefficient KCMD stored in the RAM 2b is set to a predetermined value. It is determined whether or not the value is equal to or greater than the value KBSST. This predetermined value KBSST is set to the value of the final target air-fuel ratio coefficient KCMD corresponding to the stoichiometric air-fuel ratio.

When the result of this determination is NO, that is, when the previous value of the final target air-fuel ratio coefficient KCMD is on the lean side, the routine proceeds to step 202, where it is determined whether or not the flag F_PRISM is "1". This flag F_PRI
SM is a flag indicating whether or not optimal A / F control (hereinafter referred to as “O2 · A / F control”) according to the detection signal of the O2 sensor is being executed. If it is executed, it is set to "1", and if it is not executed, it is set to "0".

When the result of this determination is YES, that is, when O
2. When the A / F control is being executed, step 2
In step 03, the final target air-fuel ratio coefficient KCMD is calculated by the KCMD calculation process for O2 · A / F control, and the process ends.

On the other hand, if the decision result in the step 202 is NO, that is, if the O2 · A / F control is not executed, the present processing is performed without updating the previous value of the final target air-fuel ratio coefficient KCMD in the RAM. To end.

On the other hand, if the decision result in the step 201 is YES.
, That is, when the previous value of the final target air-fuel ratio coefficient KCMD is on the rich side,
This processing ends.

On the other hand, if the decision result in the step 200 is NO, that is, if the combustion mode before the transition to the double injection combustion mode is not the stoichiometric combustion mode, the step 204 is executed.
Then, it is determined whether or not the combustion mode monitor S_EMOD is “1”. When the result of this determination is YES, that is, when the combustion mode before the transition to the double injection combustion mode is the lean combustion mode, the routine proceeds to step 205, where EGR is performed.
It is determined whether or not the permission flag F_EGR is “1”.

When the result of this determination is YES, that is, when E
When GR is executed, the routine proceeds to step 206, where a map (not shown) is searched based on the required torque PME and the engine speed NE obtained in step 1 to obtain a basic target air-fuel ratio coefficient for lean combustion and EGR. Ask for KBS.

Next, the routine proceeds to step 208, where the value obtained by multiplying the basic target air-fuel ratio coefficient KBS by the water temperature correction coefficient KTW obtained in step 6 is used as the final target air-fuel ratio coefficient KBS.
This is set as CMD, and the process ends.

On the other hand, if the decision result in the step 205 is NO, that is, if the EGR is not executed, the process proceeds to a step 207, and the basic target air-fuel ratio coefficient for the lean combustion, non-EGR Ask for KBS. Next, the routine proceeds to step 208, where the final target air-fuel ratio coefficient KCMD is calculated, and this processing ends.

On the other hand, if the decision result in the step 204 is NO, that is, if the combustion mode before the transition to the double injection combustion mode is the stratified combustion mode, the step 205
Steps 209 to 211 are executed in the same manner as in steps # 206 to # 206. That is, when EGR is being performed, stratified combustion, EGR are performed in the same manner as in step 206 described above.
Of the basic target air-fuel ratio coefficient KBS (step 20)
9, 210), and then execute step 208 described above.
This processing ends. On the other hand, when EGR is not executed, the basic target air-fuel ratio coefficient KBS for stratified combustion and non-EGR is determined by the same method as in step 206 (steps 209 and 211).
8 is executed, and the present process ends.

Hereinafter, the ignition timing control process will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 18 shows a main routine of this processing. This processing is executed every time a TDC signal is input, following the fuel injection control processing.

First, at step 220, an IGM
An AP calculation process is executed, and a map value IGM of the ignition timing IG is obtained.
Calculate AP. Next, the routine proceeds to step 221, where the map value IGMAP obtained in step 220 is set as the basic ignition timing IGBASi.

