Hemispherical Combustion Chamber Roof Curvature

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Solution Overview

Problem

Internal combustion engines face challenges in achieving optimal combustion efficiency due to suboptimal combustion chamber geometries, which affect turbulent kinetic energy and burning rates, leading to incomplete fuel combustion and reduced thermodynamic efficiency.

Innovation Solution

The design features a combustion chamber with a hemispherical geometry, characterized by curved cylinder head sections and a recessed piston, creating an edge-free active area that enhances tumble flow and maintains turbulent kinetic energy, along with strategically placed valve seats and a masking to optimize flame propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional combustion chamber geometries are used, then manufacturing is simpler, but turbulent kinetic energy and combustion efficiency deteriorate

Engineering Contradiction:
Improvecombustion efficiencyVSAvoidcombustion chamber geometry complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The combustion chamber roof is designed with a hemispherical geometry featuring curved cylinder head sections that create an edge-free active area. This spherical curvature optimizes flow behavior and generates turbulent kinetic energy during the intake process, significantly improving combustion efficiency compared to conventional flat or angular designs.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The combustion chamber roof incorporates localized features including squish areas positioned at specific locations, curved cylinder head sections between valve seats, and an edge-free active area. These localized geometric modifications create optimal flow patterns and turbulence in critical regions without requiring complete redesign of the entire combustion chamber.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If curved cylinder head sections are added to create hemispherical geometry, then flow behavior and turbulent kinetic energy improve, but manufacturing complexity increases

Engineering Contradiction:
Improvecombustion chamber geometry precisionVSAvoidcylinder head manufacturing ease
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The curved cylinder head sections are designed to form a hemispherical combustion chamber roof geometry. This curvature is implemented through precision machining or casting processes that can reproduce the spherical shape consistently, achieving high geometric precision while managing manufacturing complexity through standardized production methods.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Productivity

If squish areas are provided only on two opposing edge sections, then tumble flow is optimized, but valve seat area is reduced

Engineering Contradiction:
Improvecombustion efficiencyVSAvoidvalve seat area
Core Design Contradiction:
ProductivityVSArea of stationary object

Solution Approach 1:

Squish areas are strategically positioned only on two opposing edge sections of the combustion chamber roof, creating localized flow control zones that generate tumble motion without interfering with valve seat functionality. This localized approach optimizes combustion efficiency while preserving adequate valve seat area for proper valve operation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The combustion chamber roof is segmented into distinct functional zones: curved cylinder head sections for overall hemispherical geometry, localized squish areas at opposing edges for tumble flow generation, and valve seat regions for valve operation. This segmentation allows each zone to perform its specific function optimally without compromising others.

Inventive Principle:
Principle #1Segmentation

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 results in improved burning rates, complete fuel combustion, and enhanced thermodynamic efficiency with reduced fuel consumption, ensuring that the internal combustion engine operates with high efficiency and minimal unburned fuel.

Implementation Method 1

The turbulent kinetic energy results from the flow behavior of the mixture and is significantly influenced by the geometry of the combustion chamber

Methodology Applied
Scientific EffectTurbulence: Turbulence

Implementation Method 2

This results in a combustion chamber shape that is especially favorable with regard to the combustion process, namely a spherical shape. The two curved cylinder head sections are thus both located between the intake and exhaust sides of the cylinder head, so that they both contribute approximately equally to improving the flow characteristics.

Methodology Applied
Scientific EffectTumble flow:

Implementation Method 3

As the piston moves upwards, particularly towards the cylinder head, the mixture in the combustion chamber is compressed

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 4

When the piston reaches top dead center, a spark plug located in the cylinder head ignites the mixture by creating an initial flame

Methodology Applied
Scientific EffectElectrical discharge ignition: Electric Spark

Implementation Method 5

a mixture consisting of at least air and fuel is burned

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3688293B1Combustion engine
Publication Date: 2025.01.15 BAYERISCHE MOTOREN WERKE AG
  • EP3688293B1 patent drawingFigure 1
  • EP3688293B1 patent drawingFigure 2
  • EP3688293B1 patent drawingFigure 3

AI summary

Disclosed is an internal combustion engine (10) for a motor vehicle, having at least one cylinder (12), a cylinder head (14) and a piston (16) which is movably mounted in the cylinder (12) and has a combustion chamber side (18) which delimits a combustion chamber (20) with the cylinder head (14) and the cylinder (12), wherein the cylinder head (14) has a combustion chamber roof (21), in which at least two valve seats (22, 24) for at least one inlet valve (26) and at least one outlet valve (28) are provided, and wherein the combustion chamber roof (21) has at least one arched cylinder head section (46, 47) which is arranged between the at least two valve seats (22, 24) and points away from the combustion chamber (20).