JP2004232575A - Fuel injection control device of cylinder injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure stable combustion performance not influenced by properties of fuel in a cylinder injection type engine. <P>SOLUTION: In the case where used fuel is determined to be heavy fuel (fuel property is heavy) at operation in a layered combustion mode, the base compression stroke injection timing ACO corresponding to the standard fuel is corrected by timing advance in a range falling the compression stroke to set the final compression stroke injection timing AC. On the other hand, in the case where used fuel is determined to be heavy fuel at operation in a homogeneous combustion mode, the base intake stroke injection timing AIO corresponding to the standard fuel is corrected by timing lag in a range falling the intake stroke to set the final intake stroke injection timing AI. Thus, the amount of time (time for atomizing fuel) from when fuel is injected into the cylinder until ignition is performed is enlarged so that even if heavy fuel can be enough atomized to form air fuel mixture in suitable timing corresponding to each combustion mode. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection control device for an in-cylinder injection type internal combustion engine in which a fuel injection control method for an in-cylinder injection type internal combustion engine that directly injects fuel into a cylinder is improved.
[0002]
[Prior art]
Generally, adjustment of fuel injection conditions (for example, fuel injection timing) of an internal combustion engine is often performed using a fuel having standard fuel properties (standard fuel). However, the fuel properties of the fuel actually used in the market vary, and the evaporation properties and the atomization properties of the fuel injected from the fuel injection valve change depending on the fuel properties. For this reason, if heavy fuel with poor atomization characteristics is used, the injected fuel cannot be sufficiently atomized under the fuel injection conditions adapted with the standard fuel, and the combustion state deteriorates, resulting in drivability. And exhaust emissions may be degraded.
[0003]
As a countermeasure, in an intake port injection engine that injects fuel into an intake port of an intake pipe, as shown in Patent Document 1 (Japanese Patent No. 2596433), when the fuel property is determined to be heavy, Change the injection timing from the intake stroke to the compression stroke on the more advanced side, and the time from when the fuel is injected into the intake port until it is sucked into the cylinder (time to atomize the fuel at the intake port) In some cases, the atomization time corresponding to heavy fuel can be ensured by increasing the length of the fuel.
[0004]
Further, as disclosed in Patent Document 2 (Japanese Patent No. 2799021), when the fuel property is determined to be heavy, the fuel injection timing is changed from the exhaust stroke to the intake stroke on the more retarded side, The fuel injected into the intake port is put on the intake air flow and is quickly sucked into the cylinder to reduce the amount of fuel (wet) attached to the inner wall surface of the intake port. In some cases, it is possible to secure the amount of fuel to be sucked into the vehicle.
[0005]
On the other hand, in recent years, demand for an in-cylinder injection engine having features of low fuel consumption, low exhaust emission, and high output has been rapidly increasing. This in-cylinder injection engine switches between a stratified combustion mode and a homogeneous combustion mode in accordance with the operating state of the engine. In the stratified combustion mode, a small amount of fuel is directly injected into the cylinder in the compression stroke to form a stratified charge near the spark plug. In the homogeneous combustion mode, a fuel-air mixture is formed and stratified combustion is performed. In the homogeneous combustion mode, the fuel injection amount is increased, and fuel is directly injected into the cylinder during the intake stroke to form a homogeneous fuel-air mixture and perform homogeneous combustion.
[0006]
[Patent Document 1]
Japanese Patent No. 2596433 (Page 2, FIG. 2, etc.)
[Patent Document 2]
Japanese Patent No. 2799021 (page 2, FIG. 5, etc.)
[0007]
[Problems to be solved by the invention]
In the fuel injection control disclosed in Patent Documents 1 and 2 described above, when the fuel property is determined to be heavy, the process of injecting fuel is changed to a more advanced stroke or a more retarded stroke. I have to. Although these methods are effective for intake port injection engines as described above, they are problematic for in-cylinder injection engines.
[0008]
That is, in the direct injection engine, fuel is directly injected into the cylinder, so that the fuel is injected into the cylinder in a predetermined stroke corresponding to each combustion mode (an intake stroke in the homogeneous combustion mode, and a compression stroke in the stratified combustion mode). By doing so, an air-fuel mixture is formed in the cylinder at an appropriate timing corresponding to the combustion mode. Therefore, the technology of fuel injection control of an intake port injection engine shown in Patent Documents 1 and 2 is applied to an in-cylinder injection engine, and when the fuel property is determined to be heavy, the stroke of injecting the fuel is reduced. If the stroke is changed to a more advanced stroke or a more retarded stroke, a mixture (stratified mixture, homogeneous mixture) corresponding to the combustion mode can be formed normally, instead of preventing combustion deterioration due to differences in fuel properties. It will no longer be able to burn normally.
[0009]
The present invention has been made in view of such circumstances, and accordingly, an object of the present invention is to provide a cylinder capable of securing stable combustion performance independent of fuel properties and improving drivability and exhaust emission. An object of the present invention is to provide a fuel injection control device for an internal injection type internal combustion engine.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a fuel injection control apparatus for a direct injection internal combustion engine according to claim 1 of the present invention comprises: a stratified combustion mode in which fuel is injected into a cylinder in a compression stroke to perform stratified combustion; In a system that operates in at least one of the homogeneous combustion modes in which fuel is injected into a cylinder to perform homogeneous combustion, the fuel property of the used fuel is determined by the fuel property determination unit, and the fuel property is determined to be heavy. In this case, the fuel injection timing is advanced by the fuel injection correction means within a predetermined stroke corresponding to the combustion mode. That is, in the homogeneous combustion mode, the compression stroke injection timing is advanced in the compression stroke, and in the stratified combustion mode, the intake stroke injection timing is advanced in the intake stroke.
[0011]
If the fuel properties are heavy, if the fuel injection timing is advanced, the time from the injection of fuel into the cylinder to the ignition (time to atomize the fuel) is increased, and heavy fuel However, it can be atomized appropriately. Moreover, since the fuel injection timing is advanced in a predetermined stroke corresponding to the combustion mode, the stratified or homogeneous mixture is formed at an appropriate timing corresponding to the stratified or homogeneous combustion mode without being affected by other strokes. can do. As a result, stable stratification or homogeneous combustion that is not affected by fuel properties can be realized, and drivability and exhaust emission can be improved.
[0012]
By the way, in the homogeneous combustion mode in which fuel is injected in the intake stroke, the intake stroke injection timing suitable for the standard fuel may be set near the intake top dead center. Under this condition, the position of the piston is still in the position of the fuel injection valve. When the fuel is injected toward the piston when it is nearby, piston wet occurs in which the injected fuel adheres to the piston. In such a region, if the intake stroke injection timing is advanced when the fuel property is heavy, the position of the piston at the time of fuel injection becomes closer to the fuel injection valve than before the advance correction, so the piston The wetness increases, which acts in a direction that worsens the atomization of the injected fuel.
