Internal-combustion engines – Charge forming device – Including exhaust gas condition responsive means
Patent
1991-09-23
1992-11-17
Neill, Raymond A.
Internal-combustion engines
Charge forming device
Including exhaust gas condition responsive means
123114, 123494, 123674, F02M 5100
Patent
active
051634074
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.
BACKGROUND ART
Methanol is now noted as a fuel giving rise to less environmental pollution, and methanol engines are therefore being developed now. However, an 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, an 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 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 detecting device 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 feed 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 conventional photoelectric transducer has had the problems that fouling of its optical system with time must be dealt with, and the sensor cannot operate in its inactive state immediately after the time of engine starting.
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 according to which a memory blending ratio stored at the time of stoppage of an engine can be employed as a control blending ratio when the blending ratio based on the output of a blending ratio sensor and that of an O.sub.2 sensor cannot be obtained.
To attain the above object, the present invention provides a system for a fuel blending ratio detecting method comprising a blending ratio sensor for generating information regarding a blending ratio between gasoline and alcohol in fuel supplied to an engine, an O.sub.2 sensor for generating information regarding an air/fuel ratio in exhaust gases from said engine, and control means for generating a control blending ratio computed on the basis of the blending ratio information from said blending ratio sensor or the air/fuel ratio information for said O.sub.2 sensor. Besides computing said control blending ratio, said control means detects, when said engine is stopped, a stopped blending ratio detected at the time that said engine is stopped and stores said stopped blending ratio in a backup memory as a memory blending ratio, said memory blending ratio being read for use as said control blending ratio for a predetermined limited period at the time of re-starting said engine.
Thus, according to this method, the control blending ratio under the ordinary engine operating condition is computed on the basis of the output of the blending ratio sensor and that of the O.sub.2 sensor, and, when the engine is stopped, the control blending ratio detected at that time is stored in the backup memory as the control blending ratio. As a result, for the predetermined limited period at the time of re-starting the engine, the memory blending ratio can be used
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Iida Kazumasa
Kato Yoshihiko
Miyamoto Katsuhiko
Nanba Muneyoshi
Yokoyama Takanoa
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Neill Raymond A.
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