JP3984463B2 - In-cylinder injection engine control device with turbocharger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an in-cylinder injection engine with a turbocharger, and in particular, divided injection control for dividing and injecting fuel during an intake stroke or during a compression stroke and during an expansion stroke when acceleration is detected. The present invention relates to a control device for a turbocharger-equipped in-cylinder injection engine.
[0002]
[Prior art]
In the case of an engine equipped with a turbocharger, a so-called turbo lag is caused by a delay in the rise of turbine rotation at the start of acceleration. Various methods have been proposed as a method for suppressing the turbo lag. As one of the methods, the energy for driving the turbocharger turbine is increased by increasing the temperature of the exhaust gas, thereby increasing the supercharging. There are things that get an effect early.
[0003]
Japanese Patent Laid-Open No. 2000-54894 discloses split injection control for splitting and injecting fuel into a plurality of times in the range from the intake stroke to the ignition timing in the first half of acceleration in an in-cylinder injection engine with a supercharger. Further, a technique for setting the fuel injection timing on the late stage after the middle stage of the compression stroke is disclosed. According to this publication, by providing a rich region in which atomization is insufficient around the spark plug by late-stage fuel injection, afterburning is promoted and the exhaust temperature is increased.
[0004]
[Problems to be solved by the invention]
However, in general, afterburning is a phenomenon in which droplet fuel with insufficient atomization is atomized after most of the combustion is completed, leading to an oxidation reaction. However, in a situation where the ambient temperature after warm-up is sufficiently high, afterburning hardly occurs and a sufficient temperature rise of the exhaust gas cannot be expected.
[0005]
In addition, in-cylinder injection engines use in-cylinder injection valves that have the ability to spray fuel in a sufficiently atomized state in order to improve the combustion state in the so-called stratified combustion mode. It is difficult to provide a rich region with insufficient atomization around the spark plug using the injection valve, and afterburning cannot be expected.
[0006]
Furthermore, in the so-called uniform combustion mode, if the injection timing in the latter half by split injection control is set during the compression stroke before ignition to generate a rich region sufficient to cause afterburning, air is used in the rich region. As a result, the heat generation rate of the main combustion by the spark plug decreases, and there is a risk that the fuel efficiency and output increase will be worsened.
[0007]
Further, according to the above publication, when the combustion mode is changed from the stratified combustion mode to the uniform combustion mode according to the acceleration request, the valve closing operation for moving the throttle valve to the valve closing side according to the change of the air-fuel ratio is performed. However, this valve closing operation may reduce the amount of intake air, leading to a decrease in exhaust gas discharge, and delays the rise of turbine rotation.
[0008]
Further, according to the above publication, an acceleration request for shifting the engine operation region from a stratified combustion region where fuel is injected during the compression stroke to perform engine operation to a uniform combustion region where fuel is injected during the intake stroke and engine operation is performed. Is detected, immediately after the acceleration request is detected, combustion mode transition control is performed to shift the combustion mode of the engine from the stratified combustion mode to the uniform combustion mode. However, the throttle valve closing operation is performed in accordance with this combustion mode transition control, and the generated torque is kept constant until the transition from the stratified combustion mode to the uniform combustion mode is completed. This may cause the driving feeling to deteriorate.
[0009]
The present invention has been made in view of the above-described points, and an object of the present invention is to provide a control device for an in-cylinder injection engine with a turbocharger that suppresses turbo lag by raising the temperature of exhaust gas in the first half of acceleration. There is.
[0010]
[Means for Solving the Problems]
A control device for a turbocharger-equipped in-cylinder injection engine according to claim 1 that solves the above-described problem is provided with a turbocharger, an in-cylinder injection valve that directly injects fuel into a combustion chamber of the engine, and a throttle An electronically controlled throttle having a valve and an actuator for driving the throttle valve, throttle control means for adjusting the throttle opening of the throttle valve by controlling the actuator, and acceleration request detecting means for detecting an acceleration request from the driver And an acceleration start determination means for determining the start of acceleration of the engine based on the acceleration request detected by the acceleration request detection means and the engine operating state, and when the acceleration start determination means Normal injection control, in which fuel is injected all at once during the compression stroke, is applied during the intake stroke or during the compression stroke and during the expansion stroke. And a fuel injection control means for changing to split injection control for splitting and injecting fuel, and determining whether the fuel injection control means has started acceleration by the acceleration start determination means. After that, when the engine operating region is in the stratified combustion region, stratified combustion divided injection control for dividing and injecting fuel during the compression stroke and the expansion stroke is performed, and the engine operating region is changed from the stratified combustion region to the uniform combustion region. When the transition is made, uniform combustion divided injection control is performed in which fuel is divided and injected during the intake stroke and the expansion stroke.
[0011]
According to this invention, in order to accelerate the rise of the turbine rotation of the turbocharger during acceleration and suppress the turbo lag, the split injection control in which fuel is split and injected during the intake stroke or during the compression stroke and during the expansion stroke The combustion period in the combustion chamber is extended to the end of the expansion stroke period by combustion of the fuel injected during the expansion stroke, and the temperature of the exhaust gas discharged from the combustion chamber is raised.
[0012]
In the split injection control, the stratified combustion split injection control is performed while the engine operation state at the initial stage of acceleration is still in the stratified combustion region, and the engine operating region is uniformly combusted from the stratified combustion region as the engine output increases. After shifting to the region, uniform combustion split injection control is performed.
[0013]
In the engine operation with the stratified combustion mode, the throttle valve is held almost at the fully open position, and more exhaust gas is discharged than in the case of the engine operation with the uniform combustion mode. After that, while the engine operation region is in the stratified combustion region, the engine operation in the stratified combustion mode is continued to prevent a decrease in exhaust gas emission at the start of acceleration and continue the mass flow rate of a large amount of exhaust gas Can be secured. In addition, after the transition to the uniform combustion mode, by performing split injection control in which fuel is injected during the expansion stroke, it is possible to obtain an effect of increasing the temperature of the exhaust gas due to the combustion of the fuel injected during the expansion stroke.
[0014]
Therefore, it is possible to accelerate the start-up of the turbine rotation of the turbocharger, and in combination with the temperature rise effect of the exhaust gas by the fuel injection during the expansion stroke, it is possible to suppress the turbo lag and shorten the acceleration time. it can.
[0015]
According to a second aspect of the present invention, in the in-cylinder injection engine with a turbocharger according to the first aspect, when the engine operating region shifts from the stratified combustion region to the uniform combustion region, the throttle valve closing side The throttle control means performs the throttle control for prohibiting the operation of the motor.
[0016]
According to the present invention, when the engine operating region shifts from the stratified combustion region to the uniform combustion region, the operation of the throttle valve to the valve closing side is prohibited. In this state, the combustion mode is shifted from the stratified combustion mode to the uniform combustion mode while being maintained at the throttle opening or higher. Therefore, the transition of the combustion mode is performed in a state where the amount of intake air is large, and it is possible to prevent a decrease in the exhaust gas discharge amount and continuously ensure a mass flow rate of a large amount of exhaust gas.
[0017]
In addition, after the transition to the uniform combustion mode, by performing split injection control in which fuel is injected during the expansion stroke, it is possible to obtain an effect of increasing the temperature of the exhaust gas due to the combustion of the fuel injected during the expansion stroke. Therefore, it is possible to speed up the start-up of the turbine rotation of the turbocharger, and in combination with the temperature rise effect of the exhaust gas by the fuel injection during the expansion stroke, it is possible to suppress the turbo lag and shorten the acceleration time. it can.