[0013]
Therefore, when the fuel property is determined to be heavy in a state where the intake stroke injection timing is set near the intake top dead center when operating in the homogeneous combustion mode as in claims 2 and 3, It is preferable to retard the intake stroke injection timing. With this configuration, when the fuel property is determined to be heavy, the piston is lowered to some extent from the top dead center and the fuel is injected at a certain distance from the fuel injection valve, so that the piston wet is reduced. Thus, atomization of heavy fuel can be improved.
[0014]
In general, in the stratified combustion mode, fuel is injected into the cylinder at a predetermined timing when the piston rises in the compression stroke, and the injected fuel is guided to the vicinity of the ignition plug by using the upper surface of the piston to stratify. Since the stratified combustion is realized by forming the mixture, the correctable range of the compression stroke injection timing is narrow, and if the compression stroke injection timing is advanced too much, the stratified mixture cannot be formed normally, This will result in worse combustion and misfire.
[0015]
Therefore, when the compression stroke injection timing advanced in accordance with the fuel property determination in the stratified charge combustion mode exceeds a predetermined value on the advance side when the engine is operated in the stratified charge combustion mode, a stratified charge It is preferable to switch from the combustion mode to the homogeneous combustion mode. In other words, if the compression stroke injection timing after the advance correction exceeds the predetermined value on the advance side, it is determined that a stratified mixture cannot be formed normally with the compression stroke injection timing as it is, and the mode is switched to the homogeneous combustion mode. . Accordingly, when heavy fuel that cannot be dealt with by the advance correction of the compression stroke injection timing is used, the mode is switched to the homogeneous combustion mode (intake stroke injection) in which the atomization time can be sufficiently secured even with such heavy fuel. As a result, the heavy fuel can be appropriately atomized and stably burned.
[0016]
Alternatively, when the fuel property is determined to be heavy when operating in the stratified combustion mode, the mode may always be switched from the stratified combustion mode to the homogeneous combustion mode.
[0017]
By the way, in an in-cylinder injection type internal combustion engine, the mixing effect of injected fuel and intake air can be improved by operating in an intake stroke split injection mode in which fuel is divided into a plurality of times during an intake stroke and injected into a cylinder. There is an engine in which the temperature in the cylinder is lowered to increase the knock limit to increase the torque.
[0018]
When operating in the intake stroke split injection mode, at least one of the number of split injections, the ratio of the first injection amount, and the split injection interval is corrected according to the fuel property. Is also good.
[0019]
For example, if the number of divided injections is increased when the fuel property is heavy as in claim 7, the effect of mixing the injected fuel and the intake air can be further enhanced, and the atomization of the heavy fuel can be improved. .
[0020]
In the intake stroke split injection mode, the piston is located at the position closest to the fuel injection valve at the time of the first injection of the plurality of injections. If the ratio of the second injection amount is reduced, the piston wet can be effectively reduced, and the atomization of heavy fuel can be improved.
[0021]
Further, if the fuel injection is heavy and the split injection interval is lengthened, the next fuel can be injected after the atomization of the previously injected fuel has progressed to some extent. Fuel atomization can be improved.
[0022]
In the case of a system in which an intake / compression stroke injection mode in which fuel is divided into an intake stroke and a compression stroke and injected into a cylinder is set, when operating in the intake / compression stroke injection mode as in claim 10, Alternatively, the ratio of the injection amount in the intake stroke may be corrected according to the fuel property. For example, if the ratio of the amount of fuel to be injected in the intake stroke is increased when the fuel property is heavy, the injection in the intake stroke in which the time from fuel injection to ignition (fuel atomization time) is long is long. By increasing the amount, it is possible to reduce the injection amount in the compression stroke, in which the time from fuel injection to ignition is short, so that the atomization of heavy fuel can be improved and stable combustion can be achieved. realizable.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
<< Embodiment (1) >>
Hereinafter, an embodiment (1) of the present invention will be described with reference to FIGS. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of a direct injection engine 11 which is a direct injection internal combustion engine. An air flow meter 14 for detecting an intake air amount is provided downstream of the air cleaner 13. Is provided. A throttle valve 16 driven by a motor 15 such as a DC motor is provided downstream of the air flow meter 14, and the opening of the throttle valve 16 (throttle opening) is detected by a throttle opening sensor 17.
[0024]
Further, a surge tank 18 is provided downstream of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting an intake pipe pressure is provided in the surge tank 18. Further, the surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and controls the in-cylinder airflow intensity (swirl flow intensity or tumble flow intensity) in the intake manifold 20 of each cylinder. An airflow control valve 31 is provided.
[0025]
A fuel injection valve 21 for directly injecting fuel into the cylinder is attached to an upper part of each cylinder of the engine 11. An ignition plug 22 is attached to a cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22. Further, the intake valve 37 and the exhaust valve 38 of the engine 11 are provided with variable valve timing mechanisms 39 and 40 for varying valve timing, respectively.
[0026]
A knock sensor 32 for detecting knocking and a coolant temperature sensor 23 for detecting coolant temperature are attached to a cylinder block of the engine 11. A crank angle sensor 24 that outputs a crank angle signal for each predetermined crank angle is mounted on the outer peripheral side of a crank shaft (not shown). The crank angle and the engine speed are detected based on the output signal of the crank angle sensor 24.
[0027]
On the other hand, the exhaust pipe 25 of the engine 11 is provided with an upstream catalyst 26 and a downstream catalyst 27 for purifying exhaust gas, and detects an air-fuel ratio or rich / lean of the exhaust gas upstream of the upstream catalyst 26. An exhaust gas sensor 28 (air-fuel ratio sensor, oxygen sensor, etc.) is provided. In the present embodiment, a three-way catalyst that purifies CO, HC, NOx, and the like in exhaust gas near the stoichiometric air-fuel ratio is provided as the upstream catalyst 26, and a NOx storage reduction catalyst is provided as the downstream catalyst 27. . The NOx storage reduction catalyst 27 stores NOx in the exhaust gas when the air-fuel ratio of the exhaust gas is lean, and reduces and purifies and releases the stored NOx when the air-fuel ratio becomes near the stoichiometric air-fuel ratio or becomes rich. Have the property to do.
[0028]
Further, between the downstream side of the upstream catalyst 26 in the exhaust pipe 25 and the surge tank 18 downstream of the throttle valve 16 in the intake pipe 12, a part of the exhaust gas is recirculated to the intake side. An EGR pipe 33 is connected, and an EGR valve 34 for controlling an exhaust gas recirculation amount (EGR amount) is provided in the middle of the EGR pipe 33. Further, the depression amount of the accelerator pedal 35 (accelerator opening) is detected by an accelerator sensor 36.
[0029]
The outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various control routines stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 and the fuel The injection timing, the ignition timing of the ignition plug 22 and the like are controlled.
