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, leading to inaccurate results.
Innovation Solution
An abnormality determination apparatus that uses an intake flow rate detection unit and an abnormality determination unit to accumulate the rotation second-order component of the intake flow rate's fluctuation waveform over a predetermined period, determining the breather line's abnormality based on this value, which is less affected by load fluctuations, and optionally calculates the absolute value or difference between maximum and minimum values of the rotation second-order component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pulsation of the intake flow rate is monitored to determine breather line connection status, then the determination can be made based on resonant frequency changes, but the determination becomes inaccurate 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 isolating and analyzing only the rotation second-order component, the system separates the relevant diagnostic information from irrelevant load fluctuation effects, enabling accurate abnormality determination even when overall engine load changes.
Solution Approach 2:
The system changes the parameter being monitored from the overall pulsation magnitude to specifically the rotation second-order component frequency and magnitude. This parameter transformation allows the system to focus on the resonant frequency characteristics that remain stable under load fluctuation, while filtering out the variable low-order components affected by engine load changes.
2Device complexity
If the overall pulsation of intake flow rate is used for abnormality determination, then the method is simple to implement, but it produces erroneous determination results when load fluctuates
Solution Approach 1:
The system dynamically adapts the analysis by continuously tracking the rotation second-order component through real-time Fourier analysis of the intake flow rate waveform. This dynamic approach allows the system to maintain accurate abnormality determination despite changing operating conditions, as it continuously updates the frequency component analysis rather than relying on fixed thresholds.
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 value calculated from a rotation second-order component of a fluctuation waveform of the intake flow rate over a predetermined period of time and determines the abnormality of the breather line when the accumulated value is less than a predetermined threshold.