Engine Fuel Switching Delay for Stable Combustion

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Solution Overview

Problem

Traditional engine devices face issues with abnormal combustion and excessive in-cylinder pressure when switching from a gas mode to a diesel mode, due to overlapping fuel supplies or insufficient fuel, leading to unstable operation, especially in emergency situations like ship navigation.

Innovation Solution

The engine device includes an intake manifold, exhaust manifold, a gas injector for gaseous fuel, and a main fuel injection valve for liquid fuel, with the liquid fuel supply delayed relative to the gaseous fuel stop in the gas mode, ensuring non-overlapping fuel supply and confirming no gaseous fuel presence before starting liquid fuel supply in the diesel mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the liquid fuel supply starts immediately when switching from gas mode to diesel mode, then the engine can maintain continuous power supply, but excessive fuel supply occurs causing abnormal combustion and excessively high in-cylinder pressure

Engineering Contradiction:

Improvecontinuous power supplyVSAvoidabnormal combustion and excessive in-cylinder pressure

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control device delays the start timing of liquid fuel supply by a predetermined period after stopping gas supply. This preliminary delay action ensures that the cylinder is fully cleared of gaseous fuel before liquid fuel injection begins, preventing abnormal combustion and excessive pressure while maintaining continuous power supply capability.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the liquid fuel supply timing is advanced to prevent fuel shortage, then continuous combustion is maintained, but excessive fuel supply occurs causing abnormal combustion

Engineering Contradiction:

Improvecontinuous combustionVSAvoidabnormal combustion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control device uses feedback control to monitor the switching process from gas mode to diesel mode. By detecting when gas supply stops and automatically delaying liquid fuel supply by a predetermined period, the system ensures continuous combustion without excessive fuel supply, thereby preventing abnormal combustion while maintaining reliability.

Inventive Principle:

Principle #23Feedback

3Object-affected harmful factors

If simultaneous supply of gaseous fuel and liquid fuel is prevented, then abnormal combustion is avoided, but fuel shortage may occur during switching

Engineering Contradiction:

Improveabnormal combustion preventionVSAvoidfuel availability in cylinder

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The control device performs preliminary action by delaying the start of liquid fuel supply by a predetermined period after gas supply stops. This timing coordination ensures complete clearance of gaseous fuel from the cylinder before liquid fuel injection begins, preventing abnormal combustion while maintaining adequate fuel availability for continuous combustion.

Inventive Principle:

Principle #10Preliminary action

4Quantity of substance

If fuel injection timing is advanced after switching, then fuel shortage in cylinder is restrained, but excessive fuel supply cannot be prevented

Engineering Contradiction:

Improvefuel quantity in cylinderVSAvoidexcessive fuel supply

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

Instead of advancing the liquid fuel injection timing to prevent fuel shortage, the invention inverts the approach by delaying the start timing of liquid fuel supply. This reverse timing strategy ensures complete clearance of gaseous fuel before liquid fuel injection, preventing excessive fuel supply and abnormal combustion while maintaining adequate fuel quantity through proper timing coordination.

Inventive Principle:

Principle #13The other way round (Inversion)

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 prevents excessive fuel supply and abnormal combustion, ensuring stable operation by avoiding overlapping fuel supplies and ensuring fuel presence in cylinders during mode switching, thus maintaining engine stability during critical transitions.

Implementation Method 1

a gas injector which mixes a gaseous fuel with the air supplied from the intake manifold

Methodology Applied

Scientific EffectMixing:

Implementation Method 2

a main fuel injection valve configured to inject a liquid fuel into the cylinder for combustion

Methodology Applied

Scientific EffectFuel injection:

Implementation Method 3

combust the same

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS11428177B2Engine device

Publication Date: 2022.08.30 YANMAR POWER TECH CO LTD

AI summary

An engine device including an intake manifold configured to supply air into a cylinder; an exhaust manifold configured to output exhaust gas from the cylinder; a gas injector which mixes a gaseous fuel with the air supplied from the intake manifold; and a main fuel injection valve configured to inject a liquid fuel into the cylinder for combustion. At the time of switching from a gas mode in which the gaseous fuel is supplied into the cylinder to a diesel mode in which the liquid fuel is supplied into the cylinder, a supply-start timing of the liquid fuel is delayed relative to a supply-stop timing of the gaseous fuel.