Ignition timing control system for internal combustion engine

Details Ignition timing control system for internal combustion engine Ignition timing control system for internal combustion engine

2000-04-19

2001-10-16

Solis, Erick (Department: 3747)

Internal-combustion engines

Combustion chamber means having fuel injection only

Having a particular relationship between injection and...

C123S406470

Reexamination Certificate

active

06302082

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ignition timing control system for an internal combustion engine, more particularly to an ignition timing control system for a direct injection spark ignition engine, in which gasoline fuel is directly injected into the combustion chamber of the engine.
2. Description of the Related Art
In the control system of internal combustion engines, it is well-known to determine the fuel injection amount and the ignition timing based on the engine speed and engine load, for example, from Japanese Laid-Open Patent Application No. Hei 9 (1997)-4499. The system in this prior art has a dual-spark ignition coil which is connected to two cylinders whose operating cycles are 360° out of phase with each other, in which it is determined whether the electric discharging period after ignition and the fuel injection period are overlapped with each other in the associated non-combustion cylinder (ignited in the exhaust stroke) and if the result is affirmative, the fuel injection start timing is delayed until the electric discharging has been finished.
Aside from the above, a direct injection spark ignition engine has recently been proposed in which gasoline fuel is directly injected into the combustion chamber such that an ultra-lean burn combustion or a stratified combustion (in an ultra lean air/fuel ratio) or the pre-mixture charged combustion (in a uniform air/fuel ratio) occurs in the engine as is disclosed in, for example, Japanese Patent Publication No. Hei 4 (1992) - 37264.
The ignition timing is normally set to a crank angular point at which the injected fuel has atomized (vaporized) and is combustible. However, in the direct injection spark ignition engine, since fuel injection is conducted in the compression stoke when the engine is operated at the ultra-lean burn combustion, the fuel injection end timing and the ignition timing are likely to overlap each other. This overlapping may lead to misfiring or to residual of unburned fuel such as HC (hydrocarbon) in the cylinder.
The aforesaid prior art (mentioned in Japanese Laid-Open Patent Application No. Hei 9 (1997) - 4499) aimed to overcome problems including the engine torque drop due to preignition caused by the overlapping of the electric discharging period after ignition and the fuel injection period in the non-combustion cylinder. Thus, this prior art does not solve the problem of overlapping of the fuel injection end timing and the ignition timing.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide an ignition timing control system for an internal combustion engine, more particularly for a direct injection spark ignition engine which can prevent the overlapping of the fuel injection end timing and the ignition timing from happening, thereby avoiding the problem of misfiring or residual of unburned fuel in the cylinder from occurring.
This invention achieves this object by providing a system for controlling an ignition timing for a direct injection spark ignition internal combustion engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion, comprising; engine operating condition detecting means for detecting operating conditions of the engine at least including an engine speed and an engine load; fuel injection amount determining means for determining a fuel injection amount based at least on the detected engine speed and the engine load of the engine operating conditions; fuel injecting means for injecting fuel based on the determined fuel injection amount into a cylinder of the engine; ignition timing determining means for determining an ignition timing based at least on the detected engine speed and the engine load of the engine operating conditions; desired fuel injection end timing determining means for determining a desired fuel injection end timing at which injection of the determined fuel injection amount should be ended such that the fuel injecting means ends the fuel injection in response to the determined desired fuel injection end timing; margin determining means for determining a difference between the determined desired fuel injection end timing and the determined ignition timing and for determining whether the difference is less than a predetermined value indicative of margin; ignition timing correcting means for correcting the determined ignition timing by the predetermined value when the difference is determined to be less than the predetermined value; and ignition means for igniting an air-fuel mixture made of the injected fuel mixed with air based at least on one of the determined ignition timing and the corrected ignition timing.


REFERENCES:
patent: 5718203 (1998-02-01), Shimada et al.
patent: 5975047 (1999-11-01), Kamura et al.
patent: 6058906 (2000-05-01), Yoshino
patent: 6062190 (2000-05-01), Nakamina
patent: 6089206 (2000-07-01), Suzuki et al.
patent: 6173692 (2001-01-01), Hellmich et al.
patent: 4-37264 (1992-06-01), None
patent: 9-4499 (1997-01-01), None

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