Ring-Shaped Piston Cooling Channel for Stable Oil Flow
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Solution Overview
Problem
Conventional pistons for internal combustion engines suffer from reduced cooling efficiency due to backward flow of engine oil in the cooling channel, especially when the piston moves from a location close to an engine oil spray to a location far from it, leading to increased thermal fatigue and potential engine damage.
Innovation Solution
A piston design with a cooling channel core that includes a ring-shaped channel with varying cross-sectional areas and inclined surfaces to minimize resistance and induce engine oil flow from the inlet to the outlet, utilizing a ceramic or salt-based core for casting to enhance durability and flow efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional cooling channel with uniform cross-section is used, then the structure is simple and easy to manufacture, but the engine oil flows backward when the piston moves from a location close to oil spray to a location far from it, reducing cooling efficiency
Solution Approach 1:
The cooling channel cross-sectional area is varied locally along its length, with the area being larger near the oil inlet and progressively smaller toward the oil outlet. This local variation in geometry creates a pressure gradient that ensures unidirectional flow of engine oil from inlet to outlet, preventing backward flow while maintaining manufacturing feasibility through the coring method.
2Speed
If the piston moves at high speed from a location close to engine oil spray to a location far from it, then the piston can complete its reciprocation cycle efficiently, but the engine oil flows backward in the cooling channel and is discharged through both inlet and outlet, lowering cooling efficiency
Solution Approach 1:
The cross-sectional area parameter of the cooling channel is changed along its length, creating a tapered geometry that generates a pressure gradient. This parameter variation ensures that even during high-speed reciprocation, the pressure differential maintains forward flow direction, preventing oil from flowing backward and being discharged through the inlet.
3Ease of manufacture
If a ceramic or salt core is used for coring the cooling channel, then the cooling channel can be formed in the piston casting process, but the oil flow resistance may be high and flow efficiency reduced
Solution Approach 1:
The cooling channel is formed using a segmented coring approach where the core creates a ring-shaped channel with controlled cross-sectional variations. The segmentation of the core structure allows for creating the tapered geometry that reduces flow resistance while maintaining the integrity of the casting process.
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 design effectively improves cooling efficiency by ensuring consistent and efficient flow of engine oil through the cooling channel, reducing thermal fatigue and enhancing the piston's durability against high temperatures and pressures.
Implementation Method 1
a first space cross-sectional area of a first part P1 of the first channel 21 located relatively close to the refrigerant inlet H1 is less than a second space cross-sectional area of a second part P2 of the first channel 21 located relatively far from the refrigerant inlet H1
Implementation Method 2
when the conventional piston moves upward at high speed in a direction from a location close to an engine oil spray to a location far from the same, the engine oil flows backward in the cooling channel
Implementation Method 3
oil scattered due to pumping of an oil pump during vertical reciprocation of the piston is supplied through the oil inlet, circulates through the cooling channel to cool the piston
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is a piston for an internal combustion engine, the piston including a body having a piston pin boss for inserting a piston pin thereinto, and a skirt corresponding to a cylinder wall, and a cooling channel provided in the body to allow a refrigerant for cooling the body, to flow therethrough, and having a ring shape including a first channel provided from a refrigerant inlet to a refrigerant outlet along a first outer circumferential direction of the body, and a second channel provided from the refrigerant inlet to the refrigerant outlet along a second outer circumferential direction of the body.