Piston Crown Airfoil Surface Combustion Gas Flow Control
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Solution Overview
Problem
Internal combustion engine pistons face challenges in efficiently directing fuel plumes, atomization clouds, and combustion flames within the cylinder, leading to increased heat rejection, emissions, and reduced component reliability and service life due to exposure of cylinder surfaces to flame temperatures.
Innovation Solution
The piston design incorporates an airfoil surface and annular protrusions on the crown portion, which redirect and contain moving masses by creating a concave shape with expanding and converging surfaces, and optional recirculation surfaces to minimize contact with cylinder walls, thereby reducing heat transfer and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piston design with flat crown surface is used, then manufacturing is simple, but heat rejection to cylinder walls increases and component reliability decreases
Solution Approach 1:
The patent applies curvature by forming an airfoil surface on the piston crown instead of using a flat surface. The airfoil surface includes a concave portion with a radius of curvature that redirects combustion gases and fuel plumes away from the cylinder walls, reducing heat transfer and improving component reliability while maintaining manufacturing feasibility through conventional machining processes
2Loss of energy
If conventional piston design without airfoil surface is used, then device complexity is low, but heat transfer to cylinder walls increases and emissions increase
Solution Approach 1:
The airfoil surface with its concave curvature redirects hot combustion gases and fuel plumes away from the cylinder walls during the power stroke, reducing convective heat transfer and minimizing energy loss to the cylinder walls and piston skirt, thereby improving thermal efficiency while the curvature can be manufactured using conventional processes
Solution Approach 2:
The airfoil surface is positioned specifically on the crown portion of the piston where combustion occurs, creating a localized flow control feature that redirects gases in the critical region near the cylinder walls without affecting other parts of the piston, thus addressing heat transfer issues locally without requiring complex modifications throughout the entire piston structure
3Object-generated harmful factors
If conventional piston design is used, then manufacturing precision requirements are standard, but emissions control particularly soot and NOx is insufficient
Solution Approach 1:
The concave airfoil surface with its specific radius of curvature creates controlled flow patterns that enhance fuel atomization and combustion efficiency, reducing soot and NOx emissions. The curvature geometry can be manufactured with standard precision machining processes, balancing emissions control performance with manufacturing capability
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 design enhances engine efficiency, power output, and component reliability by reducing heat rejection and emissions, such as NOx and soot, while maintaining or slightly improving NOx levels, and significantly decreasing soot emissions.
Implementation Method 1
The airfoil surface creates an airfoil effect that redirects moving fluids entering the airfoil surface upwards and away from the piston
Implementation Method 2
lubrication oil from the engine is provided within the gallery of the piston during operation to convectively cool and lubricate various portions of the piston
Data Source
Figure 1~3
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Figure 8~9
AI summary
A piston (100) for an internal combustion engine includes a piston body forming a crown portion (102) and a skirt portion (104), the skirt portion (104) including a bore that is arranged to receive a pin for connecting the piston (100) to a connecting rod, the crown portion (102) forming a bowl (110) surrounded by a flat crown surface (112) having an annular shape and disposed along a plane, the bowl (110) and the flat crown surface (112) meeting along a circular edge surrounding a rim (212) of the bowl (110), and an airfoil surface (200) formed in the flat crown surface (112), the airfoil surface (200) having a convex shape and extending annularly around the rim (212) of the bowl (110).