[0018]
According to a third aspect of the present invention, in the control apparatus for a turbocharger-equipped in-cylinder injection engine according to the first or second aspect, the throttle control means is configured to perform uniform combustion split injection control from stratified combustion split injection control by the fuel injection control means. After the change to is made, the throttle control for fully opening the throttle valve is started. According to the present invention, when the uniform combustion divided injection control is started, the throttle valve is controlled to be fully opened, and the amount of intake air supplied to the engine is further increased. For this reason, turbo lag can be suppressed and acceleration time can be shortened.
[0019]
According to a fourth aspect of the present invention, in the in-cylinder turbocharger-equipped in-cylinder injection engine control apparatus according to any one of the first to third aspects, the fuel injection control means receives the acceleration start determination by the acceleration start determination means. In this case, the divided injection control is performed prior to the throttle control of the throttle valve by the throttle valve control means. According to the present invention, when it is determined that the acceleration is started, the divided injection control is performed prior to the throttle control of the throttle valve. Since the throttle valve of an electronically controlled throttle is driven by an actuator such as an electric motor, for example, a certain amount of time is required until the actual throttle opening reaches the target throttle opening after receiving a control command. Response delay of operation occurs.
[0020]
Therefore, by starting the split injection control before the actual throttle opening reaches the target throttle opening, the temperature of the exhaust gas can be raised earlier and the start-up of the turbine rotation can be accelerated. it can. Therefore, turbo lag can be suppressed and acceleration time can be shortened.
[0021]
According to a fifth aspect of the present invention, in the in-cylinder turbocharger-equipped in-cylinder injection engine control apparatus according to any one of the first to fourth aspects, the fuel injection control means is configured to cause the throttle valve control means to actually open the throttle valve. When the degree is adjusted to the fully open state, the split injection control is returned to the normal injection control in which fuel is injected in a batch during the intake stroke or the compression stroke.
[0022]
According to the present invention, the actual throttle opening of the throttle valve is adjusted to the fully open state, whereby the divided injection control is returned to the normal injection control. Split injection control is performed for the purpose of increasing the temperature of exhaust gas by fuel injection during the expansion stroke and promoting the increase in turbine rotation to suppress the occurrence of turbo lag. When the adjustment is made, the mass flow rate of the exhaust gas sufficient to drive the turbine is obtained, so that the divided injection control can be returned to the normal injection control.
[0023]
In a sixth aspect of the present invention, the control device for a cylinder injection engine with a turbocharger according to any one of the first to fifth aspects has an intake pipe internal pressure detection sensor for detecting an intake pipe internal pressure of the engine, and a fuel The injection control means returns the divided injection control to the normal injection control when the intake pipe internal pressure rises to a predetermined positive pressure value set in advance.
[0024]
According to the present invention, the divided injection control is started by the determination of the start of acceleration, and the normal injection control is returned when the intake pipe internal pressure rises to the predetermined positive pressure value. The turbo lag is likely to occur in a transition period from a state where the turbine rotational speed is extremely low and the suction pipe internal pressure is negative to an operation region where supercharging is required. Therefore, it can be said that the exhaust gas mass flow rate can be sufficiently obtained in the engine operation state in which the turbine rotation speed in the latter half of acceleration increases to some extent and the intake pipe internal pressure becomes positive. Therefore, the divided injection control can be returned to the normal injection control.
[0025]
A seventh aspect of the present invention is the control device for a turbocharger-equipped in-cylinder injection engine according to any one of the first to sixth aspects, wherein the fuel injection control means injects fuel during the expansion stroke by split injection control. The injection amount is decreased in accordance with an increase in engine output.
[0026]
According to the present invention, the fuel injection amount of the fuel injection performed during the expansion stroke of the split injection control is reduced according to the increase of the engine output. When the engine output increases, the combustion period of the fuel in the combustion chamber has a characteristic that increases, and therefore, the combustion end timing of the fuel tends to be delayed toward the late stage of the expansion stroke. Therefore, as the engine output increases due to acceleration, the period from the end of combustion of fuel injected during the intake stroke or the compression stroke to the end of the expansion stroke is shortened. For this reason, by reducing the fuel injection amount of the fuel injected during the expansion stroke in accordance with the increase in engine output, it is possible to suppress unburned fuel and to suppress the fuel consumption. Therefore, the exhaust gas can be efficiently heated.
[0027]
According to an eighth aspect of the present invention, there is provided an in-cylinder turbocharger-equipped in-cylinder injection engine control apparatus according to any one of the first to seventh aspects, wherein an intake pipe internal pressure detection sensor for detecting an intake pipe internal pressure of the engine, and an acceleration request detection Target boost pressure setting means for setting a target boost pressure based on the acceleration request detected by the means, and the fuel injection control means sets the target fuel injection amount to be injected during the expansion stroke by the split injection control. It is determined according to the deviation between the supercharging pressure and the intake pipe internal pressure detected by the intake pipe internal pressure detection sensor.
[0028]
According to the present invention, the fuel injection amount of the fuel injection performed during the expansion stroke of the split injection is a deviation between the intake pipe internal pressure detected by the intake pipe internal pressure detection sensor and the target supercharging pressure set based on the acceleration request. Will be decided accordingly. The greater the deviation between the target boost pressure and the suction pipe internal pressure, the longer the time it takes for the suction pipe internal pressure to rise to the target boost pressure and the greater the acceleration response delay. Therefore, by setting the fuel injection amount during the expansion stroke according to the deviation between the target supercharging pressure and the current suction pipe internal pressure, the exhaust gas temperature can be raised more effectively and the turbo lag can be suppressed.
[0029]
A ninth aspect of the present invention is the control device for a turbocharger-equipped in-cylinder injection engine according to any one of the first to eighth aspects, wherein the fuel injection control means injects fuel during the expansion stroke by split injection control. The injection timing is changed according to the ignition timing.
[0030]
According to this invention, the injection timing of the fuel injected during the expansion stroke is changed according to the ignition timing by the split injection control. When the ignition timing is changed in the advance or retard direction according to the knocking state of the engine, the fuel combustion period remains constant, and a phase shift occurs in the front-rear direction according to the ignition timing. For example, when the ignition timing is changed in the advance direction by a knock learning function or the like, the combustion end timing is also shifted in the advance side by the same phase. Therefore, by controlling the fuel injection timing of the fuel during the expansion stroke so as to always maintain the same phase with respect to the ignition timing, the engine operation by split injection can be stably performed, and more effective. In addition, the temperature of the exhaust gas can be increased.
[0031]
A tenth aspect of the present invention is the control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of the first to ninth aspects, wherein the fuel injection control means performs fuel injection performed during an expansion stroke by split injection control. The fuel injection amount and the fuel injection timing are set to a fuel injection timing and a fuel injection amount at which combustion ends before an exhaust valve provided between the combustion chamber and the exhaust passage starts to open.
[0032]
According to the present invention, the fuel injection timing and the fuel injection amount of the fuel injected during the expansion stroke by the split injection control are set to the fuel injection timing and the fuel injection amount at which the combustion is finished before the exhaust valve of the combustion chamber starts to open. Therefore, the fuel is discharged to the exhaust pipe side in an unburned state and the fuel is wasted and the exhaust gas is prevented from deteriorating, and the temperature of the exhaust gas can be raised more effectively.
[0033]
An eleventh aspect of the present invention is the control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of the first to tenth aspects, wherein the fuel injection control means performs a period from the intake stroke to the expansion stroke by split injection control. The total fuel injection amount injected into the engine is the basic fuel injection amount required for generating effective engine output plus the fuel injection amount required for increasing the exhaust temperature. .
