JP3695182B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device applied to a spark ignition internal combustion engine in which fuel is directly injected into a cylinder, and more specifically, the fuel injection timing set in the first half of the intake stroke when the engine is warm is set to the cold engine temperature. The present invention relates to a control device for an internal combustion engine that is sometimes changed to a retarded timing.
[0002]
[Prior art]
In a spark ignition type internal combustion engine in which fuel is directly injected into a cylinder from a fuel injection valve,
-Stratified combustion in which fuel is injected during the compression stroke, and a rich mixture that can be ignited in the vicinity of the spark plug is unevenly distributed.
・ Homogeneous combustion in which fuel is injected during the intake stroke to make the mixture in the cylinder almost homogeneous
Is selected in accordance with the engine operating state.
[0003]
In such an in-cylinder injection type internal combustion engine, compared with an internal combustion engine in which fuel is injected into an intake passage, there is a tendency that the injected fuel and the intake air are not easily mixed. In an internal combustion engine that injects fuel into the intake passage, the injected fuel is mixed to some extent with intake air in the intake passage and flows into the cylinder, whereas in a direct injection internal combustion engine, such mixing is performed. Because there is no. For this reason, when performing homogeneous combustion in a direct injection internal combustion engine, the fuel injection timing is set to the first half of the intake stroke so as to ensure the mixing time of the injected fuel and the intake air as much as possible. Yes.
[0004]
By the way, when the engine is cold, it is difficult for atomization of the injected fuel to be accelerated by the heat of the engine. It will bounce back to. As a result, the liquid injected fuel comes to adhere to the electrodes of the spark plug, and the insulation resistance between the electrodes is lowered, which may cause misfire in the worst case.
[0005]
In particular, in an internal combustion engine that performs stratified combustion, a concave portion is formed on the top surface of the piston so that the flow of injected fuel injected during the compression stroke is directed to the spark plug side, and a combustible mixture layer is formed in the vicinity of the spark plug. In many cases, the fuel is attached to the spark plug in this case.
[0006]
In order to suppress such rebound of the injected fuel, it is effective to change the fuel injection timing as described in JP-A-9-68072. In other words, if the fuel injection timing set in the first half of the intake stroke is retarded when the engine is cold and fuel is injected when the top surface of the piston is separated from the spark plug, it will collide with the top surface. It is possible to reduce the amount of injected fuel that bounces back and suppress the adhesion of fuel to the spark plug.
[0007]
[Problems to be solved by the invention]
However, when the fuel injection timing is retarded in this way, the engine combustion state changes, and it becomes difficult to ensure a good engine combustion state equivalent to that when the engine is warm.
[0008]
The reason is
-When the engine is warm, the injected fuel that has collided with the top surface of the piston or the inner peripheral wall surface of the cylinder is quickly atomized and mixed with the intake air. On the other hand, when the fuel injection timing is retarded when the engine is cold, atomization of the injected fuel due to the heat of the engine, particularly the top surface of the piston, cannot be expected, and the inner peripheral wall surface of the cylinder is not covered by the piston Since the area of the portion increases, the amount of fuel that does not contribute to combustion while remaining attached to the inner peripheral wall surface increases, and the air-fuel ratio becomes leaner than when the engine is warm.
[0009]
When the fuel is injected in the first half of the intake stroke when the engine is warm, the top surface of the piston and the spark plug are close to each other, so that the injected fuel that collides with the top surface floats around the spark plug. Although this injected fuel is mixed with the intake air introduced into the cylinder as the piston descends, it is less likely to be evenly distributed within the cylinder before ignition. Therefore, ignition is performed with the rich air-fuel mixture unevenly distributed around the spark plug.
[0010]
On the other hand, when the fuel injection timing is retarded when the engine is cold, an excessively rich air-fuel mixture is not unevenly distributed around the spark plug in this way, and atomization is promoted compared to when the engine is warm. Therefore, the injected fuel is rather unevenly distributed in the lower part of the cylinder, that is, the part away from the spark plug. Therefore, when the fuel injection timing is retarded when the engine is cold, the air-fuel mixture around the spark plug becomes leaner than when the engine is warm. When the air-fuel mixture around the spark plug becomes lean in this way, the combustion speed of the air-fuel mixture decreases, and as a result of the longer period from ignition to the maximum combustion pressure in the cylinder, the maximum combustion pressure generation time However, it will be later than a suitable time for securing the engine output.
[0011]
・ When the engine is warm, the atomization of the injected fuel is promoted by the heat of the engine, especially the top surface of the piston, whereas when the fuel injection timing is retarded when the engine is cold, the top surface of the piston As a result, it becomes impossible to expect the atomization to be accelerated by the heat of the fuel, and the injected fuel is mixed with the intake air with its particle size being large, so that the combustion is performed with insufficient mixing with the intake air. .
It can be considered.
[0012]
As described above, since the generation time of the air-fuel ratio and the maximum combustion pressure or the atomization degree of the injected fuel changes, conventionally, when the fuel injection timing is retarded when the engine is cold, it is equivalent to that when the engine is warm. It has become impossible to maintain a good engine combustion state, leading to a decrease or fluctuation in engine output and a deterioration in fuel consumption.
[0013]
The present invention has been made in view of such conventional circumstances, and the object thereof is to maintain a good engine combustion state substantially equivalent to that when the engine is warm even when the fuel injection timing is retarded when the engine is cold. An object of the present invention is to provide a control device for an internal combustion engine that can perform the above-described operation.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, the invention described in claim 1 is applied to a spark ignition type internal combustion engine in which fuel is directly injected into a cylinder, and is set in the first half of the intake stroke when the engine is warm. In a control apparatus for an internal combustion engine having a fuel injection timing changing means for changing the injection timing to a retarded timing when the engine is cold, the fuel injection timing is changed.In order to prevent the air-fuel ratio from becoming lean, the fuel injection amount changing means for increasing the fuel injection amount of the internal combustion engine more than the fuel injection amount when the engine is warm when the engine is cold is further provided. When the engine is cold, the throttle opening increases the throttle opening more than the opening when the engine is warm.A change means is provided.
[0015]
  According to this configuration,Since the air-fuel ratio is corrected to the rich side by increasing the fuel injection amount, leaning of the air-fuel ratio due to the change of the fuel injection timing can be suppressed. Further, the pumping loss when the engine is cold is reduced as compared to when the engine is warm, and the engine output when the engine is cold is increased.
[0016]
  Further, as in the invention described in claim 2, in the configuration described in claim 1,
-The fuel injection timing changing means sets the retard amount of the fuel injection timing as the engine temperature decreases.
  -The control amount changing means increases as the retardation amount increases.The fuel injection amount and the throttle openingThe change rate of
If the above structure is adopted, when the fuel adhesion to the spark plug is suppressed by the retard of the fuel injection timing, the retard amount is suppressed to the minimum necessary, and the delay of the fuel injection timing is accompanied.Making the air-fuel ratio leanTheBy increasing the fuel injection amountMore appropriate in suppressingFuel injection amountThe change rate can be set.
[0021]
  Claims3Like the invention described inFuel injection timing that is applied to a spark ignition internal combustion engine that directly injects fuel into the cylinder and changes the fuel injection timing set in the first half of the intake stroke when the engine is warm to a retarded timing when the engine is cold Have change meansIn the control device for an internal combustion engine,
  Swirl strength that increases the strength of the swirl generated in the cylinder when the engine is cold to suppress the decrease in the degree of atomization of the injected fuel due to the change in the fuel injection timing. And a throttle opening changing means for increasing the throttle opening when the engine is cold than the opening when the engine is warm.The
By adopting such a configuration, the atomization of the injected fuel is promoted by increasing the strength of the swirl, and the degree of atomization of the injected fuel is reduced and the combustion state is changed by changing the fuel injection timing. Will be able to.Further, the pumping loss when the engine is cold is reduced as compared to when the engine is warm, and the engine output when the engine is cold is increased.
[0022]
  Further, as in the invention described in claim 4, in the invention described in claim 3,
-The fuel injection timing changing means sets the retard amount of the fuel injection timing as the engine temperature decreases.
The fuel injection amount changing means sets a larger change ratio between the swirl strength and the throttle opening as the retardation amount increases.
such asIf the configuration is adopted, i.e., the configuration in which the swirl strength is increased as the retard amount of the fuel injection timing is increased, the reduction in the degree of atomization of the injected fuel is suppressed by increasing the swirl strength. A more appropriate increase rate can be set.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment embodying the present invention will be described.
[0025]
FIG. 1 shows a schematic configuration of a control device for the engine 10 in the present embodiment.
The engine 10 includes a cylinder head 11 and a cylinder block 12 formed with a plurality of cylinders 13 (only one of which is shown in FIG. 1). A piston 14 is provided in each cylinder 13 so as to be able to reciprocate. A combustion chamber 16 is defined by a top surface of the piston 14, an inner peripheral wall surface of the cylinder 13, and a lower surface of the cylinder head 11.
[0026]
The cylinder head 11 is formed with a pair of intake ports 30a and 30b constituting a part of the intake passage 30 and a pair of exhaust ports 32a and 32b constituting a part of the exhaust passage 32 (in FIG. Only the intake port 30a and the exhaust port 32a are shown). The intake ports 30 a and 30 b and the exhaust ports 32 a and 32 b communicate with the combustion chamber 16 and are opened and closed by opening and closing operations of the intake valve 20 and the exhaust valve 22 supported by the cylinder head 11.
