Measuring and testing – Vehicle chassis – Steering
Patent
1994-02-02
1998-09-15
Chilcot, Richard
Measuring and testing
Vehicle chassis
Steering
G01M 1500
Patent
active
058081860
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for detecting a misfire by the fluctuation in crankshaft rotation and more particularly, to a method for detecting a misfire in which the occurrence of the misfire can be detected exactly by eliminating the detection error in detecting the fluctuation in crankshaft rotation which detection error is caused by the error in the construction of a crank angle sensor.
BACKGROUND ART
If a misfire condition, in which combustion in a cylinder is not performed properly, occurs during the operation of an internal combustion engine due to the failure of fuel injector or the like, the exhaust gas characteristic or the like of the internal combustion engine is deteriorated. To combat this problem, the information corresponding to the number of revolutions or rotation speed is calculated on the basis of the period of each predetermined crank angle corresponding to each cylinder of an engine, and the misfire condition of engine is detected on the basis of the change amount or change rate of this information, as disclosed in Japanese Unexamined Patent Publication No. H2-49955, etc. According to Japanese Unexamined Patent Publication No. H2-49955, if a misfire is detected on the basis of the deviation of the rotational angular velocity of the internal combustion engine from the rotational angular velocity before one firing as the reference angular velocity, that is, the rotational fluctuation, which is calculated for each firing interval in synchronization with the combustion stroke in the internal combustion engine, it cannot be detected as so exactly when random misfire occurs or when a misfire occurs approximately once for several revolutions. In Japanese Unexamined Patent Publication No. H2-49955, therefore, the reference angular velocity is renewed as necessary.
As described above, the period of the predetermined crank angle is detected by using a crank angle sensor. The crank angle sensor typically includes a rotating member which has a plurality of vanes or protrusions disposed at equal angular intervals and is mounted to the crankshaft for rotation in unison therewith, and a detecting portion which is so disposed as to face the rotating member and detects the passage of the vane. The vane of the rotating member protrudes in the radial direction at the periphery of the rotating member. The number of vanes corresponds to the number of engine cylinders; for example, the crank angle sensor for a 6-cylinder engine has three vanes. With the crank angle sensor of such a construction, when the end of one of the adjacent vanes passes through the detecting portion as the engine rotates, the entering of crankshaft into the crankshaft rotational angle region corresponding to that vane is detected, and when the end of the other vane passes through the detecting portion, the leaving of crankshaft from that region is detected. Thus, the time interval from the time of entering the angle region to the time of leaving the region, that is, the period is detected. Further, the crankshaft rotational speed at the crankshaft rotational angle region is calculated on the basis of the detected period. Then, a determination as to whether the misfire occurs is made based on the magnitude of the change in rotational speed.
In such a method for detecting a misfire, the accuracy in detecting period, that is, the accuracy in detecting the misfire depends on the vane angle interval at the crank angle sensor, that is, the length in the vane circumferential direction. Nevertheless, an error in the construction of crank angle sensor, particularly an error in manufacturing and installing the vane, is inevitable, so that variations are produced in the vane angle intervals, thereby the accuracy in detecting a misfire being decreased. When the vane angle interval is larger than the design value, the crankshaft rotation at this angle region requires much time. Therefore, it is sometimes judged by mistake that the crankshaft rotational speed has decreased at that angle region, so that the occurre
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Hashimoto Toru
Kasai Satoshi
Matsumoto Takuya
Miyake Mitsuhiro
Nakajima Hiroyuki
Chilcot Richard
McCall Eric S.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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