Gaseous Fuel Engine Ignition via Propagated Flame Front

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Solution Overview

Problem

Gaseous fuel engines face challenges in achieving ignition, particularly under lean conditions, due to the difficulty in igniting gaseous fuels, which limits their widespread commercial adoption and efficiency.

Innovation Solution

A method and system for a gaseous fuel internal combustion engine that injects a pilot charge of gaseous fuel through a plurality of injection orifices to form pilot spray plumes, ignites one plume at a fixed ignition point, and propagates the flame front to ignite a main charge of gaseous fuel, using the same injection orifices for both pilot and main fuel charges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If gaseous fuel is injected directly into the cylinder for combustion, then emissions are reduced and fuel efficiency is improved, but ignition reliability deteriorates due to difficulty in igniting gaseous fuel under lean conditions

Engineering Contradiction:

ImproveemissionsVSAvoidignition reliability

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The fuel injection process is segmented into two distinct phases: pilot charge injection and main charge injection. The pilot charge (small amount of gaseous fuel) is injected first and reliably ignited by the spark plug, creating a stable flame kernel. Subsequently, the main charge (larger amount of gaseous fuel) is injected and ignited by the propagating flame front from the pilot charge. This segmentation allows reliable ignition of gaseous fuel under lean conditions while maintaining emission benefits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pilot charge of gaseous fuel is injected and ignited before the main charge injection. This preliminary action creates a prepared flame front that is ready to ignite the main fuel charge, ensuring reliable ignition without requiring complex ignition hardware or liquid pilot fuel.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If pre-chamber ignition devices or liquid pilot fuel injection is used to ignite gaseous fuel, then ignition reliability is improved, but device complexity and cost increase

Engineering Contradiction:

Improveignition reliabilityVSAvoidignition hardware complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The same fuel injection system is used for both pilot charge and main charge injections, eliminating the need for separate ignition devices or dual fuel injection systems. The standard gaseous fuel injector performs multiple functions: injecting the pilot charge, injecting the main charge, and controlling both injection events through a single control mechanism. This universal approach maintains ignition reliability while simplifying the overall system architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the pilot fuel injection and main fuel injection functions into a single fuel injection system with one injector. The injector contains multiple orifices that can be selectively activated, and a single control valve manages both fuel delivery events. This consolidation eliminates redundant components such as separate pre-chamber ignition devices or liquid pilot fuel systems, reducing complexity while maintaining reliable gaseous fuel ignition.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If complex ignition systems are implemented to achieve reliable gaseous fuel combustion, then ignition reliability is improved, but manufacturing cost increases

Engineering Contradiction:

Improveignition reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The pilot charge of gaseous fuel serves its own ignition needs by creating a flame front that automatically ignites the main charge. The system uses the fuel itself (in small pilot quantity) to generate the ignition source, eliminating the need for external ignition assistance such as pre-chamber devices or liquid pilot fuels. This self-service approach reduces manufacturing costs while ensuring reliable ignition of the main gaseous fuel charge.

Inventive Principle:

Principle #25Self-service

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 approach enhances ignition reliability and efficiency by using a propagated flame front to ignite the main fuel charge, improving combustion and reducing emissions, while simplifying the engine design and reducing the need for complex ignition hardware.

Implementation Method 1

igniting one of the plurality of pilot spray plumes at a fixed ignition point within the combustion chamber

Methodology Applied

Scientific EffectElectrical discharge ignition: Electric Spark

Implementation Method 2

propagating a flame front of the ignited pilot spray plume to the other pilot spray plumes... igniting the plurality of main spray plumes within the combustion chamber by way of the propagated flame front

Methodology Applied

Scientific EffectFlame propagation: Combustion

Data Source

PatentUS10273891B2Gaseous fuel internal combustion engine and operating method therefor

Publication Date: 2019.04.30 CATERPILLAR INC

AI summary

Operating a gaseous fuel engine includes injecting a pilot charge directly into a combustion chamber in an engine, and igniting one spray plume of the pilot charge. A flame front is propagated to other pilot spray plumes to produce an ignition flame for igniting later injected main charge spray plumes. Injection of the pilot and main charges is by way of the same fuel injection orifices.