Dual Fuel Engine Combustion Control via Segmented Pilot Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dual fuel engines face challenges in controlling combustion timing and stability when switching between gaseous fuel spark-ignited and liquid pilot-ignited modes, particularly due to variations in fuel quality and emissions issues.
Innovation Solution
A method and system for controlling a dual fuel engine by producing a phasing signal indicative of combustion phasing in the gaseous fuel spark-ignited mode, adjusting phasing control parameters to limit errors, and switching to a dual fuel liquid pilot-ignited mode through direct injection of early and second pilot shots of liquid fuel, with or without a spark, to ignite gaseous fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If gaseous fuel is used in spark-ignited mode, then emissions properties are improved, but combustion stability deteriorates
Solution Approach 1:
The fuel injection is segmented into multiple shots (early pilot shot and main injection) rather than a single injection. The early pilot shot creates a premixed charge that ignites first, providing stable combustion initiation, while the main gaseous fuel charge follows. This segmentation allows the engine to maintain emissions benefits of gaseous fuel while achieving combustion stability through the staged injection approach.
Solution Approach 2:
An early pilot shot of liquid fuel is injected and vaporized before the main gaseous fuel charge to create a premixed charge that ignites first. This preliminary action establishes stable combustion conditions that enable reliable ignition and combustion of the subsequent gaseous fuel, solving the combustion stability issue while maintaining the emissions advantages of gaseous fuel operation.
2Adaptability or versatility
If multiple operating modes are implemented, then fuel flexibility is improved, but device complexity increases
Solution Approach 1:
The fuel injection system is designed to universally handle both liquid fuel and gaseous fuel types using the same injection hardware. The system can operate in multiple modes (liquid-only compression ignition, gaseous fuel spark-ignition, and dual fuel modes) without requiring separate injection systems, thereby achieving fuel flexibility while minimizing the increase in device complexity through a unified multi-functional injection approach.
3Productivity
If combustion timing is controlled in premixed charge mode, then combustion efficiency is improved, but measurement precision deteriorates
Solution Approach 1:
A premixed charge indicator is introduced as an intermediary signal to detect and indicate the phasing of the premixed charge combustion. This indicator provides a measurable reference point that allows precise measurement of combustion timing and phasing in premixed charge mode, thereby resolving the measurement precision issue while maintaining the combustion efficiency benefits of premixed charge operation.
Data Source
AI summary
A method of controlling a dual fuel engine system includes adjusting a phasing control parameter such as air-fuel ratio (AFR), based on a phasing signal to limit an error in a phasing of combustion of gaseous fuel. The cylinder is switched to a dual fuel liquid pilot-ignited mode by commanding direct injection of an early pilot shot of liquid fuel, based on the adjustment to the phasing control parameter, and production of a spark to ignite gaseous fuel in the cylinder. Switching the cylinder to the dual fuel liquid pilot-ignited mode is completed by commanding direct injection of an early pilot shot and a second pilot shot of liquid fuel to ignite gaseous fuel in response to combustion of the early and second pilot shots in the cylinder.