Fuel Distributor Partition Wall Surface Area

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Solution Overview

Problem

Existing fuel supply devices for internal combustion engines, particularly two-stroke engines, face challenges in preventing vapor bubble formation during operation, which impairs fuel metering, and require effective cooling to maintain performance.

Innovation Solution

The fuel supply device incorporates elements to increase the surface area within the mixture channel, enhancing evaporation and cooling through a partition wall section that is either formed in one piece with the base body or connected via a press connection, allowing for improved heat conduction and effective cooling, while maintaining the separation of air and mixture ducts to prevent excessive leaning at low speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the partition wall section is made with a straight, planar design, then the device complexity is low and manufacturing is simple, but the surface area for evaporation and cooling is insufficient

Engineering Contradiction:
Improvecooling effectVSAvoidpartition wall structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The partition wall section is transformed from a straight, planar design to a three-dimensional structure with protrusions and recesses. This dimensional change increases the surface area available for fuel evaporation and heat exchange with the intake air, thereby improving the cooling effect without requiring additional separate components

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

Solution Approach 2:

The partition wall section incorporates a structured surface with protrusions and recesses that creates a porous-like geometry. This increased surface area allows greater contact between the fuel spray and the partition wall, enhancing evaporation and cooling efficiency

Inventive Principle:
Principle #31Porous materials

2Temperature

If the partition wall section is formed integrally with the base body, then heat conduction and cooling efficiency are improved, but manufacturing precision and production complexity increase

Engineering Contradiction:
Improveheat conduction efficiencyVSAvoidintegral forming accuracy
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The partition wall section is formed integrally with the base body as a single component. This merging of parts ensures excellent thermal contact and heat conduction between the fuel injection area and the intake manifold, maximizing cooling efficiency while eliminating the need for separate mounting operations

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integral design allows for optimization of thermal parameters by directly coupling the partition wall with the base body, ensuring efficient heat transfer pathways from the fuel spray zone through the partition wall to the intake air flow

Inventive Principle:
Principle #35Parameter changes

3Temperature

If the surface area of the partition wall section is increased, then evaporation and cooling are enhanced, but the circumferential length and cross-sectional area increase

Engineering Contradiction:
Improvevaporization efficiencyVSAvoidcross-sectional area
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

Instead of increasing surface area by expanding the cross-sectional area of the partition wall, the invention uses protrusions and recesses that extend into the third dimension. This allows significant surface area increase for evaporation while maintaining a compact cross-sectional profile that does not obstruct the intake flow path

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

Solution Approach 2:

The protrusions and recesses on the partition wall section create curved surfaces that increase the effective surface area for fuel contact and evaporation. The curved geometry provides greater surface area compared to flat surfaces of the same footprint, enhancing cooling without increasing the overall cross-sectional dimensions

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Reliability

If the throttle element rests against the partition section in the fully open position, then the separation of air and mixture channels is achieved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvechannel separationVSAvoidthrottle element positioning
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The partition wall section is designed with specific local geometries including protrusions and recesses that create defined contact points with the throttle element. This localized structural design ensures reliable channel separation at the critical interface between the air and mixture channels, while the robust geometric features provide tolerance compensation

Inventive Principle:
Principle #3Local quality

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 design achieves enhanced cooling and evaporation, preventing vapor bubble formation and ensuring accurate fuel metering, while maintaining efficient air throughput and low emissions by effectively transferring heat and increasing the surface area for improved evaporation and heat dissipation.

Implementation Method 1

The invention therefore provides for increasing the surface area within the mixture channel by means of at least one surface area-enlarging element, thereby achieving a higher degree of vaporization in the intake manifold section

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

The enthalpy of vaporization required to vaporize the fuel supplied to the intake manifold significantly contributes to the cooling of the fuel supply system

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP3943741B1Fuel distributor
Publication Date: 2023.10.25 ANDREAS STIHL AG & CO KG
  • EP3943741B1 patent drawingFigure 1
  • EP3943741B1 patent drawingFigure 2~3
  • EP3943741B1 patent drawingFigure 4~5

AI summary

A fuel supply device (20) has a base body (21) in which an intake channel section (22) is formed. At least one adjustable throttle element (24) is provided for controlling the free flow cross-section of the intake channel section (22). At least one fuel inlet (23) opens into the intake channel section (22). A partition section (26) is arranged upstream of the throttle element (24) in the intake channel section (22). When the throttle element (24) is fully open, the partition section (26) and the throttle element (24) divide the intake channel section (22) upstream of the throttle element (24) into a mixture channel (18), into which the fuel inlet (23) supplies fuel, and an air channel (19). To improve the cooling of the fuel supply device (20), the partition section (26) has at least one element for increasing the surface area within the mixture channel (18).