Dual-Fuel Engine Pilot-Fuel Filtration for Injection Reliability

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Solution Overview

Problem

Dual fuel engines using different fuel injection valves for diffusion and premixed combustion systems lack specific fuel paths designed for fuel purification, leading to suboptimal fuel injection and maintenance challenges.

Innovation Solution

The engine incorporates separate fuel supply paths for gaseous and liquid fuels, including a pilot fuel supply path with a purification filter and a main fuel supply path, utilizing high-pressure pumps and filters to maintain fuel cleanliness and reduce maintenance frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the same fuel injection valve is used for both diffusion combustion system and premixed combustion system, then the device complexity is reduced, but the fuel injection performance deteriorates because the two systems have different purposes of fuel injection

Engineering Contradiction:
Improvefuel injection valve typesVSAvoidfuel injection performance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The fuel injection system is segmented into two independent subsystems: a main fuel injection valve for diffusion combustion and a pilot fuel injection valve for premixed combustion. This segmentation allows each valve to be optimized for its specific function, resolving the contradiction between device simplicity and injection performance.

Inventive Principle:
Principle #1Segmentation

2Reliability

If different fuel injection valves are used for diffusion combustion system and premixed combustion system, then the fuel injection performance is improved, but the device complexity increases and specific fuel paths designed for fuel purification are needed

Engineering Contradiction:
Improvefuel injection performanceVSAvoidfuel supply path configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fuel supply system is divided into separate main fuel supply path and pilot fuel supply path, with dedicated filtration and high-pressure generation for each. This segmentation enables optimized fuel purification for each injection system while maintaining overall system manageability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A pilot fuel tank is introduced as an intermediary storage component between the liquid fuel tank and the pilot fuel injection valve. This intermediary allows for dedicated fuel purification and high-pressure generation specifically for the pilot injection system, improving performance without overly complicating the overall fuel supply architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If liquid fuel is stored in the liquid fuel tank and supplied directly to both injection valves, then the fuel supply path is simplified, but the fuel purification effectiveness deteriorates because injected fuel returns to the tank and mixes with stored fuel

Engineering Contradiction:
Improvefuel supply path structureVSAvoidfuel purification effectiveness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The pilot fuel tank extracts and isolates the pilot fuel from the main liquid fuel tank after purification and high-pressure generation. This extraction prevents the returned pilot fuel from mixing with the stored liquid fuel in the main tank, maintaining fuel purification effectiveness while keeping the supply path structure manageable.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system discards the returned pilot fuel from the combustion cycle and recycles it through the pilot fuel supply pump back to the pilot fuel tank for reuse, rather than allowing it to return to the main liquid fuel tank. This approach maintains fuel quality in both tanks while managing the fuel supply path efficiently.

Inventive Principle:
Principle #34Discarding and recovering

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 ensures reliable ignition and reduces maintenance needs by purifying pilot fuel effectively, minimizing pipe length and pressure loss, and preventing clogging in the fuel injection system.

Implementation Method 1

The pilot fuel filter is disposed in an intermediate portion of the pilot fuel supply path

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

The pilot fuel high-pressure pump is disposed in an intermediate portion of the pilot fuel supply path and sends, to the pilot fuel injection valve, pilot fuel that has passed through the pilot fuel filter

Methodology Applied
Scientific EffectHydraulic compression: Hydraulic Press

Implementation Method 3

The pilot fuel supply pump is disposed in an intermediate portion of the pilot fuel supply path and sends, to the pilot fuel filter, pilot fuel stored in the pilot fuel tank

Methodology Applied
Scientific EffectHydraulic pumping: Pump

Implementation Method 4

The engine body is configured to generate a driving force using supplied fuel

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3486474B1engine
Publication Date: 2025.08.06 YANMAR POWER TECH CO LTD
  • EP3486474B1 patent drawingFigure 1
  • EP3486474B1 patent drawingFigure 2
  • EP3486474B1 patent drawingFigure 3

AI summary

An engine (100) is operable in a premixed combustion system and a diffusion combustion system. The engine (100) includes a main fuel injection valve (79), a pilot fuel injection valve (82), a liquid fuel tank (33), a main fuel supply path (121), a pilot fuel supply path (122), a pilot fuel filter (141), a pilot fuel high-pressure pump (56), a pilot fuel tank (171), and a pilot fuel supply pump (173). The pilot fuel tank (171) stores pilot fuel sent from the pilot fuel high-pressure pump (56) and not injected by the pilot fuel injection valve (82). This pilot fuel is sent to an automatic backwash filter (174) and a pilot fuel filter (141) while not passing through the liquid fuel tank (33).