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 may 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 calculates the rotation second-order component of the intake flow rate's fluctuation waveform, accumulates instances where this component exceeds or falls below specific thresholds, and compares these values with the engine's crank revolutions to precisely determine breather line abnormalities, unaffected by load fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional abnormality determination apparatus monitors the magnitude of the pulsation of the intake flow rate to determine whether the connection portion of the breather line has come off, then the determination can be made based on simple measurement, but the determination may be erroneous when the load on the internal combustion engine temporarily fluctuates due to disturbance or the like
Solution Approach 1:
The patent extracts the rotation second-order component from the fluctuation waveform of the intake flow rate using frequency analysis. This separates the useful signal (rotation second-order component related to breather line status) from the harmful signal (fluctuations caused by load changes), enabling accurate abnormality determination even when the overall pulsation magnitude fluctuates due to disturbance.
Solution Approach 2:
The patent performs preliminary frequency analysis to calculate the rotation second-order component before making the abnormality determination. By pre-processing the intake flow rate signal to isolate the relevant frequency component, the system prepares a stable basis for determination that is not affected by subsequent load fluctuations or disturbance.
2Device complexity
If the pulsation of the intake flow rate is monitored to determine breather line connection status, then the determination process is simple, but the determination is affected by load fluctuation on the engine
Solution Approach 1:
The patent extracts the rotation second-order component from the fluctuation waveform of the intake flow rate using frequency analysis. This separates the useful signal (rotation second-order component related to breather line status) from the harmful signal (fluctuations caused by load changes), enabling accurate abnormality determination even when the overall pulsation magnitude fluctuates due to disturbance.
Solution Approach 2:
The patent changes the parameter used for determination from the overall pulsation magnitude to the rotation second-order component of the fluctuation waveform. This parameter transformation allows the system to maintain determination capability while becoming insensitive to load-induced fluctuations, as the rotation second-order component remains stable under varying load conditions.
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 calculates a rotation second-order component of a fluctuation waveform of the intake flow rate, accumulates a first number of times for which the rotation second-order component exceeds an upper threshold and a second number of times for which the rotation second-order component falls below a lower threshold, and determines the abnormality of the breather line by comparing an accumulated value of the first number of times and the second number of times with the number of revolutions of a crank.