Piston Bowl Geometry for Soot Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Internal combustion engines face challenges in reducing emissions of soot and pollutants due to inefficient fuel and air mixing in combustion chambers, which affects engine performance and compliance with stringent emissions standards.
Innovation Solution
A piston design featuring a piston bowl with a convex spherical center portion, a convex frusto-conical floor, a concave toroidal base, and a cylindrical wall, optimized with specific geometrical parameters that enhance fuel and air mixing, leading to improved soot oxidation and oxygen entrainment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the piston bowl depth is increased to enhance mixing energy, then soot oxidation is improved, but the compression ratio may become inconsistent
Solution Approach 1:
The patent applies parameter changes by precisely controlling the geometric parameters of the piston bowl, specifically maintaining the depth-to-diameter ratio between 0.25 and 0.35, and the cylindrical wall length-to-depth ratio between 0.15 and 0.25. These parameter adjustments optimize mixing energy while preserving consistent compression ratio, resolving the contradiction between emission reduction and operational reliability
Solution Approach 2:
The patent employs spheroidality by designing the piston bowl with a convex spherical center portion and a convex frusto-conical floor, creating curved surfaces that enhance turbulent mixing and oxygen entrainment. The curved geometry promotes better fuel-air mixing and soot oxidation while maintaining the required compression ratio through optimized depth limitations
2Productivity
If the cylindrical wall length is increased to improve oxygen entrainment, then mixing energy increases, but the depth-to-diameter ratio constraint becomes more difficult to maintain
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing specific ratio constraints: the cylindrical wall length-to-depth ratio is maintained between 0.15 and 0.25, and the piston bowl depth-to-diameter ratio is kept between 0.25 and 0.35. These parameter definitions allow the cylindrical wall length to be optimized for oxygen entrainment while automatically ensuring the depth-to-diameter ratio remains within acceptable tolerances
Solution Approach 2:
The patent applies dimensionality change by introducing the cylindrical wall as a vertical dimension element that extends upward from the piston bowl base. This additional dimensional feature increases oxygen entrainment and mixing energy without significantly affecting the horizontal depth-to-diameter ratio, thus resolving the contradiction between enhanced mixing and geometric precision
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
The piston design results in cleaner engine operation by reducing particulate emissions and meeting stringent emissions standards, such as Tier 4i, through enhanced mixing energy and deeper piston bowl depth while maintaining a consistent compression ratio.
Implementation Method 1
increasing mixing energy between fuel and air in the combustion chamber
Implementation Method 2
higher oxygen entrainment during a late combustion stage
Data Source
Figure 1~2
AI summary
The piston (100) has a crown (101) forming a piston bowl (102). The piston bowl (102) has a center portion (106) with a convex spherical shape, a floor (108) having a convex frusto-conical shape adjacent the center portion, and a base (110) having a concave toroidal shape surrounding the floor. The piston bowl (102) also has a cylindrical wall (112) extending tangentially from the base (110) that surrounds the center portion (106). The piston (100) has a top surface (114) perpendicular to the cylindrical wall (112) along a rim (115) of the piston bowl (102). A ratio between the piston bowl depth and the cylindrical wall length is less than 4, and a ratio between the piston bowl diameter and the piston bowl depth is 4.7.