Offset Combustion Pre-Chamber for Residual Gas Purging
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Solution Overview
Problem
Internal combustion engines with conventional combustion pre-chambers face challenges in purging residual gases and combustion byproducts, especially when using exhaust gas recirculation (EGR), which can lead to misfires and reduced combustion stability, particularly in fuel lean conditions.
Innovation Solution
The design incorporates a combustion pre-chamber offset from the central axis, with specific apertures and a fuel injector spray streamline alignment, allowing for efficient purging of residual gases and igniting a fuel-air mixture within the pre-chamber, which then vents hot exhaust gases into the main combustion chamber for a two-stage combustion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional combustion pre-chamber is used, then the engine can maintain basic combustion function, but residual gases and combustion byproducts cannot be effectively purged leading to misfires and reduced combustion stability
Solution Approach 1:
The pre-chamber is divided into multiple sealed cavities (first pre-chamber, second pre-chamber) with distinct functions. The first pre-chamber handles combustion and exhaust venting, while the second pre-chamber is dedicated to purging residual gases during intake stroke. This segmentation allows simultaneous optimization of combustion stability and gas purging without interference between functions.
Solution Approach 2:
The second pre-chamber acts as an intermediary chamber that receives residual gases from the first pre-chamber during combustion stroke and then purges them into the cylinder during intake stroke. This intermediate structure facilitates the transfer and removal of harmful gases without directly interfering with the main combustion process in the first pre-chamber.
2Adaptability or versatility
If the pre-chamber is positioned on the central axis, then the structure is simple and symmetric, but it cannot provide multiple ignition points and effective purging paths aligned with intake ports
Solution Approach 1:
The pre-chamber assembly is positioned asymmetrically relative to the cylinder axis, with the first pre-chamber offset from the center. This asymmetric positioning allows the outlet aperture to be aligned with the exhaust port for efficient exhaust gas venting, and the second pre-chamber to be positioned near the intake port for effective purging. The asymmetric configuration enables multiple ignition points and optimized gas flow paths that cannot be achieved with symmetric central positioning.
Solution Approach 2:
Different regions of the pre-chamber assembly are assigned different functional qualities. The first pre-chamber is optimized for combustion with its outlet aperture positioned for exhaust venting, while the second pre-chamber is positioned and configured specifically for purging residual gases during intake. Each local region has tailored geometry and aperture placement to optimize its specific function, achieving overall system versatility.
3Object-affected harmful factors
If exhaust gas recirculation (EGR) is used, then emissions can be reduced, but residual gases accumulate in the pre-chamber causing misfires and reduced combustion stability
Solution Approach 1:
The system employs periodic action by utilizing the intake stroke to purge residual gases from the pre-chamber. During the intake stroke, the second pre-chamber draws in fresh air through the intake port and purges it into the cylinder, actively removing accumulated residual gases and EGR products. This periodic purging during the natural intake cycle prevents misfires and maintains combustion stability while allowing EGR to be used for emissions control.
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 enhances combustion stability and efficiency by effectively purging residual gases and providing multiple ignition points in the main combustion chamber, improving engine performance even under fuel lean conditions or with EGR.
Implementation Method 1
A fuel-air mixture is ignited within a combustion pre-chamber via a spark plug positioned inside a cavity defined by the combustion pre-chamber
Implementation Method 2
the pre-chamber defines an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector
Data Source
AI summary
An internal combustion engine has a cylinder head having a cylinder roof defining first and second intake ports. The cylinder head supports a spark plug positioned between a central axis of the cylinder roof and a fuel injector. A combustion pre-chamber is connected to and extends outwardly from the roof. The pre-chamber encapsulates the spark plug, and is offset from the central axis and positioned between the central axis and the first and second intake ports. The pre-chamber defines an inlet aperture and an outlet aperture positioned along a spray streamline of the fuel injector, and defines first and second side apertures. Each side aperture is positioned adjacent to a respective one of the first and second intake ports. A method of operating an engine having a pre-chamber is also provided.