Annular Piston Engine Center Shaft Cooling

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Solution Overview

Problem

Internal combustion engines with annular piston layouts face challenges in efficiently cooling the piston and combustion chamber, leading to high operating temperatures and reduced efficiency.

Innovation Solution

A center shaft with passageways is integrated into the engine, allowing for continuous fluid flow to and from the center chamber of the annular piston, providing direct cooling to the piston and combustion chamber surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional cooling channels in the engine block are used to cool the cylinder wall, then the combustion chamber can be cooled, but the annular piston cannot be effectively cooled and operates at high temperatures (500 to 600 °F)

Engineering Contradiction:

Improvepiston operating temperatureVSAvoidcooling system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The center shaft is nested within the annular piston, with cooling passageways integrated inside the piston structure itself. This internal cooling system allows direct cooling of the piston without requiring external cooling channels in the engine block, effectively reducing piston operating temperature while maintaining a compact design.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Use of energy by moving object

If higher compression ratios and combustion temperatures are used to improve fuel economy, then efficiency increases, but piston and seal temperatures rise excessively

Engineering Contradiction:

Improvefuel economyVSAvoidpiston temperature

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

Cooling fluid is introduced into the passageways before combustion occurs, pre-cooling the piston surfaces. This preliminary cooling action allows the piston to withstand higher compression ratios and combustion temperatures that improve fuel economy, while preventing excessive temperature rise through continuous cooling during operation.

Inventive Principle:

Principle #10Preliminary action

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 solution reduces operating temperatures, enables higher compression ratios, improves fuel economy, and results in cleaner exhaust gases by allowing the use of self-lubricating graphite seals and maintaining cooler surface conditions, typically around 200 to 300 °F instead of the conventional 500 to 600 °F.

Implementation Method 1

The piston and combustion chamber are cooled with a fluid in direct and continuous contact with the piston surface during all induction, compression, expansion, and exhaust strokes

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2652287B1Internal combustion engine of the annular piston type and a center shaft for such an engine

Publication Date: 2022.04.20 SALMINEN REIJO

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AI summary

The present invention provides a novel internal combustion engine of the annular piston type and a center shaft for such an engine for further improving the cooling an internal combustion engine of the annular piston type. The internal combustion engine comprises a block having at least one annular combustion chamber and an annular piston with a center chamber. The annular piston of the engine is configured to reciprocate in the combustion chamber. The internal combustion engine further comprises a center shaft being fixed to said block and configured to fit at least partially inside the center chamber of the annular piston. The center shaft comprises at least one passageway which is configured to lead fluid flow to and from the center chamber of the annular piston.