JPH06213037A - Fuel injection control method of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent any backfire in time of the execution of ignition timing delay control, in an internal combustion engine fuel injection control method that executes this ignition timing delay control and warms up a catalyzer in its early stage at the time of engine starting. CONSTITUTION:At the nonexecution of ignition timing delay control, it is provided with a first control means, controlling a span of injection timing so as to feed a combustion chamber 5 with fuel sprayed to an intake passage 6 after being mixed with intake air, and a second control means controlling the injection timing so as to spray the fuel to only the combustion chamber 5 after at least a part of the intake air is fed to an inner part of the combustion chamber 5, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control method for an internal combustion engine.

[0002]

2. Description of the Related Art As described in Japanese Patent Laid-Open No. 62-91662, when the engine is cold started, the ignition end timing is retarded to delay the combustion end timing and the combustion is not completely completed. BACKGROUND ART There is known an internal combustion engine capable of supplying high-temperature exhaust gas to a catalytic converter, warming up a catalyst early to activate it, and purifying exhaust gas immediately after starting.

Generally, fuel is injected into the intake passage,
The mixture is sufficiently mixed with the intake air in the intake passage to be supplied as a mixture into the combustion chamber. As a result, the air-fuel mixture is made uniform in the combustion chamber, and good combustion with high torque is realized.

[0004]

However, in the above-mentioned internal combustion engine, when such fuel injection is executed when the ignition timing retard is executed, the combustion in the combustion chamber is not completed at the end of the exhaust stroke, Since this combustion continues until the beginning of the intake stroke, if fuel is present in the intake passage when the intake valve is opened, this fuel is ignited and burned to cause backfire in the intake passage.

Therefore, an object of the present invention is to use in an internal combustion engine in which the ignition timing is retarded when the engine is started to warm up the catalyst early, and to prevent the above-mentioned backfire when the ignition timing is retarded. A fuel injection control method for an internal combustion engine is provided.

[0006]

SUMMARY OF THE INVENTION A fuel injection control method for an internal combustion engine according to the present invention is a fuel for an internal combustion engine that executes an ignition timing retard at the time of starting the engine to early warm up a catalytic converter provided in an exhaust passage. In the injection control method, when the ignition timing retard is not executed, a first control means for controlling the injection timing so that the fuel injected into the intake passage is mixed with the intake air and supplied to the combustion chamber; A second control unit that controls the injection timing so that the fuel is injected only into the combustion chamber after at least a part of the intake air is supplied to the combustion chamber during execution of the retard angle. To do.

[0007]

In the above-described fuel injection control method for an internal combustion engine, when the ignition timing retard is not executed, the first control means injects fuel into the intake passage, mixes it with intake air, supplies it to the combustion chamber, and ignites it. During the timing retard, the second control means injects fuel only into the combustion chamber after at least a part of the intake air is supplied into the combustion chamber.

[0008]

1 is a sectional view of a first internal combustion engine to which a fuel injection control method according to the present invention is applied. In the figure, 1 is a cylinder block and 2 is a piston. A cylinder head 4 is attached to the cylinder block 1 via a gasket 3. A combustion chamber 5 is formed by the cylinder block 1 and the piston 2. In the cylinder head 4, a part of the combustion chamber 5 and an intake passage 6 which communicate with each other are formed, and an intake valve 7 for shutting off the two is installed. An exhaust passage is similarly formed in the cylinder head 4 and an exhaust valve is installed, but it is not shown in FIG.

An injection valve 8 for injecting fuel in a columnar shape is arranged upstream of the intake valve 7 in the intake passage 6, and its injection port is directed to the umbrella portion of the intake valve 7 when the valve is closed. When the valve is opened, the injected fuel does not contact the intake valve 7,
It collides with the wall surface of the combustion chamber 5 formed in the cylinder head 4.

The control device 10 is in charge of fuel injection control in the injection valve 8. The control device 10 includes a rotation sensor for detecting the engine speed, an air flow meter for detecting the intake air amount, and an engine temperature. A cooling water temperature sensor or the like for detection is connected, and fuel injection control is executed according to the first flowchart shown in FIG.

First, at step 101, the present engine operating state is detected by the above-mentioned sensors, and the fuel injection amount τ
To decide. Next, at step 102, it is judged if the ignition timing retard for warming up the catalyst is being executed. When this determination is denied, the routine proceeds to step 103, where based on the fuel injection amount τ determined at step 101,
The injection timing is controlled so that the fuel injection is completed immediately before the intake valve 7 is opened. As a result, most of the injected fuel collides with the umbrella portion of the intake valve 7 to become fine particles and float in the intake passage 6, and at the same time as the opening of the intake valve 7, the intake passage 6 is opened.
Is sufficiently mixed with the intake air passing through the intake passage 6 and supplied into the combustion chamber 5. Although part of the fuel adheres to the umbrella portion of the intake valve 7, it is atomized by the intake air and supplied into the combustion chamber. The fuel thus supplied into the combustion chamber becomes a uniform air-fuel mixture by ignition at the end of the compression stroke, and good combustion with high torque is realized. Such fuel injection can wash away deposits adhering to the umbrella portion of the intake valve 7.

