Dual-Fuel Engine Ignition Timing Control for Knock Prevention
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Solution Overview
Problem
Dual-fuel engines operating in premixed combustion mode face challenges in maintaining a proper air-fuel ratio, leading to knocking or misfires, which can cause engine instability and damage due to delayed ignition timing, especially in large engines with slow air supply response.
Innovation Solution
The engine device implements a control system that adjusts ignition timing based on measured intake manifold pressure and flow rate, determining air sufficiency and applying multiple-step retard or advance controls to prevent knocking and maintain combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ignition timing is retarded to avoid knocking, then knocking is reduced, but combustion efficiency deteriorates
Solution Approach 1:
The ignition timing is made dynamically adjustable through multi-step retard control. The control unit adjusts ignition timing in multiple discrete steps (first step, second step, third step) based on the degree of air insufficiency detected by the air amount predicting device. This dynamic adjustment allows the system to optimize the balance between preventing knocking and maintaining combustion efficiency under varying operating conditions.
Solution Approach 2:
The system changes the ignition timing parameter in multiple discrete steps rather than continuous adjustment. The air amount predicting device detects air insufficiency and triggers corresponding levels of ignition timing retardation. This parameter change approach enables precise control over the trade-off between knocking prevention and combustion efficiency preservation.
2Stability of the object's composition
If multiple-step retard control is applied to prevent knocking, then engine stability is improved, but control complexity increases
Solution Approach 1:
The control system segments the ignition timing adjustment into multiple discrete steps (first step retard, second step retard, third step retard) rather than continuous adjustment. Each step corresponds to a specific level of air insufficiency detected by the air amount predicting device. This segmentation simplifies the control logic while achieving stable engine operation under varying air supply conditions.
Solution Approach 2:
The air amount predicting device provides continuous feedback on the air supply status to the control unit. Based on this feedback, the control unit automatically adjusts ignition timing through the appropriate retard step. This closed-loop feedback mechanism maintains engine stability without requiring complex manual intervention or overly sophisticated control algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach stabilizes engine operation by predicting air amount surpluses and shortages, reducing knocking occurrences and preserving combustion efficiency, even in large engines with slow air supply response.
Implementation Method 1
a pressure sensor configured to measure an intake manifold pressure
Implementation Method 2
the controlling unit predicts a surplus or a shortage of an air amount in the intake manifold, based on a difference between the target value of the intake manifold pressure and the measured intake manifold pressure
Implementation Method 3
an igniter configured to ignite, in the cylinder, premixed fuel obtained by pre-mixing the gaseous fuel with the air
Data Source
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AI summary
An object is to provide an engine device that can achieve stable operation and suppress deterioration in the thermal efficiency at the same time. An engine device of the present invention includes: an intake manifold 67 configured to supply air into a cylinder 36, a gas injector 98 configured to mix fuel gas with air supplied from the intake manifold 67, and supply mixed gas to the cylinder 36, and an igniter 79 configured to ignite, in the cylinder 36, premixed fuel obtained by pre-mixing the fuel gas with the air, the engine device including a controlling unit 73 configured to determine insufficiency in an air amount in the premixed fuel in the cylinder 36. The controlling unit 73 performs in multiple steps retard control of ignition timing by the igniter 79, when the air amount is determined as to be insufficient, and performs in multiple steps advance control of the ignition timing, when the air amount is determined as to be sufficient.