Piston Cavity Curvature for Fuel Mixing and Soot Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing reentrant type combustion chamber design in internal combustion engines can lead to accumulation of non-combusted fuel between the deepest portion of the cavity and the separating step portion, resulting in high fuel concentration regions that accelerate soot generation and decrease combustion efficiency.
Innovation Solution
A piston design with a cavity featuring a lip portion, a raised portion, and a curved portion that includes an outer circumference-side curved surface, an inner circumference-side concave surface, and a convex surface, which directs non-combusted fuel to the convex surface before kinetic energy is lost, preventing accumulation and facilitating oxygen intake, thus reducing high fuel concentration regions and improving combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a separating step portion is disposed on a radially inner side of the deepest portion of the cavity to separate non-combusted fuel from the wall surface, then mixing of fuel and oxygen is facilitated, but fuel accumulates between the deepest portion and the separating step portion creating high fuel concentration regions
Solution Approach 1:
The cavity is segmented into multiple functional zones: a fuel introduction region where fuel is injected, a fuel-oxygen mixing region with turbulent flow promotion, and a combustion region. The separating step portion divides the cavity to create distinct flow paths that prevent fuel accumulation while ensuring adequate oxygen mixing.
Solution Approach 2:
The cavity design incorporates three-dimensional curved surfaces and stepped portions that create multi-directional fuel flow paths. The fuel is directed to move in multiple dimensions rather than linearly, preventing accumulation in dead zones and promoting thorough mixing with oxygen throughout the combustion chamber.
2Speed
If the non-combusted fuel flows along the wall surface of the curved portion, then the fuel is guided toward the protruding portion, but the fuel loses kinetic energy and decreases in fluidity making it difficult to take in ambient oxygen
Solution Approach 1:
The cavity incorporates curved portions with optimized radii that guide fuel flow smoothly toward the protruding portion while maintaining kinetic energy. The curved surfaces are designed to promote turbulent mixing with ambient oxygen without creating dead zones where fuel would accumulate and lose momentum.
Solution Approach 2:
The design optimizes parameters such as cavity depth, separating step height, and curved portion radius to balance fuel flow velocity and oxygen mixing. By carefully controlling these geometric parameters, the fuel maintains sufficient kinetic energy throughout its path while ensuring adequate interaction with ambient oxygen for complete combustion.
Data Source
AI summary
A piston of an internal combustion engine configured to be reciprocable along an axial direction in a cylinder includes a cavity formed to be recessed in a center of a piston top surface, and an outer circumferential edge portion located on a radially outer side of the cavity in the piston top surface. The cavity includes a lip portion, a raised portion, and a curved portion. The curved portion includes an outer circumference-side curved surface which includes a curved surface connected to the lip portion, an inner circumference-side concave surface which is located on a radially inner side of an outer circumference-side curved surface and includes a surface connected to a raised portion, the inner circumference-side concave surface including a deepest portion of the cavity, and a convex surface formed between the outer circumference-side curved surface and the inner circumference-side concave surface, as well as protruding upward.