JP3945054B2 - In-cylinder direct injection internal combustion engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a direct injection type internal combustion engine.
[0002]
[Prior art]
As a conventional control device for a direct injection type internal combustion engine, for example, there is one as shown in Japanese Patent Laid-Open No. Hei 6-288283.
In this conventional example, laser light having a wavelength that is selectively absorbed by gasoline is guided into the combustion chamber, transmitted through the combustion chamber space near the spark plug, and the transmitted light intensity is detected by a photoelectric conversion element. Based on the above, the air-fuel ratio at the ignition timing is calculated. Here, as a result of the injection timing control, it is determined whether or not the detected air-fuel ratio has changed rich compared to the previous time, and control is performed to correct the injection timing in the direction in which the rich change has been obtained (FIG. 14).
[0003]
[Problems to be solved by the invention]
However, in such a conventional control device for a direct injection type internal combustion engine, when the fuel is injected in a compression stroke, the air-fuel ratio which can be ignited due to the variation in the spray shape of the fuel injection valve and the change in the spray shape over time. Therefore, if the fuel injection timing is corrected in the direction of the rich air-fuel ratio, a misfire cycle will occur, and the spray shape changes depending on the back pressure, so the injection timing is corrected. The control is repeated without the previously detected air-fuel ratio at the ignition timing, so that the responsiveness may decrease, or if the air-fuel ratio in the vicinity of the ignition plug fluctuates from cycle to cycle near the set ignition timing There is a problem that sufficient combustion stability may not be obtained by controlling only the timing.
The present invention has been made paying attention to the above-mentioned conventional problems, and in a direct injection type internal combustion engine equipped with an air-fuel ratio measuring device installed in the vicinity of an ignition plug, in the vicinity of the ignition plug after fuel injection It is an object of the present invention to solve the above-mentioned problems by detecting the air-fuel ratio of the engine in a time series in one cycle and controlling the operation conditions of ignition timing, ignition method, and fuel injection timing individually or simultaneously.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, according to the first to fourth aspects of the present invention, in a direct injection type internal combustion engine equipped with an air-fuel ratio measuring device installed in the vicinity of a spark plug, in the vicinity of the spark plug after fuel injection. It is characterized in that the air-fuel ratio is detected in a time series in one cycle to control the operating conditions.
In particular, the invention according to claim 1 is characterized in that a time-series air-fuel ratio is measured by an air-fuel ratio measuring device installed in the vicinity of the spark plug , and control is performed so as to select a timing at which an appropriate air-fuel ratio is obtained and to set it as the ignition timing. And
In particular, in the second aspect of the invention, a time-series air-fuel ratio is measured by an air-fuel ratio measuring device installed in the vicinity of the spark plug, and the ignition method is controlled to be a multiple ignition method in which ignition is performed a plurality of times in one cycle. It is characterized by that.
In particular, in the invention described in claim 3, the time-series air-fuel ratio is measured by an air-fuel ratio measuring device installed in the vicinity of the spark plug, and the fuel injection timing is changed from the compression stroke to the intake stroke, or from the intake stroke to the compression stroke. It is characterized by controlling to change.
In particular, in the invention according to claim 4, the time series air-fuel ratio is measured by an air-fuel ratio measuring device installed in the vicinity of the spark plug, and the control and ignition method for selecting the timing when the appropriate air-fuel ratio is obtained and setting the ignition timing as 1 Control with multiple ignition system that ignites multiple times during a cycle, control with ignition method with long discharge system that makes discharge time longer than normal, change fuel injection timing from compression stroke to intake stroke, or from intake stroke to compression stroke Among the controls to be changed to the above, a plurality of controls are performed in combination .
According to a fifth aspect of the present invention, in the control apparatus for a direct injection type internal combustion engine according to the first to fourth aspects, the most retarded ignition timing obtained from a preset injection timing-ignition timing map is set as the ignition timing. One cycle is mixed in a range of a predetermined number of cycles or more.