[0030]
The ECU 30 functions as a combustion mode switching control unit by executing the routines shown in FIGS. 2 to 6 described later, and performs the homogeneous operation in the stratified combustion mode according to the engine operating state (required torque, engine rotation speed, etc.). Switch to combustion mode. In the stratified combustion mode, a small amount of fuel is directly injected into the cylinder in the compression stroke to form a stratified mixture near the ignition plug 22 and perform stratified combustion, thereby improving fuel efficiency. On the other hand, in the homogeneous combustion mode, the engine output is increased by increasing the fuel injection amount and injecting fuel directly into the cylinder during the intake stroke to form a homogeneous mixture and perform homogeneous combustion.
[0031]
At this time, the ECU 30 functions as a fuel injection correction means by executing the fuel system control routine shown in FIGS. 5 and 6, and when operating in the stratified combustion mode when the fuel property is determined to be heavy. The compression stroke injection timing is advanced in the compression stroke, and when operating in the homogeneous combustion mode, the intake stroke injection timing is advanced in the intake stroke. Thereby, when the fuel property is heavy, the time from the injection of fuel into the cylinder to the ignition (time for atomizing the fuel) is lengthened, and even heavy fuel can be atomized appropriately. To do.
[0032]
The ECU 30 functions as a fuel property determination unit by executing a fuel property determination routine (not shown), and is used based on combustion stability (rotation fluctuation) after engine start, air-fuel ratio deviation during transient operation, and the like. Determine the fuel properties of the fuel. Alternatively, the fuel property of the fuel used may be determined based on a sensor output (fuel evaporation property) of a fuel property sensor or the like provided in the fuel tank.
[0033]
Hereinafter, processing contents of each routine shown in FIGS. 2 to 6 executed by the ECU 30 will be described.
[0034]
[Engine control main routine]
The engine control main routine of FIG. 2 is executed at a predetermined cycle after an ignition switch (not shown) is turned on. When the main routine is started, first, in step 100, a required torque is calculated based on the accelerator opening, the engine speed, and the like. Thereafter, the routine proceeds to step 200, where the combustion mode determination routine of FIG. 3 is executed to determine the combustion mode. After that, the routine proceeds to step 300, where the combustion mode switching control routine of FIG. For example, the combustion mode switching control is executed, and in the next steps 400 to 600, the air system control routine (not shown), the fuel system control routine of FIGS. 5 and 6, and the ignition system control routine (not shown) are executed. Then, the combustion mode is switched by switching each control parameter of the air system, the fuel system, and the ignition system to the target value of the switching destination combustion mode at a predetermined timing.
[0035]
[Combustion mode determination routine]
When the combustion mode determination routine of FIG. 3 is started in step 200 of the engine control main routine of FIG. 2, first, in step 201, a required combustion mode determination map is searched to find the current engine operating state (for example, engine speed and engine speed). One of the stratified combustion mode and the homogeneous combustion mode is selected as the required combustion mode in accordance with the required torque. In the required combustion mode determination map, the stratified combustion mode is selected in the low rotation and low torque range with priority given to fuel economy, while the homogeneous combustion mode is selected in the high rotation and high torque range with priority given to engine output. It is set to be.
[0036]
Thereafter, the process proceeds to step 202, where it is determined whether the required combustion mode selected according to the current engine operating state is the homogeneous combustion mode. If the required combustion mode is the homogeneous combustion mode, the process proceeds to step 203, It is determined whether or not the current actual combustion mode is the homogeneous combustion mode. If the current actual combustion mode is not the homogeneous combustion mode, it is necessary to switch the combustion mode. Therefore, the routine proceeds to step 204, the combustion mode switching flag is turned on, and the routine proceeds to step 205, where the air system control mode is switched to the homogeneous mode. Set to combustion mode. On the other hand, if the current actual combustion mode is the homogeneous combustion mode, there is no need to switch the combustion mode. Therefore, the process skips step 204 and proceeds to step 205 to maintain the air system control mode in the homogeneous combustion mode.
[0037]
When it is determined in step 202 that the required combustion mode is not the homogeneous combustion mode (the stratified combustion mode), the process proceeds to step 207, and it is determined whether the current actual combustion mode is the stratified combustion mode. . If the current actual combustion mode is not the stratified combustion mode, it is necessary to switch the combustion mode. Therefore, the routine proceeds to step 208, the combustion mode switching flag is turned on, and the routine proceeds to step 209, where the air system control mode is set to the homogeneous mode. Set to combustion mode. On the other hand, if the current actual combustion mode is the stratified combustion mode, there is no need to switch the combustion mode. Therefore, the process skips step 208 and proceeds to step 205 to maintain the air system control mode in the stratified combustion mode.
[0038]
[Combustion mode switching control routine]
When the combustion mode switching control routine of FIG. 4 is started in step 300 of the engine control main routine of FIG. 2, first, in step 301, the combustion mode is being switched based on whether or not the combustion mode switching flag is ON. It is determined whether or not the combustion mode is not being switched, and this routine ends without performing the subsequent processing.
[0039]
On the other hand, if the combustion mode is being switched, the routine proceeds to step 302, where it is determined whether or not the required combustion mode is the stratified combustion mode, and if the required combustion mode is not the stratified combustion mode (that is, the required combustion mode is the homogeneous combustion mode). If so, the process proceeds to step 303, where it is determined whether the actual air-fuel ratio A / F is in the homogeneous combustion region based on whether the actual air-fuel ratio A / F is richer than the homogeneous combustion region determination value CAF2. . As a result, when it is determined that the actual air-fuel ratio A / F is leaner than the homogeneous combustion region determination value CAF2 (the actual air-fuel ratio A / F is not in the homogeneous combustion region), the subsequent processing is not performed. Then, this routine ends.
[0040]
Thereafter, when it is determined that the actual air-fuel ratio A / F has become richer than the homogeneous combustion region determination value CAF2 and the actual air-fuel ratio A / F has entered a region where homogeneous combustion can be performed, the routine proceeds to step 304, and the fuel system control is performed. After the mode is set to the homogeneous combustion mode and the fuel injection mode is switched to the intake stroke injection, the combustion mode switching flag is turned off, and this routine ends. Thereby, the actual combustion mode is switched to the homogeneous combustion mode.
[0041]
If it is determined that the combustion mode is being switched and the required combustion mode is the stratified combustion mode (if both determinations are “Yes” in steps 301 and 302), the process proceeds to step 306, where the actual air-fuel ratio A is determined. It is determined whether or not the actual air-fuel ratio A / F is in the stratified combustion region based on whether / F is leaner than the stratified combustion region determination value CAF1. As a result, when it is determined that the actual air-fuel ratio A / F is richer than the stratified combustion region determination value CAF1 (the actual air-fuel ratio A / F is not in the stratified combustion region), the subsequent processing is performed. No, this routine ends.
