Misfire Detection via Ignition Timing Reference Correction
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Solution Overview
Problem
Existing misfire detection apparatuses for internal combustion engines fail to accurately determine misfires due to the influence of inertia speed changing components and do not consider varying engine operating conditions, leading to potential inaccuracies in misfire detection.
Innovation Solution
A misfire detecting apparatus that calculates corrected rotational speed parameters by accounting for inertia speed changing components and sets reference timings based on ignition timing, allowing for accurate misfire determination across different engine operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the rotation change is calculated corresponding to the ignition timing without considering the inertia speed changing component, then the calculation is simple, but the accuracy of the calculated rotation change deteriorates when ignition timing changes
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference timing based on ignition timing. When ignition timing changes, the system modifies the reference timing parameter to compensate for the inertia speed changing component's influence, thereby maintaining measurement precision without significantly increasing calculation complexity
Solution Approach 2:
The patent introduces an intermediary correction mechanism that calculates the inertia speed changing component and uses it to correct the rotation change measurement. This intermediary approach allows the system to maintain accuracy by accounting for the inertia effect without fundamentally changing the measurement methodology
2Device complexity
If the misfire determination is performed only during the warming-up operation, then the detection is simplified, but the adaptability to different engine operating conditions deteriorates
Solution Approach 1:
The patent applies universality by making the misfire detection system applicable to multiple operating conditions (warming-up, accelerating, decelerating) through a unified correction mechanism. The same detection algorithm works across different conditions when the reference timing is appropriately adjusted for each condition, eliminating the need for separate detection systems for each operating mode
3Ease of operation
If the reference timing is set to a constant timing regardless of ignition timing, then the system is simple to operate, but the misfire determination accuracy deteriorates when ignition timing changes
Solution Approach 1:
The patent applies dynamics by making the reference timing dynamic rather than static. The reference timing automatically adjusts based on the ignition timing, allowing the system to adapt to changing operating conditions without requiring manual intervention or complex user input, thus maintaining ease of operation while improving accuracy
Data Source
AI summary
A misfire detecting apparatus is provided wherein a misfire is detected based on a rotational speed parameter indicative of a rotational speed of an internal combustion engine. An average change amount of the rotational speed parameter in a first predetermined period and an inertia speed changing component which is generated with rotation of the engine are calculated, and a first corrected rotational speed parameter is calculated by correcting the rotational speed parameter according to the average change amount and the inertia speed changing component. A first relative speed parameter is calculated according to a difference between a first reference value and the first corrected rotational speed parameter, the first reference value being the first corrected rotational speed parameter corresponding to the rotational speed parameter which is detected at a reference timing at which a piston of a cylinder, which is subjected to the misfire determination, is positioned in the vicinity of the compression top dead center. A first determination parameter is calculated by integrating the first relative speed parameter for an integration period corresponding to 720/N degrees of a crank angle (“N” is a number of cylinders of the engine), and a misfire determination is performed based on the first determination parameter. The reference timing and a start timing of the integration period are set according to the ignition timing of the engine.