Air-Fuel Ratio Imbalance Detection in Variable Working Angle Engines
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Solution Overview
Problem
In multi-cylinder internal combustion engines with variable working angles, existing methods for detecting air-fuel ratio imbalances are prone to erroneous determinations, particularly when the working angle is large, leading to insufficient detection accuracy.
Innovation Solution
A detecting apparatus and method that refrains from determining normal air-fuel ratios when the working angle is within a predetermined large range and determines normalcy only when the working angle is within a small range, using a parameter regarding rotational fluctuations to accurately detect imbalances caused by decreasing deviations in the working angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parameter detection is performed regardless of working angle, then detection coverage is maintained, but erroneous determinations occur when working angle is large
Solution Approach 1:
The detection method changes based on the working angle parameter. When the working angle is within the large working angle range, the system refrains from determining normal air-fuel ratios, while when it is within the small working angle range, determination is performed. This parameter-based adaptation resolves the contradiction by adjusting detection behavior according to working angle conditions.
2Adaptability or versatility
If determination is performed at all working angles, then detection coverage is maximized, but detection accuracy deteriorates due to erroneous determinations
Solution Approach 1:
The detection system applies different quality standards based on local working angle conditions. In the large working angle range, determination is restrained to avoid erroneous results, while in the small working angle range, full determination is performed. This local differentiation ensures high detection accuracy where conditions permit while maintaining appropriate detection coverage.
Data Source
AI summary
A detecting apparatus that detects an abnormality of imbalance of air-fuel ratios among cylinders of a multi-cylinder internal combustion engine, which is equipped with a variable working angle mechanism of an intake valve, the detecting apparatus includes an abnormality detection portion that detects a parameter regarding rotational fluctuations of each of the cylinders and detects whether or not there is an abnormality of imbalance of air-fuel ratios among the cylinders. The abnormality detection portion refrains from determining that the air-fuel ratios are normal when the working angle at the time of detection of the parameter is within a predetermined large working angle range, and determines that the air-fuel ratios are normal when the working angle at the time of detection of the parameter is within a predetermined small working angle range that is on a small working angle side with respect to the large working angle range.