Dynamic Threshold Intake Valve Diagnosis
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Solution Overview
Problem
Diagnostic systems for internal combustion engines with variable intake valve mechanisms fail to accurately diagnose reduced intake air amount abnormalities, as they do not account for changes in the working angle of the intake valve, leading to incorrect assessments during catalyst early warm-up control.
Innovation Solution
A diagnostic system and method that adjusts the abnormality determination threshold based on the mode and amount of change in the working angle of the intake valve, using an index value such as the accumulated intake air amount, to correctly diagnose reductions in intake air during idle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the working angle of the intake valve is changed to facilitate fuel and air mixing, then combustion efficiency is improved and misfire is suppressed, but the required intake air amount changes, leading to incorrect abnormality diagnosis
Solution Approach 1:
The patent applies dynamics by making the abnormality determination threshold dynamic rather than fixed. The threshold is adjusted based on the actual working angle of the intake valve, allowing the diagnostic system to adapt to changing operating conditions. This resolves the contradiction by enabling accurate diagnosis across different valve angles while maintaining combustion stability through proper threshold selection.
Solution Approach 2:
The patent changes the parameter of the abnormality determination threshold based on the working angle parameter. By establishing a relationship between the intake valve working angle and the appropriate threshold value, the system can accurately diagnose intake air amount abnormalities regardless of whether the valve angle is narrowed for better mixing or kept wide for other operational requirements.
2Device complexity
If the abnormality determination threshold is kept fixed for simple diagnosis, then diagnostic system complexity is reduced, but diagnosis accuracy deteriorates when working angle changes
Solution Approach 1:
The patent implements parameter changes by adjusting the abnormality determination threshold according to the working angle of the intake valve. Rather than using a single fixed threshold, the system selects appropriate threshold values based on the current valve angle state, thereby maintaining diagnosis accuracy across varying operating conditions without requiring overly complex diagnostic logic.
Solution Approach 2:
The patent achieves universality by creating a diagnostic threshold system that works across multiple operating conditions. The same diagnostic framework can handle both narrowed and wide valve angle scenarios by simply adjusting the threshold parameter, making the system universally applicable to different intake air amount conditions without requiring separate diagnostic paths for each scenario.
Data Source
AI summary
An internal combustion engine includes a variable mechanism that changes a working angle of an intake valve. A controller diagnoses whether there is an abnormality that an intake air amount reduces during idle operation. The controller changes an abnormality determination threshold for diagnosing an abnormality on the basis of a mode in which the working angle is changed by the variable mechanism.