Dual Fuel Injector Charge Segmentation for Minimal Fuel Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dual fuel injection systems for internal combustion engines face challenges in effectively forming and injecting a segmented fuel charge with minimal mixing of pilot and primary fuels, particularly when using liquid pilot and primary fuels.
Innovation Solution
A dual fuel injector system with a dual fuel injector housing, including a plunger cavity, spill valve, and admission valve, forms a segmented fuel charge by admitting liquid pilot fuel into a pilot fuel passage, displacing liquid primary fuel with pilot fuel, and increasing pressure to inject the segmented fuel charge into the combustion cylinder based on compression-ignition of the pilot fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single injector is used to inject both diesel fuel and alternative fuel, then device complexity is reduced, but manufacturing precision and fuel charge segmentation become difficult to achieve
Solution Approach 1:
The fuel charge is segmented into distinct regions within the injector: a first fuel charge of alternative fuel and a second fuel charge of diesel fuel. The injector housing contains separate passages and outlets for each fuel type, ensuring they remain segregated until injection. This segmentation allows precise control over fuel delivery while maintaining a single injector structure.
Solution Approach 2:
The injector design nests multiple fuel delivery systems within a single housing structure. The alternative fuel passage and diesel fuel passage are integrated into the same injector body, with the pilot fuel outlet positioned to deliver fuel at the tip of the diesel fuel plume. This nesting achieves complex multi-fuel functionality without requiring multiple separate injectors.
2Reliability
If pilot fuel is injected to ignite primary fuel, then ignition reliability is improved, but fuel mixing between pilot and primary fuel increases
Solution Approach 1:
The injector provides different local fuel delivery characteristics: alternative fuel is delivered at the tip region through a dedicated outlet, while diesel fuel is delivered in a broader plume. This local differentiation ensures the pilot fuel (alternative fuel) is positioned exactly where needed for ignition without excessive mixing with the primary fuel (diesel fuel), maintaining distinct combustion zones.
Solution Approach 2:
The fuel injection system utilizes spatial dimensionality to separate fuel paths. The alternative fuel passage and diesel fuel passage are arranged in different spatial locations within the injector housing, with outlets positioned at different depths and angles. This three-dimensional arrangement minimizes fuel mixing while ensuring proper ignition sequence.
3Use of energy by moving object
If compression-ignition is used for primary fuel, then energy efficiency is improved, but control precision over combustion timing is reduced
Solution Approach 1:
The system performs preliminary action by injecting the alternative fuel (pilot fuel) first, which then ignites via compression heating. This pre-injected pilot fuel creates controlled ignition points that subsequently ignite the diesel fuel plume. The timing and quantity of pilot fuel injection can be precisely controlled to regulate the overall combustion timing and duration, combining the efficiency of compression-ignition with improved timing control.
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 system efficiently forms and injects a segmented fuel charge with minimal mixing, enabling effective ignition and diffusion burning of the primary fuel, suitable for both legacy diesel engines and new engine systems with reduced modifications.
Implementation Method 1
a liquid primary fuel ignitable in an engine combustion cylinder based on compression-ignition of the liquid pilot fuel
Implementation Method 2
a plunger, a plunger cavity formed in part by the plunger and fluidly connected to the primary fuel passage
Implementation Method 3
an injector housing having formed therein a plurality of nozzle outlets... to inject the segmented fuel charge into a combustion cylinder
Data Source
AI summary
A dual fuel system for an internal combustion engine includes a first fuel supply of a liquid pilot fuel, a primary fuel supply of a liquid primary fuel, and a dual fuel injector. The dual fuel injector includes a spill valve fluidly connected with a plunger cavity and movable to control a start of injection and an end of injection, and an admission valve. The admission valve is movable to admit a pilot fuel into the fuel injector, such that the pilot fuel is conveyed through an outlet check to form, within a primary fuel passage fluidly connected to the plunger cavity, a segmented fuel charge of leading pilot fuel and trailing primary fuel by displacing some of the primary fuel. The liquid pilot fuel may be a higher cetane/lower octane liquid fuel, and the primary fuel may be a lower cetane/higher octane liquid fuel.