Pre-chamber Ignition for Cold Start Efficiency
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Solution Overview
Problem
Internal combustion engines face challenges in starting efficiently at cold temperatures due to poor ignition quality of ultra-lean air-fuel mixtures, which limits their ability to operate effectively and rapidly activate exhaust catalysts for emission reduction.
Innovation Solution
A method involving a pre-chamber with an igniter and fuel injector, where fuel is injected and ignited in the pre-chamber to pre-heat it before fuel injection in the main combustion chamber, enhancing ignition efficiency and allowing for quick transition to ultra-lean operation by amplifying ignition energy and distributing it through the main combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is injected and ignited directly in the main combustion chamber at cold temperatures, then the engine should start, but ignition quality is poor due to cold temperatures and ultra-lean air-fuel mixtures
Solution Approach 1:
The combustion chamber is segmented into a pre-chamber and a main combustion chamber. Fuel is first injected and ignited in the pre-chamber, which then transfers energy to the main combustion chamber through multiple orifices. This segmentation allows the pre-chamber to serve as an ignition source that amplifies the ignition energy available in the cold main combustion chamber.
Solution Approach 2:
Fuel is injected and ignited in the pre-chamber before the main combustion chamber receives the air-fuel mixture. This preliminary action creates a high-temperature ignition source in the pre-chamber that then ignites the mixture in the main combustion chamber, solving the problem of poor ignition quality in cold conditions.
2Productivity
If the engine operates with ultra-lean air-fuel mixtures to reduce emissions, then fuel efficiency improves, but ignition quality deteriorates at cold temperatures
Solution Approach 1:
By segmenting the combustion process into pre-chamber and main combustion chamber operations, the system can use ultra-lean mixtures in the main combustion chamber for efficiency while maintaining a separate ignition source in the pre-chamber that ensures reliable ignition regardless of mixture leaness or temperature.
Solution Approach 2:
The pre-chamber acts as an intermediary that decouples the ignition function from the main combustion process. It provides a controlled environment for ignition that is independent of the ultra-lean air-fuel mixture conditions in the main combustion chamber, thereby ensuring reliable ignition while maintaining fuel efficiency.
3Object-affected harmful factors
If the engine starts quickly to activate exhaust catalysts for emission reduction, then emission control improves, but stable combustion is difficult to achieve in cold conditions
Solution Approach 1:
The pre-chamber ignition occurs before the main combustion chamber combustion, creating a stable and repeatable ignition source that ensures consistent combustion from the first cycles. This preliminary ignition action allows the engine to quickly reach operating temperature and activate exhaust catalysts while maintaining combustion stability.
Solution Approach 2:
The system changes the ignition parameters by using a pre-chamber with specific geometry and multiple orifices that create turbulent jet ignition. This parameter change in the ignition process provides stable and repeatable combustion that quickly brings the exhaust system to operating temperature for effective emission 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 method improves cold start efficiency by ensuring stable and repeatable combustion within a low number of engine revolutions, reducing tailpipe emissions through rapid exhaust gas temperature increase, and enabling efficient activation of exhaust catalysts.
Implementation Method 1
ignite the injected fuel in the pre-chamber for pre-heating of the pre-chamber
Implementation Method 2
ignition device for turbulent jet ignition
Data Source
AI summary
A method for starting an internal combustion engine comprises the steps of: providing an internal combustion engine having at least one cylinder and a piston supported at a crankshaft for repeated reciprocal movement in the cylinder so as to define a main combustion chamber, the internal combustion engine further having an ignition device arranged in said cylinder with an igniter portion and a fuel injector which are both arranged at a pre-chamber, wherein the pre-chamber has a plurality of orifices for providing fluid communication between said pre-chamber and the main combustion chamber, injecting fuel in the pre-chamber, and igniting the injected fuel in the pre-chamber for pre-heating of the pre-chamber prior to injecting fuel in the main combustion chamber for combusting the injected fuel in the main combustion chamber.