Engine Mixing Structure for Soot Reduction
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Solution Overview
Problem
Compression ignition engines face challenges in reducing soot formation due to sub-optimal fuel-and-air mix ratios and high ignition delays, which degrade engine performance and violate emission regulations.
Innovation Solution
The introduction of a mixing structure that controls the ignition delay by cooling the hot gases entrained in the fuel stream, allowing for a leaner fuel-and-air mixture to form before combustion, using channels and conduits to direct the fuel-and-gas mixture into the combustion chamber, thereby reducing soot production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fuel is directly injected into compressed hot gases without a mixing structure, then the injection system is simple, but the fuel-and-air mix ratio is sub-optimal and soot is produced
Solution Approach 1:
A mixing structure is introduced as an intermediary component between the fuel injector and the combustion chamber. This structure includes a body with a central volume that receives fuel streams, gas channels that deliver gas streams, and mixture conduits that transport the mixed fuel-and-gas mixture. The mixing structure acts as a mediator to achieve optimal mixing ratios and reduce soot production while maintaining system simplicity
2Loss of time
If the temperature of entrained gases is high, then ignition delay is reduced, but the fuel-and-air mix ratio becomes sub-optimal and soot is produced
Solution Approach 1:
The mixing structure utilizes the kinetic energy of the injected fuel stream itself to draw in and mix with the gas channels' supply. The fuel stream's own momentum creates the mixing action through entrainment, eliminating the need for separate mixing mechanisms. This self-service approach achieves optimal mixing ratios while controlling ignition timing
3Object-generated harmful factors
If a mixing structure is introduced to control ignition delay and improve mix ratio, then soot production is reduced, but the device complexity increases
Solution Approach 1:
The mixing structure combines multiple functions into a single integrated body: fuel reception in the central volume, gas channel integration for gas delivery, mixture conduit formation for transport, and mixing chamber provision. By merging these functions into one component, the structure reduces overall system complexity while achieving soot reduction through controlled mixing
4Productivity
If fuel is injected without pre-mixing, then the injection process is simple and fast, but the fuel-and-air mix ratio is sub-optimal before ignition
Solution Approach 1:
The mixing structure performs preliminary mixing action within its central volume before the fuel-and-gas mixture enters the combustion chamber. Gas channels deliver gas streams that mix with the injected fuel in the central volume, creating an optimal mix ratio in advance. This preliminary action ensures stable composition upon combustion while maintaining rapid injection timing
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 mixing structure effectively delays ignition and reduces soot generation by ensuring a more homogeneous fuel-and-air mixture, improving engine performance and compliance with emission standards.
Implementation Method 1
one or more streams of the fuel mixes with the one or more streams of gas to form a fuel-and-gas mixture
Implementation Method 2
controls the ignition delay by cooling the hot gases entrained in the fuel stream
Data Source
AI summary
A fuel and gas mixing structure for an engine is provided. This mixing structure includes a body configured to be positioned between a fuel injector and a cylinder of an engine. The body defines an interior volume that is configured to receive gas from outside the body and to receive one or more streams of fuel from the fuel injector in the interior volume. The body also defines one or more mixture conduits configured to conduct plumes of the fuel and gas, while mixing, from the interior volume to one or more exit ports and therethrough to the cylinder.