Piston Bowl and Anti-Polishing Ring Geometry for Lower Hydrocarbons
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Solution Overview
Problem
Internal combustion engines face a tradeoff between reducing piston temperature, unburned hydrocarbon emissions, and carbon deposits on the piston surface, with existing designs failing to simultaneously address these issues effectively.
Innovation Solution
A piston with a contoured bowl geometry and a cuff or anti-polishing ring that includes a swirl pocket with convex and concave arcuate surfaces, and a conical portion, which promotes efficient fuel mixing and reduces carbon deposits by forcing combustion products away from the piston rings and cylinder liner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional piston geometry is used, then piston temperature is reduced, but unburned hydrocarbon emissions increase and combustion efficiency decreases
Solution Approach 1:
The piston crown incorporates a contoured bowl geometry with specific curvature radii (R1, R2, R3) that create optimized combustion chamber shapes. This curvature design improves fuel-air mixing and combustion efficiency while managing heat transfer, thereby reducing unburned hydrocarbon emissions without compromising piston temperature control
Solution Approach 2:
The piston design features localized geometric modifications including a reentrant surface at the bowl periphery and a lip portion extending into the combustion chamber. These local structural variations create specific flow patterns and combustion characteristics in different regions, enabling simultaneous optimization of combustion efficiency and heat management
2Object-generated harmful factors
If piston geometry is modified to reduce unburned hydrocarbons, then combustion efficiency improves, but piston temperature increases
Solution Approach 1:
The optimized bowl geometry with controlled curvature radii enhances combustion efficiency through improved mixing, while the specific curvature design also manages heat transfer paths to control piston temperature rise
Solution Approach 2:
The contoured bowl design extends combustion chamber geometry into three-dimensional space with specific depth and width proportions. This dimensional optimization allows separation of combustion efficiency functions from heat transfer functions, enabling independent optimization of both parameters
3Ease of manufacture
If conventional piston design is used, then manufacturing is simplified, but carbon deposits accumulate on piston surface
Solution Approach 1:
The contoured bowl geometry with smooth curved surfaces eliminates sharp corners and flat regions where carbon deposits typically accumulate. The continuous curvature design facilitates deposit removal through combustion flow patterns while maintaining manufacturability through standard machining and casting processes
Solution Approach 2:
The reentrant surface and lip portion create localized flow patterns that actively prevent carbon deposit accumulation in critical areas. These local geometric features modify combustion gas flow to sweep deposits away from the piston surface without requiring complex manufacturing processes
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 solution effectively reduces piston temperature, unburned hydrocarbon emissions, and carbon deposits, improving combustion efficiency while breaking the tradeoff seen in prior art designs.
Implementation Method 1
a swirl pocket that extends radially from the radially outer lip portion and that defines a lower axial extremity that is spaced axially away from the radially outer lip portion a first axial distance. The swirl pocket may include a convex arcuate surface extending axially downwardly and radially inwardly from the radially outer lip portion, and a concave arcuate surface extending axially downwardly to the lower axial extremity, and radially inwardly from the convex arcuate surface
Implementation Method 2
A conical portion extends axially upwardly and radially inwardly from the concave arcuate surface to an apex, the apex being spaced a second axial distance from the radially outer lip portion that is less than the first axial distance
Data Source
AI summary
An anti-polishing ring includes a ring body defining an axis of revolution, and a radial direction that is perpendicular to the axis of revolution, and a circumferential direction about the axis of revolution. The ring body includes an outer circumferential surface, a bottom surface, a top surface, and an inner circumferential surface. The inner circumferential surface defines an inner diameter, the ring body defines a radial thickness measured from the inner circumferential surface to the outer circumferential surface, and a ratio of the radial thickness to the inner diameter ranges from 0.015 to 0.020.