Outboard Motor Piston Cooling Gallery With Split Flow Pin Retention

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Solution Overview

Problem

In marine outboard motors, alignment pins used to restrict piston ring rotation can fall into cooling galleries, obstructing cooling fluid flow and leading to poor emissions and high fluid consumption, especially in vertical axis engines where gravitational effects align ring gaps.

Innovation Solution

A boss is integrated within the cooling gallery opposite the fluid inlet, providing a flow splitter surface that directs cooling fluid into separate flows around the gallery, securely retaining the alignment pin and enhancing cooling efficiency by preventing obstruction and improving fluid circulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an alignment pin is secured in a through-hole extending from the ring groove into the cooling gallery, then circumferential displacement of the piston ring is restricted, but the alignment pin may fall into the cooling gallery and obstruct cooling fluid flow

Engineering Contradiction:

Improvepiston ring position stabilityVSAvoidcooling fluid flow obstruction

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The harmful function of the through-hole is eliminated by extracting the opening from the cooling gallery side. The hole is converted into a blind hole that terminates before entering the cooling gallery, removing the pathway that allows alignment pin displacement while maintaining the alignment function.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

An intermediary structure (the blind hole termination point) is introduced between the alignment pin and the cooling gallery. This intermediary prevents direct contact between the alignment pin and cooling fluid flow path, eliminating the obstruction problem while preserving the alignment function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the alignment pin is not correctly located in the hole in the ring groove, then cooling fluid flow to the ring belt increases, but this results in poor emissions and high cooling fluid consumption

Engineering Contradiction:

Improvecooling fluid flowVSAvoidcooling fluid consumption

Core Design Contradiction:

Ease of operationVSLoss of substance

Solution Approach 1:

The blind hole design provides a simple, robust solution that prevents alignment pin displacement without requiring complex retention mechanisms. The inexpensive structural modification reliably maintains proper alignment and prevents excessive cooling fluid consumption.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Temperature

If the cooling gallery is located radially inwardly from the ring belt region, then the temperature at the rim of the combustion surface is reduced, but the alignment pin hole may interfere with cooling fluid circulation

Engineering Contradiction:

Improvepiston combustion surface temperatureVSAvoidcooling fluid flow obstruction

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The harmful intersection between the alignment pin hole and cooling gallery is eliminated by extracting the hole termination point from the cooling gallery space. The blind hole design removes the obstruction pathway while preserving the beneficial cooling gallery location for temperature control.

Inventive Principle:

Principle #2Taking out (Extraction)

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 boss securely retains the alignment pin and improves cooling performance by ensuring consistent and even cooling of the piston, reducing maximum operating temperature and emissions.

Implementation Method 1

the boss projects into the cooling gallery opposite the fluid inlet and is shaped to provide a flow splitter surface configured to divide cooling fluid flowing through the fluid inlet during use into first and second fluid flows and to direct the first and second fluid flows in opposite directions around the cooling gallery

Methodology Applied

Scientific EffectFluid flow division:

Implementation Method 2

During operation, a cooling fluid, such as crankcase oil, is circulated around the cooling gallery to reduce the temperature of the upper combustion surface of the piston

Methodology Applied

Scientific EffectConvection cooling: Convection

Data Source

PatentUS11208943B2Marine outboard motor with piston cooling gallery

Publication Date: 2021.12.28 COX POWERTRAIN LTD

AI summary

A piston for an internal combustion engine is provided. The piston includes a piston body including an upper combustion surface, an annular side wall with a ring belt region, and a cooling gallery located within the piston body having a fluid inlet. A piston ring is located in a ring groove around the ring belt region and an alignment pin is secured in a hole in the piston side wall to restrict circumferential displacement of the piston ring. The piston body further includes a boss within the cooling gallery into which the hole and the alignment pin extend. The boss projects into the cooling gallery opposite the fluid inlet and is shaped to provide a flow splitter surface configured to divide cooling fluid flowing through the fluid inlet during use into first and second fluid flows and to direct the first and second fluid flows in opposite directions around the cooling gallery.