Piston Cooling Passage Upward Inclination
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Solution Overview
Problem
Existing piston cooling systems in engines face inefficiencies in heat transfer due to lube oil accumulation and non-flowing conditions, leading to potential piston ring immobility and damage from coke formation, particularly at the uppermost piston ring region.
Innovation Solution
The piston features an upwardly-inclined cooling passage system that distributes lubricant to an outer plenum, ensuring continuous flow and enhanced heat transfer by maintaining a minimum lube oil level and optimizing the lube oil distribution system, including raised outlets to prevent oil loss during upward motion and varied cross-sectional areas for consistent flow velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lube oil is supplied to cool the piston, then cooling effect is achieved, but lube oil accumulation and non-flowing conditions occur leading to reduced heat transfer efficiency
Solution Approach 1:
The cooling passage is designed with an upwardly-inclined angle relative to the piston's longitudinal axis, creating a dynamic flow path that utilizes the piston's reciprocating motion to maintain continuous lube oil circulation. This dynamic configuration prevents oil accumulation and ensures reliable heat transfer throughout the engine operating cycle.
Solution Approach 2:
The cooling passage cross-sectional area is varied along its length, with the area increasing in the flow direction. This parameter change optimizes flow velocity distribution and prevents oil stagnation, maintaining effective cooling while avoiding harmful accumulation effects.
2Temperature
If cooling passages are added to improve cooling, then heat transfer is enhanced, but device complexity increases
Solution Approach 1:
The cooling system is segmented into functional zones: an outer plenum chamber for oil distribution, multiple cooling passages with specific orientations, and strategically positioned outlets. This segmentation allows each component to perform its function efficiently while maintaining overall system simplicity through modular integration within the piston structure.
3Loss of energy
If lube oil flow is increased to improve cooling, then heat transfer efficiency improves, but lube oil loss during upward motion increases
Solution Approach 1:
The cooling passages are positioned and oriented to deliver lube oil to critical heat-generating regions (piston rings and groove areas) before temperatures reach dangerous levels. The upwardly-inclined passages ensure oil is delivered to the outer plenum at the optimal moment in the piston cycle, maximizing cooling efficiency while minimizing excess oil loss.
Solution Approach 2:
Different regions of the piston receive differentiated cooling: the outer plenum and its associated passages specifically target the piston ring grooves and upper piston regions, while varied cross-sectional areas in different passages optimize flow distribution to specific hot spots. This localized quality approach ensures efficient cooling with minimal overall oil consumption.
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 configuration achieves improved cooling efficiency by maintaining continuous lube oil flow and heat transfer along critical surfaces, preventing coke formation and ensuring robust engine operation by maintaining the uppermost piston ring region below a certain temperature.
Implementation Method 1
The at least one cooling passage extends towards the outer peripheral wall at an upwardly-inclined angle with respect to the longitudinal axis
Implementation Method 2
At least one cooling passage is configured to receive lubricant supplied from the cooling inlet and supply the received lubricant to the outer plenum
Implementation Method 3
improved cooling efficiency by maintaining continuous lube oil flow and heat transfer along critical surfaces
Implementation Method 4
maintaining continuous lube oil flow and heat transfer along critical surfaces, preventing coke formation and ensuring robust engine operation
Data Source
Figure 1
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Figure 3
AI summary
A piston (1) for an engine (100) comprises a cooling arrangement that allows for an increased cooling efficiency of an outer peripheral wall (5) of a piston body (4) including a plurality of piston ring grooves (10, 12, 14). Lubricant is supplied to an outer plenum (22) formed adjacent to outer peripheral wall (5) via a cooling passage (26) that extends at an upwardly-inclined angle from a central plenum (28) towards the outer plenum (22). Lubricant that enters cooling passage (26) is imparted with a corresponding flow velocity component due to the upwardly-inclined orientation of cooling passage (26) prior to entering outer plenum (22) to flow along an inner surface of the same. A heat transfer between the lubricant and the inner surface of the outer plenum (22) is increased due to the resulting flow of lubricant.