Dual Fuel Injector Segmentation for Compression-Ignition Reliability
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Solution Overview
Problem
Existing dual fuel injection systems for internal combustion engines face challenges in effectively combining a liquid pilot fuel with a liquid primary fuel, leading to inefficient ignition and mixing, particularly in compression-ignition engines.
Innovation Solution
A dual fuel system with a dual fuel injector that includes a segmented fuel charge formation through a pilot fuel passage and primary fuel passage, using a plunger and spill valve to create a leading pilot fuel and trailing primary fuel charge, which is compression-ignited for efficient ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single injector is used to inject both diesel fuel and alternative fuel, then the device complexity is reduced, but the ignition reliability and fuel mixing efficiency deteriorate
Solution Approach 1:
The fuel charge is segmented into distinct zones within the injection system. The pilot fuel is injected first to create a segmented fuel charge structure, with pilot fuel at the tip and alternative fuel in the bulk, ensuring reliable compression ignition of the pilot fuel followed by alternative fuel combustion
Solution Approach 2:
The pilot fuel is injected and ignited in advance before the main alternative fuel charge. This preliminary action of compressing and igniting the pilot fuel creates the conditions necessary for subsequent alternative fuel ignition, solving the reliability issue while maintaining a single injector structure
2Reliability
If pilot fuel is injected to ignite primary fuel, then the ignition capability is improved, but the fuel mixing efficiency deteriorates
Solution Approach 1:
The fuel injection is segmented into two distinct phases: pilot fuel injection followed by alternative fuel injection. This segmentation creates a layered fuel charge structure that limits unwanted mixing while ensuring proper ignition sequencing, improving both ignition capability and mixing efficiency
Solution Approach 2:
Different regions of the fuel charge have different properties: the pilot fuel region is designed for easy compression ignition, while the alternative fuel region maintains its distinct composition for controlled combustion. This local differentiation ensures proper ignition without excessive mixing
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 ensures efficient ignition and limited mixing of fuels, enhancing engine performance by utilizing higher cetane pilot fuel to ignite lower cetane primary fuel, suitable for both legacy diesel engines and new systems with minimal modifications.
Implementation Method 1
A plunger of the dual fuel injector is movable in the plunger cavity from a retracted position to an advanced position, to increase a pressure of a primary fuel in the plunger cavity to an injection pressure
Implementation Method 2
igniting, within the combustion cylinder, the liquid primary fuel of the segmented fuel charge based on compression-ignition of the liquid pilot fuel of the segmented fuel charge
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.