[0005]
[Action]
In the first to fourth aspects of the invention, by detecting the time-series air-fuel ratio in the vicinity of the spark plug, not only the change in the air-fuel ratio at the predetermined ignition timing but also the time-series air-fuel ratio after fuel injection is obtained. It is possible to detect and control the fuel spray form as a whole.
In particular, in the first aspect of the invention, when the air-fuel ratio in the vicinity of the spark plug changes at a predetermined timing due to a change in the spray over time, the ignition timing that sets the optimal air-fuel ratio is set based on the detected time-series air-fuel ratio. This ensures combustion stability.
In particular, in the second aspect of the invention, ignition is performed a plurality of times when the fluctuation of the air-fuel ratio in the vicinity of the spark plug is large, or when the richest air-fuel ratio or the leanest air-fuel ratio within the ignitable air-fuel ratio range is rectangular. This ensures combustion stability.
In particular, in the invention according to claim 3 , when the fuel spray changes and it becomes impossible to stably supply the fuel spray of the ignitable air-fuel ratio in the vicinity of the spark plug, the fuel is deposited near the injection hole by performing the intake stroke injection. By removing the deposited deposit, the fuel spray shape can be recovered, and the fuel in the ignitable range air-fuel ratio can be stably supplied.
In particular, in the invention according to claim 4, combustion stability can be ensured by simultaneously performing a plurality of controls among the control shown in the above claims 1 to 3 and the control for making the discharge time longer than usual .
According to the fifth aspect of the present invention, an air-fuel ratio in the vicinity of the spark plug is suppressed while suppressing deterioration in engine performance by temporarily setting the most retarded ignition timing obtained from a preset injection timing-ignition timing map as the ignition timing. It is possible to perform optimal control by grasping almost the whole.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is an overall system diagram of the first embodiment.
As shown in the figure, the control device for a direct injection type internal combustion engine of the present embodiment is installed in the combustion chamber 3 with optical information obtained by an air-fuel ratio detection unit 13 installed integrally with the spark plug 1. Based on the in-cylinder pressure obtained by the in-cylinder pressure sensor 11, the ECU 10 calculates the time-series air-fuel ratio from the fuel injection timing of each cycle to the initial set ignition timing or the most retarded ignition timing, and the spark plug 1 Detect nearby air-fuel ratio. 4 is a piston, 6 is an intake valve, 7 is an exhaust valve, 8 is an intake port, 9 is an exhaust port, 12 is an air-fuel ratio measuring device, 14 is a laser source, and 15 is a photoelectric conversion element.
[0007]
FIG. 13 is a flowchart of the ignition timing control according to the present embodiment. When the engine is operated at the timing determined by the engine speed and the fuel injection timing-ignition timing map for each load in the ECU 10 from the beginning. The air-fuel ratio is detected by the above-described method, and if the air-fuel ratio is comparable to the air-fuel ratio obtained at the initial stage of the engine, the operation is continued as it is without correction.
However, if the detected air-fuel ratio is significantly different from the initial air-fuel ratio, it is necessary to correct the ignition timing in order to obtain stable combustion, and the timing at which the richest air-fuel ratio is reached is advanced as shown in FIG. If it is deviated, it can be corrected by detection until the ignition timing, but as shown in FIG. 3, if the timing at which the richest air-fuel ratio deviates to the retard side, detection until the ignition timing is insufficient, and the re-retard ignition timing The ignition timing is corrected by once delaying until the air-fuel ratio is detected in time series.
[0008]
Next, the operation will be described.
In a direct injection type internal combustion engine, the distance between the fuel injection valve 2 and the spark plug 1 is short, and the fuel spray 5 is directed directly to the vicinity of the spark plug 1. Greatly affected by form.
However, since the fuel distribution in the fuel spray 5 is not uniform, the air-fuel ratio in the vicinity of the spark plug 1 fluctuates in one cycle even in one cycle. Depending on the timing, the air-fuel ratio is richer than the ignitable air-fuel ratio. The air-fuel ratio in the vicinity of the spark plug 1 may change significantly due to the change in the spray shape over time due to deposits deposited at the injection port of the fuel injection valve 2 during operation. .
