Internal Combustion Engine Valve Phase Synchronization for Abnormality Diagnosis
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Solution Overview
Problem
Existing abnormality diagnosis methods for internal combustion engines with variable valve timing mechanisms face challenges in accurately diagnosing air-fuel ratio abnormalities due to phase differences between valves in different banks of the engine, leading to erroneous detection of rotation variations.
Innovation Solution
An abnormality diagnosis apparatus that synchronizes the phases of intake valves across both banks of the engine to a most retarded or most advanced phase, allowing for precise diagnosis by eliminating phase differences as a factor in rotation variation, using a detection unit to measure rotation variation and a diagnosis unit to adjust valve phases and detect abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VVT mechanisms are provided for both banks to independently control valve phases according to operating conditions, then engine performance and adaptability are improved, but phase differences between banks cause erroneous abnormality detection
Solution Approach 1:
The diagnosis control unit performs preliminary action by setting both VVT mechanisms to a predetermined phase (e.g., most advanced or most retarded position) before conducting abnormality diagnosis. This preliminary phase alignment eliminates phase differences between banks, ensuring that rotation variation measurements reflect actual cylinder performance rather than valve timing discrepancies, thus resolving the contradiction between adaptability and detection accuracy
2Ease of manufacture
If valve phases are allowed to differ within allowable ranges for each bank, then individual bank optimization is achieved, but rotation variation measurements become unreliable for abnormality diagnosis
Solution Approach 1:
The invention applies parameter changes by dynamically adjusting the phase parameter of VVT mechanisms. During abnormality diagnosis, the diagnosis control unit changes the phase parameter to a predetermined value, temporarily overriding individual bank optimization settings. This parameter adjustment ensures that both banks operate at identical phases during measurement, eliminating phase-induced rotation variations and enabling precise abnormality detection while maintaining manufacturing independence
Data Source
AI summary
An abnormality diagnosis apparatus for an internal combustion engine in which a phase of a first valve provided to a first cylinder is modified within a range extending from a first phase to a second phase and a phase of a second valve provided to a second cylinder is modified within the range includes: a rotation variation amount detection unit that detects a rotation variation amount of an output shaft of the internal combustion engine; and a diagnosis unit that adjusts the phase of the first valve and the phase of the second valve to the first phase, and diagnoses the presence of an abnormality on the basis of the detected rotation variation amount of the output shaft of the internal combustion engine in a state where the phase of the first valve and the phase of the second valve are at the first phase.