[0027]
FIG. 2 shows the planar cross-sectional shapes of the intake ports 30a and 30b and the exhaust ports 32a and 32b. As shown in the figure, one intake port 30a is a straight port that extends in a straight line, while the other intake port 30b is a helical port that extends with its axis curved (particularly, When these intake ports 30a and 30b are distinguished, they are referred to as “straight port 30a” and “helical port 30b”, respectively). When the intake air is introduced into the combustion chamber 16 through the helical port 30b, the flow of the intake air swirling around the axis of the piston 14 (see FIG. 1) in the combustion chamber 16 as indicated by a broken line arrow, That is, a swirl is formed.
[0028]
As shown in FIGS. 1 and 2, a swirl control valve (hereinafter abbreviated as “SCV”) 34 that is opened and closed by a motor 35 is provided in a portion communicating with the upstream side of the straight port 30 a in the intake passage 30. It has been. The SCV 34 adjusts the strength of the swirl formed in the combustion chamber 16 by opening and closing the straight port 30a and adjusting the amount of intake air passing through the helical port 30b.
[0029]
When the opening degree of the SCV 34 becomes relatively small, the ratio of the intake air passing through the intake passage 30 that passes through the helical port 30b becomes large and the strength of the swirl becomes strong, and conversely, the opening degree becomes relatively large. Then this ratio becomes smaller and the strength of the swirl becomes weaker.
[0030]
As shown in FIG. 1, a surge tank 36 is provided upstream of the SCV 34 in the intake passage 30, and a throttle valve 38 is provided inside the upstream portion of the surge tank 36. . The throttle valve 38 is driven to open and close by a throttle motor 39, thereby adjusting the amount of intake air introduced into the combustion chamber 16 according to its opening, that is, the throttle opening TA.
[0031]
One end of a purge passage 37 that connects the surge tank 36 and a canister (not shown) is connected to the surge tank 36. A purge amount control valve 33 is provided in the purge passage 37, and the amount of fuel purged from the canister to the surge tank 36 is adjusted by the purge amount control valve 33.
[0032]
The cylinder head 11 is provided with injectors 26 for directly injecting fuel into the combustion chambers 16 corresponding to the combustion chambers 16. The injector 26 is connected to a delivery pipe (not shown) to which high-pressure fuel is pumped from a fuel pump (not shown), and the fuel is supplied from the delivery pipe. The injector 26 incorporates a solenoid valve (not shown), and the fuel injection amount and fuel injection timing are adjusted based on the opening / closing operation of the solenoid valve.
[0033]
The cylinder head 11 is provided with a spark plug 24 corresponding to each combustion chamber 16, and an electrode portion at the tip thereof projects into the combustion chamber 16. The ignition plug 24 is connected to an igniter 25 via an ignition coil (not shown), and the ignition timing is adjusted by the igniter 25. The air-fuel mixture formed by the intake air introduced into the combustion chamber 16 from the intake passage 30 and the fuel directly injected from the injector 26 into the combustion chamber 16 when the intake valve 20 is opened is ignited by the spark plug 24. Burned. The air-fuel mixture thus combusted is exhausted from the combustion chamber 16 to the exhaust passage 32 when the exhaust valve 22 is opened.
[0034]
A recess 14 a is formed on the top surface of the piston 14. When the piston 14 and the injector 26 are close to each other as in the latter half of the compression stroke, the fuel injected from the injector 26 is directed together with the swirl toward the tip of the spark plug 24 by the recess 14a. It has become.
[0035]
The combustion mode of the engine 10 in the present embodiment is switched between a plurality of modes having different air-fuel ratios or fuel injection methods, that is, "stratified combustion", "weakly stratified combustion", and "homogeneous combustion". Yes. Such switching of the combustion mode is performed based on the fuel injection amount and the engine speed.
[0036]
For example, when “stratified combustion” is selected as the combustion mode, the air-fuel ratio is set to be leaner (A / F = 25-50) than the stoichiometric air-fuel ratio (A / F = 14.5), and the fuel injection timing is Set late in the compression stroke. When “weakly stratified combustion” is selected as the combustion mode, the air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio (A / F = 20 to 30), and the fuel is 2 in the intake stroke and the compression stroke. It will be injected divided into times. Further, when “homogeneous combustion” is selected as the combustion mode, the air-fuel ratio is the stoichiometric air-fuel ratio, lean (A / F = 15 to 23), and rich (A / F = 11 to 13) depending on the operating state. The fuel injection timing is set during the intake stroke.
[0037]
The engine 10 is provided with various sensors for detecting the operating state. A crankshaft (not shown) that rotates with the reciprocating movement of the piston 14 and a camshaft that rotates in conjunction with the crankshaft are located at a rotation speed (engine speed NE) and a rotation angle (crank angle) of the crankshaft. A crank angle sensor 51 and a cam angle sensor 52 for detecting (CA) are provided.
[0038]
The surge tank 36 is provided with an intake pressure sensor 53 for detecting the pressure of intake air (intake pressure PM). In the vicinity of the throttle valve 38, an accelerator sensor 54 for detecting the amount of depression of the accelerator pedal 60 (accelerator opening ACCP) is provided. An SCV opening sensor 55 for detecting the opening of the SCV 34 (actual opening SCVP) is provided in the vicinity of the SCV 34.
[0039]
The cylinder block 12 is provided with a water temperature sensor 56 (which constitutes engine temperature detection means) for detecting the temperature of the cooling water (cooling water temperature THW), and a knocking signal KCS corresponding to the magnitude of knocking generated in the engine 10. An output knock sensor 57 is provided. The exhaust passage 32 is provided with an oxygen sensor 58 that outputs an exhaust oxygen concentration signal XOX corresponding to the oxygen concentration of the exhaust gas flowing through the exhaust passage 32.
[0040]
All of the detection signals output from these various sensors 51 to 58 are input to an electronic control unit (hereinafter abbreviated as “ECU”) 40 that executes various controls of the engine 10. The ECU 40 drives the injector 26 (electromagnetic valve), the igniter 25, the purge amount control valve 33, the motors 35, 39, and the like based on the detection signals from the sensors 51 to 58, and thereby the fuel injection amount and the fuel injection. Control related to timing, ignition timing control, air-fuel ratio feedback control, purge amount control, intake air amount control, swirl intensity control, and the like are executed. The ECU 40 includes a central processing unit (CPU) 41 that performs arithmetic processing when executing these various controls, a memory 42 for storing these various control programs and function data in advance, or storing various data. Yes.
[0041]
Hereinafter, an execution procedure of various controls when “homogeneous combustion” is selected as the combustion mode among the controls executed by the ECU 40 will be described.
First, fuel injection timing control in this embodiment will be described.
[0042]
FIG. 3 is a flowchart showing an execution procedure of fuel injection timing control. The ECU 40 repeatedly executes this “fuel injection timing control routine” as an interrupt process of a predetermined crank angle cycle.
[0043]
First, at step 100, the fuel injection timing AINJ is calculated based on the intake pressure PM and the engine speed NE. The fuel injection timing AINJ is defined as a relative crank angle CA before the compression top dead center (BTDC) with reference to the compression top dead center (TDC) of the cylinder where ignition is performed. Accordingly, as the fuel injection timing AINJ increases, the fuel is injected at a relatively advanced timing, and conversely, as the fuel injection timing AINJ decreases, the fuel is injected at a relatively retarded timing.
[0044]
Next, in step 110, the coolant temperature THW is compared with the determination temperature JTHW. This determination temperature JTHW is a value for determining whether or not the fuel injection timing AINJ needs to be retarded in order to suppress fuel adhesion to the spark plug 24. If it is determined that the coolant temperature THW is lower than the determination temperature JTHW, the process proceeds to step 120, and the fuel injection timing AINJ is set equal to the cold injection timing AINJCOLD. The cold injection timing AINJCOLD is a fuel injection timing set so as to reliably suppress fuel adhesion to the spark plug 24. In step 100, the fuel set based on the intake pressure PM and the engine speed NE. It is a timing (for example, BTDC 260 ° CA) that is retarded from the range of the injection timing AINJ (for example, BTDC 300 to 360 ° CA).
[0045]
In step 130, the retard processing execution flag XCOLD is set to "1". The retard processing execution flag XCOLD determines whether or not processing for retarding the fuel injection timing AINJ (hereinafter referred to as “injection timing retarding processing”) is being performed in order to suppress fuel adhesion to the spark plug 24. It is a flag to do.
[0046]
On the other hand, if it is determined in step 110 that the coolant temperature THW is equal to or higher than the determination temperature JTHW, that is, it is not necessary to execute the injection timing retard process, the retard process execution flag XCOLD is reset to “0” in step 140. After executing the processing of step 130 or step 140, the ECU 40 once ends the processing of this routine.
[0047]
Next, fuel injection amount control in this embodiment will be described.
FIG. 4 is a flowchart showing an execution procedure of the fuel injection amount control. The ECU 40 repeatedly executes this “fuel injection amount control routine” as an interrupt process of a predetermined crank angle cycle.
[0048]
In the “fuel injection amount control routine”, the fuel injection amount increase correction is executed based on the retard processing execution flag XCOLD set in the “fuel injection timing control routine”.
