Pre-Chamber Gas Engine Ignition for Flame-Retardant Fuels

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Solution Overview

Problem

When fuels with flame retardancy are used in gas engines, insufficient combustion in the combustion chamber can lead to low in-cylinder pressure, necessitating a solution to promote combustion.

Innovation Solution

A gas engine design featuring a combustion chamber with a first sub-chamber and a second sub-chamber, connected via communication holes, and an ignition device in the second sub-chamber, along with an injection hole for gas introduction, which can be positioned to intersect the communication hole axis, and optionally includes a check valve in the supply channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If a fuel having flame retardancy (e.g., ammonia) is used to suppress CO2 emission, then environmental performance is improved, but combustion in the combustion chamber becomes insufficient leading to low in-cylinder pressure

Engineering Contradiction:
ImproveCO2 emissionVSAvoidin-cylinder pressure
Core Design Contradiction:
Object-generated harmful factorsVSStress or pressure

Solution Approach 1:

The combustion chamber is divided into a first sub-chamber and a second sub-chamber with different functions. The first sub-chamber handles main combustion, while the second sub-chamber serves as a pre-combustion chamber to generate high-temperature gas that promotes combustion in the first sub-chamber, thereby resolving the insufficient combustion problem while maintaining the use of flame-retardant fuels

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Combustion is initiated in the second sub-chamber before the main combustion chamber. The ignition device ignites the fuel-air mixture in the second sub-chamber first, generating high-temperature gas that then enters the first sub-chamber to promote combustion, ensuring sufficient combustion even with flame-retardant fuels

Inventive Principle:
Principle #10Preliminary action

2Object-generated harmful factors

If a fuel having flame retardancy is used, then emission performance is improved, but combustion promotion becomes difficult requiring additional combustion assistance

Engineering Contradiction:
ImproveemissionVSAvoidcombustion assistance structure
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The combustion chamber is segmented into two sub-chambers with distinct functions. The second sub-chamber acts as a pre-combustion chamber that generates high-temperature gas to assist combustion in the first sub-chamber, providing combustion promotion capability without requiring external assistance devices

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second sub-chamber serves multiple functions: it acts as a pre-combustion chamber to generate high-temperature gas, provides a controlled environment for ignition, and facilitates gas exchange between chambers through communication holes. This multi-functionality reduces the need for additional combustion assistance devices

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 accelerates combustion in the second sub-chamber, stabilizes ignition conditions, and promotes combustion in the main combustion chamber, enhancing combustion efficiency.

Implementation Method 1

an ignition device provided in the second sub-chamber

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

an injection hole through which a gas is allowed to be injected into the second sub-chamber

Methodology Applied
Scientific EffectGas injection: Injector

Implementation Method 3

a check valve may be provided in the supply channel so as to restrict a flow of the gas to a direction from the supply source toward the injection hole

Methodology Applied
Scientific EffectCheck valve flow restriction: Valve

Data Source

PatentEP4703573A1Gas engine
Publication Date: 2026.03.04 IHI CORP
  • EP4703573A1 patent drawingFigure 1
  • EP4703573A1 patent drawingFigure 2
  • EP4703573A1 patent drawingFigure 3

AI summary

Provided is a gas engine, including: a combustion chamber (108); a first sub-chamber (202) that is in communication with the combustion chamber (108) via a first communication hole (202b); a second sub-chamber (204) that is in communication with the first sub-chamber (202) via a second communication hole (204b), and has a volume smaller than a volume of the first sub-chamber (202); an ignition device (206) provided in the second sub-chamber (204); and an injection hole (208) through which a gas is allowed to be injected into the second sub-chamber (204).