Lightweight Engine Piston Micro-Chamber Layout for Bowl Compression
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Solution Overview
Problem
Existing gasoline direct injection (GDI) automotive engines face challenges in optimizing piston bowl dimensions for improved fuel economy and reduced emissions, particularly in achieving a combustion compression ratio of 12.5 to 1 while maintaining piston integrity and weight reduction.
Innovation Solution
The development of a lightweight piston with a reconfigured bowl diameter, depth, and profile, featuring a micro chamber located below the bowl floor and a threaded taper plug secured by circumferential friction stir welding, allows for a 60-gram reduction in piston crown weight and enhanced gasoline-air mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the bowl diameter is increased to optimize combustion compression ratio, then fuel economy is improved, but piston integrity is compromised due to insufficient aluminum between embodiments and ring grooves
Solution Approach 1:
The invention relocates the micro chamber from the traditional position above the bowl floor to below the bowl floor, utilizing the third dimension (depth) rather than increasing bowl diameter. This dimensional shift allows the bowl diameter to be increased for improved combustion while maintaining adequate aluminum structure integrity, as the micro chamber is now positioned in the space below the bowl floor rather than consuming lateral space.
2Weight of moving object
If the piston crown weight is reduced to improve engine performance, then rotational and reciprocating forces are decreased, but manufacturing complexity increases due to reconfigured bowl geometry and micro chamber integration
Solution Approach 1:
The invention segments the piston crown into distinct functional zones: the bowl area for combustion, the micro chamber below the bowl floor for charge preparation, and the aluminum structure for integrity. This segmentation allows each zone to be optimized independently - the bowl diameter can be increased for combustion efficiency, the micro chamber can be positioned below the bowl floor for weight reduction, and adequate aluminum can be maintained for structural integrity, thereby reducing overall piston crown weight while managing manufacturing complexity through clear functional separation.
3Weight of moving object
If the bowl depth is decreased to locate micro chamber below bowl floor, then piston crown weight is reduced, but combustion chamber volume optimization becomes more difficult
Solution Approach 1:
By relocating the micro chamber to below the bowl floor, the invention utilizes the depth dimension beneath the bowl rather than consuming the bowl depth itself. This allows the bowl depth to be optimized for combustion chamber volume while the micro chamber occupies the space below, effectively adding functional volume without compromising the primary combustion chamber's geometric optimization for compression ratio and mixing.
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 piston design achieves a significant weight reduction while maintaining engine performance, improving fuel economy, and reducing NOx emissions, ultra-fine particulates, and hydrocarbons, thus addressing the challenges of climate change and emissions reduction in the automotive sector.
Implementation Method 1
a present threaded taper plug embodiment (460) on the circumference to be sealed and secured with circumferential friction stir welding (515)
Implementation Method 2
including a pip (175) in the floor of the bowl to optimize tumble for air turbulence to improve a stratified charge mixture for combustion
Data Source
AI summary
An automotive internal combustion engine piston is formed to have a bowl in the piston crown, at least one micro chamber formed in a side surface of the piston body at a position lower than a floor of the bowl, and extended orifices to provide 2-way communication of gaseous materials between the micro chambers and bowl. The micro chamber volume is defined by a removable casting core that incorporates a strut to secure the core at the circumference of the piston body in the casting mold. Subsequent to casting and removal of the core material, the cavity from the strut to secure the core is prepared to receive a tapered thread plug that is sealed by circumferential friction stir welding on the outer diameter of the piston body. The micro chamber is thereby isolated except for the extended orifice to the bowl.