Piston Combustion Bowl Geometry for Flame Speed
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Solution Overview
Problem
Optimizing piston design for internal combustion engines to achieve enhanced flame speed and compression ratio is challenging due to the unpredictable effects of minor geometric changes and the need to maintain a desired compression ratio, which often requires additional modifications to the piston and engine design.
Innovation Solution
The piston design features a combustion bowl with a reentrant surface and specific dimensions, including a ratio of bowl depth to compression height between 0.30 and 0.35, which promotes turbulence and maintains a compression ratio while enhancing flame speed by allowing a close approach to the engine head, thereby inducing high-squish velocity and turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If piston geometry is modified to enhance flame speed, then combustion efficiency is improved, but compression ratio becomes unpredictable and may deviate from desired levels
Solution Approach 1:
The patent applies parameter changes by precisely controlling the bowl depth to compression height ratio within a specific range (0.30-0.35). This parameter optimization enables the piston to achieve enhanced flame speed through improved combustion chamber geometry while simultaneously maintaining the desired compression ratio, thus resolving the technical contradiction between combustion efficiency and compression ratio control.
2Reliability
If piston volume is increased to maintain compression ratio, then geometric compression ratio is improved, but flame speed decreases due to larger combustion chamber volume
Solution Approach 1:
The patent applies local quality by creating a reentrant combustion bowl with specific geometric characteristics (bowl depth to compression height ratio of 0.30-0.35) in a localized region of the piston crown. This localized geometric optimization concentrates the combustion process in a specific zone, enabling high flame speed through improved local combustion dynamics while maintaining the overall compression ratio through controlled piston volume.
3Productivity
If piston geometry is optimized for specific fuel types, then combustion performance is improved, but adaptability to different fuel types and operating conditions decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the bowl depth to compression height ratio within a flexible range (0.30-0.35) rather than a fixed value. This parameter range provides adaptability to accommodate different fuel types and operating conditions, as the specific ratio within this range can be adjusted based on fuel characteristics and engine requirements, thus maintaining both combustion performance and versatility.
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 achieves faster flame speed and maintains a desired compression ratio, improving engine efficiency and performance by creating turbulence in the combustion chamber, while minimizing the need for additional engine modifications.
Implementation Method 1
promotes turbulence and maintains a compression ratio while enhancing flame speed by allowing a close approach to the engine head, thereby inducing high-squish velocity and turbulence
Data Source
AI summary
A piston for an internal combustion engine includes a piston skirt and a piston crown attached to the piston skirt and including a combustion face. The combustion face forms a piston rim and a combustion bowl. A bowl edge defines an intersection of the combustion bowl and the piston rim, and a reentrant surface defining a reentrancy angle extends between the bowl edge and a bowl outer wall. A ratio of a bowl depth dimension coincident with the piston center axis to a compression height dimension coincident with the piston center axis is from about 0.30 to about 0.35.