[0049]
First, at step 200, the basic fuel injection amount QINJB is calculated based on the intake pressure PM and the engine speed NE. The basic fuel injection amount QINJB serves as a reference for the fuel injection amount, and is calculated as a larger value to ensure a predetermined engine output as the intake pressure PM or the engine speed NE increases.
[0050]
Next, in step 210, it is determined whether or not the retard processing execution flag XCOLD is set to “1”, that is, whether or not the injection timing retard processing is being executed. If it is determined that the retard process execution flag XCOLD is “0”, the injection timing retard process is stopped, and the process proceeds to step 240.
[0051]
On the other hand, if it is determined in step 210 that the retard processing execution flag XCOLD is “1”, in step 220, the cold basic injection amount QINJBCOLD is calculated based on the intake pressure PM and the engine speed NE. At 230, the basic fuel injection amount QINJB is set equal to the cold basic injection amount QINJBCOLD.
[0052]
The memory 42 of the ECU 40 stores function data that defines the relationship between the intake pressure PM and the engine speed NE and the cold basic injection amount QINJBCOLD, and the ECU 40 calculates the cold basic injection amount QINJBCOLD. Refer to this function data. Here, the cold basic injection amount QINJBCOLD is set to be always larger than the basic fuel injection amount QINJB calculated in step 200, and the difference between the two QINJBCOLD and QINJB, that is, execution of the injection timing retarding process is performed. The increase ratio of the fuel injection amount at the time is set so as to compensate for the deviation amount of the air-fuel ratio that shifts to the lean side with the execution of the injection timing retarding process.
[0053]
In step 240, the fuel injection time TAU is calculated based on the following equation.
TAU = QINJB × (FAF + KG) × KM (1)
Here, “FAF” is an air-fuel ratio feedback correction coefficient set based on the exhaust oxygen concentration signal XOX, etc., and “KG” is a steady deviation generated between the target air-fuel ratio (theoretical air-fuel ratio) and the actual air-fuel ratio. This is an air-fuel ratio learning value for correction. “KM” is a correction coefficient set based on the fuel injection pressure (fuel pressure in the delivery pipe), the intake air temperature, and the like.
[0054]
After the fuel injection time TAU is set in step 240, the routine is temporarily terminated.
The ECU 40 executes fuel injection by driving the solenoid valve of the injector 26 based on the fuel injection time TAU and the fuel injection timing AINJ obtained in each control routine.
[0055]
As described above, in the present embodiment, when the injection timing retarding process is performed, the cold basic injection amount QINJBCOLD is selected as the basic fuel injection amount QINJB. A lot of fuel is injected. Therefore, the amount of fuel adhering to the inner peripheral wall surface of the cylinder 13 is increased compared to when the engine is warm, and the decrease in fuel is reduced even when the engine is cold when the amount of fuel actually contributing to combustion is decreased. The amount of fuel can be offset by an increase in the injection amount, and an amount of fuel corresponding to the amount of intake air introduced into the combustion chamber 16 can be injected.
[0056]
Therefore, according to this embodiment,
(1) The lean deviation of the air-fuel ratio accompanying the injection timing retarding process can be suppressed to ensure a good combustion state, and the reduction or fluctuation in engine output caused by such an air-fuel ratio deviation can be suppressed. It becomes like this.
[0057]
[Second Embodiment]
Next, a second embodiment of the present invention will be described focusing on the differences from the first embodiment. Note that a description of a configuration equivalent to that of the first embodiment is omitted.
[0058]
In this embodiment, in addition to the “fuel injection timing control routine” and “fuel injection amount control routine” described in the first embodiment, the ignition timing is corrected depending on whether or not the injection timing retarding process is being executed. This is different from the first embodiment.
[0059]
Hereinafter, an execution procedure of such ignition timing control will be described with reference to a flowchart shown in FIG. The ECU 40 repeatedly executes this “ignition timing calculation routine” as interruption processing of a predetermined crank angle cycle.
[0060]
First, at step 300, the basic ignition timing ABSE is calculated based on the intake pressure PM and the engine speed NE. The memory 42 of the ECU 40 stores function data that defines the relationship between the intake pressure PM and the engine speed NE and the basic ignition timing ABSE. The ECU 40 refers to this function data when calculating the basic ignition timing ABSE. . This basic ignition timing ABSE is also defined as a relative crank angle CA before compression top dead center, similar to the fuel injection timing AINJ.
[0061]
Next, in step 310, it is determined whether or not the retard processing execution flag XCOLD is set to “1”. If it is determined that the retard process execution flag XCOLD is “1”, that is, if it is determined that the injection timing retard process is being performed, the process proceeds to step 320.
[0062]
In step 320, after calculating the cold basic ignition timing ABSECOLD based on the intake pressure PM and the engine speed NE, in step 330, the basic ignition timing ABSE is set equal to the cold basic ignition timing ABSECOLD.
[0063]
The memory 42 of the ECU 40 stores function data that defines the relationship between the intake pressure PM and the engine speed NE and the cold basic ignition timing ABSOCOLD, and the ECU 40 calculates the cold basic ignition timing ABSOCOLD. Refer to this function data.
[0064]
The cold basic ignition timing ABSECOLD is set so as to be always larger than the basic ignition timing ABSE calculated in step 300, that is, always to be an advance timing.
[0065]
If the fuel injection timing is retarded when the engine is cold, the fuel spray particle size is large even if the overall air-fuel ratio in the cylinder 13 is prevented from shifting to the lean side by increasing the basic fuel injection amount QINJB. Therefore, the spray is unevenly distributed below the cylinder 13, and it is inevitable that the air-fuel mixture around the spark plug 24 is partially leaned.
[0066]
As described above, when the air-fuel mixture around the spark plug 24 is partially leaned, the combustion speed of the air-fuel mixture decreases, and the generation time of the maximum combustion pressure (crank angle CA) is more suitable than the time suitable for securing the engine output. Be late. The difference between the cold basic ignition timing ABSECOLD and the basic ignition timing ABSE, that is, the advance amount of the ignition timing when the injection timing retarding process is executed, can compensate for the delay in the generation timing of the maximum combustion pressure. It is set to be possible.
[0067]
When it is determined in step 310 that the injection timing retarding process is stopped, or after the process of step 330 is executed, in step 340, the basic ignition timing ABSE, the knocking signal KCS output from the knock sensor 57, etc. Based on this, the final ignition timing AOP is calculated. After executing the processing of step 340, the processing of this routine is temporarily terminated.
[0068]
The ECU 40 executes ignition by the spark plug 24 by outputting an ignition signal to the igniter 25 when the crank angle CA before the compression top dead center coincides with the final ignition timing AOP.
[0069]
As described above, in the present embodiment, when the injection timing retarding process is executed, the cold basic ignition timing ABSECOLD is selected as the basic ignition timing ABSE. The air-fuel mixture is ignited at an early stage.
[0070]
Therefore, according to this embodiment,
(2) It is possible to ensure a good combustion state by suppressing the generation timing of the maximum combustion pressure from being delayed from a suitable timing for securing the engine output by the injection timing retarding process. Therefore, it is possible to suppress a decrease or fluctuation in engine output and a deterioration in fuel consumption caused by the delay of the maximum combustion pressure generation timing.
[0071]
[Third Embodiment]
Next, a third embodiment of the present invention will be described with a focus on differences from the first embodiment. Note that a description of a configuration equivalent to that of the first embodiment is omitted.
[0072]
In this embodiment, when retarding the fuel injection timing in the injection timing retarding process, the retard amount is variably set based on the coolant temperature THW, and the fuel injection amount is based on the retard amount of the fuel injection timing. This is different from the first embodiment in that the increase ratio is set.
[0073]
Hereinafter, the execution procedure of such fuel injection timing control will be described with reference to FIGS. 6 and 7. The ECU 40 repeatedly executes the “fuel injection timing control routine” shown in FIG. 6 as interruption processing of a predetermined crank angle cycle. In FIG. 6, it is assumed that the same steps as those in FIG.
[0074]
After step 100, if it is determined in step 110 that it is necessary to execute the injection timing retardation process, steps 112 to 120 are sequentially executed to correct the fuel injection timing AINJ.
[0075]
First, in step 112, the cold injection timing AINJCOLD is calculated based on the coolant temperature THW. The memory 42 of the ECU 40 stores function data that defines the relationship between the coolant temperature THW and the cold injection timing AINJCOLD, and the ECU 40 refers to this function data when calculating the cold injection timing AINJCOLD.
[0076]
FIG. 7 is a graph showing the function data. As shown in the figure, the cold injection timing AINJCOLD is set to a retarded timing as the coolant temperature THW decreases.
[0077]
Next, at step 114, the difference between the fuel injection timing AINJ calculated at step 100 and the cold injection timing AINJCOLD is set as a retard amount ΔAINJ. This retardation amount ΔAINJ has a correlation with the amount of deviation when the air-fuel ratio shifts to the lean side by executing the injection timing retardation processing, and is used when determining the increase ratio of the fuel injection amount.
[0078]
In step 120, after setting the cold injection timing AINJCOLD as a new fuel injection timing AINJ, in step 130, the retard processing execution flag XCOLD is set to "1".
