JPH05312083A - Engine stop time controller of spark-ignition internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the extent of exhaust emission in an internal combustion engine. CONSTITUTION:For example, at the time of engine stop operation, when a cylinder to be detected on the basis of reference signal out of a crank angle sensor is a #1 cylinder corresponding to a counter 0, those of cylinders where fuel is possibly sprayed but unburned are #1, #5, #3 and #6 cylinders. Accordingly, ignition control is continued till the time when a reference signal of a #4 cylinder whose counter value comes to 4 has been detected. With this constitution, ignition is stopped after the unburnt fuel is burned completely, thus watt consumption is kept to the minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique of fuel injection control and ignition control when engine operation is stopped in a spark ignition type internal combustion engine which injects fuel into each cylinder.

[0002]

2. Description of the Related Art In a spark ignition type internal combustion engine equipped with an electronically controlled fuel injection device, a fuel injection valve provided for each cylinder in synchronism with a REF signal output from a crank angle sensor has the same stroke, for example, for each cylinder. A sequential injection system in which fuel is injected by sequentially driving in the final stage of the exhaust stroke, or a group injection system in which each cylinder of a cylinder group divided into a plurality of cylinders is simultaneously injected is widely adopted.

[0003]

In an engine that performs such fuel injection control, generally, when a stop operation of the engine is performed, the fuel supply and the ignition operation are immediately stopped. In the conventional control method at the time of the engine stop operation, the fuel supplied before the stop operation is not burned as it is and is released as raw gas while the engine continues to rotate by inertia, or at the time of the next start. It was released as raw gas, leading to deterioration of exhaust emission performance.

Further, in order to prevent the ignition plug from being wetted by the fuel remaining before the engine is stopped and causing the ignition failure at the time of restart, the ignition signal is continuously generated for a predetermined time after the ignition switch is turned off. There is also such a method (see Japanese Patent Application Laid-Open No. 3-242466). But,
In this case, the injection control is stopped by the engine stop signal even during the injection, so even if the ignition is continued for a predetermined time, sufficient fuel is not supplied for combustion, so the combustibility is poor, Exhaust emission performance also deteriorated due to the possibility of misfire.

The present invention has been made in view of the above-mentioned conventional problems, and a spark having improved exhaust emission performance by preventing the fuel supplied before the engine stop operation from being discharged as raw gas. It is an object of the present invention to provide a stop time control device for an ignition type internal combustion engine.

[0006]

Therefore, as shown in FIG. 1, the control system for a spark ignition type internal combustion engine at stop according to the present invention is provided with a fuel injection valve for each cylinder, and the cylinder discrimination means discriminates. In a spark ignition type internal combustion engine that drives a fuel injection valve of a cylinder in a predetermined stroke to inject fuel, engine stop operation detecting means for detecting that an engine stop operation has been performed, and by detecting the engine stop operation, When the fuel is being injected at the time of detection, the fuel injection stop control means that waits for the end of the fuel injection to stop the fuel injection of all cylinders, and all of the fuel injected before the engine stop operation and at the time of the stop operation burns. A combustion end cylinder detection means for detecting a cylinder in a combustion stroke to end, and an ignition delay control means for stopping the ignition control after continuing the ignition control until the ignition timing of the cylinder where the combustion ends,
It is configured with.

[0007]

When a stop operation of the engine is detected by turning off the ignition switch or the like, if fuel is being injected at the time of stop, the end of the injection is awaited, otherwise fuel is immediately supplied to all cylinders. Injection is stopped. Then, the fuel that is injected before the stop operation or at the time of the operation and is not burned as it is unignited is burned by the ignition control continuously performed for the cylinder in which the unburned fuel remains after the engine stop operation, Immediately thereafter, the ignition control is stopped.

Here, even if an engine stop operation is performed during injection, the injection is stopped after waiting for the end of the injection, so the amount of fuel injected last is appropriate and good combustion is performed. Therefore, the exhaust emission performance can be maintained as good as possible.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows the system configuration of the first embodiment. In the figure, a crank angle sensor 1 outputs a REF signal for each reference crank angle of each cylinder and an ANGLE signal for each unit crank angle, and these signals are input to an ECU (engine control unit) 2. Further, the power supply voltage from the battery 3 is input via the contact 4b which is turned on by energizing the coil 4a of the power supply relay 4 connected to the CPU 21 in the ECU 2, and directly input to the memory 22. In addition, an ON / OFF signal from the ignition switch 5 is input to the CPU 21 as an engine stop operation detection signal.

