Piston Combustion Bowl Geometry for Flame Speed
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Solution Overview
Problem
Optimizing piston geometry for internal combustion engines is challenging due to unpredictable effects of minor changes, which can impact engine operation and performance, and modifying piston volume affects the geometric compression ratio, requiring additional design modifications.
Innovation Solution
A piston design featuring a combustion bowl with a specific ratio of bowl max dimension to bowl opening dimension (1.10 to 1.15) and a reentrant surface, along with an oil gallery and ring grooves, to enhance combustion efficiency without disturbing the geometric compression ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If piston geometry is modified to optimize combustion efficiency, then combustion performance is improved, but geometric compression ratio changes
Solution Approach 1:
The patent applies parameter changes by precisely controlling the bowl max dimension to bowl opening dimension ratio within 1.10 to 1.15, and by optimizing the reentrant surface angle between 10° to 45°, to achieve improved combustion efficiency while maintaining stable geometric compression ratio
Solution Approach 2:
The patent applies local quality by creating a reentrant surface at a specific location on the combustion bowl where the dimension ratio is between 1.10 to 1.15, concentrating the geometric modification in a localized area to enhance combustion turbulence without significantly affecting the overall compression ratio
2Stability of the object's composition
If piston volume is added or removed to adjust compression ratio, then geometric compression ratio is optimized, but other design modifications are required
Solution Approach 1:
The patent changes the dimensional parameters of the combustion bowl (max dimension to opening dimension ratio of 1.10 to 1.15) to optimize compression ratio, eliminating the need for complex multi-component design modifications
3Speed
If piston geometry is modified to enhance combustion performance, then flame speed increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges (bowl max dimension to opening dimension ratio of 1.10 to 1.15, reentrant surface angle of 10° to 45°) that balance flame speed enhancement with manufacturability, avoiding overly complex geometric features
Solution Approach 2:
The patent employs curved surfaces including the reentrant surface with specific angle ranges and the rounded bowl profile, which improve combustion performance while being more amenable to conventional manufacturing processes compared to sharp-edged or complex multi-surface geometries
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 promotes faster flame speed and high combustion efficiency through turbulent gas flow, maintaining a high geometric compression ratio and minimizing undesirable geometric changes.
Implementation Method 1
This design promotes faster flame speed and high combustion efficiency through turbulent gas flow
Data Source
AI summary
A piston for an internal combustion engine includes a piston skirt and a piston crown attached to the piston skirt. The piston crown includes a combustion face forming a piston rim extending circumferentially around a piston center axis, and a combustion bowl. The combustion face further forms a bowl edge defining an intersection of the combustion bowl and the piston rim, and includes a reentrant surface extending between the bowl edge and a bowl outer wall. A ratio of a bowl max dimension to a bowl opening dimension is from about 1.10 to about 1.15.