Then, the process proceeds to a step 222, wherein a correction term calculation process is executed to calculate each correction term described later. next,
Proceeding to step 223, by applying each correction term obtained in step 222 to the following equation (5), the total correction term IGC
Calculate R. IGCR = IGTW + IGIDL-IGTA-IGACCR + IGWOT-IGTWR-IGATR (5)

Then, the process proceeds to a step 224, wherein the final ignition timing IGABi is calculated by applying IGLOG, which is a value obtained by adding the total correction term IGCR to the basic ignition timing IGBASi, to the following equation (6). To end. This final ignition timing IGABi is output to the ignition plug 5 as the ignition timing IG. IGABi = IGLOG + IGADJ = (IGBASi + IGCR) + IGADJ (6) Here, IGADJ corrects the deviation of the detection value of the rotation angle of the crankshaft 3e or the camshaft 6, etc., and also corrects the delay of the detection signal from various sensors. And is calculated as a positive value or a negative value.

Hereinafter, the IGMAP calculation process in step 220 will be described with reference to FIG. First, in step 230, the combustion mode transition flag F
It is determined whether or not _CMOD is “1”. When the result of this determination is NO, that is, when the mode is not the two-injection combustion mode, the routine proceeds to step 231, where the combustion mode monitor S_
It is determined whether the EMOD is “0”.

When the result of this determination is YES, that is, when S
If _EMOD = 0 and the engine 3 is in the stoichiometric combustion mode, the routine proceeds to step 232, where a stoichiometric combustion IGMAPm search process described later is executed to determine a stoichiometric combustion basic map value IGMAPm.

On the other hand, if the decision result in the step 231 is NO, that is, if the mode is not the stoichiometric combustion mode, the process proceeds to a step 233 to determine whether or not the combustion mode monitor S_EMOD is "1". This determination result is YES
In other words, when the engine is in the lean combustion mode, the routine proceeds to step 234, where the IGMA for lean combustion described later is used.
Pm search processing is executed, and the basic map value I for lean combustion is
Determine GMAPm.

On the other hand, if the decision result in the step 233 is NO, that is, if S_EMOD = 2 and the engine 3
Is in the stratified combustion mode, the routine proceeds to step 235, in which a stratified combustion IGMAPm search process described later is executed, and a stratified combustion basic map value IGMAPm is obtained.

Following one of the IGMAPm search processes in steps 232, 234, and 235, the process proceeds to step 236, where the EGR correction coefficient K for the corresponding combustion mode is set.
A KEGR correction term IGKEGR is obtained by searching a table (not shown) based on the EGR (KEGR obtained in any of steps 22, 42, and 62).

Then, the process proceeds to a step 237, wherein a VTC correction term IGVTC is obtained by searching a table (not shown) based on the actual cam phase CAIN.

Next, the routine proceeds to step 238, where the KEGR correction term IGKEGR is added to the basic map value IGMAPm obtained in one of steps 232, 234 and 235.
By adding the VTC correction term IGVTC and the map value IGMAP, the process is terminated.

On the other hand, if the decision result in the step 230 is YES.
, That is, when in the double injection combustion mode,
Proceeding to step 239, the engine speed NE and the second injection end timing I obtained in step 193 are determined.
JLOGD (injection end timing for stratified combustion IJLO
GD), a basic map value IGMAPm is obtained by searching a map (not shown).

Next, the routine proceeds to step 240, where the basic map value IGMAPm is set to the map value IGMAP, and this processing ends. Thus, in the double injection combustion mode,
A map value IGMAP is obtained based on the engine speed NE and the injection end timing IJLOGD for stratified combustion, that is, the fuel injection timing θinj. In this case, as described above, the engine speed NE has a great effect on the stability of combustion in the double injection combustion mode, and the fuel injection timing θinj for the stratified combustion mode is different from that in the double injection combustion mode. The fuel injection timing is determined during the compression stroke, and the fuel injected at this time is involved in ignition. Therefore, a stable combustion state can be ensured by setting the map value IGMAP to a value at which stable ignition in the double injection combustion mode is obtained.

Next, the IGMAPm search processing for stoichiometric combustion in step 232 will be described with reference to FIG. In this process, a basic map value IGMAPm for stoichiometric combustion is obtained. First, step 25
0, the VTEC permission flag F_VTEC is “1”
Is determined. When the result of this determination is YES, that is, when the valve timing is HI. When it is set to VT, the routine proceeds to step 251, where it is determined whether or not the EGR permission flag F_EGR is "1".

When the result of this determination is YES, that is, when E
When GR is being executed, the routine proceeds to step 252, in which a map (not shown) is searched based on the engine speed NE and the required torque PME obtained in step 1 to obtain HI. Basic map value I for VT, EGR
This processing is ended after finding GMAPm.