[0079]
On the other hand, if it is determined in step 110 that it is not necessary to execute the injection timing retard process, the retard process execution flag XCOLD is reset to “0” in step 140. After executing the processes in steps 130 and 140, the process of this routine is temporarily terminated.
[0080]
Next, the execution procedure of the fuel injection amount control will be described with reference to FIGS. The ECU 40 repeatedly executes the “fuel injection amount control routine” shown in FIG. 8 as interruption processing of a predetermined crank angle cycle. In FIG. 8, each step denoted by the same reference numeral as in FIG. 4 is executed with the same process as in FIG.
[0081]
After step 200, if it is determined in step 210 that the injection timing retarding process is being executed, the processes in steps 222 to 232 are sequentially executed to correct the basic fuel injection amount QINJB.
[0082]
First, in step 222, an injection amount increase coefficient KQ is calculated based on the basic fuel injection amount QINJB (or intake pressure PM) and the retardation amount ΔAINJ. This injection amount increase coefficient KQ is for increasing the fuel injection amount in accordance with the amount of deviation when the air-fuel ratio shifts to the lean side by executing the injection timing retarding process.
[0083]
The memory 42 of the ECU 40 stores function data that defines the relationship between the basic fuel injection amount QINJB (or intake pressure PM), the retard amount ΔAINJ, and the injection amount increase coefficient KQ. FIG. 9 is a graph showing this function data.
[0084]
As shown in the figure, the larger the retard amount ΔAINJ, the larger the injection amount increase coefficient KQ is set. The reason why the injection amount increase coefficient KQ is set in this way is as follows.
[0085]
That is, as apparent from the relationship between the retardation amount ΔAINJ, the cold injection timing AINJCOLD, and the cooling water temperature THW, the larger the retardation amount ΔAINJ, the lower the cooling water temperature THW and the more difficult the atomized fuel is atomized. The amount of fuel that remains attached to the inner peripheral wall surface of the cylinder 13 increases.
[0086]
Furthermore, as the retard amount ΔAINJ increases, the distance between the injector 26 and the top surface of the piston 14 when fuel is injected increases, and the portion of the inner peripheral wall surface of the cylinder 13 that is not covered by the piston 14 increases. For this reason, the amount of fuel adhering to the inner peripheral wall surface increases.
[0087]
As the fuel adhesion amount increases, the air-fuel ratio deviates more greatly on the lean side. To properly correct this deviation, the injection amount increase coefficient KQ increases as the retard amount ΔAINJ increases. This is because it is necessary to set.
[0088]
Further, the injection amount increase coefficient KQ is set to increase as the basic fuel injection amount QINJB increases (or the intake pressure PM increases). This is because as the basic fuel injection amount QINJB increases, the proportion of injected fuel adhering to the inner peripheral wall surface of the cylinder 13 increases, and the above-described lean deviation of the air-fuel ratio tends to become more prominent.
[0089]
After calculating the injection amount increase coefficient KQ as described above, in step 232, the current basic fuel injection amount QINJB is multiplied by the injection amount increase coefficient KQ, and the multiplication value (QINJB × K) is used as a new basic fuel injection. Set as quantity QINJB.
[0090]
On the other hand, when it is determined in step 210 that the injection timing retardation process is stopped, or after the process of step 232 is executed, the ECU 40 calculates the fuel injection time TAU based on the above equation (1) in step 240. The processing of this routine is once terminated.
[0091]
As described above, in the present embodiment, the fuel injection timing AINJ is set to the relatively retarded timing as the cooling water temperature THW decreases, and the fuel injection timing AINJ is set to the retarded timing. The basic fuel injection amount QINJB is greatly increased.
[0092]
Therefore, according to this embodiment,
(3) In order to suppress the fuel adhesion to the spark plug 24, the retard amount (ΔAINJ) of the fuel injection timing (AINJ) is suppressed to the minimum necessary, and the air-fuel ratio associated with the delay of the fuel injection timing is further reduced. When the lean shift is suppressed by increasing the fuel injection amount, an appropriate increase ratio (injection amount increase coefficient KQ) can be set. As a result, it is possible to secure a better engine combustion state and to reliably suppress a decrease or fluctuation in engine output due to a lean deviation of the air-fuel ratio.
[0093]
[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described focusing on differences from the third embodiment. In addition, description is abbreviate | omitted about the structure equivalent to 3rd Embodiment.
[0094]
In this embodiment, both the “fuel injection timing control routine” and the “fuel injection amount control routine” shown in FIGS. 6 and 8 are executed, and the ignition timing is corrected as necessary based on the retard amount ΔAINJ. I am trying to calculate. Hereinafter, the calculation procedure of the ignition timing will be described with reference to FIGS.
[0095]
FIG. 10 is a flowchart showing each process of the “ignition timing calculation routine”. The ECU 40 repeatedly executes this “ignition timing calculation routine” as interruption processing of a predetermined crank angle cycle. In FIG. 10, it is assumed that the same steps as those in FIG.
[0096]
After step 300, if it is determined in step 310 that the injection timing retard process is being executed, in step 325, based on the basic fuel injection amount QINJB (or intake pressure PM) and the retard amount ΔAINJ. An ignition timing advance amount KA is calculated. This ignition timing advance amount KA is corrected to advance the ignition timing according to the retard amount when the generation timing of the maximum combustion pressure is delayed from a suitable timing for securing the engine output by the injection timing retard processing. Is to do.
[0097]
The memory 42 of the ECU 40 stores function data that defines the relationship between the basic fuel injection amount QINJB (or intake pressure PM), the retard amount ΔAINJ, and the ignition timing advance amount KA. FIG. 11 is a graph showing this function data.
[0098]
As shown in the figure, the ignition timing advance amount KA is set larger as the retard amount ΔAINJ increases. The reason why the ignition timing advance amount KA is set in this way is as follows.
[0099]
That is, when the retard amount ΔAINJ is increased, that is, when the fuel injection timing is retarded more greatly, the air-fuel mixture around the spark plug 24 described above becomes more lean and the combustion speed is increased. It will drop greatly. As a result, the generation time of the maximum combustion pressure is further delayed from a suitable time for securing the engine output. Therefore, in order to suppress such a change in the generation timing of the maximum combustion pressure, it is necessary to set the ignition timing to a more advanced timing as the retard amount ΔAINJ increases.
[0100]
Further, the ignition timing advance amount KA is set larger as the basic fuel injection amount QINJB increases (or the intake pressure PM increases). This is because as the basic fuel injection amount QINJB increases, the air-fuel mixture around the spark plug 24 becomes leaner than the air-fuel mixture in the other portions, and the deviation in the generation timing of the maximum combustion pressure as described above becomes even greater. Because it becomes.
[0101]
After calculating the ignition timing advance amount KA in this way, in step 335, the ignition timing advance amount KA is added to the current basic ignition timing ABSE, and the added value (ABSE + KA) is set as a new basic ignition timing ABSE. . After executing the processing of step 335, or when it is determined in step 310 that the injection timing retardation processing is stopped, the ECU 40 calculates the final ignition timing AOP in step 340 and temporarily ends the processing of this routine. To do.
[0102]
As described above, in the present embodiment, the basic ignition timing ABSE is advanced as the fuel injection timing AINJ set based on the coolant temperature THW is set to the retard timing. Therefore, in addition to the same operational effects as (3) described in the third embodiment, the following operational effects can be further exhibited.
[0103]
That is,
(4) In order to suppress fuel adhesion to the spark plug 24, the timing of generation of the maximum combustion pressure is deviated from a suitable timing while the retard amount (ΔAINJ) of the fuel injection timing (AINJ) is minimized. When the ignition timing is suppressed by the advance of the ignition timing, it is possible to set an appropriate advance amount (ignition timing advance amount KA). As a result, it is possible to secure a better engine combustion state, to suppress a decrease or fluctuation in engine output caused by a shift in the generation timing of the maximum combustion pressure, and to reliably suppress deterioration of fuel consumption. become able to.
[0104]
[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with a focus on differences from the first embodiment. Note that a description of a configuration equivalent to that of the first embodiment is omitted.
[0105]
In the present embodiment, the “fuel injection timing control routine” shown in FIG. 3 is executed, and the air-fuel ratio learning value KG in the air-fuel ratio control is set as different values during the execution of the injection timing retarding process and when the process is stopped. I try to learn. In the present embodiment, the “fuel injection amount control routine” shown in FIG. 4 is not executed. Therefore, the increase correction of the basic fuel injection amount QINJB based on the cold basic injection amount QINJBCOLD is not executed.
[0106]
Hereinafter, each process of the “air-fuel ratio control routine” in which the learning of the air-fuel ratio learning value KG is performed will be described with reference to the flowcharts shown in FIGS. 12 and 13. The ECU 40 repeatedly executes this “air-fuel ratio control routine” as interrupt processing of a predetermined time period.
[0107]
First, in step 500, it is determined whether an execution condition for air-fuel ratio feedback control is satisfied. If it is determined that the execution condition of the air-fuel ratio control is not satisfied, the ECU 40 once ends the processing of this routine after setting the air-fuel ratio feedback correction coefficient FAF to “1.0” in step 501. Incidentally, as a case where the execution condition of the air-fuel ratio control is not satisfied as described above, for example, the cooling water temperature THW is a predetermined temperature or less, the accelerator opening ACCP is a predetermined value or more, and the like. .