[0034]
According to the present invention, the total fuel injection amount injected from the intake stroke to the expansion stroke by the split injection control is set to the basic fuel injection amount required for generating an effective engine output, and the exhaust temperature is increased. The amount is obtained by adding the necessary fuel injection amount.
[0035]
The amount of heat required to raise the exhaust temperature is required to increase the exhaust temperature, but this amount of heat is the amount of heat remaining in the exhaust gas and is not counted as the amount of heat generated converted to engine output. In the case of the same total fuel injection amount, the engine output tends to decrease as the exhaust gas temperature increases. Therefore, when the exhaust temperature is increased by fuel injection during the expansion stroke, a decrease in engine output can be prevented by increasing the amount of fuel necessary to increase the exhaust temperature, resulting in a deterioration in running feeling. Without this, turbo lag can be suppressed.
[0036]
A twelfth aspect of the present invention is the control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of the first to eleventh aspects, wherein the fuel injection control means controls the fuel injected during the expansion stroke by the split injection control. The number of injections is set to increase as the engine speed decreases.
[0037]
According to the present invention, the number of fuel injections to be injected during the expansion stroke by split injection control is set to increase as the engine speed decreases. Since the timing of the end of combustion tends to be delayed toward the end of the expansion stroke as the engine speed increases, the combustion margin period during the expansion stroke becomes longer as the engine speed decreases. Therefore, by increasing the number of injections as the engine speed is lower, the combustion period can be extended to the end of the expansion stroke, and the temperature of the exhaust gas can be raised more effectively.
[0038]
A thirteenth aspect of the present invention is the control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of the first to twelfth aspects, wherein the fuel injection control means is a fuel injected during an expansion stroke by split injection control. The number of injections is set to increase as the generated torque decreases.
[0039]
According to the present invention, the number of times of fuel injection injected during the expansion stroke by the split injection control is set to increase as the generated torque of the engine decreases. In general, even when the engine speed is the same, the higher the generated torque, that is, the greater the amount of fuel supplied, the greater the amount of heat generated and the longer the combustion period. The combustion margin period is longer as the generated torque is lower. Therefore, by setting the number of injections to be increased as the generated torque is lower, the combustion period can be extended to the end of the expansion stroke, and the temperature of the exhaust gas can be increased more effectively.
[0040]
A fourteenth aspect of the invention is directed to the control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of the first to thirteenth aspects, wherein the fuel injection control means controls the amount of fuel injected during the expansion stroke by split injection control. The injection timing is set during a period in which flame propagation occurs in the combustion chamber.
[0041]
According to the present invention, since the fuel injected during the expansion stroke uses the flame propagation of combustion occurring in the combustion chamber as an ignition source, it can be reliably ignited by starting injection before the end of the combustion. And can be prevented from being discharged to the exhaust pipe in an unburned state. Therefore, waste of fuel and deterioration of exhaust gas can be prevented, and the temperature of exhaust gas can be raised more effectively.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view schematically showing a turbocharger-equipped in-cylinder injection engine system according to the present embodiment.
[0043]
The engine system 1 is an engine system mounted on an automobile, and an engine body 2 includes a cylinder block 5 in which a crankshaft 3 is rotatably supported and a piston 4 is removably fitted. A cylinder head 8 having an intake port 6 having an intake valve 6a and an exhaust port 7 having an exhaust valve 7a is provided.
[0044]
A spark plug 10 is attached to the cylinder head 8 so that an electrode 10a protrudes from the top of the combustion chamber 9 into the combustion chamber 9, and an in-cylinder injection valve injects fuel directly into the combustion chamber 9. 11 is attached. The in-cylinder injection valve 11 injects fuel immediately before ignition during the compression stroke in the low and medium load operation region, thereby forming a rich air-fuel mixture near the electrode 10a of the spark plug 10 and igniting the rich air-fuel mixture. It is arranged at a position where stratified combustion is possible.
[0045]
An intake passage 12 and an exhaust passage 21 are attached to the engine body 2. In this intake passage 12, an air flow meter 13 for detecting the intake air amount, a compressor 14a of a turbocharger 14 for supercharging the engine body 2, an intercooler 15 for cooling the intake air, and an electronic device for adjusting the intake air amount A control throttle 16 is provided, and an intake manifold internal pressure detection sensor 18 that detects an internal pressure of the intake manifold 17 is attached to an intake manifold 17 that communicates between the intake passage 12 and the cylinder head 8.
[0046]
The electronically controlled throttle 16 includes a throttle valve 16a and an actuator 16b such as an electric motor that drives the throttle valve 16a. The throttle opening Th of the throttle valve 16a depends on the operation state of the accelerator pedal 20 and the engine operating state. In a low load operation, the throttle opening degree Th can be controlled to be almost fully opened to obtain a lean air-fuel ratio. The electronic control throttle 16 is provided with a throttle opening sensor 19 for detecting the throttle opening Th of the throttle valve 16a.
[0047]
On the other hand, an exhaust manifold 22, a turbine 14 b of the turbocharger 14, and a catalytic converter 23 are attached to the exhaust passage 21. Exhaust gas passing through the exhaust passage 21 is disposed upstream of the catalytic converter 23. An exhaust temperature sensor 24 for detecting the temperature of the exhaust gas is attached. A wastegate valve 26 for adjusting the flow rate of the exhaust gas to the turbine 14b is attached to the bypass passage 25 that bypasses the turbine 14b of the turbocharger 14.
[0048]
The engine system 1 having the above configuration is controlled by an electronic control unit (ECU) 30. The ECU 30 is a well-known central processing unit including a CPU, a ROM storing a control program, a RAM storing various data, a backup RAM storing various learning data, an input / output circuit, and a bus line for interconnecting them. It is mainly composed of computer systems.
[0049]
As sensors connected to the ECU 30, in addition to the air flow meter 13 and the throttle opening sensor 19, a crank angle sensor that detects a crank angle and detects intake, compression, expansion, and exhaust strokes for each cylinder. 31 and a cam angle sensor 32, a cooling water temperature sensor 34 for detecting the temperature of engine cooling water, a knock sensor 35 for detecting knocking, an accelerator sensor 36 for detecting the amount of depression of the accelerator pedal 20, and the like. The actuators connected to the ECU 30 include the primary current of the ignition coil connected to the ignition plug 10 in addition to the actuator 16b of the electronic control throttle and the in-cylinder injection valve 11 provided for each cylinder. There is an igniter 36 or the like for intermittent connection.
[0050]
The ECU 30 calculates a target torque T_target, which is a required torque requested by the driver, from the input from the accelerator sensor 36 and the current engine operating state such as the engine coolant temperature Tw and the engine speed Ne, and determines an acceleration / deceleration request. At the same time, a combustion mode determination of stratified combustion or uniform combustion is performed according to a predetermined criterion, and various operating parameters such as throttle opening Th, fuel injection amount, fuel injection timing, and ignition timing are determined.
[0051]
For example, the fuel injection control means realized by the internal mechanism of the ECU 30 is previously stored in the ROM of the ECU 30 using the depression amount of the accelerator pedal 20 detected by the accelerator sensor 36 and the engine speed Ne detected by the crank angle sensor 31. The target torque T_target is obtained by performing interpolation calculation with reference to the stored constant map, and the target fuel injection amount Tp is obtained based on the target torque T_target and the intake air amount Q detected by the air flow sensor 13. When the target fuel injection amount Tp is in the stratified combustion region where the engine operation region is low and medium load, the lean air-fuel ratio is set to execute the engine operation in the stratified combustion mode, and the target fuel injection amount Tp is in the high combustion region Is set to have a normal air-fuel ratio in order to execute engine operation in a uniform combustion mode.
