Measuring and testing – Vehicle chassis – Steering
Reexamination Certificate
1999-05-28
2001-10-09
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Vehicle chassis
Steering
C073S035080
Reexamination Certificate
active
06298717
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for detecting the misfire in an internal combustion engine and, particularly, to a device for detecting the misfire in an internal combustion engine featuring improved reliability in all operation regions by detecting the misfire using either the revolution data or the ionic current depending upon the operation region.
2. Prior Art
A device for detecting the misfire in an internal combustion engine relying on a change in the pulse period ratio: as revolution data, has heretofore been well known as disclosed in, for example, Japanese Unexamined Patent Publication (Kowai) No. 79396/1993 (Japanese Patent No. 2606019).
There has also been known a device for detecting the misfire in an internal combustion engine relying on the detection levee of an ionic current as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 26090/1993 (Japanese Patent No. 2657012).
However, no device for detecting the misfire based on both the revolution data and the ionic current has yet been proposed.
It has generally been known that the reliability (S/N ratio) for detecting the misfire based on the revolution data and the ionic current, varies depending upon the operation region (rotational speed) of the internal combustion engine.
FIGS. 6 and 7
are diagrams of characteristics showing the reliability (S/N ratio) for detecting the period ratio and the ionic current relative to the rotational speed Ne [rpm] of the engine.
Referring to
FIG. 6
, the reliability for judging the misfire based on the period ratio (revolution data) deteriorates with an increase in the rotational speed Ne of the engine.
This is because, the rotational pulse period and the amount of change thereof decrease with an increase in the rotational speed Ne of the engine, and it becomes difficult to detect a change in the period ratio.
Here, it is not desirable to operate a period ratio within a short pulse section in a high-speed operation region, since the load to the computer (ECU) increases.
Referring to
FIG. 7
, furthermore, the reliability for judging the misfire based on the ionic current deteriorates with a decrease in the rotational speed Ne of the engine, and particularly deteriorates near the idling rotational speed (700 rpm) as indicated by a broken line.
This is because, in the idling operation region, the level for detecting the ionic current loses stability since the load exerted on the engine and the rotational speed of the engine vary to a great extent. Furthermore, the level for detecting the ionic current temporarily drops depending upon the fouling of the spark plugs and the properties of the fuel.
According to the conventional devices for detecting the misfire in the internal combustion engines as described above, the reliability is deteriorated during the high-speed operation when the period ratio (revolution data) is relied upon and the reliability is deteriorated during the low-speed operation when the ionic current is relied upon.
SUMMARY OF THE INVENTION
The present invention was accomplished in order to solve the above-mentioned problems, and its object is to provide a device for detecting the misfire in an internal combustion engine which features improved reliability for judging the misfire in all operation regions by using either the revolution data or the ionic current depending upon the operation region.
A device for detecting the misfire in an internal combustion engine according to the present invention comprises:
various sensors for detecting the operation conditions of the internal combustion engine;
an operation region detection means for detecting the operation region of the internal combustion engine from the operation conditions;
a control parameter operation means for operating control parameters of the internal combustion engine based upon the operation conditions;
an ignition device for igniting the internal combustion engine relying upon the control parameters;
an ionic current detection unit for detecting an ionic current generated upon the ignition of the internal combustion engine;
a first misfire judging means for judging the misfire in the internal combustion engine based upon a change in the time of the revolution data of the internal combustion engine included in the operation conditions;
a second misfire judging means for judging the misfire in the internal combustion engine based upon the ionic current; and
a misfire judgement selection means for selectively using the first misfire judging means or the second misfire judging means depending upon the operation region.
In the device for detecting the misfire in an internal combustion engine of the present invention, the operation region detection means detects at least the operation regions divided into a plurality of regions based upon the revolution data of the internal combustion engine.
In the device for detecting the misfire in an internal combustion engine of the present invention, the operation region detection means detects a first operation region where the rotational speed is lower than a first predetermined rotational speed corresponding to the idling rotational speed of the internal combustion engine, and the misfire judgement selection means uses the first misfire judging means in the first operation region.
In the device for detecting the misfire in an internal combustion engine of the present invention, the operation region detection means detects a second operation region where the rotational speed is higher than a second predetermined rotational speed which is higher than the first predetermined rotational speed, and the misfire judgement selection means uses the second misfire judging means in the second operation region.
In the device for detecting the misfire in an internal combustion engine of the present invention, the operation region detection means detects a third operation region lying between the first predetermined rotational speed corresponding to the idling rotational speed of the internal combustion engine and the second predetermined rotational speed higher than the first predetermined rotational speed, the misfire judgement selection means includes an ionic current condition judging means for judging whether the ionic current is in a proper condition or not in the third operation region, and uses the second misfire judging means in the second operation region when it is judged that the ionic current is in the proper condition in the third operation region, and uses the first misfire judging means in the second operation region when it is judged that the ionic current is not in the proper condition in the third operation region.
In the device for detecting the misfire in an internal combustion engine of the present invention, the misfire judgement selection means uses the first misfire judging means in the third operation region.
In the device for detecting the misfire in an internal combustion engine of the present invention, the misfire judgement selection means uses the second misfire judging means when it is judged that the ionic current is in the proper condition in the third operation region, and uses the first misfire judging means when it is judged that the ionic current is not in the proper condition in the third operation region.
In the device for detecting the misfire in an internal combustion engine of the present invention, the ionic current condition judging means so judges that the ionic current is not in the proper condition when a peak level of the ionic current detected in the third operation region is lower than a predetermined value.
In the device for detecting the misfire in an internal combustion engine of the present invention, the ionic current condition judging means so judges that the ionic current is not in the proper condition when an integrated value of the ionic current detected in the third operation region is smaller than a predetermined value.
In the device for detecting the misfire in an internal combustion engine of the present invention,
Fuller Benjamin R.
Mitsubishi Denki & Kabushiki Kaisha
Stevens Maurice
Sughrue Mion Zinn Macpeak & Seas, PLLC
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