[0108]
On the other hand, if it is determined in step 500 that the execution condition of the air-fuel ratio control is established, whether or not the purge control is stopped in step 502, that is, whether the purge passage 37 is closed by the purge amount control valve 33 or not. Judge whether or not. If it is determined that the purge control is stopped, it is determined in step 504 whether or not the injection timing retarding process is being executed based on the retarding process execution flag XCOLD.
[0109]
If it is determined in step 504 that the injection timing retarding process is being executed, in step 506, the cold air-fuel ratio learned value KGCOLD is read from the memory 42 of the ECU 40, and the cold air-fuel ratio learned value KGCOLD is read as the air-fuel ratio. Set as learning value KG.
[0110]
On the other hand, if it is determined in step 504 that the injection timing retarding process has been stopped, the warm time air-fuel ratio learning value KGHOT is read from the memory 42 in step 507 and the warm time air-fuel ratio learning value KGHOT is read as the air-fuel ratio learning value. Set as KG. Here, the cold time air-fuel ratio learned value KGCOLD and the warm time air-fuel ratio learned value KGHOT are both associated with these operation regions as values corresponding to a plurality of operation regions divided by the intake pressure PM and the engine speed NE. Stored in the memory 42.
[0111]
In the next step 508, an air-fuel ratio feedback correction coefficient FAF is calculated based on the exhaust oxygen concentration signal XOX. FIG. 14 shows an example of how the air-fuel ratio feedback correction coefficient FAF changes with time. As shown in the figure, the air-fuel ratio feedback correction coefficient FAF is switched between a state where the exhaust oxygen concentration signal XOX indicates that the exhaust air-fuel ratio is rich and a state where it indicates lean (timing t1, t1). The amount is increased or decreased by a certain amount at t2, t3). The amount is gradually increased or decreased during a period (timing t1 to t2, t2 to t3) until the exhaust oxygen concentration signal XOX is switched again.
[0112]
Incidentally, the operation of increasing / decreasing the air-fuel ratio feedback correction coefficient FAF by a certain amount at the switching timing (skip timing) of the exhaust oxygen concentration signal XOX in this way is called “skip control”. After this skip control, the skip timing is again set. The operation of gradually increasing or decreasing the air-fuel ratio feedback correction coefficient FAF until it arrives is called “integration operation”, and is a well-known control mode for air-fuel ratio feedback control.
[0113]
After calculating the air-fuel ratio feedback correction coefficient FAF in this way, it is determined in step 510 whether or not there is a skip timing.
If it is determined that it is the skip timing, it is determined in step 512 whether or not the average value FAFAV of the air-fuel ratio feedback correction coefficient FAF is stable and the change is within a predetermined fluctuation range. For example, when the operating state of the engine 10 is in a steady state, the fluctuation amount of the average value FAFAV is small, so that it is determined in step 512 that the average value FAFAV is stable.
[0114]
If it is determined in step 512 that the average value FAFAV of the air-fuel ratio feedback correction coefficient FAF is stable, the process proceeds to step 514 shown in FIG. 13, and the air-fuel ratio learning value KG is calculated based on the following equation (2). To do.
[0115]
KG = FAFAV-1.0 (2)
When the air-fuel ratio of the engine 10 tends to be leaner than the stoichiometric air-fuel ratio in a steady operation state, the average value FAFAV of the air-fuel ratio feedback correction coefficient FAF becomes larger than “1.0”. The air-fuel ratio learning value KG is set as a positive value, and when the air-fuel ratio tends to shift to a richer side than the stoichiometric air-fuel ratio, the average value FAFAV becomes smaller than “1.0”. The value KG is set as a negative value.
[0116]
In step 516, it is determined again whether or not the injection timing retarding process is being executed. If the process is being executed, in step 518, the air-fuel ratio learning value KG is set to the intake pressure PM and the engine speed. It is stored as a cold time air-fuel ratio learned value KGCOLD corresponding to the current operating region determined by the number NE. On the other hand, if it is determined in step 516 that the injection timing retarding process is not being executed, in step 517, the air-fuel ratio learned value KG is stored as the warm time air-fuel ratio learned value KGHOT corresponding to the current operating region.
[0117]
After executing the processes of steps 517 and 518, or when a negative determination is made in steps 502, 510, and 512, the ECU 40 once ends the process of this routine. The air / fuel ratio learned value KG learned in this way is reflected when the fuel injection time TAU is calculated as shown in the above equation (1).
[0118]
As described above, in the present embodiment, the air-fuel ratio learned value KG in the air-fuel ratio feedback control is set to the value used during the stop of the injection timing retarding process, that is, the warm time air-fuel ratio learned value KGHOT. The learning is performed by distinguishing it from the value used during the operation, that is, the cold air-fuel ratio learning value KGCOLD.
[0119]
Accordingly, during the execution of the injection timing retarding process, the amount of increase is corrected more than when the process is stopped by the air-fuel ratio learning value KG commensurate with the amount of lean deviation of the air-fuel ratio that occurs during the execution of the process. The fuel injection is executed based on the basic fuel injection amount QINJB.
[0120]
For example, when the air-fuel ratio learning value KG is not learned separately, the air-fuel ratio learning value KG is learned so that the above-described lean deviation of the air-fuel ratio can be suppressed during execution of the injection timing retarding process. Even after that, if the air-fuel ratio learning value KG is updated while the injection timing retarding process is stopped, when the injection timing retarding process is performed again, such as during a cold restart, the updated The air-fuel ratio control is executed based on the fuel ratio learning value KG. Therefore, when the air-fuel ratio feedback control is stopped, the lean deviation of the air-fuel ratio can no longer be resolved, and the feedback control is started, and the basic fuel injection amount QINJB is determined by the air-fuel ratio feedback correction coefficient FAF. Even when the amount is corrected to increase, the occurrence of lean deviation is unavoidable immediately after the start of the feedback control, and this cannot be compensated promptly.
[0121]
In this regard, according to the present embodiment,
(5) When the injection timing retard process is executed during cold restart or the like, the cold air-fuel ratio learned value KGCOLD learned during the execution of the previous injection timing retard process is read as the air-fuel ratio learned value KG. Therefore, it is possible to quickly compensate for the air-fuel ratio lean shift caused by the execution of the same process, and to suppress the decrease or fluctuation in engine output due to such air-fuel ratio shift at an earlier stage. .
[0122]
[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described with a focus on differences from the third embodiment. In addition, description is abbreviate | omitted about the structure equivalent to 3rd Embodiment.
[0123]
In this embodiment, both the “fuel injection timing control routine” and the “fuel injection amount control routine” shown in FIGS. 6 and 8 are executed, and the SCV 34 is opened according to whether or not the injection timing retarding process is executed. By controlling the degree, the strength of the swirl formed in the combustion chamber 16 is adjusted.
[0124]
Hereinafter, the opening degree control of the SCV 34 will be described with reference to FIGS. FIG. 15 is a flowchart showing the processing contents of the “SCV opening degree control routine”, and the ECU 40 repeatedly executes this routine as an interruption processing of a predetermined crank angle cycle.
[0125]
First, at step 700, the basic command opening degree SCVREQB of the SCV 34 is calculated based on the intake pressure PM and the engine speed NE. Next, in step 702, the confinement amount DSCV is calculated based on the coolant temperature THW and the engine speed NE. This confinement amount DSCV is for reducing the opening degree of the SCV 34 from the basic instruction opening degree SCVREQB, and the strength of the swirl increases as the confinement amount DSCV is set larger.
[0126]
The memory 42 of the ECU 40 stores function data that defines the relationship between the coolant temperature THW and the engine speed NE and the closing amount DSCV, and the ECU 40 refers to this function data when calculating the closing amount DSCV. . For example, as shown in FIG. 16, the confinement amount DSCV is set larger as the cooling water temperature THW decreases. The confinement amount DSCV is set in this way because the cooling water temperature THW, in other words, as the engine temperature decreases, the atomization of the injected fuel decreases and becomes difficult to mix with the intake air. This is because it is necessary to promote atomization of the injected fuel by increasing the strength. Further, the confinement amount DSCV is set larger as the engine speed NE decreases. This is because when the engine speed NE decreases, the intake air introduction speed into the combustion chamber 16 decreases and the swirl strength also decreases, and it is necessary to compensate for such a decrease in swirl strength.
[0127]
Next, in step 704, it is determined whether or not the injection timing retarding process is being executed based on the retarding process execution flag XCOLD. If it is determined that the process is being executed, a confinement amount correction coefficient KS is calculated in step 705 based on the basic fuel injection amount QINJB (or intake pressure PM) and the retard amount ΔAINJ.
[0128]
The confinement amount correction coefficient KS is used to increase and correct the swirl intensity in accordance with the degree of decrease when the atomization of the injected fuel decreases due to the execution of the injection timing retardation process.
[0129]
The memory 42 of the ECU 40 stores function data that defines the relationship between the basic fuel injection amount QINJB (or intake pressure PM), the retard amount ΔAINJ, and the confinement amount correction coefficient KS. FIG. 17 is a graph showing this function data.
[0130]
As shown in the figure, as the retardation amount ΔAINJ increases, the confinement amount correction coefficient KS is set larger. The reason for setting the confinement amount correction coefficient KS in this way is as follows.