[0052]
Moreover, ECU30 performs control for suppressing the turbo lag at the time of acceleration as one of engine operation control. Specifically, when an acceleration request requiring supercharging is made, split injection control is performed in which fuel is split and injected between the intake stroke and the compression stroke and during the expansion stroke. By the fuel injected during the expansion stroke by this split injection control, the combustion period is extended to the end of the expansion stroke, the exhaust gas temperature just below the exhaust port 7 is positively raised, and the turbine rotation of the turbocharger 14 is increased. The start-up is accelerated, the turbo lag is suppressed, and the acceleration time is shortened.
[0053]
FIG. 2 shows a form of heat generation during stratified combustion normal injection control in which fuel is injected in a batch during the compression stroke. In this case, since all fuels continuously undergo a combustion reaction due to flame propagation based on ignition at the spark plug 10, the heat generation pattern has a mountain shape close to an isosceles triangle.
[0054]
On the other hand, FIG. 3 shows the form of heat generation in the stratified combustion divided injection control in which the same total fuel injection amount as in FIG. 2 is divided and injected during the compression stroke and the expansion stroke. is there. In this case, since the first injection is performed during the compression stroke and the second injection is performed during the expansion stroke, the fuel injection amount in the first injection is reduced, and the peak of the total heat generation amount is reduced. Due to the second injection, a peak of heat generation occurs further in the later stage of the expansion stroke, and the timing of completion of combustion can be delayed.
[0055]
FIG. 6 shows the relationship between the combustion end timing and the exhaust temperature when the total amount of heat generation is substantially the same. As shown in this figure, if the total amount of heat generation is substantially the same, the generated torque may be considered to be substantially the same.From this relationship, the fuel injection during the expansion stroke by the split injection control is performed in the same operation region. It can be seen that it is effective for increasing the exhaust temperature.
[0056]
FIG. 4 shows the stratified combustion split injection control in which the same total fuel injection amount as in FIGS. 2 and 3 is divided and injected into a total of three times, once during the compression stroke and twice during the expansion stroke. The form of heat generation in is shown. In this case, the peak of the heat generation amount in the first injection is lower than that in the case of the first injection in FIG. 3, but the second heat generation and the third injection have two heat generation peaks in the latter stage of the expansion stroke. It is generated and the timing of the end of combustion can be further delayed.
[0057]
FIG. 5 shows a form of heat generation during uniform combustion split injection control in which fuel is split and injected during the intake stroke and the expansion stroke. Also in this case, similarly to the stratified combustion split injection, the second injection can further generate a heat generation peak in the later stage of the expansion stroke, and can delay the timing of the end of combustion.
[0058]
Next, the control for suppressing the turbo lag realized by the ECU 30 will be described based on the flowchart of FIG. Note that the flowchart of FIG. 10 is a program stored in advance in the ROM of the ECU, and is repeatedly executed in a predetermined program cycle.
[0059]
When the program starts, first, in step S101, detection signals are read from various sensors such as the air flow meter 13, the crank angle sensor 31, the throttle opening sensor 19, the accelerator sensor 36, etc., and the intake air amount Q, the engine rotation speed, and the like. The number Ne, the throttle opening degree Th, and the accelerator depression amount S are obtained.
[0060]
In step S102, interpolation calculation is performed by referring to a constant map stored in the ROM of the ECU 30 in advance based on the current accelerator depression amount S and the engine speed Ne obtained from the detection signal detected in step S101. A target torque T_target is calculated.
[0061]
Then, in step S103, the generated torque T is calculated by performing interpolation calculation with reference to a constant map stored in the ROM of the ECU 30 based on the throttle opening degree Th and the engine speed Ne.
[0062]
Next, in step S104, it is determined whether or not the engine operating state is accelerating. This determination is made based on whether or not the deviation between the target torque T_target and the generated torque T calculated in steps S102 and S103 is larger than a predetermined value set in advance. If it is determined in step S104 that the vehicle is accelerating (YES), the process proceeds to step S105 to determine whether or not it is necessary to perform control for suppressing the turbo lag during the acceleration. If it is determined in step S104 that the vehicle is not accelerating (NO), the process proceeds to step S117.
[0063]
In step S105, the intake pipe internal pressure Pb detected by the intake pipe internal pressure detection sensor 18 is compared with a predetermined positive pressure value Pi set in advance. Here, when it is determined that the intake pipe internal pressure Pb is less than the predetermined positive pressure value Pi (YES), acceleration is requested by the driver, but the turbine speed of the turbocharger 14 is low, and the turbo lag Therefore, it is determined that it is necessary to perform control for suppressing the turbo lag, and the process proceeds to step S106 and subsequent steps.
[0064]
Further, when it is determined in step S105 that the intake pipe internal pressure Pb is a positive pressure equal to or higher than the predetermined positive pressure value Pi (NO), the turbine speed in the latter half of acceleration is increased to some extent, and the exhaust gas mass flow rate is sufficient. Therefore, it is determined that it is not necessary to perform control to suppress the turbo lag even during acceleration, and the process proceeds to step S117.
[0065]
In steps S106 to S116, in order to suppress the turbo lag, split injection control is performed in which fuel is divided and injected during the period from the intake stroke to the compression stroke and during the expansion stroke, and the exhaust gas is discharged by the fuel injected during the expansion stroke. The temperature of the gas is positively increased to promote the increase in turbine rotation.
[0066]
First, in step S106, the operating region map shown in FIG. 9 is referred to based on the engine speed Ne and the generated torque T, and it is determined whether or not the current engine operating region is in the stratified combustion region. FIG. 9 is a diagram for explaining an operation region map in the present embodiment. As shown in the figure, the operation region map is for obtaining the operation region based on the engine speed Ne and the torque T, and the stratified combustion region A is set on the low and medium load side, and on the high load side. A uniform combustion region B is set. Further, the uniform combustion region B is divided into a non-supercharged uniform combustion region B1 where effective supercharging by the turbocharger is not performed and a supercharged uniform combustion region B2 where effective supercharging is performed. In the figure, symbol Z1 is a stratified combustion upper limit torque line indicating an upper limit torque value that can be output in accordance with the stratified combustion mode, and symbol Z2 in the figure indicates the full load torque indicating the upper limit of the supercharging uniform combustion region B2. Line.
[0067]
If it is determined in step S106 that the current engine operation region is in the stratified combustion region A (YES), the stratified combustion operation should be continued or the combustion mode is changed to the uniform combustion mode and the uniform combustion operation is performed. The process proceeds to step S107 and after.
[0068]
In step S107 to step S110, the virtual torque Ta output when the stratified charge combustion operation is executed by split injection is calculated, and it is determined whether or not the virtual torque Ta is equal to or less than the stratified charge combustion form upper limit torque T_str. Based on this determination, it is determined whether the stratified combustion operation should be continued or changed to the uniform combustion operation. Here, when the acceleration request is received, the engine does not immediately shift from the stratified combustion mode to the uniform combustion mode regardless of the engine output, but up to the stratified combustion upper limit torque T_str that can be output by the stratified combustion mode. After increasing the output, a process for shifting to a uniform combustion mode is performed.
[0069]
In the stratified charge combustion operation region A, the throttle opening of the throttle valve 16a is controlled to be in a fully open state in order to adjust to a lean air-fuel ratio, and a large amount of intake air flows into the engine and is discharged as exhaust gas. Accordingly, the stratified charge combustion operation is continued in the early stage of acceleration, and the throttle opening of the throttle valve 16a is maintained to maintain the amount of intake air flowing into the engine body 2 and to reduce the mass flow rate of the exhaust gas that drives the turbine. Can be suppressed. Thereby, a turbine speed can be raised more quickly and a turbo lag can be suppressed.
