Dual Gallery Piston Cooling for Compression Height
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Solution Overview
Problem
Internal combustion engines face challenges in reducing engine size and weight while maintaining robustness to withstand increased temperature and compression loads, as higher performance demands require stronger pistons that compromise on compactness and lightness.
Innovation Solution
A steel piston design with a toroid-shaped outer cooling gallery and a closed central inner cooling gallery, featuring radially extending reinforcement ribs and optimized oil passage configurations, enhances strength and cooling efficiency while minimizing compression height and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the compression height and size of the piston are reduced to make the engine more compact, then the engine size is reduced, but the piston cannot withstand the increased temperature and compression loads
Solution Approach 1:
The piston is divided into multiple functional zones with different wall thicknesses: a thicker ring belt region for structural strength and cooling, and a thinner compression height region for compactness. The cooling galleries are segmented into inner and outer regions with different functions.
Solution Approach 2:
Different regions of the piston have different wall thicknesses and material properties optimized for their specific functions. The ring belt region has greater thickness for strength, while the crown region is optimized for combustion. The cooling galleries are positioned to provide localized cooling where heat generation is highest.
2Strength
If the piston is made robust with steel material to withstand increased temperature and compression loads, then the piston strength is improved, but the engine weight increases
Solution Approach 1:
The piston uses selective material distribution with steel in critical high-stress regions (ring belt, gallery walls) and potentially lighter materials or thinner sections in less critical areas, reducing overall weight while maintaining necessary strength.
Solution Approach 2:
The piston employs composite construction combining steel material for structural integrity with optimized gallery designs that reduce material usage. The dual-gallery configuration allows for efficient heat dissipation that enables the use of lighter materials in certain regions.
3Productivity
If the compression height is reduced to improve fuel economy and engine compactness, then the engine efficiency is improved, but the piston must operate at higher temperatures and loads
Solution Approach 1:
The cooling system is segmented into inner and outer galleries that work together to manage heat distribution. The inner gallery provides centralized cooling while the outer gallery handles peripheral heat dissipation, enabling effective thermal management in a compact design.
Solution Approach 2:
The toroid-shaped outer cooling gallery uses a curved, continuous path that optimizes coolant flow and heat dissipation efficiency. The curved geometry allows for better thermal distribution compared to straight-line cooling passages.
4Device complexity
If a single cooling gallery design is used, then the device complexity is reduced, but the cooling efficiency is insufficient for high performance engines
Solution Approach 1:
The cooling system is divided into two independent but coordinated galleries: an inner gallery for centralized cooling and an outer toroid-shaped gallery for peripheral cooling. This segmentation allows each gallery to be optimized for its specific thermal zone.
Solution Approach 2:
The inner cooling gallery is nested within the outer toroid-shaped cooling gallery, creating a concentric dual-gallery configuration. The inner gallery is positioned centrally while the outer gallery surrounds it, allowing both to function simultaneously without interfering with each other.
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 piston assembly achieves enhanced durability and cooling, allowing for more compact and lightweight engines with improved performance, capable of withstanding higher compression loads and temperatures.
Implementation Method 1
The wrist pin has a through hole extending generally transversely to its length and the connecting rod has an oil passage aligned for fluid communication with the through hole to allow oil to flow through the connecting rod, through the wrist pin, and through the oil inlet into the inner cooling gallery
Implementation Method 2
The piston assembly achieves enhanced durability and cooling, allowing for more compact and lightweight engines with improved performance, capable of withstanding higher compression loads and temperatures
Data Source
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AI summary
A piston assembly, piston therefor and methods of construction are provided. The assembly includes a piston head and connecting rod operably coupled thereto via a wrist pin. The piston head has an upper crown with a combustion bowl and an undercrown surface. The lower crown includes axial!y aligned pin bores receiving the wrist pin. An upper wall of the lower crown has an oil inlet, an oil outlet and a concave, saddle bearing surface that bears against the wrist pin. A toroid-shaped outer cooling gallery is formed between wall portions of the upper and lower crowns, wherein the outer cooling gallery surrounds an inner cooling gallery. The connecting rod is fixed to the wrist pin for conjoint oscillation. The connecting rod has an oil passage in fluid communication with a through hole in the wrist pin to allow oil to flow therethrough into the inner cooling gallery via the oil inlet.