[0131]
That is, the greater the retard amount ΔAINJ, the longer the distance between the injector 26 and the top surface of the piston 14 when injecting the fuel. Thus, the amount of fuel adhering to the inner peripheral wall surface of the cylinder 13 also increases. Therefore, by forming a stronger swirl in the combustion chamber 16, it is necessary to promote atomization of the injected fuel and to suppress fuel adhesion to the inner peripheral wall surface of the cylinder 13.
[0132]
Further, the confinement amount correction coefficient KS is set larger as the basic fuel injection amount QINJB increases (or the intake pressure PM increases). This is because, as the basic fuel injection amount QINJB increases, the proportion of the injected fuel adhering to the inner peripheral wall surface of the cylinder 13 increases and the atomization degree of fuel spray having a poor atomization degree (large particle size) existing in the cylinder 13 increases. This is because the amount increases.
[0133]
After calculating the confinement amount correction coefficient KS as described above, in step 706, the current confinement amount DSCV is multiplied by the confinement amount correction coefficient KS, and the multiplied value (DSCV × KS) is newly confined. Set as quantity DSCV.
[0134]
After executing the processing of step 706, or when it is determined in step 704 that the injection timing retardation processing is stopped, the processing proceeds to step 708, and the indicated opening SCVREQ of the SCV 34 is based on the following equation (3). To calculate.
[0135]
SCVREQ = SCVREQB-DSCV (3)
After executing the processing of step 708, the ECU 40 once ends the processing of this routine. The ECU 40 feedback-controls the motor 35 so that the calculated opening degree SCVREQ and the actual opening degree SCVP of the SCV 34 coincide with each other.
[0136]
As described above, in the present embodiment, when the injection timing retarding process is being executed, the opening degree of the SCV 34 is decreased by increasing the closing amount DSCV. Therefore, according to the present embodiment, in addition to the same operational effects as (3) described in the third embodiment, the following operational effects can be further achieved.
[0137]
That is,
(6) It can suppress that the atomization degree of the injection fuel falls by the injection timing retardation process by increasing the intensity | strength of a swirl. As a result, it is possible to suppress a decrease or fluctuation in engine output due to combustion being performed with insufficient mixing of injected fuel and intake air without being promoted, and fuel consumption and exhaust properties are reduced. Deterioration can also be suppressed.
[0138]
Furthermore,
(7) Since the swirl strength is increased by correcting the amount of confinement DSCV as the retard amount ΔAINJ increases, the engine output decreases or fluctuates as described above, fuel consumption and exhaust properties. It becomes possible to further reliably suppress the deterioration.
[0139]
Also,
(8) Since the injected fuel becomes difficult to adhere to the inner peripheral wall surface of the cylinder 13 due to the increase in swirl strength, the occurrence of oil dilution due to such fuel adhesion can be suppressed.
[0140]
[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described focusing on differences from the third embodiment. In addition, description is abbreviate | omitted about the structure equivalent to 3rd Embodiment.
[0141]
In the present embodiment, both the “fuel injection timing control routine” and the “fuel injection amount control routine” shown in FIGS. 6 and 8 are executed, and the knock learning value AGKNK in the ignition timing control is executed during the execution of the injection timing retardation processing. Different values are learned when the processing is stopped.
[0142]
Hereinafter, each process of the “ignition timing control routine” in which the learning of the knock learning value AGKNK is performed will be described with reference to the flowcharts of FIGS. 18 and 19. The ECU 40 repeatedly executes this “ignition timing control routine” as interruption processing of a predetermined crank angle cycle.
[0143]
First, in step 800 shown in FIG. 18, the basic ignition timing ABSE and the maximum retard angle value AKMAX are calculated based on the intake pressure PM and the engine speed NE. Here, the maximum retardation value AKMAX is the maximum amount when retarding the basic ignition timing ABSE, and is set to a magnitude that can reliably suppress the occurrence of knocking.
[0144]
Next, in step 802, it is determined based on the retard processing execution flag XCOLD whether or not the injection timing retard processing is being executed. If it is determined that the injection timing retarding process is being executed, the cold knock learning value AGKNKCOLD is read from the memory 42 in step 804, and the cold knock learning value AGKNKCOLD is set as the knock learning value AGKNK. To do.
[0145]
On the other hand, if it is determined in step 802 that the injection timing retardation process is not executed, in step 805, the warm knock learning value AGKNKHOT is read from the memory 42, and the warm knock learning value AGKNKHOT is knock learned. Set as the value AGKNK.
[0146]
Next, in step 806 shown in FIG. 19, it is determined whether knocking has occurred in the engine 10 based on the knocking signal KCS. If it is determined that knocking has occurred, a predetermined angle α1 is added to the current knock control value AKCS in step 808, and the added value (AKCS + α1) is set as a new knock control value AKCS. This knock control value AKCS is a value whose magnitude changes according to the current knocking occurrence state of the engine 10.
[0147]
On the other hand, when it is determined in step 806 that knocking has not occurred, in step 809, the predetermined angle α2 is subtracted from the current knock control value AKCS, and the subtraction value (AKCS−α2) is set as a new knock control value AKCS. Set.
[0148]
After executing the processing of step 808 or step 809, in step 810, the knock retardation reflection value AKNK is calculated based on the following equation (4).
AKNK = AKMAX-AGKNK + AKCS (4)
Next, at step 812, knock control value AKCS is compared with predetermined angle β1. If it is determined that the knock control value AKCS is larger than the predetermined angle β1, then in step 816, the predetermined angle γ is subtracted from the current knock learning value AGKNK, and the subtraction value (AGKNK−γ) is set as a new knock learning value AGKNK. Set as.
[0149]
On the other hand, when it is determined in step 812 that the knock control value AKCS is equal to or smaller than the predetermined angle β1, the knock control value AKCS is further compared with the predetermined angle β2 in step 814. When it is determined that the knock control value AKCS is smaller than the predetermined angle β2, the predetermined angle γ is added to the current knock learning value AGKNK in step 817, and the added value (AGKNK + γ) is set as a new knock learning value AGKNK. .
[0150]
This knock learning value AGKNK indicates a steady tendency of knocking occurring in the engine 10, and is learned to a relatively small value when there is a tendency for frequent knocking by the processing of this routine. On the contrary, when the number of occurrences of knocking is small, a relatively large value is learned.
[0151]
Therefore, this knock learning value AGKNK is calculated when the leaning tendency of the air-fuel mixture around the spark plug 24 is changed by the execution of the injection timing retarding process in addition to the tendency of knocking according to the octane number of the fuel. A value that reflects the tendency of knocking according to the change is also learned.
[0152]
For example, during execution of the injection timing retarding process, the air-fuel ratio of the air-fuel mixture around the spark plug 24 becomes relatively lean, so that the combustion of the air-fuel mixture in the combustion chamber 16 becomes slow and knocking hardly occurs. At the same time, the generation time of the maximum combustion pressure is relatively delayed. Therefore, the knock learning value AGKNK is updated so as to be relatively large, and the ignition timing (final ignition timing AOP) is also set to the advance side by updating the knock learning value AGKNK.
[0153]
On the other hand, when the injection timing retarding process is stopped, the combustion speed of the air-fuel mixture increases, knocking is likely to occur, and the generation timing of the maximum combustion pressure is relatively advanced. For this reason, the knock learning value AGKNK is updated so as to be relatively small, and the ignition timing is set to the retard side by updating the knock learning value AGKNK.
[0154]
After executing the process of step 816 or step 817, or when a negative determination is made in step 814, it is determined in step 818 whether or not the injection timing retarding process is being executed, and the process is being executed. In step 820, the knock learning value AGKNK is stored in the memory 42 as the cold knock learning value AGKNKCOLD. On the other hand, if it is determined in step 818 that the injection timing retardation process is stopped, the knock learning value AGKNK is stored in the memory 42 as the warm knock learning value AGKNKHOT in step 821.
[0155]
In this way, the knock learning value AGKNK is separately learned according to whether or not the injection timing retarding process is being executed and stored in the memory 42. Then, in step 822, the knock retarded value is reflected from the basic ignition timing ABSE. After subtracting the value AKNK and setting the subtraction value (ABSE−AKNK) as the final ignition timing AOP, the processing of this routine is temporarily terminated.
[0156]
As described above, the knock learning value AGKNK in the ignition timing control is used during the execution of the value used when the injection timing retarding process is stopped, that is, the warm knock learning value AGKNKHOT. The learning is performed separately from the value, that is, the cold knock learning value AGKNKCOLD.
[0157]
For example, when the knock learning value AGKNK is not separately learned as described above, even if the knock learning value AGKNK is learned during the execution of the injection timing retardation processing, the injection timing retardation processing is stopped thereafter. When the knock learning value AGKNK is updated sometimes, when the injection timing retarding process is executed again, such as during cold restart, the ignition timing control is executed based on the updated knock learning value AGKNK. It will be.
[0158]
On the other hand, according to this embodiment,
(9) When the injection timing retarding process is executed at the time of cold restart or the like, the cold knock learning value AGKNKCOLD learned during the execution of the previous injection timing retarding process is read as the knock learning value AGKNK. For this reason, it is possible to quickly suppress the generation time of the maximum combustion pressure with respect to the engine output with the execution of the same process and to ensure a good combustion state. Therefore, it is possible to suppress the reduction or fluctuation of the engine output and the deterioration of the fuel consumption due to the delay of the generation timing of the maximum combustion pressure earlier.