[0070]
First, in step S107, processing for calculating the torque increase immediately after the acceleration determination as the torque increment amount T_delta is performed. The torque increment amount T_delta is a torque increase amount that can increase the engine output without causing an uncomfortable torque shock during acceleration. The torque increment amount T_delta is obtained in advance by experiments or simulations, and is based on the engine speed Ne and the generated torque T. The map is stored so as to be readable.
[0071]
Next, in step S108, the virtual torque Ta is obtained by adding the current generated torque T to the torque increment amount T_delta calculated in step S107. Then, in step S109, the stratified combustion upper limit torque T_str is read by referring to the operation region map (FIG. 9).
[0072]
In step S110, the virtual torque Ta calculated in step S108 is compared with the stratified combustion upper limit torque T_str read in step S109, and whether or not the virtual torque Ta is smaller than the stratified combustion upper limit torque T_str. Judgment is made. Here, if it is determined that the virtual torque Ta is smaller than the stratified combustion upper limit torque T_str (YES), the process proceeds to step S111 to execute the stratified combustion operation. Further, when it is determined that the virtual torque Ta is equal to or higher than the stratified combustion upper limit torque T_str (NO), the stratified charge combustion operation by split injection is impossible, so that the uniform combustion operation should be performed by switching the combustion mode. The process proceeds to step S114 and subsequent steps.
[0073]
In step S111, stratified combustion split injection control is performed. Here, the throttle valve 16a is maintained almost fully open, and the engine output depends on the fuel injection amount rather than the intake air amount. Therefore, based on the virtual torque calculated in step S108, various operating parameters such as the injection pulse width are determined by referring to the setting table, etc., and based on the various operating parameters, the first fuel is discharged during the compression stroke. The in-cylinder injection valve 11 is controlled so that the fuel is injected for the second time or more during the expansion stroke.
[0074]
The number of injections of fuel injected during the expansion stroke is set to increase as the engine speed decreases. In general, as shown in FIG. 13, the end timing of combustion tends to be delayed toward the end of the expansion stroke as the engine speed increases. Therefore, since the combustion margin period is longer as the engine speed is lower, the combustion period can be extended to the end of the expansion stroke by setting to increase the number of injections accordingly. Accordingly, the temperature of the exhaust gas immediately below the exhaust port can be raised earlier, and the start-up of the turbine rotation can be further accelerated.
[0075]
Further, the number of fuel injections during the expansion stroke is set so as to increase as the generated torque of the engine decreases. In general, even when the engine speed is the same, as shown in FIG. 14, the higher the generated torque, in other words, the greater the fuel injection amount, the greater the heat generation amount and the longer the combustion period. For this reason, the combustion end timing tends to be delayed toward the end of the expansion stroke. Therefore, since the combustion margin period is longer as the generated torque is lower, the combustion period can be extended to the end of the expansion stroke by setting to increase the number of injections accordingly. As a result, the temperature of the exhaust gas immediately below the exhaust port can be raised earlier, and the rise of the turbine rotation can be accelerated.
[0076]
Furthermore, the injection timing of the fuel injected during the expansion stroke is set to a timing at which the fuel is injected before the combustion of the previously injected fuel is completed. Therefore, it is possible to reliably ignite and combust using the flame propagation in which the previously injected fuel burns as an ignition source. For example, the second injection is performed before the combustion of the fuel of the first injection is completed. Further, when the second and third fuel injections are performed during the expansion stroke, the third injection is performed before the combustion of the fuel in the second injection is completed.
[0077]
Further, the injection timing of the fuel injected after the second time is controlled so as to maintain the same phase with respect to the ignition timing advanced and retarded. In general, when the ignition timing is advanced or retarded, the fuel combustion period is substantially constant, and a phase shift occurs before and after the ignition timing. For example, when the ignition timing is changed to the advance side as shown in FIG. 12 by knock learning control or the like, the combustion end timing is also shifted in the advance side by the same phase. Therefore, by controlling the second injection timing so as to maintain the same phase with respect to the ignition timing, the fuel injected for the second time can be reliably ignited and burned by the flame propagation of the first injected fuel, A more stable temperature increase effect of the exhaust temperature can be obtained.
[0078]
Further, the injection timing of the fuel injected after the second time is set so that the combustion ends before the opening operation of the exhaust valve starts. As a result, the exhaust valve 7a starts to open in the middle of combustion, and unburned fuel is discharged into the exhaust passage 21 to prevent the fuel from being wasted without contributing to the rise in the exhaust temperature and the deterioration of the exhaust gas. Thus, the temperature of the exhaust gas can be raised more effectively.
[0079]
Then, the fuel injection amount of the fuel injected during the expansion stroke is corrected to increase. An increase in the exhaust gas temperature requires an amount of heat corresponding to the temperature increase, but this amount of heat is the amount of heat remaining in the exhaust gas and does not contribute to the engine output. Therefore, when the fuel injection amount at the time of normal injection control and the total fuel injection amount at the time of split injection control are set to the same amount, the engine output tends to decrease as the exhaust gas temperature increases. Therefore, when the exhaust temperature is increased by fuel injection during the expansion stroke by the split injection control, a decrease in engine output can be suppressed by increasing the amount of fuel necessary to increase the exhaust temperature, and the operating feeling can be reduced. Generation | occurrence | production of a turbo lag can be suppressed, without making it worse.
[0080]
On the other hand, if it is determined in step S106 that the current engine operation region is in the uniform combustion region B (NO), the process proceeds to step S112 and subsequent steps in order to execute the uniform combustion operation by the split injection control. .
[0081]
First, in step S112, the current throttle opening Th of the throttle valve 16a is detected based on the detection signal from the throttle opening sensor 19. In step S113, it is determined whether the detected throttle opening Th is equal to or greater than a preset reference throttle opening WOT that is almost fully open or less than the reference throttle opening WOT.
[0082]
Here, when it is determined that the current throttle opening Th is less than the reference throttle opening WOT (YES), the process proceeds to step S114 and subsequent steps. If it is determined in step S113 that the current throttle opening Th is equal to or greater than the reference throttle opening WOT (NO), a large amount of intake air has flowed into the engine, and the exhaust gas mass flow rate is also Since it can be said that the state is sufficiently obtained, it is determined that it is not necessary to perform control to suppress the turbo lag, and the process proceeds to step S117.
[0083]
In step S114, uniform combustion divided injection control is performed. Here, the total fuel injection amount is determined so that the air-fuel ratio becomes substantially stoichiometric in accordance with the intake air amount at that time, and the first fuel is injected during the intake stroke based on the total fuel injection amount. The in-cylinder injection valve 11 is controlled so that the fuel is injected a second time or more during the expansion stroke. The injection timing, the injection amount, and the number of injections of the fuel injected after the second time are controlled in the same manner as in step S111.
[0084]
Then, in step S115, control for driving the throttle valve 16a to the open side is performed, and driving to the close side is prohibited. Thereby, the throttle valve 16a is controlled to a fully open state. In step S116, an ignition timing retard amount for retarding the ignition timing is determined based on the current generated torque.
[0085]
For example, when it is determined in step S110 that the virtual torque Ta is equal to or greater than the stratified combustion upper limit torque T_str and the process proceeds to step S114 to switch the combustion mode to the uniform combustion mode, the stratified combustion in which the lean combustion is performed is stepped. In addition, since it shifts to the uniform combustion at stoichio, there is a concern that the driving feeling deteriorates due to a sudden torque increase.
