Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Patent
1991-09-26
1993-03-23
Neill, Raymond A.
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
123 1A, F02B 7512
Patent
active
051954974
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 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 presently being developed. 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.
In order to deal with such a situation, the introduction of a vehicle is proposed in which both the gasoline fuel and the methanol fuel can be used, that is, a vehicle which has the degree of freedom with respect to fuel to be used. (Such a vehicle will be referred to hereinafter simply as an FFV.)
In order for the engine of such an FFV to 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 detecing device or a sensor for use 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.
There is also a method for detecting the blending ratio by the use of an O.sub.2 sensor which generates the information of oxygen concentration in the exhaust gases of an engine, that is, the air/fuel ratio.
However, the practical use of the blending ratio sensor using a known photoelectric transducer is delayed due to the difficulty of temperature compensation that is frequently required and due to frequent errors and durability problems attributable to dirt progressively accumulating on the optical system.
On the other hand, in the case of the method using the O.sub.2 sensor, the blending ratio is computed by learning on the basis of the feedback from the O.sub.2 sensor. However, the blending ratio may not be detected as desired since this feedback learning control is not successfully attained until the driving conditions of the vehicle are more or less stabilized.
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 for feeding a mixed fuel of gasoline and methanol to the internal combustion engine, an O.sub.2 sensor for 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, and control means for 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: said air/fuel ratio feedback compensation coefficient each time peak values appear; and peak mean value to compute the next current blending ratio compensation coefficient.
According to this method, the current blending ratio can be obtained by computing the air/fuel ratio feedback compensation coefficient on the basis of the air/fuel ratio information, computing the peak mean value of the air/fuel ratio feedback compensation coefficients, and updating the current blending ratio compensation coefficient on the basis of this peak mean 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 thu
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Iida Kazumasa
Kato Yoshihiko
Miyamoto Katsuhiko
Nanba Muneyoshi
Yokoyama Takanao
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Neill Raymond A.
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