[0042]
Thereafter, when the actual air-fuel ratio A / F is leaner than the stratified combustion region determination value CAF1 and it is determined that the actual air-fuel ratio A / F has entered a region where stratified combustion can be performed, the routine proceeds to step 308, where fuel system control is performed. After the mode is set to the stratified combustion mode and the fuel injection mode is switched to the compression stroke injection, the combustion mode switching flag is turned off and the routine ends. Thereby, the actual combustion mode is switched to the stratified combustion mode.
[0043]
[Injection timing correction amount calculation routine]
When the injection timing correction amount calculation routine of FIG. 5 is started in step 500 of the engine control main routine of FIG. 2, first, in step 401, it is determined whether or not the fuel used is heavy fuel (if the fuel property is heavy, Is determined), and if it is determined that the fuel is heavy, the routine proceeds to step 402, where it is determined whether the fuel system control mode is the stratified combustion mode.
[0044]
As a result, when it is determined that the fuel system control mode is the stratified combustion mode, the routine proceeds to step 403, where a map of the compression stroke injection timing correction amount AC1 for the stratified combustion mode is searched to find the current engine operating state. Then, a compression stroke injection timing correction amount AC1 is calculated according to (for example, the engine rotation speed Ne and the required torque). The compression stroke injection timing correction amount AC1 is set as an advance correction value for performing advance correction of a base compression stroke injection timing AC0 described later within a range within the compression stroke.
[0045]
On the other hand, if it is determined in step 402 that the fuel system control mode is not the stratified combustion mode (it is the homogeneous combustion mode), the process proceeds to step 404, where the map of the intake stroke injection timing correction amount AI1 for the homogeneous combustion mode is set. To calculate the intake stroke injection timing correction amount AI1 according to the current engine operating state (for example, the engine rotation speed Ne and the required torque). The intake stroke injection timing correction amount AI1 is set as an advance correction value for advancing the base intake stroke injection timing AI0 for the homogeneous combustion mode described later within a range that falls within the intake stroke.
[0046]
Thereafter, if it is determined in step 401 that the used fuel is not heavy fuel (light fuel), the process proceeds to step 405, where both the compression stroke injection timing correction amount AC1 and the intake stroke injection timing correction amount AI1 are set. Both are cleared to "0".
[0047]
[Fuel injection timing calculation routine]
When the fuel injection timing calculation routine of FIG. 6 is started in step 500 of the engine control main routine of FIG. 2, first, in step 501, it is determined whether or not the fuel system control mode is the stratified combustion mode. If it is determined that the engine is in the mode, the routine proceeds to step 502, where a map of the base compression stroke injection timing AC0 for the stratified combustion mode is searched, and the current engine operating state (for example, the engine speed Ne and the required torque) is set. The base compression stroke injection timing AC0 for the stratified combustion mode is calculated accordingly. The map of the base compression stroke injection timing AC0 for the stratified combustion mode is created by using, for example, a standard fuel (fuel having standard fuel properties) and an appropriate value.
[0048]
Thereafter, the routine proceeds to step 503, in which the base compression stroke injection timing AC0 for the stratified combustion mode is advanced using the injection timing correction amount AC1 within the compression stroke so that the final compression stroke for the stratified combustion mode is performed. The injection timing AC is obtained.
AC = AC0 + AC1
[0049]
On the other hand, if it is determined in step 501 that the fuel system control mode is not the stratified combustion mode (it is the homogeneous combustion mode), the process proceeds to step 504, where the map of the base intake stroke injection timing AI0 for the homogeneous combustion mode is displayed. A search is performed to calculate a base intake stroke injection timing AI0 for the homogeneous combustion mode according to the current engine operating state (for example, the engine speed Ne and the required torque). The map of the base intake stroke injection timing AI0 for the homogeneous combustion mode is created by using, for example, standard fuel (fuel having standard fuel properties) and using an appropriate value.
[0050]
After that, the routine proceeds to step 505, in which the base intake stroke injection timing AI0 for the homogeneous combustion mode is advanced by using the injection timing correction amount AI1 within the intake stroke so that the final intake stroke for the homogeneous combustion mode is obtained. The injection timing AI is obtained.
AI = AI0 + AI1
[0051]
An execution example of the embodiment (1) described above will be described with reference to a time chart of FIG. When operating in the stratified combustion mode, the base compression stroke injection timing AC0 corresponding to the standard fuel is calculated in accordance with the engine operating state, and further, when the used fuel is determined to be heavy fuel (fuel property is heavy). Sets the final compression stroke injection timing AC by advancing the base compression stroke injection timing AC0 within the compression stroke using the injection timing correction amount AC1 according to the engine operating state.
[0052]
On the other hand, when operating in the homogeneous combustion mode, the base intake stroke injection timing AI0 corresponding to the standard fuel is calculated in accordance with the engine operating state, and if the used fuel is determined to be heavy fuel, the engine operating state is determined. The base intake stroke injection timing AI0 is advanced by using the injection timing correction amount AI1 corresponding to the intake stroke correction amount within the intake stroke to set the final intake stroke injection timing AI.
[0053]
In the case where the used fuel is determined to be heavy fuel as described above, if the compression stroke injection timing AC and the intake stroke injection timing AI are advanced and corrected, the time from when fuel is injected into the cylinder to when it is ignited can be obtained. The time (time to atomize the fuel) can be lengthened, and even heavy fuel can be appropriately atomized. In addition, since the compression stroke injection timing AC and the intake stroke injection timing AI are advanced in a predetermined stroke corresponding to the combustion mode, the appropriate timing corresponding to the stratified or homogeneous combustion mode is not affected by other strokes. Can form a stratified or homogeneous mixture. As a result, stable combustion performance independent of fuel properties can be secured, and drivability and exhaust emissions can be improved.
[0054]
<< Embodiment (2) >>
Next, an embodiment (2) of the present invention will be described with reference to FIGS. In the homogeneous combustion mode in which fuel is injected in the intake stroke, as shown in FIG. 9, the base intake stroke injection timing AI0 for the homogeneous combustion mode corresponding to the standard fuel may be set near the intake top dead center. In this case, fuel is injected toward the piston at a timing near the top dead center of the piston, that is, at a timing when the piston is still near the fuel injection valve 21. In such a region, when the base intake stroke injection timing AI0 is advanced and the fuel property is heavy, the piston position at the time of fuel injection is closer to the fuel injection valve 21 than before the advance correction. Therefore, the amount of fuel (piston wet) adhering to the piston increases, which acts in a direction to worsen atomization of the fuel.
[0055]
Therefore, in the present embodiment (2), by executing the intake stroke injection timing correction amount calculation routine of FIG. 8 described later, when operating in the homogeneous combustion mode, the base intake stroke injection timing AI0 for the homogeneous combustion mode is changed to the intake stroke. If the fuel property is determined to be heavy in the state set near the top dead center, the base intake stroke injection timing AI0 is retarded within the range of the intake stroke, and the piston is moved from the top dead center. The fuel is injected at a timing that is lowered to some extent and separated from the fuel injection valve 21 to some extent.
