Complex Piston Oil Gallery Cooling for Diesel Combustion Bowl
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Solution Overview
Problem
Conventional piston designs with traditional circular combustion bowls struggle to effectively cool non-traditional or complex-shaped combustion bowls in diesel engines, leading to potential overheating and 'hot spots' that can cause piston failure and engine damage.
Innovation Solution
A piston design featuring a complex combustion bowl with protrusions and a corresponding oil gallery channel formed through a combination of forging and machining processes, ensuring uniform wall thickness and efficient cooling, which minimizes overheating risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional annular oil galleries with constant cross-sections are used, then the galleries are easy to manufacture, but they cannot effectively cool complex-shaped combustion bowls leading to hot spots and piston failure
Solution Approach 1:
The oil gallery cross-sectional area is varied locally to match the complex shape of the combustion bowl. The gallery has a non-constant cross-section that is larger in regions requiring enhanced cooling (such as near protrusions and the outer rim) and smaller in other regions, allowing effective cooling of complex-shaped combustion bowls while maintaining manufacturability through controlled variation in geometry
Solution Approach 2:
The invention transitions from a simple two-dimensional annular gallery cross-section to a three-dimensional variable cross-section gallery that conforms to the complex combustion bowl geometry. This dimensional adaptation allows the gallery to wrap around and cool complex features like protrusions and non-circular bowl shapes that cannot be cooled by conventional constant-cross-section galleries
2Productivity
If the combustion bowl has complex non-traditional shapes, then fuel burning efficiency is improved, but conventional machining cannot provide corresponding oil galleries leading to inadequate cooling
Solution Approach 1:
The oil gallery is designed with locally varied cross-sectional areas that correspond to the specific geometric features of the complex combustion bowl. The gallery cross-section is enlarged in regions adjacent to protrusions and other complex features to ensure adequate oil flow and cooling in these critical areas, while maintaining a smaller cross-section in regions where less cooling is required
Solution Approach 2:
The invention employs asymmetric and non-uniform gallery cross-sections that match the asymmetric complex shape of the combustion bowl. Rather than using a symmetric constant cross-section, the gallery varies its dimensions to conform to the specific asymmetric geometry of the bowl, including areas around protrusions and non-circular features
3Shape
If walls between the combustion bowl and oil gallery have significantly different thicknesses, then the complex bowl shape can be formed, but hot spots occur where material overheats and cracks
Solution Approach 1:
The oil gallery cross-sectional area is locally adjusted to compensate for variations in wall thickness. In regions where the wall between the combustion bowl and gallery is thinner, the gallery cross-section is enlarged to provide enhanced cooling capacity. This local adaptation ensures uniform temperature distribution across the piston crown, preventing hot spots in areas with varying wall thicknesses
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 maintains the combustion bowl and outer rim within acceptable temperature limits, preventing hot spots and reducing the risk of piston failure, thereby enhancing engine reliability and efficiency while reducing emissions.
Implementation Method 1
The oil circulates through the gallery and cools parts of the piston which are susceptible to damage from the heat of combustion
Data Source
AI summary
A piston for an internal combustion engine including a cooling gallery and a complex combustion surface is provided. The piston includes an upper crown member joined to a lower member, for example by hybrid induction welding. A complex combustion bowl is formed in the upper crown member by forging. The combustion bowl includes at least one protrusion, and typically a plurality of protrusions spaced from one another. After the forging step and before the joining step, portions of an undercrown surface located opposite the spaces between the protrusions are machined, and portions located directly opposite the protrusions are left as-forged. The crown member is joined to the lower member, for example by hybrid induction welding.