On the other hand, if the decision result in the step 251 is NO, that is, if the EGR is not executed, the process proceeds to a step 253, and the HI. Basic map value IGM for VT, non-EGR
This process is completed after obtaining APm.

On the other hand, if the decision result in the step 250 is NO, that is, if the valve timing is LO. If it is set to VT, the routine proceeds to step 254, where it is determined whether or not the idle flag F_IDLE is "1".

When the result of this determination is YES, that is, when the engine 3 is idling, step 255
Then, a map value IGIDLn for idling operation is obtained by searching a table (not shown) based on the target idle speed NOBJ. Next, step 256
Then, the map value IGIDLn for the idling operation is set to the basic map value IGMAPm, and the process ends.

On the other hand, if the decision result in the step 254 is NO, that is, if the engine 3 is not idling, the routine proceeds to a step 257, in which the EGR permission flag F_E
It is determined whether or not GR is “1”.

When the result of this determination is YES, that is, when E
When the GR is being executed, the process proceeds to step 258, and the LO. V
The basic map value IGMAPm for T and EGR is obtained, and this processing is ended.

On the other hand, if the decision result in the step 257 is NO, that is, if the EGR is not executed, the process proceeds to a step 259, and the LO. Basic map value IGM for VT, non-EGR
This process is completed after obtaining APm.

Next, the IGMAPm search processing for lean combustion in step 234 will be described with reference to FIG. First, in step 260, it is determined whether or not the EGR permission flag F_EGR is “1”.

When the result of this determination is YES, that is, when E
When GR is being executed, the routine proceeds to step 261, and a map (not shown) is searched based on the engine speed NE and the required torque PME obtained in step 1 to obtain a basic map value IGMAPm for EGR. This processing ends.

On the other hand, if the decision result in the step 260 is NO, that is, if the EGR is not executed, the process proceeds to a step 262, and the basic map value IGMAPm for the non-EGR is obtained by the same method as the step 261. This processing ends.

Next, the IGMAPm search processing for stratified combustion in step 235 will be described with reference to FIG. First, in step 270, it is determined whether or not the EGR permission flag F_EGR is “1”.

When the result of this determination is YES, that is, when E
When GR is being executed, the process proceeds to step 271 to determine whether or not the idle flag F_IDLE is “1”.

When the result of this determination is YES, that is, when the engine 3 is idling, step 272 is executed.
To step 172 or step 193
End timing IJLOGD in the compression stroke obtained in
By searching a map (not shown) based on the engine speed NE and the engine speed NE, the map value IG for idling operation is obtained.
Find IDLn. Next, the routine proceeds to step 273, where the map value IGIDLn for idling operation is changed to the basic map value IG.
This is set to MAPm, and this processing ends.

On the other hand, if the decision result in the step 271 is NO, that is, if the engine 3 is not idling, the process proceeds to a step 274, and in the same manner as the step 272, in the compression stroke obtained in the step 172 or the step 193, Injection end timing IJLOGD
By searching a map (not shown) based on the engine speed NE and the engine speed NE, the basic map value IGM for EGR is obtained.
This process is completed after obtaining APm.

On the other hand, if the decision result in the step 270 is NO, that is, if the EGR is not executed, the process proceeds to a step 275, and by the same method as the step 274, the step 172 or the step 193 is performed.
End timing IJLOGD in the compression stroke obtained in
Then, the basic map value IGMAPm for the non-EGR is obtained based on the engine speed NE and the engine speed NE, and the process ends.

As described above, the basic map value IGMAPm for the stratified combustion mode is obtained based on the injection end timing (the injection end timing in the compression stroke) IJLOGD for the stratified combustion, and as described above, The combustion injection end timing IJLOGD is obtained based on the final fuel injection time Tout representing the amount of fuel actually injected into the combustion chamber 3c. That is, the basic map value IGMAPm for the stratified combustion mode and the ignition timing I
Since G is determined as a value suitable for the actual fuel injection timing, a stable combustion state can be ensured even in the stratified combustion mode in which fuel is difficult to burn.

Next, the correction term calculating process in the step 222 will be described with reference to FIG. As shown in the figure, first, in step 280, IGTW calculation processing is executed. Specifically, a low water temperature correction term IGTW is obtained by searching a table (not shown) based on the engine water temperature TW.

