Spark Ignition Engine Pre-Chamber Combustion Control
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Solution Overview
Problem
Current spark-ignition internal combustion engines face challenges in operating efficiently with extremely lean fuel mixtures due to significant dilution, leading to reduced chemical efficiency, increased unburnt hydrocarbons, and variability in engine cycles, while also struggling to meet stringent emission limits and requiring costly high-pressure components for hydrogen injection.
Innovation Solution
A spark ignition internal combustion engine with an ignition chamber that controls the mixing ratio of auxiliary fuels, using 100% pure hydrogen at low loads and pure natural gas at high loads, coupled with a pressure regulator and high-voltage spark plug or laser ignition, allowing operation with extremely diluted mixtures and minimizing nitrogen oxide emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the engine operates with extremely lean fuel mixtures (excess-air coefficient about 1.65), then nitrogen oxide emissions are reduced, but chemical efficiency decreases and unburnt hydrocarbons increase
Solution Approach 1:
The combustion chamber is divided into a pre-chamber and a main combustion chamber. The pre-chamber operates with a richer fuel mixture that ignites first, then propagates flame through jets into the main chamber containing the lean mixture. This segmentation allows the lean main chamber to achieve lower NOx emissions while the rich pre-chamber ensures complete combustion and maintains chemical efficiency.
Solution Approach 2:
The pre-chamber acts as an intermediary between the fuel supply and the main lean mixture in the combustion chamber. It prepares a controlled ignition source that transfers energy to the lean mixture, enabling efficient combustion without direct injection into the main chamber and avoiding the trade-off between efficiency and emissions.
2Object-generated harmful factors
If significant dilution of the mixture is used, then nitrogen oxide content in flue gases is reduced, but combustion process stability collapses and variability increases
Solution Approach 1:
By segmenting the combustion process into pre-chamber ignition and main chamber combustion, the system maintains stable combustion at high dilution levels. The pre-chamber provides a controlled environment for fuel preparation and ignition initiation, ensuring reliable flame propagation even when the main chamber contains highly diluted lean mixtures.
Solution Approach 2:
The pre-chamber performs preliminary combustion actions by igniting a richer fuel mixture first, creating a controlled flame front that then propagates into the main chamber. This preliminary ignition ensures stable combustion starts before the lean mixture burns, preventing combustion collapse and reducing cycle-to-cycle variability.
3Ease of operation
If a non-separated combustion chamber is used, then the engine can operate with stoichiometric ratio, but chemical efficiency is significantly reduced and combustion variability increases
Solution Approach 1:
The combustion chamber is segmented into pre-chamber and main chamber, allowing different air-fuel ratios in each zone. The pre-chamber can operate richer to ensure complete combustion, while the main chamber operates lean for efficiency, resolving the contradiction between operational flexibility and energy efficiency.
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 solution enhances thermal efficiency, reduces engine cycle variability, and achieves a more favorable flue gas composition, enabling operation with excess-air coefficients greater than 2 while meeting emission standards and reducing nitrogen oxide content.
Implementation Method 1
a spark ignition internal combustion gas engine, whose fuel system comprises a fuel tank with a gaseous main fuel
Implementation Method 2
ignited by a spark, the spark gap of which is located in a non-separated combustion chamber
Data Source
Figure 1
AI summary
The invention relates to a spark ignition internal combustion gas engine (1), whose fuel system comprises a fuel tank with a main gaseous fuel and a fuel tank with a second gaseous fuel differing from the main fuel, whereby the engine cylinder(10) comprises an ignition chamber (18), in which is arranged a means for igniting the gas fuel located therein, whereby the ignition chamber (18) is connected via the interconnecting holes (20) to the main combustion space (13), whereby the pure main fuel feed opens into a supply duct (14) in front of a suction valve (16) of the cylinder (10), whereby the internal combustion engine is coupled to an engine control unit to monitor the current state of the engine operation and, depending on it, to control at least the fuel system, ignition timing system and the engine performance. The fuel system comprises a gaseous fuel mixer (6) connected to a main gaseous fuel supply (3) of the main gaseous fuel and to a supply (4) of the second gaseous fuel, whereby a means for setting the mutual ratio of the mixing of the main fuel and the second fuel in the mixer (6) is coupled to the engine control unit, whereby from the mixer (6) extends an supply pipe (61) of auxiliary fuel to the engine (1), which opens into the ignition chamber (18).