Piston Bowl Geometry for Lean Natural Gas Combustion
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Solution Overview
Problem
Internal combustion engines face challenges in achieving efficient combustion of gaseous fuels with reduced hydrocarbon (HC) emissions, as existing piston bowl geometries and ignition chamber designs often result in incomplete burnout and delayed combustion due to poor fuel-air mixture distribution and inefficient flame propagation.
Innovation Solution
The design involves a specific arrangement of reactive gas jets directed at a primary and central ignition area within a geometrically shaped piston recess, with a hemispherical or omega-shaped piston recess, and a truncated cone ignition chamber, optimizing the alignment and tilt of firing channels to enhance fuel-air mixture ignition and burnout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional piston bowl geometries and ignition chamber designs are used, then the engine structure is simple, but incomplete burnout and delayed combustion occur resulting in high HC emissions
Solution Approach 1:
The combustion chamber is divided into distinct functional zones: a central ignition region, an intermediate transition zone, and an outer compression zone. The piston bowl geometry is segmented with different curvature radii - a smaller radius in the central ignition area to concentrate flame and a larger radius in the outer compression area to maintain mixture distribution, thereby reducing HC emissions while managing geometric complexity
Solution Approach 2:
Different regions of the piston bowl are given different geometric properties tailored to their specific functions. The central region has optimized curvature for flame concentration and ignition efficiency, while the peripheral regions have different curvature characteristics for proper mixture formation and compression, achieving low emissions without requiring overall geometric complexity
2Productivity
If existing ignition chamber designs are used, then the ignition system is simple, but flame propagation is inefficient resulting in delayed combustion and reduced efficiency
Solution Approach 1:
The ignition chamber is positioned and dimensioned to enable preliminary ignition of the fuel-air mixture before main combustion. The design ensures that ignition occurs in the optimized central region first, creating a controlled flame front that propagates systematically through the intermediate and outer zones, achieving efficient combustion without requiring complex ignition systems
Solution Approach 2:
The ignition chamber design utilizes three-dimensional spatial arrangement with specific curvature radii and positioning to optimize flame propagation paths. By considering the vertical and radial dimensions separately, the design achieves efficient flame spread from the ignition region through the compression chamber without requiring additional ignition components or complex mechanisms
3Object-generated harmful factors
If fuel-air mixture distribution is poor, then the system is simple, but incomplete burnout occurs resulting in high HC emissions
Solution Approach 1:
The piston bowl employs optimized spherical curvature radii in different regions to improve fuel-air mixture distribution. The central ignition region uses a smaller radius of curvature to concentrate the mixture for efficient ignition, while the outer compression region uses a larger radius to maintain proper mixture homogeneity, reducing incomplete burnout and HC emissions through geometric optimization rather than complex mixing systems
Solution Approach 2:
The design optimizes specific geometric parameters including the radius of curvature of the piston bowl, the volume ratio between ignition and compression chambers, and the positioning of the ignition chamber. These parameter changes improve fuel-air mixture distribution and combustion completeness, reducing HC emissions without requiring additional manufacturing precision or complex systems
4Productivity
If combustion occurs later in the cycle, then the system operation is simple, but peak pressure is delayed resulting in reduced efficiency
Solution Approach 1:
The ignition chamber is designed to initiate combustion in advance of main compression chamber combustion. By positioning the ignition chamber to fire first and creating a controlled flame propagation path through the intermediate zone to the outer compression zone, the system achieves earlier peak pressure and improved combustion timing without complex timing control mechanisms
Solution Approach 2:
The design separates the ignition and main combustion events in spatial dimensions, with the ignition chamber positioned to fire first and the flame propagating through the compression chamber. This spatial-temporal separation achieves earlier and more efficient combustion timing, advancing peak pressure occurrence without requiring complex timing control systems
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 ensures low wall heat losses, complete burnout of gaseous fuel, and improved combustion efficiency, reducing HC emissions and achieving a lean natural gas combustion process with earlier peak pressure and faster fuel conversion.
Implementation Method 1
an ignition source is assigned to the ignition chamber, which ignites the gaseous fuel in the ignition chamber space of the ignition chamber at a predeterminable time, whereby ignited reactive gas jets shoot into the main combustion chamber
Implementation Method 2
ignited reactive gas jets shoot into the main combustion chamber and burn in the main combustion chamber, igniting the main combustion chamber charge together with the ignition chamber charge
Data Source
Figure 1A~1B
Figure 1C~1F
Figure 2A~2B
AI summary
The invention relates to an internal combustion engine, comprising at least one main combustion chamber (B1, B2) formed as a main chamber in a cylinder (Z) lying above the cylinder (Z) accommodating a piston (K; K1, K2). The main combustion chamber (B1, B2) is supplied with fuel via a precombustion chamber (Z1, Z2), which is connected to a fuel supply system, wherein combustion air is fed to the at least one main combustion chamber (B1, B2) via at least one dedicated inlet valve (V). An ignition source is assigned to the precombustion chamber (Z1, Z2), which ignites the fuel in the precombustion chamber (Z1, Z2) at a predefinable point in time, as a result of which ignited reactive gas jets (En) shoot into the main combustion chamber (B1, B2) and burn in the main combustion chamber (B1, B2), after which the exhaust gas is discharged from the at least one main combustion chamber (B1, B2) via an outlet valve (V), wherein the precombustion chamber (Z1, Z2) has firing channels (Sn) for the targeted introduction of reactive gas jets (En) into the main combustion chamber (B1, B2) which is delimited by a main combustion chamber roof (B1-1, B2-1) of the cylinder (Z) and by a piston bowl (KM1, KM2) formed in the piston (K; K1, K2). According to the invention, a plurality of reactive gas jets (En; n = 7) at a predefinable position (zOT) of the piston (K; K1, K2) in the cylinder (Z) are targeted at a primary ignition region (KM1-2, KM2-2) of the piston bowl (KM1, KM2) of the piston (K; K1, K2), said ignition region being located between a central region (KM1-3, KM2-3) and a squeezing edge region (KM1-1, KM2-1) located in the edge region of the piston bowl, of a piston bowl (KM1, KM2) that is designed in a geometrically specific manner.