[0159]
Furthermore, in the present embodiment, since both the “fuel injection timing control routine” and the “fuel injection amount control routine” shown in FIGS. 6 and 8 are executed, it is described in the third embodiment (3 ) And the same operational effects can be achieved.
[0160]
[Eighth Embodiment]
Next, an eighth embodiment of the present invention will be described centering on differences from the third embodiment. In addition, description is abbreviate | omitted about the structure equivalent to 3rd Embodiment.
[0161]
In the present embodiment, the “fuel injection timing control routine” shown in FIG. 6 is executed, and when the basic fuel injection amount QINJB is increased during the injection timing delay processing, the air-fuel ratio feedback control is temporarily stopped. I have to.
[0162]
Hereinafter, the fuel injection amount control of this embodiment will be described with reference to the flowchart of FIG. The ECU 40 repeatedly executes the “fuel injection amount control routine” shown in the figure as an interruption process of a predetermined crank angle cycle. In this “fuel injection amount control routine”, the same reference numerals as those shown in FIG. 8 are assigned to the same steps as those shown in FIG.
[0163]
When the ECU 40 determines in step 210 that the retard processing execution flag XCOLD is “1”, the ECU 40 calculates an injection amount increase coefficient KQ based on the basic fuel injection amount QINJB and the retardation amount ΔAINJ in step 222.
[0164]
Here, in the third embodiment, the injection amount increase coefficient KQ is calculated so that the air-fuel ratio can be prevented from deviating from the stoichiometric air-fuel ratio due to the injection timing retarding process. However, in the present embodiment, when the retardation amount ΔAINJ is particularly large, and therefore when the change in the engine combustion state due to the injection timing retardation process is large, the air-fuel ratio is made richer than the stoichiometric air-fuel ratio. An injection amount increase coefficient KQ is calculated. This is because the engine combustion state can be stabilized by setting the air-fuel ratio to be richer than the stoichiometric air-fuel ratio.
[0165]
After calculating the injection amount increase coefficient KQ in this way, the ECU 40 changes the air-fuel ratio feedback correction coefficient FAF to “1.0” in step 235. Then, after executing the processing of step 240, the ECU 40 once ends the processing of this routine.
[0166]
As described above, in the present embodiment, when the basic fuel injection amount QINJB is increased based on the injection amount increase coefficient KQ during the injection timing retarding process, the air-fuel ratio feedback control is stopped and the air-fuel ratio control is stopped. The mode is switched to open loop control.
[0167]
Therefore, according to the present embodiment, in addition to having the same effect as (3) described in the third embodiment,
(10) Since the increase operation of the basic fuel injection amount QINJB based on the injection amount increase coefficient KQ is not canceled by the air-fuel ratio feedback correction coefficient FAF, the air-fuel ratio is set to be higher than the stoichiometric air-fuel ratio during the injection timing retarding process. By setting the rich state, the engine combustion state can be reliably stabilized.
[0168]
[Ninth Embodiment]
Next, a ninth embodiment of the present invention will be described focusing on differences from the third embodiment. In addition, description is abbreviate | omitted about the structure equivalent to 3rd Embodiment.
[0169]
In this embodiment, the “fuel injection timing control routine”, “fuel injection amount control routine”, “ignition timing calculation routine”, and “SCV opening control routine” shown in FIGS. Further, in the present embodiment, in addition to each of these controls, the target throttle opening degree TATRG, which is the target control amount of the throttle opening degree TA, is set larger when the injection timing retarding process is executed than when the process is not executed. ing.
[0170]
Hereinafter, the execution procedure of such throttle opening control will be described with reference to FIG. The ECU 40 repeatedly executes the “throttle opening control routine” shown in the figure as an interruption process of a predetermined crank angle cycle.
[0171]
First, in step 900, the ECU 40 determines whether or not the retard processing execution flag XCOLD is set to “1”. Here, when it is determined that the retard processing execution flag XCOLD is not “1”, that is, when it is determined that the injection timing retardation processing is not being executed, in step 915, the accelerator opening ACCP and the engine speed NE are set. Based on this, the target throttle opening degree TATRG is calculated.
[0172]
On the other hand, when it is determined in step 900 that the retard processing execution flag XCOLD is “1”, that is, when it is determined that the injection timing retard processing is being performed, the ECU 40 performs the injection timing retard processing in step 910. A target throttle opening degree TATRG corresponding to the execution time is calculated based on the accelerator opening degree ACCP and the engine speed NE.
[0173]
In the memory 42 of the ECU 40, function data defining the relationship between the target throttle opening degree TATRG, the accelerator opening degree ACCP, and the engine speed NE, function data corresponding to the execution of the injection timing retarding process and the non-execution time Corresponding function data is stored separately. The ECU 40 calculates the target throttle opening degree TATRG by referring to the former function data in step 910 and referring to the latter function data in step 915, respectively.
[0174]
Here, if both the accelerator opening ACCP and the engine speed NE are the same, the target throttle opening degree TATRG calculated based on the processing of step 910 is calculated based on the processing of step 915. It is set to be larger than the target throttle opening degree TATRG.
[0175]
Accordingly, when the injection timing retarding process is executed, the throttle opening degree TA is set to be larger than that when the injection process is not executed, so that the pumping loss is reduced. Furthermore, since the intake pressure PM increases in accordance with the setting of the throttle opening TA, the basic fuel injection amount QINJB is set relatively large by an amount corresponding to the increase in the throttle opening TA.
[0176]
After calculating the target throttle opening degree TATRG in step 910 or 915 in this way, the ECU 40 controls the throttle motor 39 in step 920 so that the throttle opening degree TA coincides with the target throttle opening degree TATRG. finish.
[0177]
In this embodiment, the “fuel injection amount control routine”, “ignition timing calculation routine”, and “SCV opening degree control routine” are executed, so that the fuel injection amount, the ignition timing, and the SCV opening degree are delayed in the injection timing. Since it is changed so as to be adapted to the corner processing, the same effects as (3), (4), (6) to (8) described in the third, fourth, and sixth embodiments can be achieved. it can.
[0178]
Here, when the fuel injection amount, the ignition timing, and the SCV opening are changed so as to conform to the processing during the injection timing retardation processing as described above, the deterioration of the engine combustion state can be reliably suppressed. However, a decrease in engine output due to changes in the fuel injection amount, ignition timing, and SCV opening is inevitable, and so-called torque shock occurs when the injection timing retarding process is shifted from non-execution time. Tend to occur.
[0179]
In this regard, according to the present embodiment,
(11) Since the throttle opening degree TA is set to a relatively large value when the injection timing retarding process is executed, the pumping loss can be reduced when the process is executed as compared with the non-executed time. Become. As a result, it is possible to suppress the reduction of the engine output accompanying the execution of the injection timing retarding process as much as possible and to suppress the occurrence of the torque shock as described above.
[0180]
Each embodiment described above can be implemented by changing the configuration as follows.
In the second, seventh, and sixth embodiments, the ignition timing is advanced or the swirl strength is increased in addition to increasing the fuel injection amount when the injection timing retarding process is executed. It is also possible to adopt a configuration in which only the ignition timing or swirl intensity is changed when the timing retard process is executed. Further, it is possible to adopt a configuration in which both the ignition timing and the swirl intensity are changed when the injection timing retarding process is executed, and furthermore, the fuel injection amount, the ignition timing, and the swirl intensity are all changed.
[0181]
In the embodiment of the seventh embodiment, the knock learning value AGKNK is learned as a separate value depending on whether or not the injection timing retardation processing is being executed. For example, the maximum retardation value AKMAX is learned as the injection timing. It is also possible to employ a configuration that is set separately depending on whether or not the retard processing is being executed.
[0182]
In the fifth embodiment, the air-fuel ratio learning value KG is set according to whether or not the injection timing retarding process is being executed, and the fuel injection time TAU is calculated based on the air-fuel ratio learning value KG. However, a correction coefficient for correcting the fuel injection time TAU is defined separately from the air-fuel ratio learning value KG, and the value of this correction coefficient is stopped from the value when the injection timing retarding process is executed. It may be set separately for the current value.
[0183]
In the eighth embodiment, the basic fuel injection amount QINJB is increased and corrected based on the injection amount increase coefficient KQ. However, as in the first embodiment, the basic fuel injection amount QINJB is set to the cold basic injection amount. By setting it equal to QINJBCOLD, the basic fuel injection amount QINJB may be increased and corrected.
[0184]
In the ninth embodiment, the above-described “fuel injection amount control routine”, “ignition timing calculation routine”, and “SCV opening degree control routine” are all executed, but one of these processes is performed. Alternatively, two processes may be selected and executed.
[0185]
In the ninth embodiment, different function data corresponding to the execution time and non-execution time of the injection timing retardation processing are stored in the memory 42 of the ECU 40, and the function corresponding to the value of the retardation processing execution flag XCOLD is stored. The target throttle opening degree TATRG is calculated based on the data. For example, the target throttle opening degree TATRG is calculated in advance based on the accelerator opening degree ACCP and the engine speed NE, and the injection timing retarding process is executed. At this time (when it is determined that the retard processing execution flag XCOLD is “1”), the target throttle opening degree TATRG may be increased and corrected.
