Dual Fuel Injector Nozzle Purging for Mode Transition
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Solution Overview
Problem
Dual fuel common rail systems face challenges in transitioning from diesel-only operation back to dual fuel mode, particularly due to liquid fuel accumulation in gaseous nozzle chambers during a limp home mode, which can disrupt engine fueling logic and cause speed surges.
Innovation Solution
A method and system where liquid fuel is accumulated in gaseous nozzle chambers during a limp home mode and then displaced by gaseous fuel when transitioning to regular mode, with an electronic controller managing nozzle outlets to ensure proper fuel injection ratios and prevent leakage, using a dual fuel common rail system with separate fuel injectors and pressure control devices for each fuel type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system operates in limp home mode with liquid fuel injection only, then the system can continue operation during gaseous fuel supply failure, but liquid fuel accumulates in the gaseous nozzle chamber causing fueling logic disruption and speed surges
Solution Approach 1:
The patent converts the harmful effect of liquid fuel accumulation in the gaseous nozzle chamber into a beneficial transition mechanism. During mode switching from limp home to regular operation, the accumulated liquid fuel is intentionally purged through the gaseous injector, preventing fueling logic disruption and speed surges. The accumulation that would normally cause harm becomes a controlled transition phase that ensures smooth mode switching.
2Device complexity
If both fuels are injected from a single fuel injector, then the system structure is simplified, but the transition between diesel only and dual fuel modes becomes complex and problematic
Solution Approach 1:
The patent segments the single fuel injector into two distinct nozzle outlet sets within the same injector body: a first nozzle outlet set for liquid fuel injection and a second nozzle outlet set for gaseous fuel injection. This segmentation allows independent control of each fuel type while maintaining a unified injector structure, thereby simplifying hardware complexity while enabling smooth mode transitions between diesel-only and dual-fuel operation.
3Adaptability or versatility
If liquid fuel is accumulated in gaseous nozzle chamber during limp home mode, then the system can switch to dual fuel operation, but the accumulated liquid fuel must be purged to prevent engine speed surges
Solution Approach 1:
The patent implements preliminary purging action before transitioning to dual fuel operation. The electronic controller detects when the system is switching from limp home mode and actively purges the accumulated liquid fuel from the gaseous nozzle chamber through controlled injection events. This preliminary action removes the accumulated fuel that would otherwise cause engine speed surges, ensuring stable operation during and after the mode transition.
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
Enables seamless transition from limp home mode to regular mode by purging accumulated liquid fuel and adjusting fuel injection ratios, maintaining engine power and stability, and preventing gaseous fuel leakage into the liquid fuel system, ensuring efficient operation with both diesel and natural gas fuels.
Implementation Method 1
Liquid fuel is accumulated in a gaseous nozzle chamber of each fuel injector of the dual fuel system over a plurality of engine cycles when operating in the limp home mode
Implementation Method 2
The accumulated liquid fuel is displaced with gaseous fuel when transitioning from the limp home mode to the regular mode
Implementation Method 3
Liquid fuel is injected from a first nozzle outlet set and gaseous fuel injected from a second nozzle outlet set into an engine cylinder when operating the dual fuel system in the regular mode
Data Source
AI summary
A dual fuel common rail system may be operated in a regular mode in which a relatively large charge of gaseous fuel is ignited by compression igniting a relatively small injection quantity of liquid diesel fuel. The dual fuel system may be operated in a single fuel limp home mode in which liquid diesel fuel is injected at higher pressures. When transitioning from the single fuel limp home mode to the dual fuel regular mode, accumulated leaked liquid fuel in the gaseous nozzle chamber of each fuel injector is purged and burned in the respective engine cylinder.