Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2002-04-22
2003-01-21
Mohanty, Bibhu (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S480000
Reexamination Certificate
active
06508234
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This nonprovisional application claims priority under 35 U.S.C. §119(a) on patent application No. 2001-151070 filed in Japan on May 21, 2001, the entirety of which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel injection control system for an engine, and more particularly to a fuel injection control system for an engine capable of estimating a portion of a fuel injected from a fuel injection valve that is not directly supplied to a cylinder because of adhesion along an inner wall of an intake pipe or the like. Accordingly, adequate fuel injection on the basis of this estimated result is realized with the present invention.
2. Description of the Background Art
Control systems for engines in which fuel injection valves are disposed in the upstream and the downstream of a throttle valve have been known in the background art. For example, a similar control system is described in Japanese Patent Laid-open No. Hei 6-102999. This control system is configured such that a fuel is injected, in an idle rotation region, only from a downstream side fuel injection valve. Fuel is injected, in a region other than the idle rotation region, from an upstream side fuel injection valve in accordance with an engine operation state.
In this type of control unit, when the control unit operates in a region other than the idle rotation region, a fuel amount injected from the downstream side injection valve is gradually reduced to a target value. The fuel amount injected from the downstream side injector is determined in consideration of the residual portion of a fuel injected from the upstream side injection valve. The residual portion adheres on a wall surface of an intake pipe.
Fuel injection control systems for engines having a single fuel injection valve, in which a fuel injection amount is corrected in consideration of fuel adhering on an inner wall of an intake pipe, have been proposed in the background art. For example, in Japanese Patent Laid-open Nos. Hei 7-247892 and Hei 5-340285 single fuel injection valve systems are described. In particular, the control system in the latter document discloses controlling repeated fuel injection (divided injection), i.e., twice in one cycle.
According to the control system described in Japanese Patent Laid-open No. Hei 6-102999, although adhesion of a fuel on the wall surface in the upstream of the throttle valve is taken into account, it fails to examine an amount of the fuel adhering on the wall surface along the lower and remaining surfaces. Accordingly, the control system does not realize high, accurate control so as to meet a target air-fuel ratio. It is therefore difficult to improve drivability (running performance) in combination with the desired improvement of fuel consumption. Another problem of this control system is that since the number of setting parameters is increased to improve responsiveness to a change in engine state, or a change in throttle opening angle, the control of fuel injection becomes complex.
The fuel injection control system for an engine including a single fuel injection valve estimates a fuel adhesion amount specified for an engine including a single fuel injection valve. The control system does not control fuel individually in an engine including fuel injection valves disposed in the upstream and downstream of the throttle valve. Accordingly, the control systems of the background art do not estimate a fuel adhesion amount in each of the upstream and downstream positions with respect to the throttle valve in an engine including fuel injection valves disposed in both the upstream and downstream positions.
As described in the above document, Japanese Patent Laid-open No. Hei 6-102999, the calculation of a fuel injection amount is generally performed at each predetermined crank angle (at each crank angle of 180° in the control system of this document). Fuel is injected front each fuel injection valve at a rate of once per cycle (crank angle: 720°).
Accordingly, if an engine state is changed before a point of fuel injection and after calculation of a fuel injection amount is calculated, the fuel injection amount once determined cannot be changed. As a result, in an acceleration state in which the engine state is changed rapidly and/or significantly, the amount of fuel supplied may be lacking to the point of degrading drivability and/or engine operability. In particular, if a throttle opening angle is changed significantly, it is unclear to what degree a fuel injected from an upstream injection valve flows in the downstream of the throttle valve, with a result that over-rich or over-lean engine operation is liable to occur. The entirety of each of the foregoing references described in the Description of the Background Art of the present application are hereby incorporated by reference into the present application.
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
An object of the present invention is to provide a fuel injection control system for an engine capable of accurately determining an amount of fuel supplied in response to a current engine state on the basis of a fuel flow-in state from a position upstream of a throttle valve.
These and other aspects of the present invention are accomplished by a fuel injection control system for an engine comprising a throttle valve; at least one upstream injection valve being,disposed in an upstream position with respect to the throttle valve; at least one downstream injection valve being disposed in a downstream position with respect to the throttle valve; means for calculating a required fuel amount for a predetermined calculation cycle and calculating actual fuel amounts to be injected during a fuel injection process from the upstream injection valve and the downstream injection valve on the basis of the required fuel amount; and means for calculating, after the fuel injection process, a lack of fuel amount immediately before recalculating a recalculated required fuel amount at the calculation cycle coming at the end of an intake stroke, the lack of fuel amount being calculated by subtracting the required and the actual fuel amounts from the recalculated required fuel amount.
These and other aspects of the present invention are further accomplished by a method of calculating a fuel injection amount for a cylinder using the foregoing system, the method comprising calculating a fuel injection amount of at least one of the upstream fuel injection valve and the downstream fuel injection valve according to a respective fuel pressure of the upstream fuel injection valve and the downstream fuel injection valve; and controlling a fuel injection time period to control the fuel injection amount.
These and other aspects of the present invention are further accomplished by a fuel injection control system for an engine including a fuel injection valve, the fuel injection control system comprising means for calculating a required fuel amount during a predetermined calculation cycle and for calculating a injected fuel amount to be injected from the fuel injection valve on the basis of the required fuel amount; means for calculating, after a fuel injection of a fuel from the fuel injection valve on the basis of the calculated injected fuel amount, a lack of fuel amount immediately before a re-calculation of a required fuel amount during the calculation cycle at the end of an intake stroke, the lack of fuel amount being calculated by subtracting the calculated injected fuel amount from the re-calculated required fuel amount; the lack of fuel amount being additionally injected during the intake stroke; the lack of fuel injection amount being calculated by addition of a fuel injected from the fuel injection valve and deposited on an inner wall of an intake pipe to achieve a first amount, and subtracting a fuel released from the deposited fuel to flow into
Hirakata Yoshiaki
Machida Kenichi
Takeda Toru
LandOfFree
Fuel injection control system for engine 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 control system for engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel injection control system for engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3044196