Gas Engine Knocking Control via Ignition Timing Delay Calculation
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Solution Overview
Problem
The existing knocking control systems for gas engines face instability in knocking occurrence ratios, leading to unstable engine operation and insufficient knocking suppression, especially when the threshold is set high to avoid significant changes in fuel feed and ignition timing, which can result in underestimation of knocking occurrence and reduced engine driving power.
Innovation Solution
A knocking control system that includes an ignition device, a knocking detector, a phase angle detector, and a controller that calculates a knocking occurrence ratio using a delay calculation based on past data to adjust the ignition timing, allowing for stable operation and desired engine driving power by retarding or advancing the ignition timing according to the calculated deviation from a target value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the threshold for knocking occurrence ratio is set larger to avoid significant changes in fuel feed amount and ignition timing, then the engine operation stability is improved, but the knocking suppression capability deteriorates
Solution Approach 1:
The system performs delay calculation on the knocking occurrence ratio to predict future knocking trends before they fully manifest. By calculating the occurrence ratio delay value based on historical data, the system proactively adjusts ignition timing to prevent knocking before it becomes severe, rather than reacting to current knocking levels alone.
Solution Approach 2:
The system establishes a closed-loop feedback mechanism where the knocking occurrence ratio is continuously monitored, compared against the threshold, and used to adjust ignition timing. The feedback loop includes delay calculation to smooth out fluctuations and prevent overreaction, ensuring stable yet responsive knocking control.
2Reliability
If the fuel feed amount is reduced to suppress knocking occurrence, then the knocking suppression capability is improved, but the engine driving power deteriorates
Solution Approach 1:
Instead of changing the fuel feed amount, the system changes the ignition timing parameter to suppress knocking. By adjusting the ignition timing based on the knocking occurrence ratio and its delay value, the system achieves knocking suppression while maintaining fuel injection levels that preserve engine driving power.
3Reliability
If the ignition timing is frequently adjusted to respond to knocking occurrence ratio changes, then the knocking suppression capability is improved, but the engine operation stability deteriorates
Solution Approach 1:
The system performs delay calculation on the knocking occurrence ratio to smooth out short-term fluctuations before using it for ignition timing adjustment. This preliminary processing of the knocking data prevents overreaction to temporary variations and ensures more stable engine operation.
Solution Approach 2:
The system dynamically adjusts the ignition timing based on the relationship between the current knocking occurrence ratio and its delay value. When the current ratio exceeds the threshold while the delay value remains below it, indicating a sudden change, the system responds appropriately while maintaining overall stability through controlled adjustment rather than frequent large changes.
4Power
If a high threshold is set for knocking occurrence ratio to maintain engine power, then the engine driving power is maintained, but the knocking detection accuracy deteriorates
Solution Approach 1:
The system performs delay calculation to predict knocking trends before they become severe. This allows the use of a higher threshold for normal operation while still detecting emerging knocking issues through the delay value, which reflects historical patterns and can signal problems before they exceed the threshold.
Solution Approach 2:
The occurrence ratio delay value acts as an intermediary indicator between the current knocking occurrence ratio and the threshold comparison. It provides an additional layer of detection that can signal potential knocking issues even when the current ratio remains below the threshold, thereby improving detection accuracy without requiring a lower threshold.
Data Source
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AI summary
A knocking control system (20) for a gas engine (1) of the present invention, being configured to calculate a knocking occurrence ratio (SEV) which is a ratio of a cycle number of cycles in which a predetermined knocking occurs for a period of the cycles of the predetermined cycle number, to the predetermined cycle number, decide a target value of an ignition timing of the ignition device based on a deviation (ΔSEV) between an occurrence ratio delay calculation value (SEVAVE) obtained by performing delay calculation of the knocking occurrence ratio and a predetermined occurrence ratio target value (SEVSET), and drive the ignition device so that the ignition timing reaches a command value (IGN) decided according to the target value.