[0056]
The intake stroke injection timing correction amount calculation routine of FIG. 8 is executed at a predetermined cycle during the homogeneous combustion mode operation. When this routine is started, it is first determined in step 601 whether or not the fuel used is heavy fuel (whether or not the fuel property is heavy). If it is determined that the fuel is heavy fuel In step 602, it is determined whether the current base intake stroke injection timing AI0 for the homogeneous combustion mode is near the intake top dead center (whether C1 <AI0 <C2).
[0057]
As a result, when it is determined that the base intake stroke injection timing AI0 is near the intake top dead center, it is determined that the base intake stroke timing AI0 needs to be retarded, and the routine proceeds to step 603, where the retardation is determined. A map of the injection timing correction amount AI1 for correction is searched to calculate an injection timing correction amount AI1 for retard correction in accordance with the current engine operating state (for example, the engine speed Ne and the required torque). The injection timing correction amount AI1 for retard correction is set as a retard correction value for retarding the base intake stroke injection timing AI0 within the intake stroke.
[0058]
On the other hand, if it is determined in step 602 that the base intake stroke timing AI0 is not near the intake top dead center, it is determined that the base intake stroke timing AI0 needs to be advanced, and the process proceeds to step 604. A map of the injection timing correction amount AI1 for advanced angle correction is searched to calculate the injection timing correction amount AI1 for advanced angle correction in accordance with the current engine operating state (for example, the engine speed Ne and the required torque). The injection timing correction amount AI1 for advance correction is set as an advance correction value for performing advance correction of the base intake stroke injection timing AI0 within a range that falls within the intake stroke.
[0059]
Thereafter, when it is determined in step 601 that the used fuel is not heavy fuel (light fuel), the process proceeds to step 605, and the injection timing correction amount AI1 is cleared to “0”.
[0060]
According to the embodiment (2) described above, as shown in the time chart of FIG. 9, when operating in the homogeneous combustion mode, the base intake stroke injection timing AI0 corresponding to the standard fuel is set near the intake top dead center. If the used fuel is determined to be heavy fuel (heavy fuel properties) in the set state, the base intake stroke injection timing AI0 is set within the intake stroke by using the injection timing correction amount AI1 for retard correction. , And the final intake stroke injection timing AI is set by performing the retard correction within the range of. As a result, the fuel is injected at a timing that the piston descends from the top dead center to some extent and is apart from the fuel injection valve 21 to some extent, so that the piston wet can be reduced and the atomization of heavy fuel can be improved. Even heavy fuel can be stably burned.
[0061]
<< Embodiment (3) >>
In general, in the stratified charge combustion mode, fuel is injected into the cylinder at a predetermined timing when the piston rises in the compression stroke, and the injected fuel is guided to the vicinity of the ignition plug 22 using the upper surface of the piston. Since stratified combustion is realized by forming a stratified mixture, the correctable range of the fuel injection timing is narrow, and if the compression stroke injection timing is advanced too much, the stratified mixture cannot be formed normally, This will result in worse combustion and misfire.
[0062]
Therefore, in the embodiment (3) of the present invention, by performing a fuel injection timing calculation routine shown in FIG. 10 described later, the advance angle is corrected in accordance with the fuel property heavy determination when operating in the stratified combustion mode. When the compression stroke injection timing AC for the stratified combustion mode exceeds the advance side guard value G1, which is a correction limit value on the advance side, the stratified combustion mode is switched to the homogeneous combustion mode.
[0063]
The fuel injection timing calculation routine of FIG. 10 is obtained by adding the processing of steps 506 and 507 after step 503 of the routine of FIG. 6 described in the above embodiment (1). It is the same as FIG.
[0064]
In this routine, when the fuel system control mode is the stratified combustion mode, the base compression stroke injection timing AC0 for the stratified combustion mode corresponding to the standard fuel is calculated according to the engine operating state, and the base compression stroke injection timing AC0 is calculated. The advance angle is corrected by the injection timing correction amount AC1 to obtain the final compression stroke injection timing AC for the stratified combustion mode (steps 501 to 503).
AC = AC0 + AC1
[0065]
Thereafter, the routine proceeds to step 506, in which it is determined whether or not the advanced stroke corrected compression stroke injection timing AC for the stratified combustion mode exceeds the advanced side guard value G1. As a result, if it is determined that the compression stroke injection timing AC for the stratified combustion mode has exceeded the advance side guard value G1, the stratified mixture cannot be normally formed as it is, and combustion deterioration and misfire may occur. When it is determined that there is a possibility of inviting, the process proceeds to step 507 and the required combustion mode is switched to the homogeneous combustion mode. Thereby, the air-based control mode and the fuel-based control mode (= ignition-based control mode) are each switched at a predetermined timing to the homogeneous combustion mode, and the actual combustion mode is switched to the homogeneous combustion mode.
[0066]
On the other hand, if it is determined in step 506 that the compression stroke injection timing AC for the stratified combustion mode has not exceeded the advance side guard value G1, the routine skips step 507 and ends the routine. In this case, the fuel is injected at the compression stroke injection timing AC in which the advance angle has been corrected in step 503.
[0067]
In the embodiment (3) described above, when operating in the stratified charge combustion mode, the compression stroke injection timing AC for the stratified charge combustion mode, which is advanced in accordance with the determination of the fuel property, is set to the advance side guard value G1. Is exceeded, the stratified combustion mode is switched to the homogeneous combustion mode. Therefore, if heavy fuel that cannot be dealt with by the advance correction of the compression stroke injection timing AC is used, even such heavy fuel is used. The mode can be switched to the homogeneous combustion mode (intake stroke injection) in which a sufficient atomization time can be secured, and the heavy fuel can be appropriately atomized and stably burned.
[0068]
It should be noted that a determination value for switching the combustion mode is set separately from the advance side guard value G1, and the compression stroke injection timing AC, which has been advanced in accordance with the determination of the heavy fuel property, is set when operating in the stratified combustion mode. When the determination value for the combustion mode switching is exceeded, the stratified combustion mode may be switched to the homogeneous combustion mode.
When the fuel property is determined to be heavy when operating in the stratified combustion mode, the mode may always be switched from the stratified combustion mode to the homogeneous combustion mode.
[0069]
<< Embodiment (4) >>
Next, an embodiment (4) of the present invention will be described with reference to FIGS. As shown in FIG. 12, the in-cylinder injection engine 11 operates in an intake stroke split injection mode in which fuel is divided into a plurality of injection strokes and injected into the cylinder, thereby reducing the mixing effect between the injected fuel and the intake air. In some cases, the knock limit is expanded by increasing the temperature or lowering the temperature in the cylinder to increase the torque.
