Gas Engine Check Valve Arrangement for Soot Prevention

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Solution Overview

Problem

In conventional gas engines with spark plugs, soot accumulation due to imperfect combustion often causes adhesion issues with check valves and solenoid valves, leading to malfunctions, and there is a loss due to dead volume in the fuel inlet passage.

Innovation Solution

A spark ignition gas engine design featuring a solenoid valve and two check valves, where the first check valve is positioned after the solenoid valve to prevent backflow and soot entry, and the second check valve is placed above the pre-combustion chamber to prevent combustion gas backflow, with cooling grooves to manage temperature and reduce dead volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single check valve is arranged just above the pre-combustion chamber, then the structure is simple, but soot accumulation causes adhesion and malfunctions

Engineering Contradiction:
Improvecheck valve arrangementVSAvoidsolenoid valve operation
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single check valve is divided into two separate check valves positioned at different locations: one in the fuel inlet passage and another in the fuel passage. This segmentation allows each valve to handle specific flow control tasks, preventing soot accumulation from causing adhesion and malfunctions while maintaining system reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A fuel inlet connecting piece is introduced as an intermediary component between the solenoid valve and the pre-combustion chamber. This connecting piece houses the first check valve and provides a dedicated fuel inlet passage, acting as a mediator that separates the solenoid valve from direct exposure to soot and combustion gases.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the fuel inlet passage is long to connect solenoid valve and pre-combustion chamber, then the arrangement is flexible, but dead volume increases causing fuel gas supply loss

Engineering Contradiction:
Improvecomponent arrangement flexibilityVSAvoidfuel gas supply
Core Design Contradiction:
Adaptability or versatilityVSLoss of substance

Solution Approach 1:

The fuel inlet passage is segmented into two distinct passages: a fuel inlet passage for supplying fuel gas from the solenoid valve to the first check valve, and a fuel passage for supplying fuel gas from the second check valve to the pre-combustion chamber. This segmentation allows for optimized passage lengths that minimize dead volume while maintaining arrangement flexibility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fuel inlet connecting piece serves as an intermediary that efficiently connects the solenoid valve assembly to the pre-combustion chamber assembly. By housing the first check valve and providing dedicated fuel inlet passages within this connecting piece, the design minimizes unnecessary passage length and dead volume while maintaining flexible component arrangement.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If check valve is positioned close to pre-combustion chamber, then structure is compact, but high temperature causes soot generation and adhesion

Engineering Contradiction:
Improveoverall assembly sizeVSAvoidsoot accumulation
Core Design Contradiction:
Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The check valve system is segmented into two valves positioned at different thermal environments: the first check valve is positioned in the fuel inlet passage away from direct combustion heat, and the second check valve is positioned in the fuel passage closer to the pre-combustion chamber. This segmentation allows the first valve to be protected from high temperatures and soot generation while the second valve handles the high-temperature zone.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fuel inlet connecting piece acts as an intermediary structure that houses the first check valve in a location protected from direct combustion heat. By separating the first check valve from the immediate vicinity of the pre-combustion chamber while maintaining functional connectivity through dedicated passages, the design reduces soot accumulation and adhesion issues.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively prevents soot accumulation on the solenoid valve, reduces malfunctions, and minimizes dead volume, enhancing the protection of the solenoid valve and optimizing fuel gas flow.

Implementation Method 1

a first check valve that is provided posterior to a discharge side of the solenoid valve in the fuel inlet passage, so that the combustion gas generated in the pre-combustion chamber is prevented from flowing backwards in a direction from the pre-combustion chamber toward the solenoid valve

Methodology Applied
Scientific EffectCheck valve mechanism: Valve

Implementation Method 2

a second check valve arranged at a location just above the pre-combustion chamber in the fuel passage in the mounting hardware piece, thereby preventing the combustion gas generated in the pre-combustion chamber from flowing backwards, from the pre-combustion chamber toward the fuel inlet passage

Methodology Applied
Scientific EffectCheck valve mechanism: Valve

Implementation Method 3

a solenoid valve that performs open-close control of the fuel gas which streams into a fuel inlet passage bored in the fuel inlet connecting piece

Methodology Applied
Scientific EffectSolenoid actuation: Solenoid

Implementation Method 4

the fuel gas supplied in the pre-combustion chamber is ignited by spark discharge at the spark plug that is fitted on a fitting seat surface in the mounting hardware piece

Methodology Applied
Scientific EffectSpark discharge: Electric Spark

Implementation Method 5

a plurality of cooling grooves or bore-cooling holes is provided in the mounting hardware piece; and a tip part of the fuel inlet connecting piece is inserted in a circumferential wall surface of the mounting hardware piece, so that the cooling grooves or bore-cooling holes face an outlet end of the fuel inlet connecting piece

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP2372135B8Gas engine
Publication Date: 2018.09.12 MITSUBISHI HEAVY IND ENGINE & TURBOCHARGER LTD

AI summary

Provided is a gas engine having a spark plug provided with a pre-combustion chamber and a check valve, the gas engine, in which the check valve is arranged in the neighborhood of the pre-combustion chamber, being capable of preventing adhesion of a solenoid controlled valve provided at an upstream side of the check valve due to soot accumulation, and dead volume in a fuel inlet passage. In a gas engine in which fuel gas is supplied to the pre-combustion chamber through the fuel gas inlet passage and the fuel gas supplied in the pre-combustion chamber is ignited by spark discharge at the spark plug that is fitted to a mounting hardware piece via a seat surface, a solenoid valve for performing open-close control of the fuel gas is provided, and a first check valve is also provided posterior to a discharge side of the solenoid valve so as to prevent back flow of the combustion gas from the pre-combustion chamber to the solenoid controlled valve.