Then, the process proceeds to a step 281, wherein the IGID
Perform L calculation processing. In this process, an idle rotation correction term IGIDL is obtained by searching a table (not shown) based on the engine speed NE during idle operation.

Next, the routine proceeds to step 282, where IGTA calculation processing is executed. Specifically, based on the intake air temperature TA,
An intake temperature correction term IGTA is obtained by searching a table (not shown).

Next, the routine proceeds to step 283, where the IGAC
Execute the CR calculation process. Specifically, the vehicle acceleration AC
An acceleration correction term IGACCR is obtained by searching a table (not shown) based on the CR.

Next, the flow advances to step 284, where IGWOT is set.
Execute the calculation process. Specifically, based on whether or not the throttle valve opening TH detected by the throttle valve opening sensor 32 is in the fully open state, a fully open correction term IGWOT is obtained by searching a table (not shown).

Then, the process proceeds to a step 285, wherein the IGTW
An R calculation process is performed. The specific contents of this processing will be described later.

Next, the process proceeds to a step 286, wherein the IGATR
The calculation process is executed, and the process ends. In this process, an AT shift correction term IGATR is obtained by searching a table (not shown) based on the gear position NGAR of the automatic transmission detected by the gear position sensor 31.

Next, the IGTWR calculation processing of the above step 285 will be described with reference to FIG. As shown in the figure, in this processing, first, in step 290,
It is determined whether the combustion mode monitor S_EMOD is not “2”. When the result of this determination is YES, that is, when the engine is not in the stratified combustion mode, the routine proceeds to step 291, and based on the engine coolant temperature TW, TW− shown in FIG.
By searching the IGTWR table, the high water temperature correction term IGTWR for uniform combustion is calculated, and the process ends.

In this TW-IGTWR table,
The curve shown by the solid line is the high water temperature correction term IGTW for uniform combustion.
8 shows a table value of R, and the table value is set to a larger value as the engine coolant temperature TW is higher.
This is for the following reason. That is, step 22
As shown in Expression (5) of Equation (3), the high water temperature correction term IGTWR is a subtraction term.
GABi, that is, the ignition timing IG is corrected to the retard side.
On the other hand, in general, as the engine coolant temperature TW is higher, knocking is more likely to occur due to a higher combustion temperature. Therefore, as described above, by setting the high water temperature correction term IGTWR to a larger value as the engine water temperature TW is higher, knocking can be prevented by increasing the retard correction amount of the ignition timing IG.

On the other hand, if the decision result in the above step 290 is N
In the case of O, that is, in the stratified combustion mode, the process proceeds to step 292, and the high water temperature correction term IGTWR for stratified combustion is calculated by the same method as in step 291.
This processing ends. In this case, in FIG. 25, a curve shown by a broken line in the figure is a high water temperature correction term IGTW for stratified charge combustion.
The table value of R is shown, and this table value is set to a smaller value in the same tendency as that for the uniform combustion. This is due to the following two reasons. First, in the stratified combustion mode, fuel is injected into the concave portion 3d of the piston 3a, and the fuel is vaporized by heat exchange with the piston 3a at that portion to generate a mixture, so that the higher the engine coolant temperature TW, The vaporization of the mixture is promoted. In the stratified charge combustion mode, the air-fuel mixture is
Is ignited when it reaches the vicinity of, and since the surroundings of the air-fuel mixture at the time of the ignition are air, knocking hardly occurs compared to the uniform combustion mode.

The IGTWR calculation process may be executed by a method shown in FIG. 26 instead of the above method.
As shown in FIG.
Are the same as steps 290 and 291 described above, so only step 297 will be described. This step 2
At 97, the high water temperature correction term IGTWR for stratified charge combustion has a value of 0
Is set to That is, in this processing, the retard correction by the high water temperature correction term IGTWR is omitted in the stratified combustion mode. This is because knocking hardly occurs in the stratified combustion mode, as described above.

Next, with reference to FIG. 28, a description will be given of a combustion mode transition determination process for determining the start and end of the double injection combustion mode when transitioning between the uniform combustion mode and the stratified combustion mode. This process is executed every predetermined time (for example, 10 msec) by setting a program timer.