[0086]
Conventionally, when switching the combustion mode from the stratified combustion mode to the uniform combustion mode, a method of suppressing the torque step by closing the throttle valve 16a and reducing the intake air amount Q has been adopted. In this case, the mass flow rate of the exhaust gas is reduced, making it difficult to start up the turbine at an early stage, and it is impossible to improve the turbo lag.
[0087]
Therefore, in the present embodiment, the throttle valve 16a is not closed, and a rapid torque increase is suppressed by retarding the ignition timing. As a result, since the combustion mode is shifted in a state where the intake air amount is large, it is possible to secure a larger mass flow rate of exhaust gas even when shifting to the combustion mode, and to start up the turbine rotation earlier. Can do. Therefore, it is possible to suppress the turbo lag and shorten the acceleration time.
[0088]
Further, in step S117, it is not necessary to perform control for suppressing the turbo lag, and normal injection control for performing engine operation in the combustion mode corresponding to the current engine operation region is performed. The current engine operation region is determined by referring to the operation region map of FIG. 9. For example, when it is the stratified charge combustion operation region A, stratified charge combustion normal injection control is performed and when it is the uniform combustion operation region B The uniform combustion normal injection control is performed.
[0089]
FIG. 7 is a time chart for explaining the engine operating state when control for suppressing turbo lag is performed during engine operation in the uniform combustion mode. If an acceleration request is received from the driver during engine operation in the uniform combustion mode, the uniform combustion split injection control is first started (step S114). Then, the control for making the throttle opening of the throttle valve 16a fully open is started (step S115).
[0090]
Since the throttle valve 16a is driven by the actuator 16b, the throttle valve 16a is disposed with a certain delay time with respect to the actually designated throttle opening Th. Therefore, the temperature of the exhaust gas can be raised earlier by starting the split injection prior to the throttle control of the throttle valve 16a when the driver requests acceleration. Therefore, the rise of the turbine rotation of the turbocharger 14 is accelerated compared to the conventional case indicated by the broken line in the drawing, the turbo lag is greatly improved, and the acceleration time is shortened.
[0091]
In the case of the example shown in FIG. 7, when the actual throttle opening of the throttle valve 16a is fully opened, a mass flow rate of exhaust gas sufficient to drive the turbine 14b is obtained. The divided injection control is returned to the normal injection control on the assumption that there is no need to continue the control for suppressing the turbo lag.
[0092]
FIG. 8 is a time chart for explaining the engine operating state when control for suppressing turbo lag is performed during engine operation in the stratified combustion mode.
[0093]
Conventionally, as shown by the broken line in the figure, when an acceleration request is received from the driver during engine operation in the stratified combustion mode, control for shifting the combustion mode from the stratified combustion mode to the uniform combustion mode is immediately started. In order to prevent a torque shock due to an increase in the intake air amount when shifting to the combustion mode, a throttle valve control instruction value for controlling the throttle valve in the closing direction is output. Therefore, the throttle valve 16a also moves in the closing direction so as to follow it, and the pressure in the intake pipe temporarily drops. For this reason, the rise of the turbine rotation is delayed and a turbo lag is generated.
[0094]
However, in the case of the present invention, when an acceleration request is received from the driver during engine operation in the stratified combustion mode, split injection control is performed with the combustion mode remaining in the stratified combustion mode (step S111), and the generated torque of the engine Until the stratified combustion upper limit torque T_str is reached, the stratified combustion divided injection control is continued.
[0095]
When the generated torque exceeds the stratified combustion upper limit torque T_str (step S110), the combustion mode is changed from the stratified combustion mode to the uniform combustion mode, and the uniform combustion divided injection control is performed (step S114). Then, the throttle control for controlling the throttle valve 16a to the fully open state is started in accordance with the change of the combustion mode (step S115), and at the same time, the ignition timing retard control is performed (step S116). Then, when the throttle valve 16a is actually fully opened, the uniform combustion normal injection control is performed (step S117).
[0096]
When the acceleration request is received in this way, the combustion mode is not immediately shifted from the stratified combustion mode to the uniform combustion mode, but is increased after the torque is increased to the stratified combustion upper limit torque T_str that can be output by the stratified combustion mode. By shifting to the combustion mode, the throttle valve 16a is maintained at a throttle opening that is almost fully open in the early stage of acceleration, a large amount of intake air is introduced into the engine, and the mass flow rate of the exhaust gas is prevented from decreasing. Yes. Further, by continuing the divided injection control even after shifting to the uniform combustion mode, an effect of raising the temperature of the exhaust gas by combustion of the fuel injected during the expansion stroke can be obtained. Therefore, it is possible to accelerate the start-up of the turbine rotation of the turbocharger, and in combination with the effect of the temperature rise of the exhaust gas by the fuel injection during the expansion stroke, the turbo lag is greatly improved and the acceleration time is shortened. be able to.
[0097]
Then, as in the case of FIG. 7, when the actual throttle opening of the throttle valve 16a is fully opened, the exhaust gas mass flow rate sufficient to drive the turbine is obtained, and this is continued. Therefore, the split injection control is returned to the normal injection control because it is not necessary to perform control for suppressing the turbo lag.
[0098]
Further, the timing at which the divided injection control is terminated may be not when the actual throttle opening of the throttle valve 16a is fully opened but when the intake pipe internal pressure Pb becomes a predetermined positive pressure value. In general, turbo lag is likely to occur during transient operation from the negative intake pipe internal pressure Pb, where the turbine rotation speed is extremely low, to the operation area where supercharging is required. In an operating state in which the pipe internal pressure Pb is positive, it can be said that the exhaust gas mass flow rate is sufficiently obtained. Therefore, by returning the divided injection control to the normal injection control when the intake pipe internal pressure Pb reaches a predetermined positive pressure value, the temperature of the exhaust gas can be increased more effectively and the turbo lag can be improved. .
[0099]
The timing for terminating the split injection control is not until the throttle valve 16a is actually fully opened, but until the end of acceleration is determined as shown in the time chart of FIG. 11, and further during the expansion stroke. The fuel injection amount of the fuel to be injected may be gradually decreased as the generated torque increases from the start of acceleration to the completion of acceleration. In general, the combustion period of fuel increases due to an increase in generated torque, and therefore, the combustion end time tends to be delayed toward the later stage of the expansion stroke. Therefore, by gradually reducing the fuel injection amount of the fuel injected during the expansion stroke in accordance with the increase in the generated torque during the period from the start of acceleration to the completion of acceleration, it is possible to prevent unburned fuel, Fuel consumption can be reduced. Therefore, it is possible to effectively raise the temperature of the exhaust gas.
[0100]
The present invention is not limited to the above-described embodiment, and can be modified without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the combustion mode is the uniform combustion mode and the case where the combustion mode is shifted from the stratified combustion mode to the uniform combustion mode have been described, but the same applies to the case of the stratified combustion mode.
[0101]
【The invention's effect】
According to the control device for a cylinder turbocharger-equipped in-cylinder injection engine according to the first aspect of the present invention, in order to accelerate the rise of the turbine rotation of the turbocharger during acceleration and suppress the turbo lag, the compression is performed during the intake stroke or compression. Divided injection control is performed in which fuel is divided and injected during the expansion stroke and during the expansion stroke, and the combustion period in the combustion chamber is extended to the end of the expansion stroke period by combustion of the fuel injected during the expansion stroke. The temperature of the exhaust gas discharged from the engine is increased.
[0102]
In the split injection control, the stratified combustion split injection control is performed while the engine operation state at the initial stage of acceleration is still in the stratified combustion region, and the engine operating region is uniformly combusted from the stratified combustion region as the engine output increases. After shifting to the region, uniform combustion split injection control is performed.