[0186]
Further, at this time, the rate of increasing the target throttle opening degree TATRG may be variably set based on the retard amount ΔAINJ of the fuel injection timing AINJ. With this configuration, the target throttle opening degree TATRG can be increased and corrected by an amount commensurate with the decrease in engine output accompanying the execution of the injection timing retarding process, and the occurrence of torque shock can be more reliably suppressed. become able to.
[0187]
In the ninth embodiment, when the basic fuel injection amount QINJB is increased and corrected by executing the injection timing retarding process, the air-fuel ratio feedback control is stopped. In addition to this stop condition, Similarly, when the basic fuel injection amount QINJB is corrected to increase when the engine is started or when the cooling water temperature of the engine 10 is low, the air-fuel ratio feedback control may be stopped.
[0188]
In each of the above embodiments, the fuel injection amount, the ignition timing, and the swirl intensity are corrected together with the execution of the injection timing retarding process. In addition to these various control amounts, for example, the fuel injection pressure and the throttle valve 38 The opening degree may be corrected, or a mechanism for adjusting the opening / closing timing and lift amount of the intake valve 20 and the exhaust valve 22 may be provided, and the adjustment amount by this mechanism may be corrected.
[0189]
In each of the above embodiments, the cooling water temperature THW is selected as the engine temperature, and based on this cooling water temperature THW, it is determined whether or not there is an operation state in which fuel adhesion to the spark plug 24 occurs. Instead of this cooling water temperature THW, such an operating state can be determined based on the lubricating oil temperature, the intake air temperature, the elapsed time since the engine 10 was started, the accumulated fuel injection amount, and the like.
[0190]
In each of the above embodiments, when retarding the fuel injection timing AINJ when the engine is cold, the timing is set to the intake stroke, but it may be further retarded to the first half of the compression stroke.
[0191]
-Although each said embodiment applied the control apparatus of the engine 10 which switches a combustion form between stratified combustion, weak stratified combustion, and homogeneous combustion, the control which concerns on this invention with respect to the engine which performs only homogeneous combustion A device can also be applied.
[0192]
【The invention's effect】
According to the first to sixth aspects of the present invention, the change in the combustion state of the engine accompanying the change in the fuel injection timing is suppressed, and even when the fuel injection timing is retarded when the engine is cold, it is substantially the same as when the engine is warm. It is possible to maintain a good engine combustion state.
[0193]
In particular, according to the second aspect of the present invention, when the fuel adhesion to the spark plug is suppressed by the retard of the fuel injection timing, the retard amount is kept to a minimum and the delay of the fuel injection timing is suppressed. In order to suppress the change in the engine combustion state due to the corner, it becomes possible to set a more appropriate change rate of the control amount. As a result, a good engine combustion state can be reliably maintained.
[0194]
According to the third aspect of the invention, the lean air-fuel ratio accompanying the change in the fuel injection timing can be suppressed by increasing the fuel injection amount, and the engine output resulting from the lean air-fuel ratio can be reduced. Reduction and fluctuation can be suppressed. In particular, if the fuel injection amount increase ratio is increased as the retard amount of the fuel injection timing is increased, a more appropriate increase ratio is set. Therefore, it is possible to reliably suppress a decrease or fluctuation in engine output. become able to.
[0195]
Furthermore, according to the fourth aspect of the present invention, it is possible to suppress the generation timing of the maximum combustion pressure from changing to the retard timing by the advance of the ignition timing according to the change of the fuel injection timing. Thus, it is possible to suppress a decrease or fluctuation in engine output and a deterioration in fuel consumption due to the time when the maximum combustion pressure is generated being shifted to a time retarded from a suitable time. In particular, if the advance amount of the ignition timing is increased as the retard amount of the fuel injection timing is increased, a more appropriate advance amount of the ignition timing is set. It becomes possible to reliably suppress the deterioration.
[0196]
According to the invention described in claim 5, it is possible to suppress the atomization degree of the injected fuel from being lowered and the combustion state from being changed by changing the fuel injection timing by increasing the strength of the swirl. It is possible to suppress the reduction and fluctuation of engine output, and further deterioration of fuel consumption and exhaust properties caused by combustion performed without sufficient mixing of injected fuel and intake air. . In particular, if the increase rate of swirl strength is increased as the retard amount of the fuel injection timing is increased, a more appropriate increase rate is set. Therefore, such a decrease or fluctuation in engine output, deterioration of fuel consumption or exhaust properties. Can be reliably suppressed.
[0197]
According to the sixth aspect of the present invention, the pumping loss when the engine is cold is reduced as compared to when the engine is warm, and the engine output when the engine is cold is increased. As a result, the difference in engine output between when the engine is cold and when the engine is warm can be reduced, and the occurrence of torque shock at the time of transition from when the engine is cold to when the engine is warm can be suppressed. become able to.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an engine control device.
FIG. 2 is a cross-sectional view showing shapes of an intake port and an exhaust port.
FIG. 3 is a flowchart showing an execution procedure of fuel injection timing control.
FIG. 4 is a flowchart showing an execution procedure of fuel injection amount control.
FIG. 5 is a flowchart showing a procedure for calculating an ignition timing.
FIG. 6 is a flowchart showing an execution procedure of fuel injection timing control.
FIG. 7 is a graph showing the relationship between cooling water temperature and cold injection timing.
FIG. 8 is a flowchart showing an execution procedure of fuel injection amount control.
FIG. 9 is a graph showing the relationship between the basic fuel injection amount and retard amount and the injection amount increase coefficient;
FIG. 10 is a flowchart showing a procedure for calculating an ignition timing.
FIG. 11 is a graph showing the relationship between the basic fuel injection amount and retard amount and the ignition timing advance amount.
FIG. 12 is a flowchart showing an execution procedure of air-fuel ratio control.
FIG. 13 is a flowchart showing an execution procedure of air-fuel ratio control.
FIG. 14 is a timing chart showing an example of how the air-fuel ratio feedback correction coefficient changes.
FIG. 15 is a flowchart showing an execution procedure of SCV opening degree control.
FIG. 16 is a graph showing the relationship between the cooling water temperature and the amount of confinement.
FIG. 17 is a graph showing a relationship between a basic fuel injection amount and a retard amount and a confinement amount correction coefficient.
FIG. 18 is a flowchart showing a procedure for calculating an ignition timing.
FIG. 19 is a flowchart showing a procedure for calculating an ignition timing.
FIG. 20 is a flowchart showing an execution procedure of fuel injection amount control.
FIG. 21 is a flowchart showing an execution procedure of throttle opening control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Cylinder head, 12 ... Cylinder block, 13 ... Cylinder, 14 ... Piston, 14a ... Recess, 16 ... Combustion chamber, 20 ... Intake valve, 22 ... Exhaust valve, 24 ... Spark plug, 25 ... Igniter, 26 ... Injector, 30 ... Intake passage, 30a, 30b ... Intake port, 32 ... Exhaust passage, 32a, 32b ... Exhaust port, 33 ... Purge amount control valve, 34 ... SCV, 35 ... Motor, 36 ... Surge tank, 37 ... Purge passageway, 38 ... throttle valve, 39 ... throttle motor, 40 ... ECU, 42 ... memory, 51 ... crank angle sensor, 52 ... cam angle sensor, 53 ... intake pressure sensor, 54 ... accelerator sensor, 55 ... SCV opening sensor 56 ... Water temperature sensor, 57 ... Knock sensor, 58 ... Oxygen sensor, 60 ... Accelerator pedal.

Claims (4)

A fuel injection timing that is applied to a spark ignition internal combustion engine that directly injects fuel into the cylinder, and changes the fuel injection timing set in the first half of the intake stroke when the engine is warm to a retarded timing when the engine is cold In a control device for an internal combustion engine having a changing means,
Fuel injection amount to increase than the fuel injection amount of time between the fuel at the time between the engine is cold in order to suppress the air-fuel ratio to lean I accompanied the injection timing of changing the internal combustion engine the fuel injection amount the engine temperature of A control apparatus for an internal combustion engine, comprising: a changing means; and further a throttle opening changing means for increasing the throttle opening more than the opening when the engine is warm when the engine is cold . The control apparatus for an internal combustion engine according to claim 1,
The fuel injection timing changing means sets the retard amount of the fuel injection timing as the engine temperature decreases,
The control device for an internal combustion engine, wherein the control amount changing means sets a change ratio between the fuel injection amount and the throttle opening as the retardation amount increases. Fuel injection timing that is applied to a spark ignition internal combustion engine that directly injects fuel into the cylinder and changes the fuel injection timing set in the first half of the intake stroke when the engine is warm to a retarded timing when the engine is cold the control apparatus for chromatic an internal combustion engine to change means,
A swirl that increases the strength of the swirl generated in the cylinder when the engine is cold to suppress the decrease in the atomization degree of the injected fuel due to the change in the fuel injection timing. provided with a strength changing means, further control apparatus for an internal combustion engine, characterized in Rukoto a throttle opening degree changing means for increasing than the opening degree at the time between the engine warm the throttle opening at the time between the engine cold. The control apparatus for an internal combustion engine according to claim 3 ,
The fuel injection timing changing means sets the retard amount of the fuel injection timing to be larger as the engine temperature is lower,
Control apparatus for an internal combustion engine, wherein the fuel injection amount changing means is shall be set large change ratio between the throttle opening and the swirl intensity as the retardation amount increases.

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