Valve Ignition Prechamber Combustion Stability
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Solution Overview
Problem
Spark ignition engines face challenges in achieving efficient combustion when operating with high levels of cooled Exhaust Gas Recirculation (EGR), leading to increased misfires, reduced thermodynamic efficiency, and higher unburned hydrocarbons and carbon monoxide emissions due to the difficulty in initializing and developing combustion in a diluted and oxygen-poor environment.
Innovation Solution
The valve ignition prechamber design, which includes a lamination cavity, a lamination valve, and gas ejection holes, allows for the injection of a pilot load into a prechamber that maintains the pilot load close to the spark plug electrodes, preventing dispersion and overheating, and uses a lamination valve to control gas flow, ensuring efficient ignition and rapid combustion development by directing hot gas torches into the main combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cooled EGR is introduced into the combustion chamber to improve thermodynamic efficiency and reduce NOx emissions, then the combustion initialization becomes difficult and misfires increase
Solution Approach 1:
The combustion chamber is segmented into a prechamber and a main chamber. The prechamber serves as a separate ignition zone where combustion can be reliably initialized with a small pilot load, while the main chamber receives the diluted air-fuel mixture. This segmentation allows the prechamber to maintain reliable ignition conditions independent of the high EGR rates in the main chamber.
Solution Approach 2:
The prechamber acts as an intermediary between the spark plug and the main combustion chamber. It receives a small amount of pilot load, ignites it reliably, and then uses the resulting hot gas torches to ignite the main diluted charge. This intermediary structure bridges the gap between the ignition source and the difficult-to-ignite diluted mixture.
2Reliability
If a prechamber is used to improve ignition efficiency with diluted loads, then the pilot load may disperse and overheat, reducing ignition efficiency
Solution Approach 1:
The prechamber incorporates a movable valve that dynamically controls the connection between the prechamber and the main combustion chamber. During the ignition phase, the valve closes to confine the pilot load and prevent dispersion. During the power stroke, the valve opens to allow hot gas torches to exit and ignite the main charge. This dynamic control optimizes both ignition efficiency and temperature management.
Solution Approach 2:
The prechamber valve operates periodically, closing during the compression and ignition phases to contain the pilot load, and opening during the expansion phase to release hot gases. This periodic action ensures that the pilot load remains confined and does not overheat, while still enabling effective ignition of the main charge at the appropriate time.
3Reliability
If the prechamber valve opens early to release hot gases, then the pilot load disperses and ignition efficiency decreases, but if it opens late, then combustion development is delayed
Solution Approach 1:
The prechamber valve operation is synchronized with the engine's combustion cycle through feedback from the crankshaft position sensor. The valve closes at the precise moment needed to contain the pilot load during ignition, and opens at the optimal moment to release hot gases for main charge ignition. This feedback-based timing control ensures both efficient ignition and rapid combustion development without premature dispersion or delayed ignition.
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 design enhances the ignition efficiency, reduces energy consumption, minimizes the pilot load's mass and pressure, prevents overheating, and maintains combustion stability even at high EGR rates, leading to improved thermodynamic efficiency and reduced emissions.
Implementation Method 1
a spark plug (12) which can ignite the pilot load (9)
Implementation Method 2
the combustion of the pilot load (9) heats up the prechamber (23) until the latter reaches a predetermined temperature
Implementation Method 3
when the pressure in said prechamber (23) reaches a value which is higher by a predetermined amount than the pressure in said combustion chamber (5), said lamination valve (13) automatically opens
Data Source
AI summary
Disclosed is a valve ignition prechamber for an internal combustion engine which includes a combustion chamber in which a main load more or less diluted with a neutral gas is ignited, the prechamber including a lamination cavity into which an ignition unit opens and in which a lamination injector can inject under pressure an easily flammable pilot load, a lamination valve being able to close all or part of the lamination duct, in particular under the effect of the pressure of the gases prevailing in the combustion chamber.