[0103]
In the engine operation with the stratified combustion mode, the throttle valve is held almost at the fully open position, and more exhaust gas is discharged than in the case of the engine operation with the uniform combustion mode. After that, while the engine operation region is in the stratified combustion region, the engine operation in the stratified combustion mode is continued to prevent a decrease in exhaust gas emission at the start of acceleration and continue the mass flow rate of a large amount of exhaust gas Can be secured.
[0104]
In addition, after the transition to the uniform combustion mode, by performing split injection control in which fuel is injected during the expansion stroke, it is possible to obtain an effect of increasing the temperature of the exhaust gas due to the combustion of the fuel injected during the expansion stroke. Therefore, the start-up of the turbine rotation of the turbocharger can be accelerated, and the turbo lag can be improved in combination with the effect of increasing the temperature of the exhaust gas by the fuel injection during the expansion stroke.
[0105]
According to the second aspect of the invention, when the engine operating region shifts from the stratified combustion region to the uniform combustion region, the operation of the throttle valve to the valve closing side is prohibited. The combustion mode is shifted from the stratified combustion mode to the uniform combustion mode while being maintained at the throttle opening or more during the split injection control. Therefore, the combustion mode is shifted in a state where the amount of intake air is large, and it is possible to prevent a decrease in the exhaust gas discharge amount and to ensure a large mass flow rate of the exhaust gas continuously. In addition, after the transition to the uniform combustion mode, by performing split injection control in which fuel is injected during the expansion stroke, it is possible to obtain an effect of increasing the temperature of the exhaust gas due to the combustion of the fuel injected during the expansion stroke. Therefore, it is possible to speed up the start-up of the turbine rotation of the turbocharger, and in combination with the temperature rise effect of the exhaust gas by the fuel injection during the expansion stroke, it is possible to suppress the turbo lag and shorten the acceleration time. it can.
[0106]
According to the invention of claim 3, when the uniform combustion split injection control is started, the throttle valve is controlled to be fully opened, and the intake air amount supplied to the engine is further increased. Therefore, turbo lag can be suppressed and acceleration time can be shortened.
[0107]
According to the fourth aspect of the present invention, when the acceleration start is determined, the divided injection control is performed prior to the throttle control of the throttle valve, so that the actual throttle opening reaches the target throttle opening. By starting the split injection control before and injecting fuel during the expansion stroke, it is possible to start raising the temperature of the exhaust gas at an earlier stage and to promote the rise of the turbine rotation, thereby speeding up the rise of the turbine rotation. Therefore, turbo lag can be suppressed and acceleration time can be shortened.
[0108]
According to the fifth aspect of the present invention, the actual throttle opening of the throttle valve is adjusted to the fully open state, whereby the divided injection control is returned to the normal injection control. Split injection control is performed for the purpose of increasing the temperature of exhaust gas by fuel injection during the expansion stroke and promoting the increase in turbine rotation to suppress the occurrence of turbo lag. When the adjustment is made, the mass flow rate of the exhaust gas sufficient to drive the turbine is obtained, so that the divided injection control can be returned to the normal injection control.
[0109]
According to the sixth aspect of the invention, the split injection control is started by the determination of the start of acceleration, and is returned to the normal injection control when the intake pipe internal pressure rises to a predetermined positive pressure value. The turbo lag is likely to occur in a transition period from a state where the turbine rotational speed is extremely low and the suction pipe internal pressure is negative to an operation region where supercharging is required. Therefore, it can be said that the exhaust gas mass flow rate can be sufficiently obtained in the engine operation state in which the turbine rotation speed in the latter half of acceleration increases to some extent and the intake pipe internal pressure becomes positive. Therefore, the divided injection control can be returned to the normal injection control.
[0110]
According to the invention of claim 7, the fuel injection amount of the fuel injection performed during the expansion stroke of the split injection control is reduced according to the increase of the engine output. When the engine output rises, the combustion period of the fuel in the combustion chamber increases, and the combustion end time of the fuel tends to be delayed later in the expansion stroke. The period from the end of combustion of fuel injected during the compression stroke to the end of the expansion stroke is shortened. Therefore, by reducing the fuel injection amount of the fuel injected during the expansion stroke in accordance with the increase in engine output, it is possible to suppress the unburned fuel and to suppress the fuel consumption. Therefore, the exhaust gas can be efficiently heated.
[0111]
According to the invention of claim 8, the fuel injection amount of the fuel injection performed during the expansion stroke of the split injection is the target boost pressure set based on the intake pipe internal pressure detected by the intake pipe internal pressure detection sensor and the acceleration request. It is determined according to the deviation. The greater the deviation between the target boost pressure and the suction pipe internal pressure, the longer the time it takes for the suction pipe internal pressure to rise to the target boost pressure and the greater the acceleration response delay. Therefore, by setting the fuel injection amount during the expansion stroke according to the deviation between the target supercharging pressure and the current suction pipe internal pressure, the exhaust gas temperature can be raised more effectively and the turbo lag can be suppressed.
[0112]
According to the ninth aspect of the invention, the injection timing of the fuel injected during the expansion stroke is changed according to the ignition timing by the split injection control. If the ignition timing is changed to the advance or retard direction according to the engine knocking state, the fuel combustion period remains constant, and a phase shift occurs in the front-rear direction according to the ignition timing. By controlling the fuel injection timing so as to always maintain the same phase with respect to the ignition timing, the engine operation by split injection can be stably performed, and the exhaust gas temperature can be raised more effectively. It can be carried out.
[0113]
According to the invention of claim 10, the fuel injection timing and the fuel injection amount of the fuel injected during the expansion stroke by the split injection control are the fuel injection timing and the fuel for ending the combustion before the exhaust valve of the combustion chamber starts to open. Since the injection amount is set, it is possible to raise the temperature of the exhaust gas more effectively by preventing the fuel from being wasted in the unburned state and exhausting the fuel and preventing the exhaust gas from deteriorating. it can.
[0114]
According to the eleventh aspect of the present invention, the total fuel injection amount injected from the intake stroke to the expansion stroke by the split injection control is equal to the basic fuel injection amount necessary for generating an effective engine output, and the exhaust temperature. It is an amount obtained by adding the fuel injection amount necessary for the increase. The amount of heat required to raise the exhaust temperature is required to increase the exhaust temperature, but this amount of heat is the amount of heat remaining in the exhaust gas and is not counted as the amount of heat generated converted to engine output. In the case of the same total fuel injection amount, the engine output tends to decrease as the exhaust gas temperature increases. Therefore, when the exhaust temperature is increased by fuel injection during the expansion stroke, a decrease in engine output can be prevented by increasing the amount of fuel necessary to increase the exhaust temperature, resulting in a deterioration in running feeling. Without this, turbo lag can be suppressed.
[0115]
According to the twelfth aspect of the present invention, the number of fuel injections to be injected during the expansion stroke by the split injection control is set to increase as the engine speed decreases. Since the timing of the end of combustion tends to be delayed toward the end of the expansion stroke as the engine speed increases, the combustion margin period during the expansion stroke becomes longer as the engine speed decreases. Therefore, by increasing the number of injections as the engine speed is lower, the combustion period can be extended to the end of the expansion stroke, and the temperature of the exhaust gas can be raised more effectively.
[0116]
According to the thirteenth aspect of the present invention, the number of times of fuel injection injected during the expansion stroke by the split injection control is set so as to increase as the generated torque of the engine decreases. Even when the engine speed is the same, as the generated torque increases, that is, as the fuel supply amount increases, the heat generation amount increases and the combustion period increases accordingly, so the timing of completion of combustion is delayed toward the end of the expansion stroke. The combustion margin period is longer as the generated torque is lower. Therefore, by setting the number of injections to be increased as the generated torque is lower, the combustion period can be extended to the end of the expansion stroke, and the temperature of the exhaust gas can be increased more effectively.