[0009]
For this reason, in a direct injection type internal combustion engine, it is necessary to determine the ignition timing in consideration of the temporal change of the form of the fuel spray 5, and the ignition timing is set so that the optimum air-fuel ratio is obtained by the detected time-series air-fuel ratio. Set. As shown in FIG. 3, when the ignition timing is controlled to advance, it can be controlled by detecting the air-fuel ratio until the normal ignition timing. In this case, a cycle in which the most retarded ignition timing determined by a preset injection timing-ignition timing map (see FIG. 4) is set as the ignition timing is set to 1 within a range of a predetermined number of cycles or more. By operating in a mixed cycle and grasping almost the entire time-series fuel spray form without causing deterioration in engine performance, it is possible to detect the air-fuel ratio in a wider range and perform appropriate control. To ensure combustion stability.
[0010]
(Embodiment 2)
Next, a second embodiment will be described.
In the second embodiment shown in FIGS. 5 to 7, when the time-series air-fuel ratio fluctuates greatly from the rich air-fuel ratio to the lean air-fuel ratio including the ignitable air-fuel ratio range, the non-uniform fuel moves near the spark plug. If the air-fuel ratio is rectangularly close to the rich air-fuel ratio limit or near the lean air-fuel ratio limit, it is on the boundary of whether or not ignition can be performed, and in either case, it is once In this ignition, the air-fuel mixture cannot be ignited stably, or even if it can be ignited, there is a possibility of misfiring at the lean air-fuel ratio when the flame diffuses. Control is performed to suppress misfire, and ignition can be performed reliably to ensure combustion stability.
[0011]
(Embodiment 3)
Next, Embodiment 3 will be described. The third embodiment is implemented in combination with at least one of the first and second embodiments described above and the fourth embodiment described later.
In the third embodiment shown in FIG. 8 to FIG. 10, when the time-series air-fuel ratio fluctuates greatly from the rich air-fuel ratio to the lean air-fuel ratio including the ignitable air-fuel ratio range, the non-uniform fuel is found in the vicinity of the spark plug. If the air-fuel ratio is rectangularly close to the rich air-fuel ratio limit or near the lean air-fuel ratio limit, it is on the boundary of whether or not ignition is possible. During the ignition period, the air-fuel mixture cannot be ignited stably, or even if it can be ignited, there is a possibility of misfiring at the lean air-fuel ratio when the flame diffuses. Control is performed so as to suppress misfire by performing discharge, so that ignition can be reliably performed and combustion stability is ensured.
[0012]
(Embodiment 4)
Next, a fourth embodiment will be described.
In the fourth embodiment shown in FIG. 11 and FIG. 12, when the fuel is injected in the compression stroke, the time-series air-fuel ratio does not change in series, or it is only on the lean air-fuel ratio side from the ignitable air-fuel ratio range. If the air-fuel ratio becomes extremely rich, or there is a high possibility that the spray will change over time due to deposits deposited at the injection port of the fuel injection valve, the cylinder pressure The effect of removing the deposits in the nozzle hole due to the relatively strong spray penetration force due to the low pressure, the effect of spreading the spray and removing the deposit around the nozzle hole, and the effect of vaporizing the residual fuel in the nozzle hole due to the strong in-cylinder flow By controlling the fuel spray shape to be recovered by, etc., it is possible to supply a fuel spray with an appropriate air-fuel ratio in the vicinity of the spark plug so that ignition can be reliably performed and combustion is stabilized. To secure.
[0013]
【The invention's effect】
As described above, according to the present invention, in the control device for a direct injection type internal combustion engine, the air fuel ratio measuring device installed in the vicinity of the spark plug allows the vicinity of the spark plug after fuel injection in one cycle. Combustion stability can be ensured by detecting the air-fuel ratio in time series and controlling the operating conditions of the ignition timing, ignition method, and fuel injection timing individually or simultaneously.
