Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Patent
1991-09-26
1993-03-30
Argenbright, Tony M.
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
123494, F02D 4500, F02D 1908, F02D 4114
Patent
active
051974517
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a fuel blending ratio detecting method for detecting the blending ratio of a mixed fuel supplied to an internal combustion engine without the use of a blending ratio sensor.
BACKGROUND ART
Methanol is now noted as fuel giving rise to less environmental pollution, and methanol engines are also being developed now. However, immediate change-over of fuel used in all kinds of automotive vehicles from gasoline to methanol is almost impossible, and, at the time of change-over, a situation will occur where at least temporarily both the methanol fuel and the gasoline fuel are used.
With a view to deal with such a situation, introduction of a vehicle is proposed in which both the gasoline fuel and the methanol fuel can be used, that is, the vehicle has a degree of freedom with respect to fuel to be used. (Such a vehicle will be referred to hereinafter simply as an FFV.)
In order that the engine of such an FFV can be accurately controlled, the blending ratio which is the mixing ratio of fuel between the gasoline and the methanol is to be continuously detected so as to execute various required controls on the engine. A blending ratio detector or a sensor for use in such a purpose has been developed and is now in use which can be directly associated with the fuel supply system of the engine so as to directly detect the blending ratio of the fuel.
However, the practical use of the blending ratio sensor using a conventional photoelectric transducer is delayed due to the difficulty of temperature compensation that is frequently required and due to frequent error and durability problems attributable to dirt progressively accumulating on the optical system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a fuel blending ratio detecting method capable of detecting the blending ratio by the output of an O.sub.2 sensor.
To attain the above object, the present invention provides a fuel blending ratio detecting method for an internal combustion engine having a fuel feed system feeding a mixed fuel of gasoline and methanol to the internal combustion engine, an O.sub.2 sensor generating information of an air/fuel ratio in exhaust gases from the internal combustion engine, the sensor output being increased or decreased with time relative to a rich/lean decision voltage, a memory for storing an initial blending ratio compensation coefficient as a current blending ratio compensation coefficient, and control means computing an air/fuel ratio feedback compensation coefficient by a method including at least an integral control of the output of said O.sub.2 sensor thereby regulating the quantity of supplied fuel so that an air/fuel ratio of the fuel supplied to the internal combustion engine corresponds to a target value, comprising the steps of: compensation coefficient at intervals of a predetermined period; memory; feedback learned value to compute the next blending ratio compensation coefficient; and the current blending ratio compensation coefficient.
According to this method, the blending ratio can be obtained by computing the feedback compensation coefficient on the basis of the air/fuel ratio information, computing the feedback learned value on the basis of the feedback compensation coefficient, and updating the blending ratio compensation coefficient on the basis of this feedback learned value.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
FIG. 1 is a block diagram illustrating the method for an embodiment of the present invention;
FIGS. 2a to 2e are waveform diagrams showing how an air/fuel ratio output and other characteristic values change with time according to the method for an embodiment of the present invention;
FIG. 3 schematically shows the structure of an engine control system to which the method for an embod
REFERENCES:
patent: 4706629 (1987-11-01), Wineland et al.
patent: 5094208 (1992-03-01), Adam et al.
Iida Kazumasa
Kato Yoshihiko
Miyamoto Katsuhiko
Nanba Muneyoshi
Yokoyama Takanao
Argenbright Tony M.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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