Piston Cooling Channel Layout to Prevent Oil Backflow

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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 at high speed, leading to increased thermal fatigue and potential engine damage.

Innovation Solution

A cooling channel design with a refrigerant inlet and outlet configuration that includes varying cross-sectional areas and channel shapes to induce engine oil flow efficiently from the inlet to the outlet, utilizing a ceramic or salt-based core for casting, ensuring optimal flow resistance and discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional cooling channel with equal cross-sectional area is used, then the structure is simple and easy to manufacture, but the engine oil flows backward at high piston speeds reducing cooling efficiency

Engineering Contradiction:

Improvecooling channel structureVSAvoidcooling efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The cooling channel is designed with non-uniform cross-sectional area where the area near the refrigerant inlet is smaller and the area near the refrigerant outlet is larger. This local variation in geometry creates different flow resistance characteristics at different locations, ensuring unidirectional oil flow even at high piston speeds, thereby resolving the contradiction between manufacturing simplicity and cooling reliability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cross-sectional area parameter of the cooling channel is changed along its length rather than maintaining a constant value. This parameter change creates a pressure gradient that prevents backward flow of engine oil, improving cooling efficiency while maintaining a relatively simple overall structure

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the piston moves upward at high speed, then the engine oil spray reaches the piston more effectively, but the oil flows backward in the cooling channel and is discharged through both inlet and outlet

Engineering Contradiction:

Improveoil spray coverageVSAvoidcooling energy loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The cooling channel has different cross-sectional areas at different locations - smaller near the inlet and larger near the outlet. This local quality difference creates flow resistance that prevents backward flow, ensuring that even during high-speed upward motion, oil is discharged only through the outlet and cooling energy is not lost

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of trying to prevent backward flow by increasing flow velocity or pressure, the invention inverts the approach by creating higher flow resistance at the inlet end through smaller cross-sectional area. This resistance gradient forces unidirectional flow from inlet to outlet, preventing the harmful backward flow effect

Inventive Principle:

Principle #13The other way round (Inversion)

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 enhances cooling efficiency by minimizing flow resistance and ensuring effective oil circulation within the cooling channel, reducing thermal fatigue and improving engine durability.

Implementation Method 1

Methodology Applied

Scientific EffectFlow resistance: Drag

Data Source

PatentEP3242008B2Piston for internal combustion engine, and cooling channel core

Publication Date: 2023.04.19 DONG YANG PISTON CO LTD

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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.