Vented Pre-Chamber Assembly for Engine NOx Reduction
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Solution Overview
Problem
Engines with prechambers face significant NOx emissions due to hot exhaust gases being re-compressed and held at high temperature and pressure in the prechamber, leading to excessive NOx production.
Innovation Solution
A prechamber assembly with a non-actuated, fixed orifice that allows hot combustion gases to exit the prechamber and be replaced by cooler gases from the main chamber, utilizing a passageway that expands and cools the gases, thereby reducing NOx formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a prechamber is used to achieve high compression ratios and power output, then engine power and compression ratio are improved, but NOx emissions increase due to high temperature and pressure in the prechamber
Solution Approach 1:
The patent extracts the hot exhaust gases from the prechamber through a dedicated passageway and orifice, separating them from the main combustion chamber. This allows the prechamber to maintain its power-generating function while removing the source of NOx formation by venting hot gases to the exhaust manifold.
Solution Approach 2:
The patent introduces an intermediary system consisting of a passageway and orifice that mediates between the prechamber and exhaust manifold. This intermediary structure provides a controlled path for hot gases to exit the prechamber, reducing NOx formation while maintaining engine performance.
2Productivity
If hot exhaust gases are re-compressed in the prechamber to maintain pressure, then combustion efficiency is improved, but temperature increases leading to excessive NOx production
Solution Approach 1:
The patent extracts hot exhaust gases from the prechamber before they can be re-compressed to excessive temperatures. The passageway and orifice provide a release path that prevents temperature buildup while maintaining adequate pressure for combustion efficiency.
Solution Approach 2:
The patent creates a dynamic system where hot gases can be vented from the prechamber to the exhaust manifold based on pressure differentials. This dynamic venting mechanism allows the system to adapt to varying combustion conditions, maintaining efficiency while controlling temperature.
3Ease of operation
If a valve system is used to control gas flow in the prechamber, then gas flow control is improved, but device complexity and component cost increase
Solution Approach 1:
The patent employs a self-service system where the orifice and passageway automatically regulate gas flow based on pressure differentials between the prechamber and exhaust manifold. No external control system is needed - the geometry of the orifice and pressure gradients naturally control the venting process.
Solution Approach 2:
The patent extracts the control function from a complex valve system and replaces it with a simple geometric feature (the orifice). This extraction of the control mechanism simplifies the overall system while maintaining effective gas flow management.
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 solution effectively reduces NOx emissions by 23% to 54% by cooling and venting hot gases, simplifying engine controls and reducing component costs.
Implementation Method 1
A non-actuated, fixed orifice is formed in the body and extends between the prechamber volume and a passageway formed in the body to permit combustion gases in the prechamber volume to enter the passageway
Implementation Method 2
the passageway is configured to vent combustion gases therein out of the body
Implementation Method 3
utilizing a passageway that expands and cools the gases, thereby reducing NOx formation
Data Source
AI summary
A prechamber assembly for a cylinder of a combustion engine is disclosed in which a plurality of ports placing a prechamber volume in fluid communication with the cylinder. A non-actuated, fixed orifice extends between the prechamber volume and a passageway formed in the prechamber assembly to permit combustion gases in the prechamber volume to enter the passageway. The passageway is configured to vent combustion gases therein out of the body. The orifice may reduce NOx emissions produced in the prechamber volume.