Dual Spark Plug Control for Pre-Chamber Engine Stability
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Solution Overview
Problem
The combustion state of pre-chamber internal combustion engines becomes unstable, particularly in low load regions where intake airflow decreases, and when there are rapid changes in operating points due to load fluctuations, EGR introduction, and other factors.
Innovation Solution
A control device that manages combustion modes by using a first spark plug in the pre-chamber for steady-state ignition and a second spark plug in the combustion chamber for ignition during operating point changes, transitioning through a third combustion mode that uses both spark plugs after the point transition is completed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If pre-chamber ignition is used in steady state to improve thermal efficiency, then combustion energy is efficiently converted into pressure, but combustion state becomes unstable when operating point changes rapidly
Solution Approach 1:
The system dynamically switches between pre-chamber ignition mode and direct combustion chamber ignition mode based on operating conditions. When operating point changes are detected (load fluctuation, EGR introduction), the system transitions to direct ignition mode to maintain combustion stability, then returns to pre-chamber ignition mode when steady state is restored, optimizing both efficiency and reliability
Solution Approach 2:
The ignition system changes its operational parameters by switching between two distinct ignition modes. The control device monitors operating parameters and adjusts the ignition method accordingly, changing from pre-chamber spark ignition to direct combustion chamber spark ignition to adapt to varying operating conditions and prevent combustion instability
2Object-affected harmful factors
If fuel injection timing is delayed to suppress preignition in low load region, then preignition is suppressed, but fuel-air mixture is not sufficiently mixed and combustion becomes unstable
Solution Approach 1:
The pre-chamber acts as an intermediary combustion zone that improves fuel-air mixing before the main combustion event. By introducing a separate pre-chamber ignition process, the system achieves better mixture preparation and combustion stability without requiring delayed main fuel injection timing, thus suppressing preignition while maintaining reliable combustion
3Device complexity
If single spark plug ignition is used to simplify the system, then device complexity is reduced, but combustion state becomes unstable during operating point transitions
Solution Approach 1:
The ignition system achieves multi-functionality by incorporating both pre-chamber spark plug and combustion chamber spark plug. This dual-spark configuration provides universal ignition capability across different operating conditions, enabling the system to maintain combustion stability during both steady-state operation and transient operating point changes
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 configuration ensures stable combustion by rapidly transitioning through combustion modes in response to operating point changes, minimizing thermal efficiency reduction and preventing unstable combustion states.
Implementation Method 1
igniting the fuel-air mixture flowing into the pre-chamber through the communication hole in the pre-chamber by a compression stroke
Implementation Method 2
ignition is performed by a spark plug in the pre-chamber
Implementation Method 3
ignition is performed by a spark plug in a main combustion chamber
Implementation Method 4
ignition is performed by a spark plug in the pre-chamber and the second ignition means in the combustion chamber
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
[Problem to be Solved] The combustion state is prevented from becoming unstable when an operating point fluctuates in a pre-chamber internal combustion engine. [Solution] In an internal combustion engine including: a combustion chamber; a pre-chamber communicating with an upper center part of the combustion chamber via an injection hole; a fuel injection valve that injects fuel into an intake passage; first ignition means that faces an inside of the pre-chamber; and second ignition means that faces the combustion chamber, the control device is configured to perform: (i) a first combustion mode that performs ignition in the pre-chamber (50) by the first ignition means (5) in a steady state, (ii) transition to a second combustion mode that performs ignition in the combustion chamber (20) by the second ignition means (7) when a change in an operating point is determined in the steady state; (iii) transition to a third combustion mode that performs ignition by both of the first ignition means (5) and the second ignition means (7) when transition of the operating point is completed and it is determined that combustion of the second combustion mode is stable, and (iv) transition to the first combustion mode when it is determined that combustion of the third combustion mode is stable.