Air-Assisted Jet Flame Ignition for High EGR Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High exhaust gas recirculation (EGR) rates in internal combustion engines lead to unstable combustion and decreased flame propagation speed, making it difficult to achieve reliable ignition and efficient combustion.
Innovation Solution
An air-assisted jet flame ignition device with a fuel-air premixing unit is introduced, which includes a fuel injector, air injection valve, and premixing sleeve to create a premixed fuel-air mixture that is ignited in a prechamber, generating flame jets to stabilize combustion in the main combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If high EGR rate is applied to reduce NOx emissions, then NOx emissions are reduced, but combustion stability deteriorates and flame propagation speed decreases
Solution Approach 1:
The combustion chamber is divided into a prechamber and a main chamber. The prechamber serves as a separate ignition source that generates high-velocity flame jets, which then propagate into the main combustion chamber. This segmentation allows the prechamber to operate under different conditions (with sufficient oxygen and fuel) compared to the main chamber (with high EGR and lean mixture), thereby maintaining combustion stability even at high EGR rates
Solution Approach 2:
Fuel is injected into the prechamber before the main combustion event, and a spark plug ignites this pre-charged mixture. This preliminary action creates a ready-to-burn charge in the prechamber that, when ignited, produces intense flame jets that rapidly propagate into the main combustion chamber, ensuring reliable ignition and stable combustion under high EGR conditions where direct ignition would fail
2Object-generated harmful factors
If high EGR rate is applied to reduce NOx emissions, then NOx emissions are reduced, but flame propagation speed decreases
Solution Approach 1:
The combustion process is segmented into two stages: first, rapid combustion in the prechamber generates high-velocity flame jets; second, these flame jets propagate into the main combustion chamber. The prechamber acts as a flame acceleration device, producing jet velocities that significantly enhance the overall flame propagation speed in the main chamber, counteracting the retarding effect of high EGR rates
Solution Approach 2:
The invention changes the physical parameters of the combustion process by creating a separate prechamber environment with different pressure, temperature, and mixture composition compared to the main chamber. The prechamber maintains a more favorable mixture for rapid combustion, and the resulting high-velocity flame jets (achieved through pressure differential and geometric design) dramatically increase the flame propagation speed in the main combustion chamber
3Reliability
If fuel-air premixing unit is added to achieve reliable ignition in high EGR conditions, then ignition reliability is improved, but device complexity increases
Solution Approach 1:
The prechamber serves multiple functions simultaneously: it acts as a fuel-air mixing chamber, an ignition chamber for the spark plug, a reservoir for generating flame jets, and a flow control element. By integrating these functions into a single component, the invention achieves reliable ignition in high EGR conditions without proportionally increasing overall device complexity
Solution Approach 2:
The fuel injector and air injection valve are nested within or around the prechamber structure, with the premixing sleeve integrated into the prechamber wall. This nested arrangement allows multiple functional elements to occupy overlapping or adjacent spaces, reducing the overall volume and component count while maintaining the necessary fuel-air premixing and ignition functions
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
The device ensures stable ignition and improved combustion efficiency in high EGR conditions by injecting a premixed fuel-air mixture into the prechamber, utilizing high ignition energy from the jet flame to ignite the main combustion chamber, while reducing the device size and minimizing fuel wall-wetting.
Implementation Method 1
a fuel-air premixing unit, wherein an inner wall surface of the premixing sleeve and an outer wall surface of the premixing sleeve inner core form a premixing sleeve inner cavity
Implementation Method 2
a spark plug in a prechamber cavity body to ignite a prechamber charge to inject flame jets into a main combustion chamber
Implementation Method 3
ignite a prechamber charge to inject flame jets into a main combustion chamber, thus achieving stable combustion
Implementation Method 4
air-assisted jet flow ignition device
Data Source
AI summary
An air-assisted jet flame ignition device includes a housing, a fuel-air premixing unit, and a prechamber. The fuel-air premixing unit includes a fuel injector, an air injection valve, a premixing sleeve, a premixing sleeve inner core placed in the premixing sleeve, and a fuel injector fastening bolt. An inner wall surface of the premixing sleeve and an outer wall surface of the premixing sleeve inner core form a premixing sleeve inner cavity. An inner wall surface of the premixing sleeve inner core, a lower end surface of a nozzle of the fuel injector, and an upper end surface of an air inlet of the air injection valve form a premixing cavity. The premixing cavity coupled to the premixing sleeve inner cavity via a through hole on the sidewall of the premixing sleeve inner core. A prechamber nozzle is fixedly coupled to the lower part of the housing.