First, in step 300, it is determined whether or not the combustion mode transition flag F_CMOD is "0". If the determination result is YES, that is, if the double injection combustion mode is not being executed, step 301
To the previous value S_EM of the combustion mode monitor S_EMOD
ODn-1 is “2” and the current value S_EMODn
Is not “2”. This is Engine 3
This is a process for determining whether or not the operating region of FIG. 3 has shifted from the stratified combustion region to the uniform combustion region shown in FIG.

If the determination result is YES, it is determined that the operating range of the engine 3 has shifted from the stratified combustion region to the uniform combustion region in this loop, and the double injection combustion mode should be started. Then, the combustion mode transition flag F_CMOD indicating that is set to “1”, and this processing ends.

On the other hand, if the decision result in the step 301 is NO, the process proceeds to a step 303, where the combustion mode monitor S_
The previous value of EMOD S_EMODn−1 is not “2”,
And it is determined whether or not the current value S_EMODn is “2”. If the determination result is YES, it is determined that the operating region of the engine 3 has shifted from the uniform combustion region to the stratified combustion region in this loop, and the double injection combustion mode should be started. As in step 302, the combustion mode transition flag F_CMOD is set to “1”, and the process ends.

On the other hand, if the decision result in the step 303 is NO, that is, if the operating region of the engine 3 has not shifted between the stratified combustion region and the uniform combustion region in this loop, the routine proceeds to a step 305, where The timer value tmCCMOD of the injection combustion mode timer is set to “0”, and this processing ends. This double injection combustion mode timer determines the end timing of the execution period of the double injection combustion mode.

On the other hand, if the result of the determination in step 300 is N
If O, that is, if the double injection combustion mode is being executed, the routine proceeds to step 306, where the timer value tmCCM
Increment OD. Next, proceeding to step 307, the timer value tm incremented in step 306
It is determined whether or not CCMOD is longer than a predetermined time X_TMCCMOD. This predetermined time X_TMCCMOD is
This is a value representing the responsiveness of the EGR control valve 16, for example, EG
When the EGR control valve 16 is closed to compensate for the response delay of the R control valve 16, the actual valve lift LA
It is set as the closing time required for the CT to change from 100% to 5%.

When the result of this determination is NO, that is, when tm
If CCMOD ≦ X_TMCCMOD and the predetermined time X_TMCCMOD has not elapsed from the start of the double injection combustion mode, the present process is terminated as it is, and the execution of the double injection combustion mode is continued.

On the other hand, if the decision result in the step 307 is YES.
, Ie, tmCCMOD> X_TMCCMOD
A predetermined time X_ from the start of the double injection combustion mode.
When TMCCMOD has elapsed, it is determined that the double injection combustion mode should be ended, and the process proceeds to step 308, and
To indicate this, the combustion mode transition flag F_CMOD is set to “0”, and this processing ends.

As described above, the execution period of the double injection combustion mode is the predetermined time X which is the closing time of the EGR control valve 16.
Determined based on _TMCCMOD. As described above, the target valve lift amount LCMD of the EGR control valve 16
Is usually greatly different between the stratified combustion mode and the uniform combustion mode, and therefore, when the combustion mode is shifted between these two combustion modes, the EGR control valve 16 operates until the target valve lift amount LCMD after the shift. It takes time to change. Therefore, as described above, the EGR control valve 16
The predetermined time X_TMCCMOD considering the response of
By setting the execution period of the multiple injection combustion mode,
The double injection combustion mode can be continuously executed until the valve lift amount of the EGR control valve 16 reliably changes to the valve lift amount for the combustion mode after the double injection combustion mode. As a result, since a stable combustion state can be ensured after the double injection combustion mode, for example, stable drivability with small output fluctuation can be ensured before and after the double injection combustion mode. In addition, since the execution period of the double injection combustion mode is determined as described above, the execution period of the double injection combustion mode can be shortened to a necessary minimum, and thus, the NO
Deterioration of exhaust gas characteristics due to an increase in x can be suppressed to a minimum.

