Prechamber Shield Layout for Spark Plug Heat Protection

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Solution Overview

Problem

Prechamber engines in piston engines face high temperature issues leading to hot corrosion and stringent requirements for spark plugs, especially in gas engines with extreme pressure gradients and high pressures.

Innovation Solution

A prechamber arrangement with a shield element separating the spark plug cavity from the prechamber, equipped with nozzle holes for fluid communication and a fuel inlet in the spark plug cavity to cool the spark plug, allowing the use of less expensive spark plugs and maintaining efficient combustion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a prechamber is used for combustion in piston engines, then combustion efficiency is improved, but the spark plug is exposed to high temperatures causing hot corrosion and requiring expensive high-performance spark plugs

Engineering Contradiction:
Improvecombustion efficiencyVSAvoidhot corrosion of spark plug
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention divides the combustion system into two separate chambers: a prechamber where combustion occurs at high temperature, and a main combustion chamber where the spark plug is located. The prechamber acts as an isolated zone for combustion, preventing direct exposure of the spark plug to extreme temperatures while maintaining combustion efficiency through the prechamber design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The prechamber serves as an intermediary between the spark plug and the main combustion process. It receives the spark ignition, performs the initial combustion, and then transfers the ignited mixture to the main combustion chamber, thereby protecting the spark plug from direct contact with high-temperature combustion products.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If expensive high-performance spark plugs are used to withstand high temperatures, then reliability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvespark plug durabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention enables the use of less expensive spark plugs by isolating them from the high-temperature prechamber environment. The prechamber design allows standard, more cost-effective spark plugs to be used while maintaining system reliability through the protective barrier and controlled combustion process.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Temperature

If the spark plug cavity is isolated from the prechamber, then spark plug protection from heat is improved, but fluid communication between chambers must be maintained

Engineering Contradiction:
Improvespark plug temperatureVSAvoidfluid communication system
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The invention extracts the spark plug from the high-temperature prechamber environment by placing it in a separate main combustion chamber. The prechamber and main combustion chamber are kept spatially distinct, with the spark plug cavity isolated from direct thermal exposure while maintaining necessary fluid communication through controlled pathways.

Inventive Principle:
Principle #2Taking out (Extraction)

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

The solution effectively protects spark plugs from prechamber heat, enabling the use of cheaper alternatives while maintaining efficient combustion by introducing a richer fuel mixture and cooling the spark plug, thus reducing corrosion and operational costs.

Implementation Method 1

The shield element protects the spark plug from the heat of the prechamber

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

By introducing at least part of the fuel into the spark plug cavity, the spark plug is cooled down

Methodology Applied
Scientific EffectEvaporative cooling: Evaporative Cooler

Implementation Method 3

a spark plug, which is configured to ignite air/fuel mixture

Methodology Applied
Scientific EffectElectrical discharge: Electric Spark

Implementation Method 4

The combustion thus starts in the prechamber, but main part of the combustion takes place in a main combustion chamber

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3833859B1Prechamber arrangement
Publication Date: 2024.03.06 WARTSILA FINLAND OY
  • EP3833859B1 patent drawingFigure 1~3
  • EP3833859B1 patent drawingFigure 4~7

AI summary

The prechamber arrangement for a piston engine comprises a prechamber (1), which is provided with one or more openings (2) for establishing fluid communication between the prechamber (1) and a main combustion chamber (3), a spark plug cavity (6), which is arranged outside the prechamber (1) and in fluid communication with the prechamber (1), and a spark plug (5), which is configured to ignite air/fuel mixture and which is arranged at least partly in the spark plug cavity (6). The arrangement further comprises a shield element (7), which is separate from the spark plug (5) and separates the spark plug cavity (6) from the prechamber (1) and which is provided with at least one nozzle hole (8) for establishing fluid communication between the prechamber (1) and the spark plug cavity (6).