Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2003-10-02
2004-10-05
Solis, Erick (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
Reexamination Certificate
active
06799560
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 2002-310649 filed on Oct. 25, 2002, including the specification, drawings and abstract, is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to fuel injection amount control apparatus and method of an internal combustion engine, and particularly relates to such fuel injection amount control apparatus and method that estimates an amount of fuel deposited on an intake system of the engine, and determines a fuel injection amount depending upon the estimated fuel deposition amount.
2. Description of Related Art
A known example of the above type of the fuel injection amount control apparatus is disclosed in, for example, Japanese Patent No. 2606226. The fuel injection amount control apparatus disclosed in this publication is adapted to estimate an amount of fuel deposited on a wall of an intake passage, based on a fuel behavior simulation model (or a fuel deposition model), and determine an amount of fuel to be injected, depending upon at least the estimated fuel deposition amount.
Also, after the engine stops rotating, the control apparatus disclosed in the above-identified publication estimates an evaporation speed or rate of the fuel deposited on the wall of the intake passage during a stop of the engine, and estimates the amount of fuel deposited on the intake passage wall during the stop of the engine, based on the estimated evaporation speed. Upon a re-start of the engine, the control apparatus sets the fuel deposition amount estimated during the stop of the engine, as an initial value of the fuel deposition amount used by the above-indicated fuel behavior simulation model. Thus, the control apparatus is able to estimate, with high accuracy, the amount of fuel deposited on the intake passage wall at the time of the re-start of the engine.
The above-identified publication (JP-B2-2606226) discloses that the estimated evaporation speed is a function of the intake passage wall temperature only, but does not disclose a specific method for accurately estimate the evaporation speed. Also, the fuel deposition amount on the intake passage wall, which is estimated by the apparatus during a stop of the engine, does not necessarily coincide with the actual fuel deposition amount on the intake passage wall.
Accordingly, the above-described control apparatus may suffer from reduced accuracy with which the fuel deposition amount is estimated at the time of a re-start of the engine. In this case, the amount of fuel injected during re-starting of the engine cannot be determined to be an appropriate amount. Consequently, the air/fuel ratio of the engine cannot be set to a target air/fuel ratio, which may result in deterioration of starting characteristics (such as ease of starting) at the time of the re-start of the engine, and an increase in the amount of emissions from the engine.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide fuel injection amount control apparatus and method of an internal combustion engine, which are able to more appropriately determine the fuel injection amount upon a re-start of the engine.
To accomplish the above object, there is provided according to one aspect of the invention a fuel injection amount control apparatus of an internal combustion engine, which is arranged to start injection of a fuel when a certain engine start condition is satisfied, and stop the injection of the fuel when a certain engine stop condition is satisfied, which apparatus comprises: (a) a fuel injecting unit that injects the fuel in an intake passage that is connected to a combustion chamber of the engine; (b) a fuel deposition amount estimating unit that estimates a fuel deposition amount that is an amount of fuel deposited on an intake passage forming member that defines the intake passage; (c) a fuel injection amount determining unit that determines a fuel injection amount that is an amount of fuel injected from the fuel injecting unit, based on the estimated fuel deposition amount; and (d) a particular process executing unit that executes a particular process for making an actual fuel deposition amount on the intake passage forming member substantially equal to zero, after the engine stop condition is satisfied and before the injection of the fuel is started under a condition that the engine start condition is satisfied.
Here, the “the intake passage forming member” may include an intake pipe (including an intake manifold), an intake valve (in particular, a back face of the intake valve), an intake control valve, such as SCV, disposed in the intake passage. The actual fuel deposition amount is made equal to “substantially zero” not only when the amount is exactly equal to zero but also when the amount is equal to a certain non-zero value. The non-zero value may be determined such that a difference between the fuel injection amount determined by the fuel injection amount determining unit in the case where the fuel deposition amount is equal to the non-zero value and the fuel injection amount determined in the case where the fuel deposition amount is equal to zero is sufficiently small, and a target (desired) air/fuel ratio can be substantially achieved even if the non-zero value is treated as zero.
The “engine start condition is satisfied”, for example, when the driver operates an ignition switch from ON to START while the engine is being stopped, or when a vehicle in which control is performed for effecting or stopping injection of fuel depending upon the running conditions of the vehicle after a start of the engine shifts from an operating state in which the control for stopping fuel injection is executed to an operating state in which the control for effecting fuel injection is executed. Such a vehicle may be, for example, a so-called hybrid vehicle provided with an internal combustion engine and other power source(s), such as an electric motor, or a vehicle that is provided with an internal combustion engine as a single power source and performs control for effecting or stopping injection of fuel depending upon the running conditions for the sake of reduction of energy consumption. Similarly, the “engine stop condition is satisfied”, for example, when the driver operates the ignition switch from ON to OFF while the engine is being operated with fuel injected, or when the vehicle in which control is performed for effecting or stopping injection of fuel depending upon the running conditions of the vehicle after a start of the engine shifts from an operating state in which the control for effecting fuel injection is executed to an operating state in which the control for stopping fuel injection is executed.
With the control apparatus as described above, after a certain engine stop condition is satisfied and before injection of fuel is started under a condition that a certain engine start condition is satisfied (i.e., during a stop of the engine), the actual amount of fuel deposited on the intake passage forming member is made substantially equal to zero. Accordingly, upon a start of the injection of the fuel with the engine start condition satisfied (i.e., upon a re-start of the engine), if the fuel deposition amount estimating unit is arranged to start estimation of the fuel deposition amount in a condition that the initial value of the fuel deposition amount estimated by the fuel deposition amount estimating unit is set to zero (or a certain value in the case where a certain amount of fuel is injected by the fuel injecting unit during a stop of the engine), the estimated and actual values of the fuel deposition amount on the intake passage forming member obtained at the time of the re-start of the engine can be surely made substantially equal to each other. As a result, the fuel injection amount for the time of a re-start of the engine can be determined to be an appropriate value, to thereby provide a target air/fuel ratio, thus assuring improved starting characteristics of the engine upon the re-start
Kako Junichi
Kojima Kazunori
Ueda Koichi
Solis Erick
Toyota Jidosha & Kabushiki Kaisha
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