Misfire Detection via Inter-Cylinder Frequency Analysis
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Solution Overview
Problem
Conventional misfire detection systems in internal combustion engines face accuracy issues due to noise disturbances, which can lead to false detection of misfires when noise frequencies coincide with ignition cycles.
Innovation Solution
A misfire detection device that includes a rotation acquisition unit, an analysis unit for frequency analysis, and an inter-cylinder determination unit to differentiate between misfire and noise by comparing the inter-cylinder component with a threshold, using the frequency analysis of rotation signals and angular acceleration signals to accurately determine misfire occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency analysis is performed on rotation signal to detect misfire, then misfire detection capability is improved, but false detection increases when noise frequency coincides with ignition cycle
Solution Approach 1:
The patent segments the frequency spectrum into multiple frequency bands, analyzing the rotation signal in different frequency ranges separately. By dividing the frequency analysis into multiple bands, the system can identify the specific frequency component corresponding to the ignition cycle and distinguish it from noise in other frequency ranges, thereby reducing false detections while maintaining misfire detection accuracy.
Solution Approach 2:
The patent applies local quality by focusing analysis on specific frequency characteristics rather than the entire spectrum. It identifies and emphasizes the frequency component corresponding to the ignition cycle while suppressing or ignoring other frequency components that may contain noise. This selective focus on the relevant frequency band improves detection reliability without sacrificing accuracy.
2Ease of operation
If conventional misfire detection compares ignition cycle frequency with transition cycle frequency, then detection simplicity is maintained, but detection accuracy decreases under noise disturbance
Solution Approach 1:
The patent changes the detection parameter from a simple frequency comparison to a multi-band frequency spectrum analysis. Instead of merely comparing the magnitude of ignition cycle frequency with transition cycle frequency, the system analyzes the distribution of energy across multiple frequency bands and identifies characteristic patterns. This parameter transformation maintains operational simplicity through automated processing while significantly improving detection accuracy under noisy conditions.
Data Source
AI summary
A rotation acquisition unit acquires a rotation signal correlated with a rotational state of an internal combustion engine. An analysis unit performs frequency analysis of the rotation signal acquired with the rotation acquisition unit. An inter-cylinder determination unit determines whether an inter-cylinder component is smaller than an inter-cylinder threshold representing occurrence of misfire. The inter-cylinder component is a frequency component of an inter-cylinder cycle. The inter-cylinder cycle is computed by dividing an ignition cycle, which is one burning cycle of the internal combustion engine, by a number of cylinders of the internal combustion engine.