Breather Line Abnormality Detection Using Intake Flow Second-Order Component
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Solution Overview
Problem
Conventional abnormality determination apparatuses for internal combustion engines often erroneously determine if the breather line connection has come off due to fluctuations in engine load caused by disturbances, affecting the accuracy of pulsation measurements in the intake flow rate.
Innovation Solution
An abnormality determination apparatus that detects the intake flow rate and uses a bandpass filter to extract the rotation second-order component of the fluctuation waveform, accumulating time for which this component exceeds a threshold to precisely determine breather line abnormalities, unaffected by load fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pulsation of the intake flow rate is monitored to determine breather line connection status, then the abnormality can be detected, but the determination may be erroneous when engine load fluctuates due to disturbance
Solution Approach 1:
The fluctuation waveform of the intake flow rate is segmented into multiple frequency components through Fourier analysis. By separating the waveform into rotation first-order components, rotation second-order components, and other frequency components, the system can selectively analyze only the rotation second-order component which is less affected by load fluctuations, thereby improving determination reliability
Solution Approach 2:
The system changes the parameter being monitored from the overall pulsation magnitude to specifically the rotation second-order component's RMS value. This parameter transformation allows the system to focus on frequency components that are characteristic of breather line connection status while filtering out noise from load fluctuations
2Measurement precision
If the rotation second-order component is extracted using Fourier analysis, then the determination precision is improved, but the calculation complexity increases
Solution Approach 1:
The system extracts only the necessary rotation second-order component from the complex fluctuation waveform using Fourier analysis. By taking out only the relevant frequency component and discarding others, the system achieves high measurement precision while keeping the processing focused and manageable
Solution Approach 2:
The system replaces complex mechanical vibration analysis with mathematical Fourier transformation. This substitution allows for precise extraction of specific frequency components through computational methods, achieving high measurement precision with relatively simple digital signal processing
Data Source
AI summary
An abnormality determination apparatus for an internal combustion engine in which an intake passage upstream of a supercharger and a crankcase are connected by a breather line includes: an intake flow rate detection unit that detects an intake flow rate in the intake passage; and an abnormality determination unit that determines abnormality of the breather line. The abnormality determination unit accumulates a time for which a rotation second-order component of a fluctuation waveform of the intake flow rate is equal to or more than a threshold over a predetermined period of time and determines the abnormality of the breather line when the accumulated value is less than a predetermined accumulation threshold.