Then, the ECU 2 outputs an ignition signal to the ignition coil 6 provided for each cylinder based on the above-mentioned signals and also outputs a fuel injection signal to the fuel injection valve 7 provided for each cylinder. The ignition control and the fuel injection control according to the invention are performed. Hereinafter, each control operation in the embodiment applied to the internal combustion engine of the sequential injection type will be described with reference to the flowcharts shown in FIGS.

FIG. 3 shows a cylinder discrimination routine. This routine is interrupted by the REF signal from the crank angle sensor 1. After the software counter is incremented by 1 in step (denoted as S in the figure. The same applies hereinafter), every time the counter value reaches 6 in the judgment of step 2, and the pulse width of the REF signal is larger than the others in FIG. Even when a wide cylinder discrimination signal is detected, the process proceeds to step 3 and the counter value is reset to zero.

Then, in step 4, the cylinder to which the fuel is next injected and the cylinder to which the next ignition is to be performed are determined according to the values counted as described above. It should be noted that the crank angle sensor 1 and the routine shown in FIG. Next, the fuel injection control routine will be described with reference to FIG.

In step 11, it is determined whether the ignition switch is ON or OFF. If it is ON, step 12
In step 13, the fuel injection prohibition determination flag is reset to "0", and in step 13, fuel injection control during normal operation is performed.
If it is determined to be OFF in step 11, the process proceeds to step 14 to determine the value of the fuel injection prohibition determination flag,
If it is not set to 1, the routine proceeds to step 15, where it is judged if fuel injection is currently being performed. If it is not injecting, or if it is injecting, it waits for the end of injection to proceed to step 16, and the flag for fuel injection prohibition determination is set to 1 in order to stop the fuel injection thereafter.

Next, the value of the counter when the flag for prohibiting the fuel injection is set to 1 in step 17 is stored in the memory 22. In step 14, the flag is set to 1
When it is determined that the fuel injection valve 7 is set to, the fuel injection from each fuel injection valve 7 thereafter is prohibited.
In addition, the ignition switch 5 and the step of FIG.
The function of 11, 14, 16 constitutes an engine stop operation detecting means, the function of steps 15, 18 constitutes a fuel injection stop control means, and the function of step 17 constitutes a combustion end cylinder discriminating means.

Next, the ignition control routine will be described with reference to FIG. In step 21, the value of the fuel injection prohibition flag is determined. If it is not set to 1, step 22
To execute the normal fuel injection control, but the flag is 1
If it is set to, go to step 23
The value of the counter when the flag is set is read from 22 and control is performed to burn all the supplied fuel.

First, in step 24, the read counter value is compared with the current counter value. Here, for example, when the value of the read counter is “0”, the next ignition cylinder is # 1 or # 5, and referring to the ignition sequence shown in FIG. 6, fuel is injected and burned before that. Since the cylinders that may not be activated are # 1, # 5, # 3, and # 6, after the injection prohibition flag is set to 1, ignition is performed until the ignition timing of the # 6 cylinder. That is, the power is turned off when the current counter value reaches 4.

The function of steps 25 and 26 in FIG. 5 constitutes ignition delay control means. FIG. 7 shows the relationship between the counter value when the fuel injection prohibition flag is set to 1 and the current counter value when the power is turned off. Therefore, in step 25, the current value of the counter is turned off as shown in FIG.
It is judged whether or not the current count value matches, and when it matches, the routine proceeds to step 26, where the power supply to the coil 4a of the power relay 4 is cut off. As a result, the contact 4b is opened and the input of the main power supply voltage from the battery 3 is turned off.

With this configuration, after the engine is stopped by turning off the ignition switch 5, if fuel injection is in progress, fuel injection is prohibited after waiting for the end of the fuel injection, and the unburned fuel injected is injected. Until it is burned out
Since the ignition is continued, the amount of fuel injected last is also controlled to an appropriate amount corresponding to the target air-fuel ratio, and good combustion is performed to the end. Therefore, it is possible to prevent the unburned fuel from being discharged as raw gas during the inertial rotation after the stop operation of the engine, and the exhaust emission performance can be improved as much as possible. Further, since the ignition is kept to the minimum necessary, the power consumption can be reduced as much as possible.

