Engine Misfire Detection During Ignition Retardation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control apparatuses for internal combustion engines incorrectly determine misfires when the ignition timing is intentionally retarded, as the torque decrease is misinterpreted as a misfire, leading to erroneous diagnoses and increased processing load.
Innovation Solution
A control apparatus that decides a basic ignition timing based on engine load, calculates torque, determines misfires using a second threshold smaller than the first during retardation processes, and considers air-fuel ratios to accurately assess misfire occurrence, thereby reducing erroneous determinations and processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the ignition timing is controlled toward a retardation side from the basic ignition timing, then the torque generated on the output shaft becomes smaller, but it may be erroneously determined that a misfire has occurred
Solution Approach 1:
The patent applies dynamics by making the misfire determination threshold dynamic rather than fixed. The threshold is adjusted based on whether the ignition timing is at the basic timing or retarded, allowing the system to adapt to different operating conditions. When ignition timing is retarded, a different threshold criterion is used to prevent false misfire detection while maintaining detection accuracy under normal conditions.
2Measurement precision
If a threshold is set as an upper-limit of a range of a torque at which a misfire can be regarded as having occurred, then misfire can be detected, but erroneous determination occurs when ignition timing is intentionally retarded
Solution Approach 1:
The patent applies parameter changes by modifying the torque threshold parameter based on the ignition timing condition. When ignition timing is retarded, the system changes the threshold parameter to a value that accounts for the expected torque reduction, preventing false misfire determination. This dynamic parameter adjustment allows accurate misfire detection while avoiding erroneous results during intentional retardation.
3Reliability
If misfire determination is performed continuously, then accurate misfire detection is maintained, but processing load increases during retardation processes
Solution Approach 1:
The patent applies periodic action by making the misfire determination process conditional rather than continuous. The system periodically evaluates whether ignition timing is at the basic timing or retarded, and only performs full misfire determination when appropriate. This conditional periodic execution maintains detection reliability while reducing unnecessary processing during retardation phases.
Data Source
AI summary
An internal combustion engine of a vehicle is equipped with a plurality of cylinders, and ignition devices provided for the cylinders respectively. The vehicle is mounted with an ECU. The ECU performs an ignition timing decision process for deciding a basic ignition timing of the ignition devices in accordance with a load of the internal combustion engine. The ECU performs a misfire determination process for determining that a misfire has occurred on a condition that the torque has decreased below a threshold set in advance. The ECU performs a retardation process for controlling an ignition timing toward a retardation side from the basic ignition timing when a state of the vehicle satisfies a condition determined in advance. A determination on the occurrence of a misfire based on a relationship in magnitude between the torque and the threshold is not made during the retardation process, in the misfire determination process.