Note that the combustion mode shift determination processing may be executed by a method shown in FIG. 28 instead of the above method. In this process, the execution period of the double injection combustion mode is determined by the deviation dLACT of the valve lift amount instead of the timer value of the double injection combustion mode timer described above. As shown in FIG.
Step 14 is the same as steps 300 to 304 in FIG. 27 described above, and thus description thereof will be omitted and only different points will be described.

In this process, if the decision result in the step 313 is NO, that is, if the engine 3 is not in the double injection combustion mode, the present process is terminated as it is.

On the other hand, if the decision result in the step 310 is NO, that is, if F_CMOD = 1, the routine proceeds to a step 315, where a deviation dLACT of the valve lift amount is calculated. The deviation dLACT is calculated as an absolute value of a deviation between the target valve lift amount LCMD and the actual valve lift amount LACT detected by the valve lift amount sensor 26.

Then, the process proceeds to a step 316, wherein a step 3
The deviation dLACT calculated in step 15 is a predetermined deviation X_DLac
It is determined whether it is smaller than tCM. This predetermined deviation X_
DLactCM is a threshold value for determining whether or not the actual valve lift amount LACT of the EGR control valve 16 has converged to the target valve lift amount LCMD, and is a value representing the responsiveness of the EGR control valve 16.

When the result of this determination is NO, that is, when dL
When ACT ≧ X_DLactCM, it is determined that the actual valve lift amount LACT of the EGR control valve 16 has not sufficiently reached the target valve lift amount LCMD after the start of the two-injection combustion mode, and the present process ends.

On the other hand, if the decision result in the step 317 is YES.
, Ie, when dLACT <X_DLactCM, after the start of the double injection combustion mode, the EGR control valve 1
Assuming that the actual valve lift amount LACT of No. 6 has sufficiently reached the target valve lift amount LCMD, the process proceeds to step 318 to end the double injection combustion mode, and the combustion mode transition flag F_CMOD is set to “0” to indicate this. Is set, and the process ends. As described above, the deviation dLAC
The end timing of the double injection combustion mode is determined by whether or not T has become smaller than the predetermined deviation X_DLactCM, that is, whether or not the actual valve lift amount LACT of the EGR control valve 16 has reached the target valve lift amount LCMD. Therefore, the same effect as the processing shown in FIG. 27 described above can be obtained.

As described above, according to the control device 1 of the present embodiment, the target valve lift amount LCMD for both combustion modes is used.
And the final target air-fuel ratio coefficient KCMD and the fuel injection timing θinj for the uniform combustion mode are determined by the engine speed NE and the required torque PME, which indicate the load, or the engine speed NE.
And the intake pipe absolute pressure PBA. Therefore, immediately after the transition from the stratified combustion mode to the uniform combustion mode, even if the intake air becomes unstable, each combustion parameter for the uniform combustion mode is determined based on the intake air amount. Unlikely, it can be decided appropriately without being affected.

The basic map value IGMAPm of the ignition timing IG for the stratified charge combustion mode is obtained based on the injection end timing IJLOGD for the stratified charge combustion. The injection end timing IJLOGD for the stratified charge combustion is determined by the final fuel injection time Tout. Is determined based on As described above, the injection end timing IJLO is based on the final fuel injection time Tout representing the amount of fuel actually injected into the combustion chamber 3c.
Since the ignition timing IG is obtained based on the GD and the injection end timing IJLOGD thus obtained, the ignition timing IG for the stratified combustion mode can be obtained as a value suitable for the actual injection end timing IJLOGD. Thereby, a stable combustion state can be obtained even in the stratified combustion mode in which the fuel is difficult to burn. As described above, in each of the uniform combustion mode and the stratified combustion mode, by appropriately determining each combustion parameter including the ignition timing IG, a stable combustion state can be ensured, and as a result, good fuel economy can be obtained. , Drivability and exhaust gas characteristics can be ensured.

In the embodiment, the target valve lift amount LCMD, the final target air-fuel ratio coefficient KCMD, and the fuel injection timing θinj are shown as the combustion parameters for the two combustion modes obtained based on the load. The throttle valve opening TH may be used. In this case, the throttle valve opening TH is determined by searching a map for each combustion mode based on the engine speed NE and the required torque PME, for example, similarly to the other combustion parameters described above.
It is determined.