[Brief description of the drawings]
FIG. 1 is an overall system diagram of an embodiment of the present invention.
FIG. 2 is a diagram showing ignition timing control.
FIG. 3 is a diagram showing ignition timing control based on a difference in an air-fuel ratio detection range.
FIG. 4 is a diagram (injection timing-ignition timing map) showing the combustion stable region and the most retarded ignition timing at each injection timing.
FIG. 5 is a diagram showing multiple ignition control in the case of large air-fuel ratio fluctuations.
FIG. 6 is a diagram showing multiple ignition control in the case of a rich limit air-fuel ratio.
FIG. 7 is a diagram showing multiple ignition control in the case of a lean limit air-fuel ratio.
FIG. 8 is a diagram showing long discharge control in the case of large air-fuel ratio fluctuations.
FIG. 9 is a diagram showing long discharge control in the case of a rich limit air-fuel ratio.
FIG. 10 is a diagram showing long discharge control in the case of a lean limit air-fuel ratio.
FIG. 11 is a diagram showing fuel spray aging detection in the case of large air-fuel ratio fluctuations.
FIG. 12 is a diagram showing fuel spray aging detection in the case of a lean air / fuel ratio.
FIG. 13 is a flowchart of ignition timing control.
FIG. 14 is a flowchart showing control of a conventional row.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Spark plug 2 Fuel injection valve 3 Combustion chamber 4 Piston 5 Fuel spray 6 Intake valve 7 Exhaust valve 8 Intake port 9 Exhaust port 10 ECU
11 In-cylinder pressure sensor 12 Air-fuel ratio measuring device 13 Air-fuel ratio detector 14 Laser source 15 Photoelectric conversion element

Claims (5)

In a direct injection type internal combustion engine equipped with an air-fuel ratio measuring device installed in the vicinity of a spark plug,
The air-fuel ratio in the vicinity of the spark plug after fuel injection is detected in time series during one cycle,
A control apparatus for an in-cylinder direct injection internal combustion engine, wherein control is performed so that an ignition timing is selected by selecting a timing at which an appropriate air-fuel ratio is obtained . In a direct injection type internal combustion engine equipped with an air-fuel ratio measuring device installed in the vicinity of a spark plug,
The air-fuel ratio in the vicinity of the spark plug after fuel injection is detected in time series during one cycle,
A control apparatus for an in-cylinder direct injection internal combustion engine, wherein the ignition method is controlled to be a multiple ignition system in which ignition is performed a plurality of times in one cycle . In a direct injection type internal combustion engine equipped with an air-fuel ratio measuring device installed in the vicinity of a spark plug,
The air-fuel ratio in the vicinity of the spark plug after fuel injection is detected in time series during one cycle,
A control apparatus for a direct injection type internal combustion engine, wherein the fuel injection timing is controlled to be changed from a compression stroke to an intake stroke or from an intake stroke to a compression stroke . In a direct injection type internal combustion engine equipped with an air-fuel ratio measuring device installed in the vicinity of a spark plug,
The air-fuel ratio in the vicinity of the spark plug after fuel injection is detected in time series during one cycle,
Control for selecting an appropriate air-fuel ratio and setting the ignition timing, control for setting the ignition method to a multiple ignition method for igniting a plurality of times in one cycle, and long discharge method for making the ignition method longer than usual. And a control device for a direct injection type internal combustion engine, wherein a combination of a plurality of controls is performed among the control to change the fuel injection timing from the compression stroke to the intake stroke or from the intake stroke to the compression stroke . Injection timing is set in advance - claim, characterized in that the cycle for setting a most retarded ignition timing obtained by the ignition timing map to the ignition timing, thereby one cycle mixed in a given cycle number at over 1 to claim 4 The control apparatus for a direct injection type internal combustion engine according to any one of the above.

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