[0070]
In the present embodiment (4), the fuel property is determined to be heavy when operating in the intake stroke split injection mode by executing the split stroke count calculation routine for the intake stroke split injection mode of FIG. 11 described later. In such a case, the number of divided injections when the fuel is divided and injected in a plurality of times in the intake stroke is increased to improve the atomization of heavy fuel.
[0071]
The split injection number calculation routine for the intake stroke split injection mode in FIG. 11 is executed at a predetermined cycle after an ignition switch (not shown) is turned on. When this routine is started, first, at step 701, it is determined whether or not there is a split injection request. This split injection request is generated when the split injection execution condition at the time of high load is satisfied or when the split injection execution condition at the time of warm-up is satisfied.
[0072]
Here, the split injection execution condition under high load is, for example, to satisfy all of the following conditions (1) to (3).
(1) The engine speed is lower than a predetermined value CNE1.
(2) The required torque is larger than the predetermined value CTQ1
(3) The cooling water temperature is higher than the predetermined value CW1
[0073]
If all of the above conditions (1) to (3) are satisfied, the split injection execution condition under a high load is satisfied, but if any of the conditions (1) to (3) is not satisfied, The split injection execution condition at the time of high load is not satisfied.
[0074]
On the other hand, the split injection execution condition at the time of warm-up is, for example, to satisfy all of the following conditions (4) to (6).
(4) The engine speed is lower than a predetermined value CNE2.
(5) The required torque is smaller than the predetermined value CTQ2
(6) Cooling water temperature is lower than predetermined value CW2
If all of the above conditions (4) to (6) are satisfied, the split injection execution condition at the time of warm-up is satisfied, but if any of the above conditions (4) to (6) does not satisfy any of the conditions, The split injection execution condition during warm-up is not satisfied.
[0075]
When one of the split injection execution condition at the time of high load and the split injection execution condition at the time of warm-up is satisfied and it is determined that there is a split injection request, the process proceeds to step 702, and the used fuel is heavy fuel. It is determined whether or not there is (the fuel property is heavy).
[0076]
As a result, when it is determined that the used fuel is heavy fuel, the routine proceeds to step 703, in which a map of the number of divided injections N for heavy fuel is searched, and the current engine operating state (for example, engine speed) is searched. Ne and the required torque) are calculated as the number N of divided injections for heavy fuel. The map of the number of divided injections N for heavy fuel is set such that the heavy fuel has a larger number of divided injections N than the light fuel when the engine operation state is the same.
[0077]
On the other hand, if it is determined in step 702 that the used fuel is not heavy fuel (light fuel), the process proceeds to step 704, in which a map of the light fuel split injection frequency N is searched to find the current fuel injection number N. The number of light fuel split injections N is calculated according to the engine operating state (for example, the engine speed Ne and the required torque).
[0078]
Thereafter, in step 701, when the split injection execution condition at the time of high load and the split injection execution condition at the time of warm-up are both not satisfied, and it is determined that there is no split injection request, the process proceeds to step 705, Set to no injection (number of injections = 1).
[0079]
According to the above-described embodiment (4), when operating in the intake stroke split injection mode, as shown in FIG. 12A, if it is determined that the fuel is light fuel (the fuel property is light), the fuel is split. The number of injections N is reduced, and as shown in FIG. 12B, when it is determined that the fuel is heavy (the fuel property is heavy), the number of divided injections N is increased. If the number of divided injections N is increased in the case of heavy fuel, the mixing effect between the injected fuel and the intake air can be further enhanced to improve the atomization of the heavy fuel, and the heavy fuel can be stably burned. .
[0080]
<< Embodiment (5) >>
In the embodiment (5) of the present invention, the fuel property is determined to be heavy when operating in the intake stroke split injection mode by executing the fuel injection amount calculation routine for the intake stroke split injection mode of FIG. 13 described later. In such a case, the ratio of the first fuel injection amount when the fuel is divided into a plurality of injections during the intake stroke is reduced to improve the atomization of heavy fuel.
[0081]
The fuel injection amount calculation routine for the intake stroke split injection mode in FIG. 13 is executed at a predetermined cycle after an ignition switch (not shown) is turned on. When this routine is started, it is first determined in step 801 whether or not there is a split injection request. If it is determined that there is a split injection request, the flow proceeds to step 802, and the fuel used is heavy fuel. Is determined (whether or not the fuel property is heavy).
[0082]
As a result, if it is determined that the fuel used is heavy fuel, the process proceeds to step 803, where a map of the distribution ratio KSP for heavy fuel is searched, and the current engine operating state (for example, the engine speed Ne) is searched. And the required torque) are calculated. The distribution ratio KSP is a ratio of the first fuel injection amount QI1 to the total fuel injection amount Qtotal (when the number of divided injections is two, the first fuel injection amount QI1 + the second fuel injection amount QI2). The map of the distribution ratio KSP for heavy fuel is such that the distribution ratio KSP of heavy fuel is smaller than that of light fuel and the first fuel injection amount QI1 is smaller if the engine operation state is the same. Is set.
[0083]
On the other hand, if it is determined in step 802 that the used fuel is not heavy fuel (light fuel), the process proceeds to step 804, in which a map of the distribution ratio KSP for light fuel is searched to find the current engine. A light fuel distribution ratio KSP according to the operating state (for example, the engine speed Ne and the required torque) is calculated.
[0084]
After calculating the distribution ratio KSP, the routine proceeds to step 806, where the total fuel injection amount Qtotal is multiplied by the distribution ratio KSP to obtain the first fuel injection amount QI1 in the intake stroke, and the first fuel injection amount Qtotal is used to calculate the first fuel injection amount QI1 in the intake stroke. Is subtracted to obtain a second fuel injection amount QI2 in the intake stroke (when the number of divided injections is two).
QI1 = Qtotal × KSP
QI2 = Qtotal-QI1
Thereafter, if it is determined in step 801 that there is no split injection request, the flow advances to step 805 to set no split injection (distribution ratio KSP = 100%).
[0085]
According to the above-described embodiment (5), when operating in the intake stroke split injection mode, as shown in FIG. 12A, if the fuel is determined to be light fuel (the fuel property is light), the fuel is distributed. The fuel injection amount QI1 in the first intake stroke is increased by increasing the rate KSP, and as shown in FIG. 12C, when it is determined that the fuel is heavy (the fuel property is heavy), the distribution rate KSP is determined. And the first fuel injection amount QI1 in the intake stroke is reduced. In the intake stroke split injection mode, the fuel is injected at the timing when the piston comes closest to the fuel injection valve 21 during the first injection of a plurality of injections. Therefore, in the case of heavy fuel, the first fuel injection amount QI1 is used. If the value is reduced, the piston wet can be effectively reduced, the atomization of the heavy fuel can be improved, and the heavy fuel can be stably burned.