In addition, an in-cylinder injection type engine of the type described in the present embodiment, that is, the injector 4 is disposed substantially at the center of the top wall of the combustion chamber 3c, and during stratified charge combustion, fuel is injected from the injector 4 to the piston 3a side. In particular, although no data is shown here for the head-injection type, it has been confirmed by experiments that the above effects can be obtained optimally.

The present invention is not limited to the in-cylinder injection type engine 3 of the present embodiment in which the injector 4 is disposed substantially at the center of the top wall of the combustion chamber 3c, but may be of a type in which the arrangement of the injector is different. The invention may be applied to an in-cylinder injection type engine.

[0206]

As described above, according to the control apparatus for an internal combustion engine of the present invention, in both the uniform combustion mode and the stratified combustion mode, the combustion parameters such as the ignition timing are appropriately adjusted according to the operating state and the combustion state. By ensuring a stable combustion state,
Good fuel efficiency, drivability and exhaust gas characteristics can be secured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a control device according to an embodiment of the present invention and an internal combustion engine to which the control device is applied.

FIG. 2 is a flowchart illustrating a main routine of a fuel injection control process.

FIG. 3 is a diagram showing a map used in an S_EMOD setting process in step 1 of FIG. 2;

FIG. 4 is a flowchart showing a subroutine of a stoichiometric combustion mode control process in step 13 of FIG. 2;

FIG. 5 is a flowchart showing a subroutine of a lean combustion mode control process in step 14 of FIG. 2;

FIG. 6 is a flowchart showing a subroutine of a stratified combustion mode control process in step 15 of FIG. 2;

FIG. 7 is a flowchart showing a subroutine of a double injection combustion mode control process in step 16 of FIG. 2;

FIG. 8 is a flowchart showing a subroutine of a Tibase calculation process of FIGS. 4 to 7;

FIG. 9 is a flowchart illustrating a subroutine of an LCMD calculation process of FIGS. 4 to 7;

FIG. 10 is a flowchart showing a subroutine of an injection timing calculation process of FIGS. 4 to 7;

FIG. 11 is a diagram illustrating an example of an NE-ToutdbD table.

12 is a flowchart showing a subroutine of an injection end timing calculation process for stoichiometric combustion in step 132 of FIG. 10;

FIG. 13 is a diagram illustrating an example of a TW-IJTW table.

FIG. 14 is a flowchart showing a subroutine of an injection end timing calculation process for lean combustion in step 135 of FIG. 10;

FIG. 15 is a flowchart illustrating a subroutine of a stratified combustion injection end timing calculation process in step 136 of FIG. 10;

FIG. 16 is a flowchart showing a subroutine of an injection end timing calculation process for double injection combustion in step 140 of FIG. 10;

FIG. 17 is a flowchart illustrating a subroutine of a KCMD calculation process in step 84 of FIG. 7;

FIG. 18 is a flowchart illustrating a main routine of an ignition timing control process.

FIG. 19 is a flowchart illustrating a subroutine of an IGMAP calculation process in step 220 of FIG. 18;

20 is a flowchart showing a subroutine of IGMAPm search processing for stoichiometric combustion in step 232 of FIG. 19;

FIG. 21 shows the I value for lean combustion in step 234 of FIG. 19;
It is a flowchart which shows the subroutine of GMAPm search processing.

22. IG for stratified combustion in step 235 of FIG.
It is a flowchart which shows the subroutine of MAPm search processing.

FIG. 23 is a flowchart showing a subroutine of a correction term calculation process in step 222 of FIG. 18;

FIG. 24 is a flowchart showing a subroutine of IGTWR calculation processing in step 285 of FIG. 23;

25 is a diagram illustrating a TW- used in the IGTWR calculation process of FIG. 24;
It is a figure showing an example of an IGTWR table.

FIG. 26 is a flowchart showing a modification of the subroutine of the IGTWR calculation process in step 285 of FIG. 23.

FIG. 27 is a flowchart showing a combustion mode shift determination process.

FIG. 28 is a flowchart illustrating a modification of the combustion mode shift determination processing.