On the other hand, when the determination at step 102 is affirmative, the routine proceeds to step 104, where fuel injection is started based on the fuel injection amount τ determined at step 101, a while after the intake valve 7 is opened, The injection timing is controlled so as to be completed before the intake valve 7 is closed. As a result, the combustion in the combustion chamber 5 continues until the early stage of the intake stroke due to the ignition timing retard, but the intake air is supplied into the combustion chamber 5 at the same time when the intake valve 7 is opened, and this combustion is forcibly ended. The temperature in the combustion chamber 5 is lowered, and then the fuel is directly supplied into the combustion chamber. This fuel does not erroneously ignite in the combustion chamber 5 because the temperature in the combustion chamber 5 has dropped, and it is atomized by collision with the wall surface and becomes uniform to some extent by the ignition at the end of the compression stroke. The generated air-fuel mixture can be formed in the combustion chamber 5, and relatively good combustion can be realized. Also,
At the beginning of the intake stroke, there is no fuel in the intake passage 6, and the intake passage 6 has been generated by the previous combustion that continues until this time.
It is possible to prevent backfire in which fuel is ignited and burned.

FIG. 3 is a sectional view of a second internal combustion engine to which the fuel injection control method according to the present invention is applied. First below
Only the difference from the internal combustion engine will be explained. In this internal combustion engine, a combustion chamber 5 formed in a cylinder head 4 is provided with an injection valve 8'for injecting fuel into a conical shape, and its injection direction is communicated with the combustion chamber 5 by an intake valve 7 when opened. Is directed to the intake passage 6.

The control device 10 ', which is in charge of fuel injection control of the injection valve 8', is connected with the same sensors as those connected to the control device 10 described above, and this control is performed according to the second flow chart shown in FIG. Run. Only the differences from the first flowchart will be described below.

In step 202, it is determined whether the ignition timing retard for warming up the catalyst is being executed.
When this determination is denied, the routine proceeds to step 203, where the injection timing is set so that fuel injection is started after the intake valve 7 is opened and before it is closed based on the fuel injection amount τ determined at step 201. Controlled. As a result, the fuel injected as fine particles in a conical shape is sufficiently mixed with the intake air passing through the intake passage 6 and supplied into the combustion chamber 5, and this fuel is mixed evenly by the ignition at the end of the compression stroke. Anxiously, good combustion with high torque is realized.

On the other hand, when the determination in step 202 is affirmative, the routine proceeds to step 204, where fuel injection is started after the intake valve 7 is closed based on the fuel injection amount τ determined in step 201, and at least until ignition. The injection timing is controlled so as to end at. Thereby, the combustion in the combustion chamber 5 continues until the beginning of the intake stroke due to the ignition timing retard, but the intake air is supplied into the combustion chamber 5 in the intake stroke,
This combustion is forcibly ended and the temperature in the combustion chamber 5 is lowered, and then the fuel is injected so as to collide with the intake valve 7 which is closed. This fuel does not erroneously ignite in the combustion chamber 5 because the temperature in the combustion chamber 5 is lowered, and the fuel is injected in a conical shape.
Since the distance from the injection port of the injection valve 8 ′ to the intake valve 7 is relatively short, the injection valve 8 ′ collides with the intake valve 7 at a relatively high speed and is atomized.

Therefore, by the ignition at the end of the compression stroke, the air-fuel mixture that has been made uniform to some extent is formed in the combustion chamber 5, and relatively good combustion can be realized. Further, at the beginning of the intake stroke, there is no fuel in the intake passage 6, and it is possible to prevent backfire in which the fuel is ignited and burned in the intake passage 6.

[0018]

As described above, according to the fuel injection control method for the internal combustion engine of the present invention, when the ignition timing retard is executed at the time of engine start and the like to realize the early warm-up of the catalytic converter, the fuel is After at least a part of the intake air is supplied into the combustion chamber, it is injected only into the combustion chamber, so the ignition timing retard causes the previous combustion to continue until the beginning of the intake stroke, but this combustion is forced to end due to intake air. And the temperature inside the combustion chamber is lowered, and the fuel injected into the combustion chamber thereafter is
A mixture is formed by ignition without accidental ignition. Further, at this time, there is no fuel in the intake passage, and a backfire in which fuel is ignited and burned in the intake passage when the intake valve is opened by the previous combustion is prevented. On the other hand, when the ignition timing is not retarded, the fuel is injected into the intake passage and is mixed with the intake air and supplied to the combustion chamber, so that a uniform mixture is formed by ignition and good combustion with high torque is realized. To be done.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first internal combustion engine to which a fuel injection control method according to the present invention is applied.

FIG. 2 is a first flow chart for fuel injection control in a first internal combustion engine.

FIG. 3 is a sectional view of a second internal combustion engine to which the fuel injection control method according to the present invention is applied.

FIG. 4 is a second flowchart for fuel injection control in the second internal combustion engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder block 2 ... Piston 4 ... Cylinder head 5 ... Combustion chamber 6 ... Intake passage 7 ... Intake valve 8,8 '... Injection valve 10, 10' ... Control device

Claims (1)

[Claims] 1. A fuel injection control method for an internal combustion engine, wherein an ignition timing retard is executed at engine startup or the like to early warm up a catalytic converter provided in an exhaust passage, and when the ignition timing retard is not executed. First control means for controlling the injection timing so that the fuel injected into the intake passage is mixed with the intake air and supplied to the combustion chamber; and at the time of executing the ignition timing retard, at least a part of the intake air is present in the combustion chamber. And a second control means for controlling the injection timing so as to inject the fuel only into the combustion chamber after the supply of the fuel.