It is needless to say that the number of divided injections in the intake stroke is not limited to two, but may be three or more.
[0086]
<< Embodiment (6) >>
In the embodiment (6) of the present invention, the fuel property is determined to be heavy when operating in the intake stroke split injection mode by executing the split injection interval calculation routine for the intake stroke split injection mode of FIG. 14 described later. In such a case, the divided injection interval (divided injection interval) for performing the injection in a plurality of times in the intake stroke is increased to improve the atomization of the heavy fuel.
[0087]
The split injection interval calculation routine for the intake stroke split injection mode in FIG. 14 is executed at a predetermined cycle after an ignition switch (not shown) is turned on. When this routine is started, it is first determined in step 901 whether or not there is a split injection request. If it is determined that there is a split injection request, the process proceeds to step 902, and the fuel used is heavy fuel. Is determined (whether or not the fuel property is heavy).
[0088]
As a result, if it is determined that the used fuel is heavy fuel, the process proceeds to step 903, where a map of the heavy fuel split injection interval ITV is searched to find the current engine operating state (for example, the engine speed). Ne and the required torque) are calculated for the heavy fuel split injection interval ITV. The map of the heavy fuel split injection interval ITV is set such that the heavy fuel has a longer split injection interval ITV than the light fuel if the engine operation state is the same.
[0089]
On the other hand, if it is determined in step 902 that the fuel used is not heavy fuel (light fuel), the process proceeds to step 904, in which a map of the light fuel split injection interval ITV is searched to find the current fuel injection map. A light fuel split injection interval ITV according to the engine operating state (for example, the engine rotation speed Ne and the required torque) is calculated.
[0090]
After the calculation of the divided injection interval ITV, the routine proceeds to step 905, where the second fuel injection timing TI2 is obtained by delaying the first fuel injection timing TI1 in the intake stroke by the divided injection interval ITV (the number of divided injections is two). Case).
TI2 = TI1−ITV
Thereafter, if it is determined in step 901 that there is no split injection request, the flow advances to step 906 to set no split injection (split injection interval = 0).
[0091]
According to the above-described embodiment (6), when operating in the intake stroke split injection mode, as shown in FIG. 12A, if it is determined that the fuel is light (the fuel property is light), the fuel is split. The injection interval ITV is shortened, and as shown in FIG. 12D, when it is determined that the fuel is heavy (the fuel property is heavy), the split injection interval ITV is lengthened. If the split injection interval ITV is lengthened in the case of heavy fuel, the next fuel can be injected after the atomization of the previously injected fuel has advanced to some extent, and the atomization of heavy fuel can be improved. In addition, heavy fuel can be stably burned.
[0092]
The number of divided injections in the intake stroke is not limited to two, but may be three or more.
Further, two or three of the above embodiments (4) to (6) may be implemented in combination.
[0093]
<< Embodiment (7) >>
Next, an embodiment (7) of the present invention will be described with reference to FIGS. As shown in FIG. 16, the in-cylinder injection type engine 11 may be operated in an intake / compression stroke injection mode in which fuel is injected into a cylinder during an intake stroke and a compression stroke, respectively.
[0094]
In the present embodiment (7), the fuel property is determined to be heavy when operating in the intake / compression stroke injection mode by executing a fuel injection amount calculation routine for the intake / compression stroke injection mode of FIG. In this case, the ratio of the amount of fuel injected in the intake stroke is increased to improve the atomization of heavy fuel.
[0095]
The fuel injection amount calculation routine for the intake / compression stroke injection mode shown in FIG. 15 is executed at a predetermined cycle after an ignition switch (not shown) is turned on. When this routine is started, it is first determined in step 1001 whether or not there is a split injection request. If it is determined that there is a split injection request, the process proceeds to step 1002, and the fuel used is heavy fuel. Is determined (whether or not the fuel property is heavy).
[0096]
As a result, if it is determined that the fuel used is heavy fuel, the process proceeds to step 1003, where a map of the distribution ratio KSP for heavy fuel is searched, and the current engine operating state (for example, the engine rotational speed Ne) is searched. And the required torque) are calculated. The distribution ratio KSP is a ratio of the fuel injection amount QI in the intake stroke to the total fuel injection amount Qtotal (fuel injection amount QI in the intake stroke + fuel injection amount QC in the compression stroke). The map of the distribution ratio KSP for heavy fuel is such that the distribution ratio KSP of heavy fuel is larger than that of light fuel and the fuel injection amount QI in the intake stroke is larger when the engine operation state is the same. Is set.
[0097]
On the other hand, if it is determined in step 1002 that the fuel used is not heavy fuel (light fuel), the process proceeds to step 1004, where a map of the distribution ratio KSP for light fuel is searched to find the current engine. A light fuel distribution ratio KSP according to the operating state (for example, the engine speed Ne and the required torque) is calculated.
[0098]
After calculating the distribution ratio KSP, the routine proceeds to step 1008, where the total fuel injection amount Qtotal is multiplied by the distribution ratio KSP to determine the fuel injection amount QI in the intake stroke, and the fuel injection amount QI in the intake stroke is calculated from the total fuel injection amount Qtotal. Is subtracted to obtain the fuel injection amount QC in the compression stroke.
QI = Qtotal × KSP
QC = Qtotal-QI
[0099]
Thereafter, if it is determined in step 1001 that there is no split injection request, the process proceeds to step 1005, where it is determined whether the fuel system control mode is the stratified combustion mode, and it is determined that the fuel cell control mode is the stratified combustion mode. In this case, the process proceeds to step 1006, in which the split injection is not performed (the distribution ratio KSP = 0%), and only the injection in the compression stroke is performed.
[0100]
On the other hand, if it is determined in step 1005 that the fuel system control mode is not the stratified combustion mode (it is the homogeneous combustion mode), the process proceeds to step 1007, where the split injection is not performed (distribution ratio KSP = 100%). Therefore, only the injection in the intake stroke is performed.
[0101]
According to this embodiment (7) described above, when operating in the intake / compression stroke injection mode, as shown in FIG. 16A, when it is determined that the fuel is light fuel (fuel property is light), The fuel injection amount QI during the intake stroke is reduced by reducing the distribution ratio KSP. As shown in FIG. 16B, when it is determined that the fuel is heavy (the fuel property is heavy), the distribution ratio KSP is increased. Then, the fuel injection amount QI in the intake stroke is increased. If the fuel injection amount QI in the intake stroke is increased in the case of heavy fuel, the fuel injection amount QI in the intake stroke injection, in which the time from fuel injection to ignition (fuel atomization time) is long, is increased. Then, the fuel injection amount QC of the compression stroke injection, in which the time from fuel injection to ignition is short, can be reduced, so that atomization of heavy fuel can be improved. Stable combustion can be achieved.