[Explanation of symbols]

1 control device 2 ECU (load detection means, combustion parameter determination means,
Uniform combustion mode ignition timing determining means, stratified combustion mode ignition timing determining means, final fuel injection amount determining means, fuel injection timing determining means, engine speed detecting means, required torque determining means) 3 internal combustion engine 3c combustion chamber 4 fuel Injection valve 22 Crank angle sensor (load detecting means, engine speed detecting means) 24 Intake pipe absolute pressure sensor (load detecting means) 30 Accelerator opening sensor (load detecting means, accelerator opening detecting means) AP Accelerator opening (load NE Engine speed (Parameter representing load) PME Required torque (Parameter representing load) PBA Absolute pressure in intake pipe (Parameter representing load) KCMD Final target air-fuel ratio coefficient (Combustion parameter) LCMD Target valve lift ( Combustion parameter) θinj Fuel injection timing (combustion parameter) IJLOGH Uniform fuel End timing for combustion (combustion parameters, fuel injection timing for uniform combustion mode) IJLOGD Injection end timing for stratified combustion (combustion parameters, fuel injection timing for combustion mode) IG ignition timing IGMAPm Basic map value (for uniform combustion mode) Ignition timing, stratified combustion mode ignition timing) Tout Final fuel injection time (final fuel injection amount)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 330 F02D 41/04 335C 335 43/00 301B 43/00 301 301J 45/00 314H 45/00 314 F02P 5/15 C (72) Inventor Isao Komoriya 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Hiroshi Taue 1-4-1 Chuo, Wako-shi, Saitama Stock Company Honda R & D F-term (reference) 3G022 AA07 BA01 CA09 DA02 EA02 FA06 GA01 GA02 GA05 GA07 GA08 GA09 GA20 3G023 AA02 AA03 AB03 AC05 AD01 AD29 AG01 AG02 AG03 3G084 AA04 BA02 BA05 BA09 BA13 BA15 BA17 DA02 EA11 EB08 EB12 EB24 EC02 EC04 FA06 FA10 FA11 FA18 FA20 FA30 FA33 FA37 FA38 FA39 3G301 HA04 HA13 HA14 HA16 HA19 JA02 JA12 JA13 JA21 JA22 KA01 KA07 KA08 LA00 LA03 LB04 LC03 MA01 MA11 MA18 MA20 MA26 MA27 MA29 NA08 NA09 NC02 NC08 ND01 ND45 NE13 NE14 NE15 PA07Z PA09Z PA10Z PA14Z PA17Z PB03Z PB08Z PB10Z PD04A PD09A PD09Z PD15Z10 PDZZ PE15Z10

Claims (5)

[Claims] 1. A control device for an in-cylinder injection type internal combustion engine operated by switching a combustion mode between a uniform combustion mode in which fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in a compression stroke. Load detection means for detecting a load of the internal combustion engine; and a combustion parameter determination for determining combustion parameters for the uniform combustion mode and the stratified combustion mode other than the ignition timing according to the detected load. Means, a uniform combustion mode ignition timing determining means for determining the uniform combustion mode ignition timing in accordance with the detected load, and a stratified combustion mode ignition timing other than the determined ignition timing. And a stratified combustion mode ignition timing determining means for determining in accordance with the stratified combustion mode combustion parameter. 2. The combustion parameter used for determining the ignition timing for the stratified combustion mode is a fuel injection timing, and the combustion parameter determining means is configured to determine whether the final combustion mode is to be injected into the cylinder during the stratified combustion mode. A final fuel injection amount determining unit that determines a fuel injection amount according to the load; anda fuel injection timing determining unit that determines the fuel injection timing according to the determined final fuel injection amount. The control device for an internal combustion engine according to claim 1, wherein: 3. After the fuel injection timing of the combustion cycle is determined by the fuel injection timing determination means, the combustion timing is determined by the stratified combustion mode ignition timing determination means in accordance with the determined fuel injection timing. 3. The control device for an internal combustion engine according to claim 2, wherein the ignition timing of the cycle is determined. 4. The load detecting means includes: an engine speed detecting means for detecting an engine speed; an accelerator opening detecting means for detecting an accelerator opening; ,
The control device for an internal combustion engine according to any one of claims 1 to 3, further comprising a required torque determining means for determining a required torque as the load. 5. A fuel injection valve for injecting fuel into the cylinder is provided at a central portion of a top wall of a combustion chamber of the cylinder, and is configured to inject fuel downward. The control device for an internal combustion engine according to any one of claims 1 to 4, wherein