Dual-Gallery Steel Piston With Partitioned Oil and Air Cooling
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Solution Overview
Problem
Pistons in internal combustion engines face challenges in maintaining optimal temperature control, as high temperatures lead to oil degradation and coking, which can cause oxidation, erosion, and reduced engine efficiency, necessitating continuous high oil flow and frequent oil changes.
Innovation Solution
A piston design featuring a partitioned cooling gallery, where one portion contains air for insulation and the other contains cooling oil, preventing weld slivers from entering the oil and optimizing temperature management by isolating hot areas from the oil, thereby reducing oil degradation and improving engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling oil is sprayed into the cooling gallery to moderate piston temperature, then the piston temperature is reduced, but the oil degrades over time and must be changed frequently
Solution Approach 1:
The cooling gallery is divided into a first cooling gallery and a second cooling gallery by a partition. The first cooling gallery receives cooling oil for active cooling, while the second cooling gallery is isolated from oil to prevent coking and degradation at high temperatures. This segmentation allows different regions of the piston to be cooled differently, extending oil life while maintaining temperature control.
Solution Approach 2:
A partition acts as an intermediary barrier between the high-temperature zone and the cooling oil. The partition prevents direct contact between the oil and the hottest regions of the piston (bowl rim and apex), thereby preventing oil coking and degradation while still allowing heat to be managed through the cooled portions of the piston.
2Temperature
If high flow of cooling oil is maintained constantly to control piston temperature, then temperature control is improved, but oil degradation accelerates and engine life is reduced
Solution Approach 1:
The cooling gallery is segmented into oil-cooled and oil-free zones. The partition creates distinct regions where oil is only exposed to necessary cooling functions away from the hottest zones. This reduces overall oil degradation rate, allowing longer oil service intervals and extending engine life while maintaining adequate temperature control in critical areas.
3Temperature
If cooling gallery temperature exceeds 350°C, then oil coking increases and adheres to gallery surfaces, but temperature control becomes more challenging
Solution Approach 1:
The partition divides the cooling gallery into temperature zones. The first cooling gallery operates at lower temperatures with cooling oil, while the second cooling gallery can tolerate higher temperatures without oil present. This prevents oil coking in the hottest regions while maintaining temperature control through the cooled first gallery.
Solution Approach 2:
The harmful element (cooling oil) is extracted from the high-temperature zone where it would undergo coking. The partition removes oil from the second cooling gallery that would otherwise be exposed to temperatures exceeding 350°C, eliminating the source of coking and deposits while preserving cooling functionality in the first gallery.
4Reliability
If partition is added to divide cooling gallery into first and second portions, then oil degradation is reduced, but device complexity increases
Solution Approach 1:
A relatively simple partition structure divides the cooling gallery into two functional zones. The partition can be a straightforward structural element integrated into the piston design, creating the necessary separation without adding complex mechanisms. This achieves oil protection and temperature management with minimal structural complexity.
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 partitioned cooling gallery design effectively manages piston and engine temperatures, reducing oil degradation, extending engine oil life, and preventing carbon buildup, while maintaining high in-cylinder temperatures for improved engine performance.
Implementation Method 1
one portion contains air for insulation and the other contains cooling oil, preventing weld slivers from entering the oil and optimizing temperature management by isolating hot areas from the oil
Implementation Method 2
cooling oil is sprayed into the cooling gallery as the piston reciprocates along a cylinder bore of the engine. The oil flows along the inner surface of the crown and dissipates heat away from the crown
Implementation Method 3
one portion contains air for insulation... effectively manages piston and engine temperatures... maintaining high in-cylinder temperatures for improved engine performance
Data Source
AI summary
A piston capable of operating at a high temperature and consequently contributing to a high in-cylinder temperature, as well as reducing engine oil temperature, when used in an internal combustion engine, is provided. The piston includes an upper portion and a lower portion welded together to present a cooling gallery therebetween. The cooling gallery extends circumferentially around a center axis of the piston and is spaced the center axis. A partition is located in the cooing gallery and extends from one inner surface to another inner surface of the cooling gallery. The partition extends circumferentially around the center axis, and divides the cooling gallery into at least a first gallery portion and a second gallery portion. The partition can be formed as one piece with the upper portion or the lower portion. Alternatively, the partition can be formed as a separate piece from the upper portion and the lower portion.