Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2003-04-16
2004-11-02
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S19600W, C123S294000
Reexamination Certificate
active
06810858
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 2002-163578 filed on Apr. 26, 2002, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fuel injection timing control apparatus for an in-cylinder injection internal combustion engine, which controls a fuel injection in an in-cylinder injection internal combustion engine in which fuel is directly injected into a cylinder.
2. Description of the Related Art
In the past, an in-cylinder injection internal combustion engine in which fuel is directly injected into a cylinder of the internal combustion engine has been proposed. This in-cylinder injection internal combustion engine aims to improve fuel economy and the like by precisely controlling the mixture state of a mixture within the cylinder by injecting fuel late in the compression stroke. In this in-cylinder injection internal combustion engine, however, the following problems may occur, particularly when the engine is cold, when the fuel is directly injected into the cylinder.
That is, when the engine is cold, fuel within the cylinder does not readily atomize, resulting in a tendency for a large amount of the injected fuel to adhere to the top face of an engine piston (hereinafter referred to simply as “piston top face”) and the cylinder inner peripheral face. Therefore, ordinarily when the engine is cold, the fuel injection timing is set to during the intake stroke (hereinafter referred to as “intake stroke injection”), thus increasing the time between fuel injection and ignition to as long as possible to promote atomization of the injected fuel. Even if this intake stroke injection is performed, however, it is still difficult to completely prevent the adherence of fuel on the piston top face and cylinder inner peripheral face; some of the injected fuel is not burned, but remains adhered after engine combustion.
The fuel adhered to the piston top face, in particular, atomizes gradually during later engine combustion, and is discharged from the cylinder without being completely combusted, leading to a deterioration of exhaust gas emissions, such as the generation of black smoke and an increase in unburned components.
The fuel adhered to the cylinder inner peripheral face mixes with lubricating oil adhered to the cylinder inner peripheral face in order to provide lubrication for the piston. As a result, the lubricating oil is diluted by the fuel and so-called fuel dilution occurs. The lubricating oil in the cylinder that has been diluted by the fuel is scraped down the cylinder inner peripheral face from the reciprocating motion of the piston and returned to the oil pan, after which it is again supplied to the internal combustion engine to provide lubrication. Therefore, if fuel dilution of the lubricating oil occurs frequently, the ratio of fuel mixed in with the overall lubricating oil gradually increases until finally adverse effects result, such as a decline in the lubricating performance in the internal combustion engine.
Japanese Patent Laid-Open Publication No. 2001-304026 and Japanese Patent Laid-Open Publication No. 2002-13428 disclose related art in which the fuel injection timing during the intake stroke injection is set taking into consideration the distribution of the amounts of fuel adhered to the piston top face and the cylinder inner peripheral face from the fuel injection so that only one of the amounts of the adhered fuel does not increase to an extreme in order to deal with both deterioration in exhaust gas emissions and fuel dilution.
Therefore, even if the lubricating oil is diluted by the fuel following an injection of fuel into the cylinder when the engine is cold, that fuel dilution is only temporary, and unless it occurs frequently, the ratio of fuel contained in the lubricating oil to the overall lubricating oil will not change much. Further, the fuel contained in the lubricating oil decreases by gradually evaporating over time. Therefore, despite the possibility of adverse effects described above, such as a reduction in lubricating performance, ultimately caused by fuel dilution, if fuel dilution of the overall lubricating oil is at a level where it is not progressing, the adverse effects are also in a range where they can actually be effectively ignored. That is, a certain degree of fuel dilution of the lubricating oil that occurs from the injection of fuel into the cylinder can be allowed when considering the fact that the degree of the adverse effects on the internal combustion engine that are caused by that degree of fuel dilution is negligible.
On the other hand, deterioration of the exhaust gas emissions due to fuel adhered to the piston top face is to a great extent unavoidable, and the allowable range in consideration of the degree of the adverse effects on the internal combustion engine is extremely narrow.
Therefore, although fuel dilution due to an increase in fuel adhering to the cylinder inner peripheral face is allowable to some degree, it is preferable, or realistic, when fuel dilution of the overall lubricating oil is not effectively progressing, to inhibit the deterioration of the exhaust gas emissions by changing the fuel injection timing or the like so as to reduce as far as possible the amount of fuel that adheres to the piston top face.
Although the art in the foregoing publications performs fuel injection control considering both deterioration of the exhaust gas emissions due to fuel adhering to the piston top face and fuel dilution of the lubricating oil due to fuel adhering to the cylinder inner peripheral face, there still remains room for improvement with respect to flexibly dealing with these problems according to the actual degree of adverse effects they have on the internal combustion engine.
SUMMARY OF THE INVENTION
In view of this room for improvement with the related art, it is an object of this invention to provide a fuel injection control apparatus for an in-cylinder injection internal combustion engine, which can flexibly control a fuel injection mode according to an actual degree of adverse effects on the internal combustion engine from both deterioration of exhaust gas emissions caused by fuel adhering to a piston top face and fuel dilution caused by fuel adhering to a cylinder inner peripheral face.
Hereinafter, a method for solving the foregoing problems, as well as an effect of that method, will be described. According to one aspect of the invention, a fuel injection control apparatus for an in-cylinder injection internal combustion engine, in which fuel is directly injected into a cylinder of the internal combustion engine, is provided with a dilution degree estimation portion that estimates a degree of dilution by fuel in an overall lubricating oil provided to lubricate the internal combustion engine, and a control portion that controls a fuel injection mode so as to inhibit dilution by fuel of the lubricating oil when the estimated degree of fuel dilution is larger than a predetermined value.
According to this construction, when the degree of fuel dilution of the overall lubricating oil is small, for example, it is possible to give priority to suppressing the adhesion of fuel on the piston top face in order to inhibit, to as great an extent as possible, deterioration of the exhaust gas emissions, such as the generation of black smoke, and temporarily allow a fuel injection even if that fuel injection would increase the amount of fuel adhered to the cylinder inner peripheral face and cause the fuel dilution to progress. In contrast, when the degree of fuel dilution of the overall lubricating oil increases to the point where, if it progresses any farther the resultant adverse effects, such as a decline in lubricating performance, can no longer be ignored, the fuel injection mode is controlled so as to inhibit dilution by fuel of the lubricating oil. As a result, it is possible to inhibit adverse effects from the fuel dilution of the lubricating oil on
Hirose Kiyoo
Honda Koji
Ito Yukikazu
Argenbright Tony M.
Kenyon & Kenyon
LandOfFree
Fuel injection timing control apparatus and control method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel injection timing control apparatus and control method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel injection timing control apparatus and control method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3317229