Prechamber Nozzle Geometry for Piston Engine Thermal Load Control

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Solution Overview

Problem

Modern four-stroke piston engines face high thermal loads in combustion chambers, limiting output power and necessitating costly modifications or material upgrades to withstand these loads.

Innovation Solution

A prechamber arrangement with nozzle openings configured to guide fluid flow more towards the piston on the exhaust valve side of the cylinder, utilizing angled and chamfered or rounded edges, and varying cross-sectional areas to distribute thermal loads more evenly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the ratio between output power and cylinder volume is increased to improve thermal efficiency, then engine power is improved, but thermal load on cylinder components increases

Engineering Contradiction:
Improveoutput powerVSAvoidthermal load
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The prechamber arrangement creates local quality differences by directing different proportions of combustion products to different sides of the cylinder. The exhaust valve side receives a higher proportion of combustion products that are guided more towards the piston, while the intake valve side receives a lower proportion, creating localized thermal management that reduces peak thermal loads on critical components

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention adds a spatial dimension to thermal management by using the prechamber nozzle geometry to control the three-dimensional distribution of combustion products. By adjusting the angle and orientation of nozzle openings, the system distributes thermal energy across different spatial zones within the cylinder, moving heat away from critical thermal zones near the cylinder liner and head

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If thermal load is reduced through additional cooling systems or material upgrades, then thermal resistance is improved, but manufacturing costs increase

Engineering Contradiction:
Improvethermal resistanceVSAvoidmanufacturing costs
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The prechamber arrangement enables the combustion system to self-regulate thermal loads through its geometric configuration. The nozzle openings are designed to naturally guide combustion products away from thermal critical zones without requiring external cooling systems or specialized materials. The system uses the existing combustion process to achieve thermal management, eliminating the need for additional costly components

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the geometric parameters of the prechamber nozzle openings, specifically the angle of the openings relative to the cylinder axis. By optimizing these parameters, the system achieves favorable flow distribution that reduces thermal loads on cylinder components, providing a cost-effective solution that relies on geometric optimization rather than material or system upgrades

Inventive Principle:
Principle #35Parameter changes

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

Reduces thermal stress on the cylinder liner and head, allowing for increased engine power without additional cooling systems or material changes.

Implementation Method 1

the nozzle openings of the prechamber are configured to guide the flow from the prechamber into the main combustion chamber on the exhaust valve side of the cylinder more towards the piston than on the intake valve side of the cylinder

Methodology Applied
Scientific EffectFluid flow guidance:

Implementation Method 2

utilizing angled and chamfered or rounded edges, and varying cross-sectional areas to distribute thermal loads more evenly

Methodology Applied
Scientific EffectThermal load distribution:

Data Source

PatentEP4295021B1Prechamber arrangement, cylinder head and piston engine
Publication Date: 2025.07.23 WARTSILA FINLAND OY
  • EP4295021B1 patent drawingFigure 1
  • EP4295021B1 patent drawingFigure 2~5

AI summary

The prechamber arrangement for a cylinder (1) of a piston engine comprises a prechamber (4) that is provided with at least one intake valve side nozzle opening (6a) that is configured to discharge fluids from the prechamber (4) into a main combustion chamber (7) on an intake valve side (14) of the cylinder (1), and at least one exhaust valve side nozzle opening (6b) that is configured to discharge fluids from the prechamber (4) into the main combustion chamber (7) on the exhaust valve side (15) of the cylinder (1). The nozzle openings (6a, 6b) of the prechamber (4) are configured to guide the flow from the prechamber (4) into the main combustion chamber (7) on the exhaust valve side (15) of the cylinder (1) more towards the piston (2) than on the intake valve side (14) of the cylinder (1).