Vessel Engine Knocking Control via Intake Limiting
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Solution Overview
Problem
Existing engine systems for vessel propulsion devices struggle to reliably reduce knocking when abnormal conditions occur, such as using fuel with an octane number lower than designated, as they rely on ignition timing retardation which may not suffice, leading to insufficient knocking suppression and repeated engine damage.
Innovation Solution
An engine system with an integrated abnormality judging unit that detects continuous knocking and limits the intake amount to prevent knocking, continuing this limited intake until the engine stops, ensuring consistent operation and reducing engine damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ignition timing is retarded to suppress knocking, then knocking level is reduced, but when abnormality occurs (lower octane fuel), knocking suppression becomes insufficient
Solution Approach 1:
The system changes the control parameter from ignition timing retardation to intake amount limitation when abnormality is detected. The abnormality judging unit monitors knocking levels and detects when retard control becomes insufficient, then the intake amount limiting unit activates to limit the intake amount, providing a different control approach to suppress knocking under abnormal conditions.
Solution Approach 2:
The system implements feedback control by continuously monitoring knocking levels through the knocking sensor and using this information to adjust control strategies. The abnormality judging unit receives feedback on knocking levels and determines when to switch from retard control to intake limitation control, creating a closed-loop system that adapts to changing engine conditions.
2Object-affected harmful factors
If retard control is applied continuously, then knocking is suppressed temporarily, but the retard control margin becomes small and abnormality detection becomes difficult
Solution Approach 1:
The system performs preliminary monitoring of knocking levels and retard control effectiveness before abnormality fully develops. The abnormality judging unit continuously assesses the state of retard control and knocking levels, enabling early detection of abnormal conditions before they cause significant damage, and allows timely switching to intake limitation control.
3Object-affected harmful factors
If intake amount is limited continuously, then knocking is prevented, but engine output is reduced and cruising stability deteriorates
Solution Approach 1:
The system dynamically adjusts the control strategy based on real-time knocking levels and engine conditions. The intake amount limiting unit only activates when abnormality is detected and can adjust the limitation level based on the severity of the abnormal condition, allowing the system to balance knocking prevention with maintaining engine output and cruising stability under normal operating conditions.
Data Source
AI summary
An engine system for a vessel propulsion device includes an engine including an intake amount adjusting unit and an ignition plug, and configured to generate a drive force for the vessel propulsion device. The engine system includes an ignition timing control unit, a knocking detecting unit, a knocking retard control unit that retards the ignition timing of the ignition plug by a unit retard amount when the knocking detecting unit detects knocking, an abnormality judging unit that, when a state where the knocking detecting unit detects knocking at intervals within a predetermined time continues, judges that an abnormality has occurred based on a continued state of knocking detection, and an intake amount limiting unit that limits the intake amount of the engine based on judgment of an abnormality made by the abnormality judging unit.