[0102]
In each of the embodiments (1) to (7), the fuel property is determined in two stages (heavy and light) and the fuel injection condition is switched in two stages. However, the fuel property is determined in three or more stages. And the fuel injection condition may be switched to three or more stages.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an entire engine control system according to an embodiment (1) of the present invention.
FIG. 2 is a flowchart showing a flow of processing of an engine control main routine.
FIG. 3 is a flowchart showing the flow of processing of a combustion mode determination routine.
FIG. 4 is a flowchart showing a processing flow of a combustion mode switching control routine.
FIG. 5 is a flowchart showing the flow of processing of an injection timing correction amount calculation routine according to the embodiment (1).
FIG. 6 is a flowchart showing the flow of processing of a fuel injection timing calculation routine according to the embodiment (1).
FIG. 7 is a time chart showing an execution example of the embodiment (1).
FIG. 8 is a flowchart showing the flow of processing of an intake stroke injection timing correction amount calculation routine according to the embodiment (2).
FIG. 9 is a time chart showing an execution example of the embodiment (2).
FIG. 10 is a flowchart showing the flow of processing of a fuel injection timing calculation routine according to the embodiment (3).
FIG. 11 is a flowchart showing a flow of a split injection number calculation routine for an intake stroke split injection mode according to the embodiment (4).
12A is a diagram illustrating an example of an injection pulse at the time of light fuel determination according to the embodiments (4) to (6), and FIG. 12B is a diagram illustrating an injection pulse at the time of heavy fuel determination according to the embodiment (4). FIG. 3C is a diagram illustrating an example, FIG. 3C is a diagram illustrating an example of an injection pulse at the time of heavy fuel determination according to the embodiment (5), and FIG. 4D is an example of an injection pulse at the time of heavy fuel determination according to the embodiment (6). Illustration
FIG. 13 is a flowchart showing the flow of processing of a fuel injection amount calculation routine for an intake stroke split injection mode according to the embodiment (5).
FIG. 14 is a flowchart showing a flow of a divided injection interval calculation routine for an intake stroke divided injection mode according to the embodiment (6).
FIG. 15 is a flowchart showing the flow of processing of a fuel injection amount calculation routine for an intake / compression stroke injection mode according to the embodiment (7).
16A is a diagram illustrating an example of an injection pulse at the time of light fuel determination according to the embodiment (7), and FIG. 16B is a diagram illustrating an example of an injection pulse at the time of heavy fuel determination according to the embodiment (7);
[Explanation of symbols]
11: In-cylinder injection engine (in-cylinder injection internal combustion engine), 12: Intake pipe, 16: Throttle valve, 21: Fuel injection valve, 22: Spark plug, 25: Exhaust pipe, 30: ECU (fuel property determination means) , Fuel injection correction means, combustion mode switching control means).

Claims (10)

In-cylinder injection operating in at least one of a stratified combustion mode in which fuel is injected into a cylinder in a compression stroke to perform stratified combustion and a homogeneous combustion mode in which fuel is injected into a cylinder in an intake stroke to perform homogeneous combustion. In a fuel injection control device for an internal combustion engine,
Fuel property determining means for determining the fuel property of the fuel used;
A direct injection internal combustion engine comprising: fuel injection correction means for advancing the fuel injection timing within a predetermined stroke corresponding to a combustion mode when the fuel property is determined to be heavy. Engine fuel injection control device. When operating in the homogeneous combustion mode, when the fuel property is determined to be heavy in the state where the intake stroke injection timing is set near the intake top dead center, the fuel injection correction means performs the intake stroke 2. The fuel injection control device for a direct injection internal combustion engine according to claim 1, wherein the injection timing is corrected for retard. In a fuel injection control device of an in-cylinder injection type internal combustion engine operating in a homogeneous combustion mode in which fuel is injected into a cylinder during an intake stroke to perform homogeneous combustion,
Fuel property determining means for determining the fuel property of the fuel used;
If the fuel property is determined to be heavy in a state where the intake stroke injection timing is set near the intake top dead center when operating in the homogeneous combustion mode, the fuel for retarding the intake stroke injection timing is corrected. A fuel injection control device for a direct injection internal combustion engine, comprising: an injection correction unit. A combustion mode switching control means for switching between the stratified combustion mode and the homogeneous combustion mode,
The combustion mode switching control means, when operating in the stratified combustion mode, the compression stroke injection timing advanced by the fuel injection correction means in accordance with the determination of the fuel property heavy exceeds a predetermined value on the advance side. The fuel injection control device for a direct injection internal combustion engine according to claim 1 or 2, wherein the switching from the stratified combustion mode to the homogeneous combustion mode is performed in a case where the fuel injection control is performed. In-cylinder injection provided with combustion mode switching control means for switching between a stratified combustion mode in which fuel is injected into a cylinder in a compression stroke to perform stratified combustion and a homogeneous combustion mode in which fuel is injected into a cylinder in an intake stroke to perform homogeneous combustion. In a fuel injection control device for an internal combustion engine,
A fuel property determining means for determining the fuel property of the fuel used;
The in-cylinder injection method, wherein the combustion mode switching control means switches from the stratified combustion mode to the homogeneous combustion mode when the fuel property is determined to be heavy when operating in the stratified combustion mode. A fuel injection control device for an internal combustion engine. In a fuel injection control device for an in-cylinder injection internal combustion engine operating in an intake stroke split injection mode in which fuel is divided into a plurality of times during an intake stroke and injected into a cylinder,
Fuel property determining means for determining the fuel property of the fuel used;
Fuel injection correcting means for correcting at least one of the number of divided injections, the ratio of the first injection amount, and the divided injection interval when operating in the intake stroke divided injection mode according to the fuel property; A fuel injection control device for a direct injection internal combustion engine. 7. The in-cylinder according to claim 6, wherein the fuel injection correction means increases the number of divided injections when the fuel property is determined to be heavy when operating in the intake stroke divided injection mode. A fuel injection control device for an injection type internal combustion engine. 7. The fuel injection correction unit according to claim 6, wherein when operating in the intake stroke split injection mode, when the fuel property is determined to be heavy, the ratio of the first injection amount is reduced. A fuel injection control device for a direct injection internal combustion engine according to claim 7. 9. The fuel injection correcting means according to claim 6, wherein when operating in the intake stroke split injection mode, if the fuel property is determined to be heavy, the split injection interval is lengthened. 3. A fuel injection control device for a direct injection internal combustion engine according to claim 1. In a fuel injection control device for an in-cylinder injection type internal combustion engine operating in an intake / compression stroke injection mode in which fuel is divided into an intake stroke and a compression stroke and injected into a cylinder,
Fuel property determining means for determining the fuel property of the fuel used;
A fuel injection correcting means for correcting a ratio of an amount of fuel injected during an intake stroke in accordance with the fuel property when operating in the intake / compression stroke injection mode. Engine fuel injection control device.

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