Piston Crown Protrusions for Combustion Flow Control
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Solution Overview
Problem
Direct-injection engines face inefficiencies and increased emissions due to fuel dispersion and interaction with combustion chamber surfaces, leading to uneven fuel-air mixing and higher temperatures, which are exacerbated by swirling air momentum making it difficult to achieve quiescent conditions consistently.
Innovation Solution
The design incorporates a piston crown with a concave bowl and protrusions having asymmetrical side surfaces to redirect and segregate fuel jets radially, counteracting swirling air momentum and guiding the flame towards the center of the combustion chamber for improved mixing and burning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel is injected directly into the combustion chamber, then engine efficiency is improved, but fuel dispersion and interaction with chamber surfaces cause increased emissions and uneven mixing
Solution Approach 1:
The piston crown is segmented into multiple protrusions (typically 3-6) arranged radially around the combustion chamber center. Each protrusion acts as an independent flow control element that segments the fuel jet into multiple sub-jets, preventing premature dispersion and interaction with chamber surfaces while maintaining efficient combustion.
Solution Approach 2:
Each protrusion features asymmetric surface geometry with a concave leading surface facing the fuel injector and a convex trailing surface. This asymmetry creates a flow redirection effect that directs fuel radially outward while preventing backflow, improving mixing uniformity and reducing localized rich/lean zones that cause emissions.
2Quantity of substance
If fuel jets interact with combustion chamber surfaces, then fuel dispersion occurs, but this causes localized rich and lean burning areas increasing emissions
Solution Approach 1:
The protrusions serve as intermediary flow control elements positioned between the fuel injector and the combustion chamber walls. They mediate the fuel jet by redistributing it radially outward in a controlled manner, preventing direct impingement on chamber surfaces while ensuring uniform fuel-air mixing before combustion.
3Power
If swirling air momentum is present, then combustion occurs, but flames are carried to one side towards cylinder wall decreasing efficiency
Solution Approach 1:
The protrusions create localized flow control zones at specific radial positions around the combustion chamber. Each protrusion generates a localized counter-swirl effect that opposes the global air swirl, creating a more quiescent central region where combustion can occur more efficiently with reduced heat transfer to cylinder walls.
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 fuel efficiency, reduces heat rejection, and lowers emissions by achieving a more uniform fuel-air mixture and directing flames towards oxygen-rich areas, effectively transforming a swirling combustion system into a quiescent one.
Implementation Method 1
a first side surface having a generally concave shape, the second side surface having a generally flat or convex shape. During operation of the engine, a swirling air mass provided into the combustion chamber through the air intake valve is mixed with a counter-swirling mass of burning air and fuel that has been provided through the fuel injector.
Implementation Method 2
The expanding flame counters the swirling air such that the flame is directed towards a center of the combustion chamber where additional oxygen is present to promote an efficient burning of fuel in the cylinder.
Data Source
AI summary
A piston for an internal combustion engine includes a crown portion having a bowl that includes a plurality of protrusions. Each of the plurality of protrusions includes a first side surface and a second side surface, the first side surface having a generally concave shape, the second side surface having a generally flat or convex shape.