[0117]
According to the fourteenth aspect of the present invention, since the fuel injected during the expansion stroke uses the flame propagation of combustion occurring in the combustion chamber as an ignition source, the injection is started before the combustion ends. Therefore, it is possible to prevent ignition and exhaust to the exhaust pipe side in an unburned state. Therefore, waste of fuel and deterioration of exhaust gas can be prevented, and the temperature of exhaust gas can be raised more effectively.
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing a cylinder injection engine system with a turbocharger according to an embodiment.
FIG. 2 shows a form of heat generation during stratified combustion normal injection control in which fuel is injected in a batch during a compression stroke.
FIG. 3 shows a form of heat generation during stratified combustion divided injection control in which the same total fuel injection amount as in FIG. 2 is divided and injected during a compression stroke and an expansion stroke.
FIG. 4 is a stratified combustion split injection control in which the same total fuel injection amount as in FIGS. 2 and 3 is divided and injected into a total of three times, once during the compression stroke and twice during the expansion stroke. The form of heat generation in is shown.
FIG. 5 shows a form of heat generation during uniform combustion divided injection control in which fuel is divided and injected during an intake stroke and an expansion stroke.
FIG. 6 shows the relationship between the combustion end timing and the exhaust temperature when the total amount of heat generation is substantially the same.
FIG. 7 is a time chart for explaining an engine operation state when control for suppressing turbo lag is performed.
FIG. 8 is a time chart illustrating an engine operating state when control for suppressing turbo lag is performed.
FIG. 9 is a diagram for explaining an operation region map in the present embodiment.
FIG. 10 is a flowchart for explaining control for suppressing turbo lag.
FIG. 11 is a time chart illustrating an engine operating state when control for suppressing turbo lag is performed.
FIG. 12 is a time chart for explaining the relationship between the ignition timing and the injection timing of the second injection.
FIG. 13 is a diagram for explaining a relationship between an engine speed and a combustion period.
FIG. 14 is a diagram for explaining the relationship between the generated torque of the engine and the combustion period.
[Explanation of symbols]
1 Engine system
2 Engine body
11 In-cylinder injection valve
13 Air flow meter
14 Turbocharger
14a Compressor
14b turbine
16 Electronically controlled throttle
16a Throttle valve
16b Actuator
18 Intake pipe internal pressure detection sensor
19 Throttle opening sensor
31 Crank angle sensor
32 Cam angle sensor
34 Water temperature sensor

Claims (14)

A turbocharger,
An in-cylinder injection valve that directly injects fuel into the combustion chamber of the engine;
An electronically controlled throttle having a throttle valve and an actuator for driving the throttle valve;
Throttle control means for adjusting the throttle opening of the throttle valve by controlling the actuator;
Acceleration request detection means for detecting an acceleration request from the driver;
Acceleration start determination means for determining acceleration start of the engine based on the acceleration request detected by the acceleration request detection means and the engine operating state;
Fuel injection control means for performing split injection control for splitting and injecting fuel during the intake stroke or during the compression stroke and during the expansion stroke when the acceleration start determining means determines that acceleration has started;
In a cylinder supercharger-equipped in-cylinder injection engine control device,
The fuel injection control means includes
After the acceleration start determining means determines that acceleration has started, when the engine operation region is in the stratified combustion region, stratified combustion divided injection control is performed to divide and inject fuel during the compression stroke and the expansion stroke. In-cylinder injection with a turbocharger that performs uniform combustion split injection control that splits and injects fuel during an intake stroke and an expansion stroke when the region shifts from a stratified combustion region to a uniform combustion region Engine control device. The throttle control means includes
2. The turbocharger according to claim 1, wherein when the engine operating region shifts from a stratified combustion region to a uniform combustion region, throttle control is performed to prohibit operation of the throttle valve toward the valve closing side. A control device for an attached cylinder injection engine. The throttle control means includes
2. The throttle control for fully opening the throttle valve is started after the fuel injection control means has changed from the stratified combustion split injection control to the uniform combustion split injection control. 2. A control apparatus for a turbocharger-equipped in-cylinder injection engine according to 2. The fuel injection control means includes
4. The split injection control is performed prior to the throttle control of the throttle valve by the throttle valve control means when the acceleration start determination means receives an acceleration start determination. A control apparatus for an in-cylinder turbocharger-equipped in-cylinder injection engine. The fuel injection control means includes
When the actual throttle opening of the throttle valve is adjusted to the fully open state by the throttle valve control means, the split injection control is returned to the normal injection control in which fuel is injected in a batch during the intake stroke or the compression stroke. The control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of claims 1 to 4. An intake pipe internal pressure detection sensor for detecting the intake pipe internal pressure of the engine;
The fuel injection control means performs normal injection control for injecting fuel in a batch during the intake stroke or the compression stroke when the intake pipe internal pressure rises to a predetermined positive pressure value set in advance. The control apparatus for a cylinder injection engine with a turbocharger according to any one of claims 1 to 5, wherein The fuel injection control means includes
The in-cylinder turbocharger-equipped in-cylinder injection engine according to any one of claims 1 to 6, wherein the fuel injection amount injected during the expansion stroke by the split injection control is decreased in accordance with an increase in engine output. Control device. An intake pipe internal pressure detection sensor for detecting the intake pipe internal pressure of the engine, and a target boost pressure setting means for setting a target boost pressure based on the acceleration request detected by the acceleration request detection means,
The fuel injection control means determines a fuel injection amount injected during the expansion stroke by the split injection control according to a deviation between the target boost pressure and an intake pipe internal pressure detected by the intake pipe internal pressure detection sensor. The in-cylinder injection engine control apparatus with a turbocharger according to any one of claims 1 to 7. The fuel injection control means includes
The in-cylinder turbocharger-equipped in-cylinder injection engine according to any one of claims 1 to 8, wherein an injection timing of fuel injected during an expansion stroke by the split injection control is changed according to an ignition timing. Control device. The fuel injection control means includes
Combustion in the combustion chamber ends before the exhaust valve provided between the combustion chamber and the exhaust passage starts to open at the fuel injection amount and fuel injection timing of fuel injection performed during the expansion stroke by the split injection control The control apparatus for a turbocharger-equipped in-cylinder injection engine according to any one of claims 1 to 9, wherein the fuel injection timing and the fuel injection amount are set. The fuel injection control means includes
The total fuel injection amount injected from the intake stroke to the expansion stroke by the split injection control is changed to the basic fuel injection amount required for generating effective engine output, and the fuel injection amount required for raising the exhaust temperature. The control device for a turbocharger-equipped in-cylinder injection engine according to any one of claims 1 to 10, wherein The fuel injection control means includes
The turbocharger attached according to any one of claims 1 to 11, wherein the number of fuel injections performed during the expansion stroke by the split injection control is set to increase as the engine speed decreases. In-cylinder engine control device The fuel injection control means includes
The turbocharger according to any one of claims 1 to 12, wherein the number of fuel injections performed during the expansion stroke by the divided injection control is set to increase as the generated torque decreases. A control device for an in-cylinder injection engine. The fuel injection control means includes
14. The turbocharge according to claim 1, wherein a fuel injection timing of fuel injection performed during the expansion stroke by the split injection control is set during a period in which flame propagation occurs in the combustion chamber. Control device for in-cylinder injection engine with a feeder.

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