Next, an embodiment applied to the group injection type internal combustion engine will be described. Since the hardware is the same as that shown in FIG. 2, its explanation is omitted. As shown in FIG. 8, when simultaneously injecting an A group consisting of # 1, # 5, and # 3 cylinders and a B group consisting of # 6, # 2, and # 4 cylinders into each group, for example, When the engine is stopped while the REF signal of the cylinder is detected, the fuel injected into the # 1, # 5, and # 3 cylinders is completely burned in synchronization with the detection of the REF signal of the # 1 cylinder. It is the time when the combustion of the # 3 cylinder is completed for the second time after the injection. That is, even if the fuel for the # 3 cylinder that was injected in the middle of the intake stroke with the most time lag from the next combustion stroke, some is burned in the combustion stroke immediately after injection, but the rest is in the next intake stroke. This is because it is supplied to the combustion chamber and completely combusted. Similarly, if the engine is stopped while the REF signal of the cylinders of the B group is detected, the most recently injected fuel is completely burned because the combustion of the # 4 cylinder is the second time after the injection. At the end. Therefore,
The relationship between the value of the counter when the fuel injection prohibition flag is set to 1 and the current value of the counter when the power is turned off is shown in FIG.

Therefore, the cylinder discrimination and the fuel injection control are executed in the same manner as in the embodiment of the sequential injection system shown in FIGS. 4 and 5, but the ignition control is executed as shown in FIG. That is, from step 31 to step 35,
The procedure is the same as steps 21 to 25 in FIG. 5, but since it is necessary to examine the second count value after the injection is prohibited, the count value is the first count value after the injection is prohibited in step 35.
When it is determined that the value matches the value shown in step 37, the flag 2 indicating the second time is set to 1 in step 37, and when the value of the flag 2 is examined in step 36 and it is determined to be the second time, the power is turned on in step 38. It is turned off.

Also in this system, as in the case of the sequential injection system, after the engine operation is stopped, ignition is performed until the unburned fuel injected before or during the stop operation is completely burned, and then the power source is turned on. Since it is turned off, the emission of raw gas can be prevented and the exhaust emission performance can be improved with the minimum power consumption. In this embodiment, the ignition delay control means is constructed by the functions of steps 35 to 38 in FIG.

[0022]

As described above, according to the present invention, after the engine is stopped, if the engine is stopped in the middle of injection, the injection is stopped after the end of the injection, and the unburned fuel is completely burned. Since the ignition control is stopped after that, the emission of raw gas (unburned fuel) can be reliably prevented with the minimum power consumption, and the exhaust emission performance can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 is a block diagram of hardware common to the first and second embodiments of the present invention.

FIG. 3 is a flowchart showing a cylinder discrimination routine of the above embodiment.

FIG. 4 is a flowchart showing a fuel injection control routine of the same.

FIG. 5 is a flowchart showing an ignition control routine.

FIG. 6 is a time chart showing the ignition sequence and various signal states of the internal combustion engine according to the embodiment.

FIG. 7 is a diagram showing a pattern used for control of the embodiment.

FIG. 8 is a time chart showing the ignition sequence and various signal states of the internal combustion engine according to the second embodiment of the present invention.

FIG. 9 is a time chart showing the ignition sequence and various signal states of the internal combustion engine according to the embodiment.

FIG. 10 is a flowchart showing an ignition control routine of the same.

[Explanation of symbols]

 1 crank angle sensor 2 ECU 3 battery 4 power supply relay 5 ignition switch 6 ignition coil 7 fuel injection valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F02D 43/00 A 7536-3G F02P 5/15 E 9/00 303 B

Claims (1)

[Claims] 1. A spark ignition internal combustion engine in which a fuel injection valve is provided for each cylinder, and a fuel injection valve of a cylinder in a predetermined stroke determined by a cylinder determination means is driven to inject fuel, the engine stop operation is performed. The engine stop operation detecting means for detecting that the engine has been broken, and the detection of the engine stop operation, when the fuel is being injected at the time of the detection, the fuel injection stop for waiting the completion of the injection of the fuel and stopping the fuel injection of all the cylinders. Control means, combustion end cylinder detection means for detecting a cylinder in a combustion stroke in which all of the fuel injected before the engine stop operation and at the time of stop operation have finished burning, and ignition control up to the ignition timing of the cylinder where the combustion ends. An ignition delay control means for stopping ignition control after continuing, and an engine stop control device for a spark ignition type internal combustion engine.